Mixing AGM and wet cells...

[eddiec]

I know this has been raised before a few times, but just wanting to clarify before I splash out the big bucks...

Picked up an SC80 off drivesafe to take care of the new battery system a few weeks back. Am now looking at batteries, and the current (ha!) plan is to get a couple of AGM deep cycle batteries. One 85a/H to sit under the seat box with the existing starter battery (wet cell) which will keep the fridge running (fridge stays in the 'fender), and one 40a/H to sit somewhere else inside the car which can be removed and taken to the tent, etc...

Now - is there a problem with using an AGM deep cycle and wet cell starter together to run the fridge, even with the SC80 sitting in between them?

And is it worth splurging on the AGMs really? I know the one inside the car should be an AGM for fume reasons, but is it really worth the price difference otherwise? Experiences/opinions? Ta muchly....

[scanfor]

Eddie

I'm happy to be proven wrong here, but I don't see the problem with gassing of a wet cell inside the vehicle.

A properly managed wet cell battery (i.e. being charged within its specified limits and not being boiled) doesn't really gas very much at all. The regulator on the alternator circuit stops the battery from boiling.

I have one inside a battery box in the rear of my 110 wagon, and I'm yet to smell it gassing. It gets charge from both the alternator and a solar panel and runs a 55 litre fridge all day every day.

AGMs are hugely expensive when compared to the wet cell batteries. Maybe there's an advantage that I have yet to discover.

Regards
Scott

[slug_burner]

I don't know that you would get to smell gas from a battery, Hydrogen gas in its pure form is odourless. It could be that some other element is involved but I am no chemist and high school chemistry was a while ago now. Problem with hydrongen gas venting is that it is explosive and in an area where it is not well ventilated it can build up.

From Battery Tutorial | Batterystuff.com (http://www.batterystuff.com/tutorial_battery.html)


"Wet Cell (flooded), Gel Cell, and Absorbed Glass Mat (AGM) are various versions of the lead acid battery. The wet cell comes in 2 styles; serviceable, and maintenance free. Both are filled with electrolyte and I prefer one that I can add water to and check the specific gravity of the electrolyte with a hydrometer. The Gel Cell and the AGM batteries are specialty batteries that typically cost twice as much as a premium wet cell. However they store very well and do not tend to sulfate or degrade as easily or as easily as wet cell. There is little chance of a hydrogen gas explosion or corrosion when using these batteries; these are the safest lead acid batteries you can use. Gel Cell and some AGM batteries may require a special charging rate. I personally feel that careful consideration should be given to the AGM battery technology for applications such as Marine, RV, Solar, Audio, Power Sports and Stand-By Power just to name a few. If you don't use or operate your equipment daily; this can lead premature battery failure; or depend on top-notch battery performance then spend the extra money. Gel Cell batteries still are being sold but the AGM batteries are replacing them in most applications. There is a little confusion about AGM batteries because different manufactures call them different names; some of the popular ones are sealed regulated valve, dry cell, non spillable, and sealed lead acid batteries. In most cases AGM batteries will give greater life span and greater cycle life than a wet cell battery.
SPECIAL NOTE about Gel Batteries: It is very common for individuals to use the term GEL CELL when referring to sealed, maintenance free batteries, much like one would use Kleenex when referring to facial tissue or "Xerox machine" when referring to a copy machine. Be very careful when specifying a battery charger, many times we are told by customer they are requiring a charger for a Gel Cell battery and in fact the battery is not a Gel Cell."

AGM sprial wound batteries like the yellow tops are tightly packed and resist vibration better that your standard plate battery suspended in electrolite.

[JDNSW]

Eddie

I'm happy to be proven wrong here, but I don't see the problem with gassing of a wet cell inside the vehicle.

A properly managed wet cell battery (i.e. being charged within its specified limits and not being boiled) doesn't really gas very much at all. The regulator on the alternator circuit stops the battery from boiling.

I have one inside a battery box in the rear of my 110 wagon, and I'm yet to smell it gassing. It gets charge from both the alternator and a solar panel and runs a 55 litre fridge all day every day.

AGMs are hugely expensive when compared to the wet cell batteries. Maybe there's an advantage that I have yet to discover.

Regards
Scott

The problem with a wet cell battery inside the vehicle is not the hydrogen - as you point out, unless there is a regulator failure (and these DO happen), there will be little gassing, although the amount depends on how much hardening metal is alloyed into the plates (most modern batteries have very little).

There are two problems - the first is that the small amount of gas that is given off is carrying an aerosol of sulphuric acid (which is what you smell) which even in very small concentrations is very corrosive. The second problem is that in case of an accident, especially a rollover, the vented battery will spill acid into the interior of the car.

John

[drivesafe]

I'm happy to be proven wrong here, but I don't see the problem with gassing of a wet cell inside the vehicle.

There is no real reason for not using flooded wet cell batteries inside a vehicle and in fact is still a common practice used in many of the vehicles imported from Europe.

VW vans and Fiat small trucks, used for camper vans and small motor homes come with wet cell cranking batteries located inside the cab, usually under or just behind the seats.

The irony is that the house batteries, which are most likely to be AGMs, are usually mounted in an externally vented battery box elsewhere in the the vehicle.

[scanfor]

JDNSW

I agree with you about the spillage in the event of a rollover.

My judgement on the potential for problems caused by the corrosive nature of the gassing is based solely upon the premise that the battery box under the passenger seat is full of relays and electrical contacts and none of these seems to have any corrosion evident after 10 years of being located in the same compartment as the main wet cell starting battery.

I'm not sure how much gas would be emitted by either the start battery or the deep-cycle battery when it is recovering from discharge. It would be interesting to know.


Regards
Scott

[eddiec]

Thanks guys - so gassing isn't a huge issue (I assume with how drafty the Defender is anyway, gassing wouldn't be too much of a problem regardless! The entire car's vented to the outside :) )

But the other issues:

- are AGMs worth the difference, if we ignore the gassing? I've read things about quicker charging and longer life span, greater ability to discharge deeper, etc. which might make it worth the extra money...
- and does mixing an AGM with a wet cell battery when using a smart device like the SC80 work ok?

Cheers

Eddie.

[drivesafe]

Hi eddiec, first off, contrary to all the myths, there is no problems with mixing battery types.

Next, personally, I think good old fashion Flooded Wet Cell batteries are still the best choice in “MOST” cases.

There are some circumstances where AGMs are the better choice but this comes down more to how you are going to store them when not in use.

If the auxiliary battery is going to be permanently mounted the your vehicle then there is no real advantage to forking out the extra expense for an AGM as a wet cell will be well maintained and as such should last for years.

[Disco95]

Hi eddiec, first off, contrary to all the myths, there is no problems with mixing battery types.

Next, personally, I think good old fashion Flooded Wet Cell batteries are still the best choice in “MOST” cases.

There are some circumstances where AGMs are the better choice but this comes down more to how you are going to store them when not in use.

If the auxiliary battery is going to be permanently mounted the your vehicle then there is no real advantage to forking out the extra expense for an AGM as a wet cell will be well maintained and as such should last for years.


Hi drivesafe, are you able to shed any light on the issues I've been having in this thread?
http://www.aulro.com/afvb/technical-chatter/63486-battery-question.html

[harry]

did i miss something here with the worry about having a 'normal' wet cell battery in the car?
eddiec
didn't your car come with a lead acid wet cell battery under the seat from the factory?
as for mixing the two, they both do the same job, store and supply electricity - so what is the problem?

[eddiec]

did i miss something here with the worry about having a 'normal' wet cell battery in the car?
eddiec
didn't your car come with a lead acid wet cell battery under the seat from the factory?
as for mixing the two, they both do the same job, store and supply electricity - so what is the problem?

the gassing wasn't really the biggest issue, as i'm aware there's a wet cell under the seat already.

there has been some discussion in a range of places about charging wet cells and AGMs in parallel, and potential for damage. Wasn't sure if it was just scaremongering.... i'm sure others could explain the details better than me, but there were some issues about charging and discharging rates and capacities, etc. etc... all too technical for me.

the other issues around AGMs which tempt me to get them aren't just about no gassing, but more around decreased charge times and the potential for them to be discharged more deeply. Things which both might be an advantage for the work we do with them. If it was just the gassing that was the only issue, it would be a no-brainer...

[knp]

We've been running a 92Ah AGM battery in the rear LHS of storage bin.
It is connected to the main battery via one of those smart relays that connect it once the main battery has reached a certain voltage. We got this from battery world. The wiring runs from the +ve main battery terminal via fuse in engine bay through the firewall just above the accelerator pedal (there's a large rubber grommet with a thick loom running through it which I used) then it runs up the driver's side A pillar, across the roof lining, down the C pillar and into the rear bin (at the time I figured it was easier this way than under the carpet). The relay is mounted inside the bin just above the battery.

The cable was that nice thick oxygen free copper high current stuff from Jaycar (4AWG WH-3064) and the relay kit had all the rest of the connectors required. Only ran the positive cable and using the vehicle chassis as the earth.

This all seems to work great except that the 2nd battery is now stuffed. Turns out it was stuffed before I put it in but I didn't know it. It works well enough to keep the fridge (Engel 40) running for a few hours during a picnic or something but not enough for overnight.

Anyway the point is the main cranking battery is fine. It gets enough charge even with the 2nd battery requiring more of a top up than usual. The relay disconnects them both when ignition is off so this also stops the 2nd battery from flattening the main one.

I'm not sure I'd put a flooded cell in the cabin. If it started to produce too much gas for what ever reason then you'd initially get a few fumes and eventually some serious rust neither of which can be real good for anything. I also had a cranking battery explode in the engine bay of my old XP a few yearsa back. It was not a faulty alternator and the battery was brand new but was caused by a spark that ignited some gas. I sounded like a back fire. I'd hate for that to happen inside or under my seat not to mention having to wash out the acid afterwards.

HTH cheers
Peter

[slug_burner]

I also had a cranking battery explode in the engine bay of my old XP a few yearsa back. It was not a faulty alternator and the battery was brand new but was caused by a spark that ignited some gas. I sounded like a back fire. I'd hate for that to happen inside or under my seat not to mention having to wash out the acid afterwards.

HTH cheers
Peter

To say nothing of having to wash out your pants:eek:

[knp]

To say nothing of having to wash out your pants:eek:
Yup!
:):):):):):D:D:D

[p38arover]

I'm running a calcium wet cell under the bonnet as my starter battery and an AGM (for the fridge, etc.) in the rear underfloor wheel well. It is charged via an SC40.

I picked the AGM as the wheel well is reasonably well sealed (well, not leaky like a Defender!) and it also contains my LPG tank. The AGMs won't spill acid if they fall over or, I believe, if the case splits).

[Remy]

1. Gas is typically only produced in significant quantites if the battery is overcharged hence why the caps are taken off a normal Pb-acid battery when charging and why charging should occur in a well ventilated area. I agree the biggest danger with them is acid leakage from a roll over or excessive bumping. Normal alternator charging won't overcharge your battery.

2. Both normal car batteries and the deep cycle are Pb-acid but the deep cycle are sealed.

3. They can be charged together and run together. Your alternator won't charge the deep cycle to it's capacity as the alternator is typically 80-90% efficient. Good to give your deep cycle a top up with a balance charger every now and then.

4. The batteries are designed differently. Normal car battery designed to give a large current over a short period (hence thin plates more surface area). A deep cycle is designed to give a steady current over a longer time (thicker plates). That is why deep cycle are recommended for applications such as fridge and lights in camping situations where current draw is low but sustained for longer periods. Car batteries will work but won't like being discharged too much (say 60-80% might be ok) and recharged.

5. A deep cycle can be discharged over several hundred discharge/recharge cycles. A typical car battery is not designed to be totally discharged and if it does to many times the thin plates weld together or fail.

6. Deep cycle can be discharged almost completely but it isn't good for them. Typically if you want to maintain a long life then discharge them to around 30% and recharge them to 100% (i.e. special charger when you return from hols) to top up the alternator which only gets them to 80-90%

Hope that helps.

[drivesafe]

Hi Remy, the only reason an alternator doesn’t fully charge any automotive battery is because the alternator has not been given the chance too and not because it can’t.

As long as the alternator has an output voltage of 13.8 or higher, there is no reason why an alternator, given a reasonable time, can not fully charge any 12 volt battery.

This myth that states an alternator can only charge the vehicle’s battery(s) to around 70 to 80% is based on what I call “Shopping Trolley Syndrome”, where the vehicle is only ever driven for short periods of time and as such, the alternator is never given enough time to fully charge the cranking battery.

This is not the same as the alternator can not fully charge the battery, when in actual fact, the alternator in any vehicle can not only fully charge the battery, when there are two, three or even four batteries, an alternator can charge them quicker than any of the devices being pushed these days, with claims they are the only way to get your batteries fully charged.

This is no more than sales hype being fed to unsuspecting people who have no real idea of how batteries and alternator function.

Cheers.

[Remy]

Hi drivesafe,

Completely agree that the alternator needs to be given a chance to charge the battery (limiting discussion to deep cycle batteries) and that in many application it isn't (take for example a "typical" family camping trip with a long trip to start to get to the destination (battery semi-full http://www.aulro.com/afvb/images/smilies/smile.gif) followed by short trips once at the destination- battery not given enough charge to semi-fill). There are many other factors that will compromise the alternators job, all centered around load e.g. stereos, fridges, aircon, lights (spotties), number of batteries as you point out and not the least of which is temperature which effects the batteries ability to accept charge and charging rates. The last of which differs depending on the architecture and chemistry of the battery type.

Now the issue here for DEEP CYCLE BATTERIES isn't strictly the output of the alternator (but it is important - noting your comment 13.8v which i will get back to) it is more the voltage regulator (closed loop controller) which controls the output of the alternator and prevents it rising above a set level (e.g 13.8v your value but they range and after all we are talking LR alternators http://www.aulro.com/afvb/images/smilies/smile.gif). Once the battery reaches a higher charge (say 50-60%- they are different) the regulator begins limiting the charge going in until it reaches its threshold value (your 13.8v). In normal car batteries the regulator replaces relatively small voltage drops ( taken out by starting the car) fairly fast i.e. a low charge but does it fast.

In deep cycle batteries due to the architecture of the cells you need to overcome battery counter voltage which increases as charging increases (hence deep cycle batteries typically use a high voltage charge to overcome this say 14.4 volts for a short period 15-20min). This voltage is above what your standard car regulator allows 13.8v). Without this high charge the standard alternator regulator system cannot fully charge a deep cycle battery and typically will only charge it to ??? % for arguments sake 80.

Now to this "This is no more than sales hype being fed to unsuspecting people who have no real idea of how batteries and alternator function"

Deep cycle battery manufactures have spent a great deal of money developing specialised chargers/ regulators that cost a bomb to deal with these issues. I don't think it is just to fleece the public. The architecture and chemistry of these batteries differ from your standard Pb-acid car battery and therefore the charging systems have been adapted to suit. In application where deep cycle batteries are bieng used your standard automotive regulator can be replaced with a SMART regulator to overcome these problems.

I hope that clears up some of the myths.

Cheers
Remy

P.S. for normal car batteries your statements are correct.

[drivesafe]

Sorry Remy, I don’t know where you are getting your info from but you have it wrong.

It makes no difference what type of 12 volt battery you have, ALL 12 volt batteries can be fully charged AT ROOM TEMPERATURES with a supply voltage of 13.8 volts. Batteries under the bonnet will actually fully charge form a marginally lower voltage because of the increased temperature.

Next, most vehicles, including Land rovers, have an average output voltage of 14 to 14.2 volts and many of the Disco 2s have a working voltage of 14.7.

If your vehicles working voltage, the operating voltage after the vehicle warms up, is just 13.8 volts, it’s time to get the reg looked at.

Again, so there is no misunderstanding, all lead acid batteries can be fully charged with a supply voltage of 13.8 volts. It may take longer to charge some types of batteries compered to others but it is still the minimum voltage for any battery to be able to get a full charge.

Cheers.

[Remy]

Hi drivesafe,

I will agree to disagree. I think it is getting a bit off the topic anyway.
However, I have asked a fair few battery suppliers and read a fair bit about this and got the battery shop to test my deep cell battery before i bought the expensive charger.

Start here
Silicon Chip Online - A Charger For Deep-Cycle 12V Batteries, Pt.1 (http://www.siliconchip.com.au/cms/A_103191/article.html)
Car and Deep Cycle Battery FAQ (http://www.rpc.com.au/products/batteries/car-deepcycle/carfaq13.htm)
AGM Batteries (http://www.fridge-and-solar.net/agm.htm)

I can find a lot more sites for you but i think these say enough. Either way i am happy if you don't believe me and i do my things my way and you do them yours. Others can decide what they want to believe after doing their own research.

Cheers,
Remy

[dck7aok]

Just thought i would pass my experience with very similar set up in my disco 1 use 15 plate start battery as main. sc80 with one circuit to winch battery(100 Ah agm) and second circuit to removeable 140Ah(dual 6 volt agms) for fridge plus freezer plus lights, inverter etc, etc, etc. All works very well if car is driven weekly for decent amounts of time. If tripping and drawing off accessory battery/s I find problems with near flat start battery tooooo frequently. What occurs is that the agm batteries have lower internal resistances(why they charge faster) and hog all the alternator output. SC80 runs all batteries down to 11.4 volts(Fluke RMS meter) before isolation occurs. On recharge start battery misses out untill agm batteries have sufficient charge to increase internal resistance. Have now developed my own isolation charging system(as per rotronics etc.) using 2 modifies sc80 and relays. All works fine, although alternator(std) struggles with load.
Before the AGM batteries were installed, was running deep cycle wet cells and did not have problem as they have higher internal resistance to cranking battery.. Hope this helps not hinders.

[drivesafe]

Remy, Silicon chip is an electronic magazine, hardly an authority on automotive batteries.

I’ve read RPCs info before and if you care to read it all, you find that it contradicts itself repeatedly, but this might be because the info is not theirs but a collection of articles, mostly from the States and you have to know what they are on about to workout what is battery charger info and what actually relates to vehicle use.

Fridge & Solar just happen to sell AGM batteries and as a means of convincing you to buy them, they have posted worst case scenarios but let you think that this is the norm. Not lying but a good bit of exaggeration and I might add, many of the points they raised, I have already covered earlier in this thread.

There is tonnes of info on the internet but if you want correct info about your specific battery, go to that battery manufacturer’s web site and get the real info.

Cheers

[Lionel]

Just thought i would pass my experience with very similar set up in my disco 1 use 15 plate start battery as main. sc80 with one circuit to winch battery(100 Ah agm) and second circuit to removeable 140Ah(dual 6 volt agms) for fridge plus freezer plus lights, inverter etc, etc, etc. All works very well if car is driven weekly for decent amounts of time. If tripping and drawing off accessory battery/s I find problems with near flat start battery tooooo frequently. What occurs is that the agm batteries have lower internal resistances(why they charge faster) and hog all the alternator output. SC80 runs all batteries down to 11.4 volts(Fluke RMS meter) before isolation occurs. On recharge start battery misses out untill agm batteries have sufficient charge to increase internal resistance. Have now developed my own isolation charging system(as per rotronics etc.) using 2 modifies sc80 and relays. All works fine, although alternator(std) struggles with load.
Before the AGM batteries were installed, was running deep cycle wet cells and did not have problem as they have higher internal resistance to cranking battery.. Hope this helps not hinders.

This sounds wrong! Initially, on start up,the SC80 is supposed to keep the aux battery isolated from the main, so that the main gets charged first. Then, and only then, the SC80 will allow connection to the other battery so that it will charge. I understood that the main battery has to be at 12.5V for the main and aux to connect together.

Are you sure it is connected correctly? The SC80 may be set as if it is to run accessories from, and then disconnect when the battery gets too low. This is not how you set it to keep main & aux batteries charged. (see diagams on Traxide web-site).

Cheers,

Lionel

[drivesafe]

Hi dck7aok, for a starter, your SC80 would be faulty if you were getting down to 11.4 before the SC80 isolated the cranking battery, but this is still irrelevant to how your batteries are charging.

Next, for your cranking battery to be “missing out” there has to be something wrong with your voltage regulator or you have a very small alternator, because the voltage flowing to your AGMs ( unless you have rewired your vehicle ) has to pass the cranking battery first and if the voltage is there, the cranking battery will still charge at it’s normal rate.

If your alternator is a small one then the current draw the AGMs are trying to pull will cause a voltage drop that will slow the charging of your cranking battery BUT, it will also slow the charging of your AGMs as well.

I think you might have an unrelated problem, so give me some more details.

[Tombie]

Just back to the original discussion..

A Wet Cell Battery, be it in an enclosure or open, inside the vehicle, which is not vented externally only... Is illegal under Aus ADRs...

The Defender battery box is externally vented, and the lid "seals" around the top.

[Remy]

Remy, Silicon chip is an electronic magazine, hardly an authority on automotive batteries.

I’ve read RPCs info before and if you care to read it all, you find that it contradicts itself repeatedly, but this might be because the info is not theirs but a collection of articles, mostly from the States and you have to know what they are on about to workout what is battery charger info and what actually relates to vehicle use.

Fridge & Solar just happen to sell AGM batteries and as a means of convincing you to buy them, they have posted worst case scenarios but let you think that this is the norm. Not lying but a good bit of exaggeration and I might add, many of the points they raised, I have already covered earlier in this thread.

There is tonnes of info on the internet but if you want correct info about your specific battery, go to that battery manufacturer’s web site and get the real info.

Cheers

Hi drivesafe,

I see you are providing information to back your opinion.
Siliconchip are a reputable electronics magazine! The article is a good one- buy it and read on. There are numerous other articles that say the same thing and the majority of battery stores will tell you exactly the same.
I am not saying the car alternator won't charge a deep cycle just that it won't charge it to its full capacity.
Anyway i have spent enough time on this. As i said before I am happy to disagree. But manufacturers have made these chargers for a reason. I wonder why?

ENJOY!

[Tombie]

Hi drivesafe,

I see you are providing information to back your opinion.
Siliconchip are a reputable electronics magazine! The article is a good one- buy it and read on. There are numerous other articles that say the same thing and the majority of battery stores will tell you exactly the same.
I am not saying the car alternator won't charge a deep cycle just that it won't charge it to its full capacity.
Anyway i have spent enough time on this. As i said before I am happy to disagree. But manufacturers have made these chargers for a reason. I wonder why?

ENJOY!

SALES.....

Simple, concise answer, SALES....

Make a product, market it till people believe they need to have it....

I have NEVER needed an expensive charger to keep any of my battery systems charged.. EVER....

I just use decent cabling with excellent connections and make sure everything is optimum...

And I would ALWAYS believe Drivesafe over those magazines....
And his words are also reflected by the electrical engineers here at work.

[eddiec]

Just thought i would pass my experience with very similar set up in my disco 1 use 15 plate start battery as main. sc80 with one circuit to winch battery(100 Ah agm) and second circuit to removeable 140Ah(dual 6 volt agms) for fridge plus freezer plus lights, inverter etc, etc, etc. All works very well if car is driven weekly for decent amounts of time. If tripping and drawing off accessory battery/s I find problems with near flat start battery tooooo frequently. What occurs is that the agm batteries have lower internal resistances(why they charge faster) and hog all the alternator output. SC80 runs all batteries down to 11.4 volts(Fluke RMS meter) before isolation occurs. On recharge start battery misses out untill agm batteries have sufficient charge to increase internal resistance. Have now developed my own isolation charging system(as per rotronics etc.) using 2 modifies sc80 and relays. All works fine, although alternator(std) struggles with load.
Before the AGM batteries were installed, was running deep cycle wet cells and did not have problem as they have higher internal resistance to cranking battery.. Hope this helps not hinders.

hmm... bugger... just 30 minutes after i went and ordered 2 agms (an 85 and a 40)... I guess I'll have a test run and see what happens...

[Remy]

I knew i was going to get that response with my last sentence - sorry i should have left it alone.

hmmm - OK i promise this is the last one from me on this topic
I value all opinions so just giving mine but this has got a bit out of hand and taking away from the intent of the original questions. I don't know drivesafe but see he has the ability to close threads nevertheless i remain firm on my opinion about DEEP CYCLE batteries and the specialist chargers for them. I know other chargers will work but they won't be as good for the battery.

Now to address this in the way i should have at the start!

Let us look at some peer-reviewed journal articles by people who research in this area! Feel free to purchase the articles if the abstracts are not enough for you. I can access them through my work.

ScienceDirect - Journal of Power Sources : Search for an optimized cyclic charging algorithm for valve-regulated lead–acid batteries (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TH1-408X4RC-7&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_version=1&_urlVersion=0&_userid=10&md5=fd132cc61d17390870bcd55b143aa2f2)

Welcome to IEEE Xplore 2.0: Design considerations for charge equalization of an electricvehicle battery system (http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=740842)

read the conclusion of this research

http://photovoltaics.sandia.gov/docs/PDF/caploss.pdf

I can find plenty more JOURNAL ARTICLES that have been peer-reviewed by scientists in these fields that show that these DEEP CYCLE batteries should be charged in special ways to maintain full charge and a long life.

In conclusion the specialist chargers are not just for SALES.

Now as i started saying a while back i also use my alternator to charge the deep cycle but use the charger designed for these batteries to top it up and maintain good battery condition. My deep cycle has never been full from car charging even after a 10+ hour drive from Brisbane back to home. i.e. my charger spent an hour throwing more charge into it before telling me it was finally charged.

All opinions have been valued - i hope mine is too!

No more from me - sorry for the distraction - gone for now.
cheers
Remy

[drivesafe]

hmm... bugger... just 30 minutes after i went and ordered 2 agms (an 85 and a 40)... I guess I'll have a test run and see what happens...

Hi eddiec, just fit them and after you have used them and need to get them charged, you will see that ALL your batteries will FULLY charge off your alternator.

I have been making these units for 20 years now and have thousands and thousands of them in daily use and dck7aok’s problem is the first I have heard of.

As posted, I think he has an unrelated problem which needs to be sorted.

[r.over]

Let us look at some peer-reviewed journal articles by people who research in this area! Feel free to purchase the articles if the abstracts are not enough for you. I can access them through my work.

ScienceDirect - Journal of Power Sources : Search for an optimized cyclic charging algorithm for valve-regulated lead–acid batteries (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TH1-408X4RC-7&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_version=1&_urlVersion=0&_userid=10&md5=fd132cc61d17390870bcd55b143aa2f2)

Welcome to IEEE Xplore 2.0: Design considerations for charge equalization of an electricvehicle battery system (http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=740842)

read the conclusion of this research

http://photovoltaics.sandia.gov/docs/PDF/caploss.pdf

I can find plenty more JOURNAL ARTICLES that have been peer-reviewed by scientists in these fields that show that these DEEP CYCLE batteries should be charged in special ways to maintain full charge and a long life.

In conclusion the specialist chargers are not just for SALES.

Now as i started saying a while back i also use my alternator to charge the deep cycle but use the charger designed for these batteries to top it up and maintain good battery condition. My deep cycle has never been full from car charging even after a 10+ hour drive from Brisbane back to home. i.e. my charger spent an hour throwing more charge into it before telling me it was finally charged.

All opinions have been valued - i hope mine is too!

No more from me - sorry for the distraction - gone for now.
cheers
Remy
Interesting articles, but they appear to deal with solar and other power systems. They do not seem to deal with motor vehicle batteries. The question of proper charging in the articles appears to deal with increasing the number of cycles that can be obtained from the battery. Important in a power system, not so important in a motor vehicle. Due to the use of the batteries in in the article, they are attempting to squeeze every bit of power they can store in them. By the graph in one of the articles, at 14.5 volts (alternator output), you will charge them to 90% plus. To most of us, that is close enough to fully charged. It appears that you are attempting to argue fine points that are not overly relevant to motor vehicle drivers, or it might mean that your fridge cuts out an hour earlier.

Based on your articles, an alternator will not fully charge a car battery, but it will get close.

[p38arover]

Is this true? It seems odd.


Standard car and truck alternators are designed, for various good reasons to recharge car batteries to only 70-80%, and this works very well for normal cars and trucks, ....

Noting most cars get used for short journeys and have a lot of start/stop cycles, wouldn't this be very bad for a battery?

[drivesafe]

Is this true? It seems odd.

Noting most cars get used for short journeys and have a lot of start/stop cycles, wouldn't this be very bad for a battery?

Hi Ron, this is the “Shopping Trolley Syndrome” I mentioned earlier in this thread. It is really not relevant to most people on this forum as their vehicles are more likely to be driven for quite a few hours between uses while on a trip, when the auxiliary battery is required.

As I also pointed out, the article is based more on a sales ploy than on the reality of long distance driving.

[p38arover]

Tim, like many people who use the 'net, I've become increasingly sceptical of stuff I read.

As you know, I'm an electronics tech by training (not that I've done much in the past few years) but batteries are not my field of expertise. I rely on the experts. I don't know who to believe! :(

I'd have thought that blokes like Collyn Rivers would know their stuff (I first came across him back in the Seventies or Eighties when he was editor of Electronics Today International).

I've just been hunting around the 'Net for some of his stuff. I see he also mentions the 70% charge for car batteries.


A vehicle charging system is deliberately designed to drastically cut back charging at 70% of full charge. The only really safe ways to approach 100% charge (90% is a realistic target) is via adequate capacity solar modules and solar regulator; or via a ‘smart’ charger – also increasing known as a three-stage charger

I do note he says about himself (elsewhere):


This is a field that's a long way from rocket science and I seek no credit for apparently uncovering it. Any electrical engineer would have done the same (and probably much quicker because I'm a research engineer). But there appear to be hardly any electrical engineers working in the practical side of the RV industry.

[Remy]

Sorry i cannot help myself - broken promises i know!

Interesting articles, but they appear to deal with solar and other power systems. They do not seem to deal with motor vehicle batteries. Yes they deal with Deep Cycle batteries what i have been talking about not your standard car battery.

"By the graph in one of the articles, at 14.5 volts (alternator output), you will charge them to 90% plus. To most of us, that is close enough to fully charged. " Yes agreed - for me that is close enough too while driving. But not fully charged which is how this all started!
When i get home i make sure the DEEP CYCLE is looked after, fully charged using a three stage charger so that i get more cycles and have a full battery for my next trip.
"It appears that you are attempting to argue fine points that are not overly relevant to motor vehicle drivers, or it might mean that your fridge cuts out an hour earlier." Without a doubt i am discussing a optimised situation and maybe the extra hour of fridge life is important to ME especially when i have been charging using solar or other means because the car is stationary while i am fishing :). This may not suit all but i think it wrong to completely dismiss the research and say these chargers are just for SALES and that the alternator is perfect. I think the system that drivesafe has designed and sells appears to be great (BTW i didn't know that when i started these posts), reasonably priced and practical for an automotive application. I use a similar system! I NEVER said an alternator based charging system wasn't practical just pointed out the research about charging and care of DEEP CYCLE batteries and was told i was wrong.

"Based on your articles, an alternator will not fully charge a car battery, but it will get close." YES that is all i have said all along. We could argue about % but in the real word in doesn't really matter if you need more hours add more batteries. For ME cycles is also important because they are expensive batteries so i take a bit more care

Better go to work to earn the money for my next trip.

cheers
Remy

[eddiec]

Hi Ron, this is the “Shopping Trolley Syndrome” I mentioned earlier in this thread. It is really not relevant to most people on this forum as their vehicles are more likely to be driven for quite a few hours between uses while on a trip, when the auxiliary battery is required.

As I also pointed out, the article is based more on a sales ploy than on the reality of long distance driving.


So - stupid question.... if you'll permit me.

In between the long trips, when I don't need the auxiliary battery, should I leave it sitting in the battery box connected up, constantly being topped up by the alternator. Or should I disconnect it? Which would keep the battery in the best condition?

[slug_burner]

if left in the car, leave it connected to the charging system via an isolator.

best thing is to take it out of the vehicle a leave it in cool dry place with a trickle charger or better still a charger that monitors the battery condition and charges accordingly. K-Mart has such a charger.