Motorhome Solar Power System Issue

[fluffyboxerfan]

Hello all,

Well I have had the batteries tested, as yet haven't got the report at hand, will pick them all up tommorrow. It would seem they are as everyone has thought and not very healthy. Apparently they tested well below what they should have done, all 3 of them. The chap at Battery Power believes it is an issue with not charging adequately? As it is very unusual that all 3 would have failed at once?

This is a link to the batteries we have:
http://www.ebay.com.au/itm/12-VOLT-...933621?hash=item417745be35:g:a8wAAOSwMmBVtW3a

I have also spoken to the chap we bought them off of, and he agreed that the charger we were sold would really only do one 130ah battery and would need a minimum of 34 to 40 ah battery charger. So Condor your suggestion of a 50 ah is not unrealistic (unlike the price 8.( .
So I guess we are looking at not only a new charger but new batteries as well. Any comments on the quality of the ones we have or what brands etc., would be recommended?

I will post the results of the tests tommorrow after I pick them up.

All of your suggestions and posts are much appreciated, I have certainly learned a lot about batteries..they're not just batteries....

Cheers

Karen

 

[blisters]

I'd get dedicated deep cycle batteries those you linked to look like a compromise between deep cycle and cranking which means a medium duty deep cycle. As a firdt step you could try using a constant current charger or an old school type and overcharge for 12 hours or so. If they aren't getting full charge they probably have sulphated and you'll lose capacity. Over time this may not be reversible but if it is soft then overcharging/boiling may correct it.
Jon

 

[fluffyboxerfan]

Thanks Jon,

will keep that in mind, there's nothing to lose by overcharging them, can't make them any worse I guess. That hasn't been suggested before. And yes they do have a cranking capacity as Bill thought if ever the truck battery went flat he could use them to start it with, but that is probably very unlikely to happen and we have a 7 kva generator anyway if it does.

Karen

 

[blisters]

To clarify I'd only overcharge under performing batteries. Undercharging will create sulphation which increases internal resistance and capacity. Overcharging goes the other way and corrodes battery internals.

I'd only look at reputable battery suppliers for replacements particularly solar suppliers for your batteries. Also I don't think the info from your battery supplier about your charger not being large enough is correct. It should easily supply 2 amps constant current to each battery. If you left it at that rate your battery will cook and fail in a relatively short time frame.

The charger should at least provide a constant current until a particular voltage is reached e.g.15. Then it will hold the constant voltage until the current reduces to an particular value, then it will drop to a constant float voltage to maintain the battery.

Jon

 

[cairnspom]

Many of the 'smart chargers' have a battery reconditioning setting, that is supposed to deal with sulphation

 

[fluffyboxerfan]

The charger we were using is a Projecta IC700 7 stage switch mode intelli-charger, which is supposed to deal with the sulphation issue plus lots of other things in the charging process. Would the batteries have still sulphated if not getting charged enough.i.e charger not large enough it does state it's output current is 7A and battery range 50-140Ah. We were sold the battery charger as being large enough to charge 2 batteries, then we decided to get 3 instead.
But as I mentioned in earlier posts the batteries are on the charger for between 2 - 4 weeks continuously before the motorhome is taken out usually for no longer than a week at a time then the batteries only source is the charging system of the vehicle and solar power (2 x 250) watt panels. I still can't wrap my head around the fact that this wouldn't be enough to keep the 490 ah's of battery charged.

 

[condor22]

Fluffy, Forget the batteries you have, if they are buggered, they are buggered. Some say they can be reconditioned, but I don't recommend it.

As I have previously said, an AGM needs to be properly charged to maintain life and equally their depth of cycle managed to maintain life. A 3, 5 or 7 stage charger is the only way to go. The minimum is 3 stage - Boost, Absorption & Float. I use the 7 stage Projecta myself, mine being a bit over double the output of yours for a battery 1/3 your bank.

I repeat, 10 to 20% of capacity, less takes forever to charge, too much can fry the batteries. If you intend to replace these batteries as Blisters states, get dedicated Deep Cycle, not duel purpose. If you get 3 more x 130AH = 390AH total in parallel the range of charger should be 39A to 78A. I have roughly 15% so that equates to near enough to 50A.

Also, when not in use leave the motorhome plugged in to mains, use the correct charger and leave it on. The Intellicharge range of chargers will bring the batteries up to full and enter float mode and every few weeks will check the battery for conditioning. AGMs love to stay on charge.

Although solar will do similar, it's a stop - start charge cycle, in that at night the AGM is not on charge. A really shallow cycle can be nearly as bad for an AGM as drawing too much. My battery monitor uses about 0.1A, so will drop battery over time if not on charge.

The circuit breakers on my panels are off when in the driveway for this reason and the van plugged into the house mains 24/7. The panels only get switched on when camped up, or if there are any problems with other methods.

As I also have said previously, the only way to truly manage a battery circuit, is to know what goes out, what goes in and as much as possible limit cycle depth to about 25% if on a long long trip or 50% if used for a few weeks 2 or 3 times a year.

Fluffy, how old were these batteries? I ask because the one I replaced late last year was nearly 10 years old and went downhill quickly. Age rather than use or charge, bit like me lol.

 

[Nightjar]

Hello all,

I have also spoken to the chap we bought them off of, and he agreed that the charger we were sold would really only do one 130ah battery and would need a minimum of 34 to 40 ah battery charger.
Karen

Not a full quid on the technicalities of solar/chargers/batteries but I find the above information given to Karen seems false. If your charger is lesser output, the bottom line would be it will just take longer to charge all three batteries. After all we use trickle chargers to keep batteries full. Find this sort of information very misleading?
While free camping we generally run the generator most evenings for approx 1/2 hour to run van microwave for vegies/gravy etc, top up the two paralleled 110AH van batteries via 240V xantrex charger and the ute fridge battery via 240V 30amp charger.
At night the only draw down on the van batteries is LED lighting & 12V TV + Vast Satellite system powered by a mini inverter plugged into cigarette socket.
(Having said that, we are fowls not owls and the lights are out by 2030 hrs. We did find if the TV & Vast were left on standby the batteries were slightly down by morning.
Apart from that the two panels on van and one on the ute keep the batteries up.
This season two 60W portable panels are now wired in series running through a Victron MPPT controller. While we are parked up detecting will plug into ute via Anderson plug.

 

[blisters]

That's true but with multistage chargers an overcharging issue probably arises by using a charger that is too small. The reason is that the constant voltage stage (absorption) switches to float when the current drops to a certain value. By having three batteries in parallel the current at the charger will be three times that at each battery when normally the charger would drop into float if charging only one. The charger will then stay in this mode for too long over gassing the batteries resulting in premature failure. So an overcharge (equalising) will probably not uncactus your batteries I'm afraid. Also AGM would not react favorably to repeated doses as you cannot replace lost fluid as in wet lead acid.

Having a too small charger in the first stage (bulk charge) only has the issue where the battery takes longer to charge increasing the risk of sulphation. I'm not sure that's going to be a problem in this situation but given the above it's a moot point.

If your batteries require float only as in the original post then it should be ok if it stays in float and doesn't kick back up into the absorption stage. But that assumes your batteries are charged when you put them on.

So thinking about it outside a single phase charger, condor22 is 100% correct in sizing the charger to the capacity of the battery bank for the reasons above assuming I am not talking crap. I used to build 3 stage chargers for our geophysics gear in early 90s so I had the luxury of tweaking each stage to suit the battery manufacturers specs. So in the case of bought equipment it will be important to match the capacity as that should be how the charger is designed. I'm not sure how the charger you have has such a wide capacity window I'd have to read up to find out whether that's fine or just a compromise. So maybe look for a closer tolerance charger for your new batteries. That's why I'd go to a specialist who sizes systems, not a boat or 4wd shop for example.

Jon

 

[condor22]

First, do not be confused re charging. The trickle charging of a wet cell cold crank car start battery is totally different to that required by a deep cycle, particularly the AGM. If you try to charge a wet cell start battery to quickly the electrolite will evaporate and needs constant monitoring. The same will occur with an AGM, except you can't see or get to the electrolyte.

Next, if you have 3 x 130 Amp AGMs in parallel the total resistance to charge is 390 amps and would be treated exactly the same as if you had 1 x 390AH battery. A 3 stage smart charger's algorithm in boost, absorption and float varies the voltage and the current during each stage.

The Projecta intellicharge 50 amp charger can be set to 2, 6, 12, 25 & 50 amp charge rates. So it can be used on a bank of 3 x 130 AH AGMs. It could be used @ 12 amps for a single 100 amp AGM if set appropriately. Even my 15 A Intellicharge can be set to 2, 4, 8 & 15 amp outputs.

In the 3 stages of charge;

BULK - The charger will output up to the set current and constant voltage for the battery type to about 80% charge.
ABSORPTION - The current gradually decreases until the battery is fully charged. This can take several hours.
FLOAT - In simple terms, this holds the battery in a fully charged state without overcharging the battery allowing the charger to remain connected.

One of the important reasons to use a good quality charger is that if your charger is in float mode and you draw a small amount of current, cheaper versions will kick into Absorption mode straight away. i.e. a LED light. A good charger has a "time out" function that senses the load and forces the charger to stay in float mode, until such time as the battery has discharged enough to warrant going into a charging cycle.

If the charger stays in Absorption mode because of a small load, the electrolite gets hot and can "cook" the gel.

I'm commenting on the Intellicharge because that is the one I use, but most good multi stage chargers do the same things. Of note, in particular, the Intellicharge, if left on all the time, will monitor the battery constantly and automatically enter whatever mode is needed even recondition.

****This is of course for charging from mains, generator or in a caravan park****

 

[condor22]

****Charging on the run****

The same principles apply when charging from a vehicle alternator and DC to DC chargers, such as the Redarc BCDC series are still multi stage chargers, the main difference being the input voltage. There is another popular brand i.e. CTEK however there are several reasons I favour Redarc.

• They are Australian Owned, Designed and Manufactured.[/*]
• The input voltage is defined as low as 9VDC and will step up to the appropriate charging voltage. All I've ever been able to source re CTEK (D250S) is an input voltage of 12VDC.[/*]
• The solar version of the Redarc will accept up to 32VDC, whereas the CTEK's maximum input is 23VDC.[/*]

I have no affiliation with Redarc, I am purely stating my personal preference.

As I've also said several times, the 13.8V output from most vehicles is NOT enough to properly charge an AGM and by the time it's gone through the vehicle and into a caravan, it's much lower. Most good quality smart chargers, wether 240VAC or DC to DC charge an AGM at 14.4 or 14.5V

 

[condor22]

Finally,

The same principles apply for Solar charging. Use MPPT in preference to a PWM (both work but MPPT is better). Use one that is at least 3 stage and sized to the panel array output as well as the battery bank size. (Nominally a 100W panel puts out approx. 6.0 amps) My 2 x 100W panels, I know put out 14.8A total, but may go higher. My controller is an MPPT rated at 20 amps, so it will handle the input from the panels and output to my 130AH AGM within the 10 to 20% recommended charge size.

Also the better regulators are also programmable for different battery types.

If charging from 240VAC and DC to DC and Solar you need to look at the whole system re sizing.

My final comment is this, regardless of all of the above and repeated yet again, KNOW WHAT YOU USE - KNOW WHAT YOU CHARGE.

 

[blisters]

Next, if you have 3 x 130 Amp AGMs in parallel the total resistance to charge is 390 amps and would be treated exactly the same as if you had 1 x 390AH battery. A 3 stage smart charger's algorithm in boost, absorption and float varies the voltage and the current during each stage.

I'm not following this bit as resistance is in ohms, resistances in parallel decreases the overall resistance which at any voltage will increase the respective overall current as resistors (batteries) are added in parallel.

The combined resistance of three identical batteries in parallel will be one third the resistance of one of the batteries.

In regards to the algorithm I think we are saying the same thing as follows?

I haven't dealt with the latest chargers but the ones I built did the following:
BULK
Constant current until the threshold voltage is reached e.g 15v. Then it changes to absorption.
ABSORPTION
Constant voltage e.g 15v until the current reduces to a predefined level and it switches to float.
FLOAT
Float keeps the battery at a voltage to maintain charge e.g 13.8v

The thing is a battery is a variable resistor. As it charges the resistance increases so in bulk mode at a constant charging current the battery voltage increases proportionally to the increase in battery resistance. In absorption mode the voltage is kept constant so as the battery resistance increases the charging current decreases. In float mode the charging voltage is constant to maintain charge.

Jon

 

[fluffyboxerfan]

These are the results of the battery testing. I would be keen to see what everyone makes of the results and any advice concerning them. (3 x 130ah agm deep cycle batteries)

Kind Regards,

Karen

 

[fluffyboxerfan]

oops it didn't include the titles of the pictures. first two are from one battery. 2nd two are from one battery (did two tests on each)
3rd is from the 3rd battery, he didn't think it was worth doing more tests on that one.
He seems to think it is "user error" not battery failure?

thanks again.

Love to hear your thoughts.

 

[condor22]

Sorry Blisters, I wasn't referring to Resistance as in Ohms but more in the effort it takes. Poor choice of words on my part.

 

[blisters]

No probs condor22 terminology can be a bugger sometimes.

Jon

 

[condor22]

No probs condor22 terminology can be a bugger sometimes.

Jon

Yup, but given my electrical knowledge I should know better, lol. Aaah "the wood for the trees" etc especially when we have so many words in our language with 2 or more meanings. Shows just how specific we need to be in interpreting our thoughts into the written......

 

[condor22]

Fluffy, had a good look at the test results, might I ask if you have a boat?

If so you now have 3 spare anchors.....

Re your test results - after a 20amp load for 1 to 2 hours your batteries should be at approx. 80% @ 12.5V and 60% @ 12.15V. That they are nearer 9V (which is dead) shows they are as above, boxes of scrap metal. BTW I got a bit over $30 for my 100AH last year from a scrap merchant, so you have about $100 in that regard.

I asked if you knew how old they were?

The 2 common reasons for this happening if they are not that old are;

• Improper charging - know what you put in[/*]
• Cycling too deep, too often - Know what you take out[/*]

 

[blisters]

Found the specs here:

http://www.fusionagmbatteries.com.a...t/tabid/323/mode/details/pid/691/Default.aspx

You should be getting around 4 hours at 25 amps according to the discharge graph to a voltage of around 10.5 volts. At 20 amps you are around the hour mark so they're done for as condor22 said.

When looking for a deep cycle battery consider the reserve capacity along side the c/20 capacity and cycles verses discharge depth. I don't see the rc listed for this battery although you can derive it from the graph. :| The rc value is how long a battery can be discharged at 25a until it reaches 10.5v.

Well off for a dig

Jon