Thread: solar battery maintenance

Originally Posted by Magnet6x6

Is 12.7v to 13v the correct voltage to disconnect at?

Hi Magnet, 13.0v is way to low and you will not charge a battery or batteries.

You need a CONSTANT charge voltage of at least 13.7v or the batteries will never reach a fully charged state.

The MINIMUM voltage required to be able to fully charge an Optima is 13.65v

With solar charging, the voltage is not CONSTANT, so if you don't allow the charge voltage to get to at least 14.0+v ( 14.7v is the maximum safe voltage for any lead acid battery ) for part of the day's charge cycle, again, the batteries will never reach a fully charged state.

Furthermore, with your setup, where you will be charging two batteries at once and replacing the energy your isolator draws overnight, the current load being applied to the 20w solar panel means it is highly unlikely you will ever get much over the 14.0v.

Originally Posted by Magnet6x6

I was screwing around with the panel to see how it was constructed and whether or not I could remount the cells and ....... I broke it Well I cut one of the wire traces. It took a while before I soldered it up so no meaningful readings today


Thanks for the feed back Dave
Is 12.7v to 13v the correct voltage to disconnect at?
The light bulb idea is really clever, I'll be getting a reg but you've got to love that idea

Dave slightly off topic
I've recently read a post from you suggesting a diode and one cheap reg per panel.
I've read a number of posts recommending that for mobile panels the reg be placed as close to the battery as possible
How does that work with one reg per panel?

the one diode and cheap reg is for different panel set ups where you have the panels setup for different things, (one on the car, one on the camper and one portable for example) using different size panels.

If you gang panels into a single array then usually you would put in the diode at each panel and the reg near the battery, Most regs now include a blocking diode function so if you go one reg per panel you remove the need for the diode.

Regulator as near to the battery is the right way to go as it helps reduce cable losses

13.0V will charge a battery but only from a lower state. to charge a battery to full capacity you need a higher voltage 13.8V is what I consider to be the floating voltage and 14.4 a normal maximum charging voltage For what you are doing which is maintaining the battery on an essentially unregulated panel I would only want to see 13.8V as the maximum voltage. Regulated with a properly staged regulator 14.4 for bulk or absorption charges, 14.7 for the peak charge voltage with a 13.8v -14.2 for the float depending on the battery and any parasitic loads.

Other than the few minor differences in opinion about max voltages, rates and panel regulation setups Drivesafe is giving you good oil from the same page of the book as I am. His setup and voltages give you a much higher state of charge than mine (remember I'm only aiming to stave off sulphation and enough to start) but carry more potential risk if something goes wrong. My numbers leave you with a lower state of charge in the batteries (but not a flat battery) and in the main part thats due to what we are personally willing to accept due to what we expect from the system and have experienced in our employment in this field.

Conversly Drive safes systems cut out earlier and shut down with more left in the battery which gives you a better option if you get desperate. Stuff I do tends to leave you a lot closer to battery damage and having dead flat batteries IF you use all of whats available

All of drivesafes info below I agree with

Originally Posted by drivesafe

Hi Magnet, 13.0v is way to low and you will not charge a battery or batteries.

You need a CONSTANT charge voltage of at least 13.7v or the batteries will never reach a fully charged state.

The MINIMUM voltage required to be able to fully charge an Optima is 13.65v

With solar charging, the voltage is not CONSTANT, so if you don't allow the charge voltage to get to at least 14.0+v ( 14.7v is the maximum safe voltage for any lead acid battery ) for part of the day's charge cycle, again, the batteries will never reach a fully charged state.

Furthermore, with your setup, where you will be charging two batteries at once and replacing the energy your isolator draws overnight, the current load being applied to the 20w solar panel means it is highly unlikely you will ever get much over the 14.0v.

This is the key difference between drivesafes setup and mine. He is advising from what happens in 99.5+5 of situations.

I'm safe guarding against the .5% as well BUT if you follow what I'm advising your battery might only ever get to say 80% charge if you go with drivesafe it will get to nearer 100% charge BUT IF something oddball happens you carry a slightly higher risk of something having its life expectancy shortened OR burning out.

Gentlemen thank you both for your patience and the continuing education. I find this stuff to be quite fascinating and the more I look the more questions I have, consequently this post is a bit long winded

Originally Posted by drivesafe

Hi Magnet, 13.0v is way to low and you will not charge a battery or batteries ..............

Originally Posted by Blknight.aus

Other than the few minor differences in opinion about max voltages, rates and panel regulation setups Drivesafe is giving you good oil from the same page of the book as I am ..............

His setup and voltages give you a much higher state of charge than mine .... but carry more potential risk ...I'm only aiming to stave off sulphation and enough to start

...My numbers leave you with a lower state of charge in the batteries (but not a flat battery) ...Stuff I do tends to leave you a lot closer to battery damage and having dead flat batteries IF you use all of whats available

Drive safes systems cut out earlier and shut down with more left in the battery which gives you a better option if you get desperate.

This is the key difference between drivesafes setup and mine. He is advising from what happens in 99.5+5 of situations.

I'm safe guarding against the .5% as well BUT if you follow what I'm advising your battery might only ever get to say 80% charge if you go with drivesafe it will get to nearer 100% charge BUT IF something oddball happens you carry a slightly higher risk of something having its life expectancy shortened OR burning out.

Gentlemen forgive me, I think I muddied the waters by asking two different sets of questions and changing back and forth between the two. And I'm about to add a third set.

Originally my questions were specifically related to the unregulated charging of my Traxide equipped D3 and then I swapped to the unregulated charging of stand alone batteries as individuals and when banked

You've given me terrific information on both setups and despite appearances I haven't confused the two.

So far I've only experimented with the monitored charging of a couple of individual, stand alone batteries which is why I was asking about the appropriate voltage, (Vm I guess?), at which to disconnect. However this morning I've connected up to the D3 through the rear Anderson and I'll report my findings as I go.

To muddy things up even more I'm going to ask a few questions about customising the panels

Originally Posted by drivesafe

.....Furthermore, with your setup, where you will be charging two batteries at once and replacing the energy your isolator draws overnight, the current load being applied to the 20w solar panel means it is highly unlikely you will ever get much over the 14.0v.

I've seen Traxide based installations that used three batteries. Would the the traxide and solar combination apply the same charge & maintenance parameters to a three battery, (or more) installation?

Specifically I'm wondering if I could further leverage the benefits of the solar traxide combination by connecting a stand alone battery, by way of a temporary lead, to my D3's auxiliary battery. Would the temporarily attached stand alone battery, or a camp battery box etc, receive the same level of charge & maintenance?

Originally Posted by Blknight.aus

..... 13.0V will charge a battery but only from a lower state .... For what you are doing which is maintaining the battery on an essentially unregulated panel I would only want to see 13.8V as the maximum voltage.

Just what I was looking for, thanks. In that specific application I'll experiment with covering parts of the panel to get that sort of performance

Originally Posted by Blknight.aus

..... If you gang panels into a single array then usually you would put in the diode at each panel

Can I take it that the item in the photo is a diode? I'm learning about how these things work but it surprised me to see it bridging both the + & - panel connections.

With regard to ganging panels, I'm running a CF50, a few lights and a computer and research suggests that I need 160w of panel. That figure varies from author to author anywhere between 80w and 160w. I need to figure out what's correct for my needs.

I thought I'd start out with 80w, set it up at home and run it day and night for a week and see how that fairs. I can use the Wattsup meters to get real world information. If required I can add additional panels until I get to total self sufficiency.

The 20w panel I have is of a manageable size for handling, transport and storage so I thought I'd hinge them in pairs and have as many pairs as required.

The downside is that the panel and frame combined are 30mm deep. Whilst not outrageous it's bulkier than it needs to be. The current depth is just enough to be above the plastic junction box that houses the diode.

To make it easier to pack I'd like to cut the frame down to a depth of 10mm of which 5mm would be panel. I want to cut off the plastic box and either embed sockets into the frame or have a trailing lead coming directly off the panel.

All of the above leads to the questions,

• If paired together does each individual panel still require a diode or will one for each pair of panels suffice?

• If there's insufficient space within the frame, where & how to mount the diode?

• Can I incorporate the diode into any of the leads, perhaps the panel to panel lead or the leads that join the pairs of panels together or in the main extension that runs to the reg?

Gentlemen, all of the points made in your responses have been well received and taken together have given me an excellent grounding and much improved understanding of the subject. I've still got a fair way to go so I'm sure there'll be further questions at some point but in the mean time many thanks for the education

lots of questions gets lots of answers, remember the only dumb question is the one you thought of but never asked.

Proof of that can be found on aulro generally by the thanks a post gets, as a ready reckoner if you see an informative post in a tech thread and it has a lot of thanks on it then roughly speaking it means the people who put thanks on it gained information from the post thats in reply to the original question.

the first question Im going to answer is the one that relates to what size panel you need. Thats one of those that depends answers.

Theres 2 schools of thought on solar on vehicles.

1. The panels need to provide enough to allow you to remain in place with out an external power input (running the engine/genny/powered camp site)
2. The panels are only a back up supply that provide limited charging ability to allow you to extend your stay in an unpowered location for longer than just your battery system normally allows. (Im in this bracket my setup allows for a weeknds camping but my aux battery is flat by the morning of day 3 and Im depending on the panel to get through day 3.)

If you're in the first group your going to wind up with big panels and smaller batteries (as the batteries only need to deal with over night) and the second usually have smaller panel setups but more battery capacity.

with that question answered you can then work out how much of each you need. but to do that you need to know how much your going to draw so you can work out how much you have to replace. Very vaguely speaking.. Those from group 2 generally put on just enough panel to keep up with the load during the day and tax their batteries during the night (and 80w is about right for a single fridge a radio and some other intermittent misc loads) and the first group generally just take that number and double it (theres your 160w answer) they also tend to have better panel setups that are removable tiltable with top of the line regulators.

Next... Charging and unregulated panels..

Charging batteries is an art form ,just as some people will allude spark wrangling and spanner twirling can be art forms... sure almost anyone can paint by numbers and do it but that only gets you so far. So heres my intro 101 paint by numbers level on charging batteries from unregulated panels

For charging..

Batteries have lots of numbers around them and cover lots of details, the 2 that count most for basic charging are 1. the max charge rate (amps) and 2. the max charge voltage.

Now assuming you only want to keep your batteries between 60 and 80% charge (more than enough to start your car) with the 20W panel what you need to work out is what is 10% of the maximum charge rate of your batteries.. if the panel is capable of putting out more than that 10% then Dont do unregulated charging.

If the panel can only ever put out less than 10% of the max charge rate then you're good to run unregulated.

heres the kicker for you, you have a traxide and more than one battery. So hook the 20 w maintenance panel up to the main battery. When the panel charges up the main battery (and lets just for this example say that the panel is too big for the main battery by itself) the traxide links the aux batteries in (and lets say that by themselves they are too small for the panel by themselves) when you add all the batteries together if 10% of the total charging amps (they add together because the traxide parallels batteries) is more than best amps the panel can put out you are good to go. Plug in the batteries to the traxide put the panel on the main battery and forget about it it will self regulate because ... (insert more complicated white man magic explanation here or re-read one of drivesafes earlier posts for the general gist)

No, when you hook all of the batteries up via a traxide unit and plug a small panel on they dont all get the same charging characteristics, But we're faffing about in a world of technicalities you dont need to get caught up in for what you need to know. the basic (10% of total charge amps of all batteries) > (max panel output amps) covers what you need to know. In a perfect world On average all off the batteries will receive their portion of the panels out put based on the following formula (Panel output)/(# of batteries)

the thing in your picture is infact a diode, and it looks like its wired up as a shunting diode. ( only looked at the small pic and your description)

Diodes are one way gates for sparky bits and on solar configurations they can be used as shunts or as blocks and depending on what you do you may need both.

as a shunt its there to bypass the panel in an array so if the panels not putting out enough grunt the rest of the power from the array can pass through.

As a block its there to stop the panel from drawing power when its not working.


Where you mount it is simply a case of working out what you need it to do (if you need it) and then sticking it into the wiring in such a way that if you were to look at it from a wiring diagrams perspective its wired in the same way. BUT if you're using long removable cables and put the diode in the cable you need to both polarize and orient the cable so the diode cant go in the wrong way.

Hope that helps.

Wow Dave, awesome information. I think for the first time in a long time I'm out of questions. Well that's until the morning when I've slept on it

Originally Posted by Blknight.aus

Theres 2 schools of thought on solar on vehicles.

In relation to this discussion I'm in the first group.

Summer temps are 40-55? ambient with high 30?C at night not uncommon so every thing is working very hard. The majority of my trips are one or two nights, some times a bit longer. However nearly every day sees me doing several hours of driving. Along with a couple of tricks,

..... who ever the person was who came up with the wet t-towel as a zone divider between frozen and chilled deserves a ?kin knighthood and a free beer from every fridge running travel that he or she meets for the rest of their lives! .......

I turn the temp down while driving and turn it up overnight. The awesome traxide system, does exactly what it says on the tin & supports this style of travelling brilliantly. If I do my bit with managing the fridge correctly every thing is fine. On rare occasions I mess it up and the fridge is off when I wake up but the contents are always as cool as they need be i.e. frozen is still frozen and beer is still chilled. Of course the car starts perfectly so things are quickly back to how they should be. There are settings on the ABG25 and the fridge that can be changed and I'm sure that if I played with these I'd never have any issues but by the time I stop again and have the time I've forgotten all about them so they've never been interfered with.

That said, I'm hoping to start getting away for longer trips where I hit a spot and stay. There'll little or no daily driving, I may need to run a second fridge or freezer and I hope to be out there for a week at time, some times longer. That's what puts me in the first group


Originally Posted by Blknight.aus

Charging and unregulated panels..
.... assuming you only want to keep your batteries between 60 and 80% charge
.... 10% of the maximum charge rate of your batteries.
.... if the panel is capable of putting out more than that 10% then Dont do unregulated charging

Another great rule of thumb, thank you

Originally Posted by Blknight.aus

On average all off the batteries will receive their portion of the panels out put based on the following formula (Panel output)/(# of batteries)

Brilliant.

Originally Posted by Blknight.aus

Plug in the batteries to the traxide put the panel on the main battery and forget about it

Thinking in the abstract and still with unregulated could I make up and use an Anderson Y adapter lead that allowed a simultaneous connection between the panel, the D3 and anything else that I wanted on charge at the same time, using the SC80 to keep voltage in check?

For regulated battery maintenance for the D3 I'm looking at this from the point of view that the vehicle is parked in a reasonable state of charge so the isolator will be open and both batteries connected so at the moment I've plugged into the rear Anderson.

I appreciate that if before the solar connection is made the battery voltage had dropped (12.7 and below?) the isolator would have done its job & a connection through the rear Anderson wouldn't charge the crank battery. In such cases I know that when the car is started and crank battery voltage is sufficient the isolator will rejoin both batteries. What I'm unsure about is whether or not the isolator automatically rejoins the both batteries when it senses the aux battery has reached a decent level of charge. If that's the case then I can use the rear Anderson for all charging, if its not I may have to consider a comfort lead. In my situation its a bit of a mute point because when I park up the isolator's always open and the connection would be made at the rear for pure convenience.

However every now and then the car doesn't move for a week or two and occasionally I've been caught out with flat batteries. Last time I had to recharge using a USB phone charger. That's why I not only asked about the correct way of using a panel but also about the down and dirty, battle field options for when its all gone horribly wrong. The light bulb trick is genius, I haven't got any but its still genius.

Originally Posted by Blknight.aus

Diodes ..... can be used as shunts or as blocks and depending on what you do you may need both.

More great info. I'll try and leave the configuration as it is and rely on the regulator for polarity protection

Absolutely brilliant info, many thanks for taking the time to break it al down for me

Now I'm getting onto what you actually want to be able to do.

I believe the newer version of the traxides sense from both sides so so long as A battery gets above its nominal voltage the system will hook them all up. If you have the newest one you should be good to go.

Battlefield charging as you're calling it (emergency charging) is not about looking after anything, its whatever it takes to get enough into the battery to get you a start. in which case grab your 160w panel hook it up to the battery and watch the multimeter, as soon as it shows 14V crank the engine and disconnect the panels.

Due to the short time you do it the panels never punch enough into the battery to get to the damaging voltage phase.


For maintenance charging off of an unregulated panel while the no more than 10% max rule will stop you from hurting things if you go to small then the panel wont keep up with your parasitic load or the self discharge rate of the batteries.

What I think you want is...

about 100AH of actual battery capacity over and above the discos starting battery

about 200w worth of mounted regulated charging panels for when you're out camping and staying fixed for a week at a time (this just manages 2 fridges in good conditions)

a 20w maintenance panel for when you have to park it up for a week without the fridges and stuff on.

Originally Posted by Blknight.aus

the newer version of the traxides sense from both sides

I have the older one, perhaps I'll get an upgrade from Santa

Yesterday morning I connected into the D3s rear Anderson, I believe I measured 11.9v at that time. The car had been parked for five days having only made a couple of short trips to the village and back before that.

This morning I discovered that I had previously been talking tosh when I checked yesterday's performance the isolator had done its job and the rear connection was only charging the aux.

I fired up the D3 for a minute or so, the isolator opened and I continued charging from the rear Anderson. It proves your point about a crank battery connection being the bullet proof one. I'll need to pay attention to voltage before making the rear connection in future.

Its probably just me but I find using the rear quicker and cleaner than going under the bonnet.

Originally Posted by Blknight.aus

emergency charging .... watch the multimeter, as soon as it shows 14V crank the engine and disconnect the panels.

Brilliant

Originally Posted by Blknight.aus

What I think you want is...
... 100AH over and above the discos starting battery
... 200w regulated .... when you're ...staying fixed for a week
.... 20w maintenance panel

Again brilliant, than you. This gives me a great .......... starting point

So your battle field calc for ?group 1 stay in one place people? is a 2w:1aH ratio

For now I'm only running the one fridge so I'll start with the 80w discussed earlier and see how that goes.

If a second fridge/freezer is required I'll upgrade to the 200w

Perhaps not the ideal choice, I have a spare Optima red top looking to make its self useful, together with the yellow top already fitted that puts me within spitting distance of your 100aH

You're the man Dave, many thanks


Now you'll have to excuse me, I'm off to PM drivesafe about a new isolator and a handful of Andersons

Olly

Originally Posted by Magnet6x6

Brilliant


So your battle field calc for ?group 1 stay in one place people? is a 2w:1aH ratio

Not quite, thats just how the rough numbers worked out in this case. When people want me to spec up a stay in place system theres a lot more questions and real life testing done to confirm numbers because no one runs "just a fridge" everyone has a lot of other little things that add up over time.

For the numbers I threw down for you I basically took the numbers for my system, doubled the fridge draw left the misc values totaled them then doubled it for the solar watts needed and rounded up to the next convenient panel size. I then doubled the aux battery capacity to deal with the extra fridge over night. What should get you though on that is the doubling of the misc values + the round up factor combined with the benefits of the bigger batteries and the traxide. IT should get you to about 7 maybe 8 days but you'll still wind up against batteries in a lower state of charge than when you started.

For the stay and live on solar deal you need (roughly) 3 times the amount of draw you expect the system to deal with as your charge ability and thats only properly viable while everything is 100% in reality i'd spec up nearer to 4 times.

Originally Posted by Magnet6x6

For now I'm only running the one fridge so I'll start with the 80w discussed earlier and see how that goes.

With that you're running essentially the same system I am, with just a single engle and no accessory load that will just about keep you infront indefinately but add some sub optimal charging factors, some lights, a radio, charge a phone and the laptop and you're behind. I think that this will get you about 3 days in location but the battery will be drained on day 3 and you'll need to move on to charge the batter(ies). The traxide will give you a little more by the magic it does But I dont have one fitted because of a very special way I need to be able to abuse my setup that the traxide system was never intended to deal with (jump starting 24V out of a 12V system and welding off the batteries)

Originally Posted by Magnet6x6

If a second fridge/freezer is required I'll upgrade to the 200w

Perhaps not the ideal choice, I have a spare Optima red top looking to make its self useful, together with the yellow top already fitted that puts me within spitting distance of your 100aH

The configuration and build sequence you really want here is a little different..

Fit the 80w panel to the vehicle, add its regulator and couple it to the main batery. Your now set to go with a single fridge for about 3 days. Your system, charge wise wont be any better than mine but you have the advantage of the traxide which in terms of real life will put you about 30% ahead of how my setup works. maybe more if you use better batteries, panels and regulators. I've put this first as it sounds like you already have all of this gear.

next get yourself the upgraded traxide you wont see an obvious and immediate change to how your system works but trust me for the next bit you will.

then get yourself a second panel set or array when you start hooking up the next fridge/freezer. This set you hook up to your aux battery or the anderson plug with a dedicated regulator.

This gives you the most cost effective and flexible setup. youve got a panel set on the vehicle that looks after the main battery all the time and via the magic of the traxide the aux battery as well when the main battery is mostly charged. (which means you're not letting solar power goto nowhere when the battery is charged)

When you expand you have a second complete solar system that is not anchored to the vehicle so you can use it elsewhere or position it else where and with the newer traxide looking after things if you have to park the vehicle in the shade you can use the solar or any other charger to get all the batteries back up. IF you want you can even remove the second (third) battery and mount it to the second solar system to look after one of the fridges if you need the space in the vehicle.

if your parking it all up you can put the small maintenance panel onto the system anywhere and it will look after everything. (with the early traxide you must connect to the main battery with the later any will work)