Thread: Mixing AGM and wet cells...

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

Originally Posted by 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.

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

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.

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.

Originally Posted by 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

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!

Originally Posted by Remy

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.

Originally Posted by 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.

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...

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

Welcome to IEEE Xplore 2.0: Design considerations for charge equalization of an electricvehicle battery system

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