Problem with batteries and discharge

Jumper_C

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I have a Sundance 580PR when i charge the batteries (I have 2x110amp) to full charge the gauge reads 13.8v or better so you would expect them to last longer than 3 days on lights only, but thats all I get. I have a charger which I brought for my last van which can coup with the two batteries but I can still only last 3 days. The gauge in the van when everthing is switch off still as a drain of .2amp, Does anyone esle have this problem.
 
Are the batteries ancient, they will still show 13.8V or even more when fully charged but if in a poor state they will soon drop under load. Are the batteries just reading flat or are they actually not able to run a couple of lights after 3 days.
Even new batteries will soon show something like 12.7V quite soon after being put under load but then take a lot longer to drop to total discharge at around 10.5V. The 0.2 amp load you have would consume about 15A over 3 days so not enough to flatten healthy batteries but may be enough to drop them from 13.8V to say 12.7V.
 
hi . i use a drop tester on my batteries . you can get a sealey drop tester for about 30 quid puts a big load on for 10 seconds then see what you get. there are full details of how to use it in the box.cant really test batteries with out one. just using volts or the christmas tree testers isnt good enough . they are a guide but a good drop test finds the bad ones easily.
 
Save £30 and after charging just turn on a big load eg headlights+ heater fan etc then test with voltmeter,should give enough indication of dodgey batteries.
 
You don't want to use any more than about 50% of you battery capacity. Any deeper will seriously shorten your battery life even on most so called leisure batteries.

So you probably have 110 Ah to play with.

It depends on your lighting. If you have Halogen and it's taking say 50 watts, that's 4A at 12V. So it will last only 27.5 hours at 110 Ah. That could be used up in 3 days full timing with long winter evenings, say 8-9 hours a day use.

If you have fluo or LED lighting and it's taking only 12W that's only 1A at 12V so you'll get 110 hours. Basically two weeks at 8 hours a day.

If you tell us exactly what lights you have and their total wattage and also how long a day you use them for, it will be easier to tell if your battery is faulty. If ***** had LED lights, for example, and you had Halogen it's still possible the endurance would be 4 times as long for him given the same batteries.
 
What type of batteries are they.
How old?
Both the same type

What type of charger to you have - three stage, fixed voltage converter, or single stage taper charger.

What measuring instrument are you using to tell whether they are fully charged?

Exactly what loads to you have connected and for how many hours when you are camping

Have you tried charging up the two batteries separately and then connecting one at a time to see whether one is better than the other.
What is the battery voltage with no load connected after being off charge for at least 4 hours.

Is the 0.2A measured with a digital multimeter or analogue and is it there if you physically disconnect the charger.
 
Tony Lee said:
What type of batteries are they.
How old?
Both the same type

What type of charger to you have - three stage, fixed voltage converter, or single stage taper charger.

What measuring instrument are you using to tell whether they are fully charged?

Exactly what loads to you have connected and for how many hours when you are camping

Have you tried charging up the two batteries separately and then connecting one at a time to see whether one is better than the other.
What is the battery voltage with no load connected after being off charge for at least 4 hours.

Is the 0.2A measured with a digital multimeter or analogue and is it there if you physically disconnect the charger.
Click to expand...

Tony
The two Batteries are 110amp both of same age they were being charge by the van charger, all of my lights in the van have been changed over to LED's, with all of the lights on they draw no more than 2amps max, we normally go away for three nights max as I'm still working but last weekend we were away for four nights and on the third night the alarm come on the battery was down to 10.4v so had to use the cab battery, we did not use the TV nor did we leave any lights on when we went out.
I have an Hydrometer to tell me the state of the batteries i don't have any meters but both batteries were fully charged before we left.
Graham
 
Certainly doesn't add up - particularly if the SG on all 12 cells was showing close to the same value and all were into the green section.

If you didn't check ALL cells then it is possible you have a crook cell in just one battery.


You could disconnect both batteries (just the positives) from each other and with everything switched off, first check the battery voltage and then use the mains charger to charge each battery separately, monitoring the battery voltage every hour or two to make sure it is coming up steadily. If you have a three-stage charger, the voltage should gradually rise to about 14.4V, hold steady for an hour or two (or up to 4 hours depending on the settings) and then drop back to around 13.7V which is the long term float voltage. If you leave it on float overnight and then disconnect the charger and leave it for say 4 hours, it should read around 12.7V (.1 more or less depending on battery) if the battery is close to fully charged.
If you then put a 5 amp load on it (headlight bulb) the voltage should immediately drop to say 12.5V and then over the next 10 hours, it should gradually drop to ?? - maybe 11V, bit less - at which stage the battery should be roughly half discharged. If you remove the load and let the battery rest for an hour the voltage will rise to ??? - about 12V (I haven't got the resting voltage vs state of charge figures at hand) which corresponds to a battery about half full, which is a good point to stop taking charge from the battery before recharging. (if you are on a weekend away and can make sure you charge the battery asap when you get home, then it is "OK" to go down further BUT anything below 11V at the loads you say you are drawing means the battery is well and truly flat and if the battery police catch you they will charge you with batterycide. At 10.4V at 2A load, you should be tarred and feathered already but for a first offence (admitted) you get another chance.

Yes, you will need a cheap DIGITAL multimeter to do these tests but it will be a few pounds well invested because although cell electrolyte SG is a good measure of state of charge (provided it is corrected for electrolyte temperature, is a quality instrument and read carefully etc etc), it is pretty useless for working out what is actually going on. Battery voltage under charge and load and no load will tell you a lot once you have figured out the sequence.

Repeat the tests with the other battery and compare the results. (best if you do the measurements at the same elapsed time, but not essential) Can even draw a voltage-time graph to show the results in a format that makes it easy to see any anomalies.

Let us know what the results are because it adds to all our personal knowledge-bases as well as yours.

BTW - if you have a converter or fixed output voltage charger the sequence of events during charge will be different and it will take much longer to get to full charge, but the discharge part will be the same.

I know this all sound pretty tedious and it is but I figure it is a learning experience. An expert, armed with just a multimeter, could work it out in a few minutes just by switching the charger on, noting how the voltage rises, switching it off and then applying a load for a few minutes. Regardless of expertise, having two batteries in parallel can mask the problem which is why it makes it much simpler to look at them individually

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It will turn out to be something very basic, but since you reported the SGs correct, that puts an extra spin on the situation. A careful remeasuring of all SGs may point to what is wrong

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Your phantom drain of 0.2 Amps might be the battery charger itself, but you could check that by physically disconnecting the charger. Some chargers drag up to half an amp even when switched off and they can flatten a battery in a week, but your 0.2A over three days wouldn't come close to explaining your situation.
 
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Have you tried the simplest thing first and disconnected the battery and then put a multimeter (Amps setting) in series ie between cable and battery terminal just to check if you have more than .2A consumption, then switch the lights on that you normally use and check that the consumption still appears to be correct. This will help confirm whether it's the batts or not. It might be that if the van was previously owned that some additional circuit was installed byepassing the inbuilt meter.
 
Haven't been around for a while, but seems we're still all talking about batteries:

Tony Lee said:
Certainly doesn't add up - particularly if the SG on all 12 cells was showing close to the same value and all were into the green section. [...] but since you reported the SGs correct, that puts an extra spin on the situation.
Click to expand...

SG readings are not the be-all-and-end-all for State of Charge (SoC) measurement.

If the batteries have been mistreated then it's quite likely that there is some degree of sulphation on the plates. If you can't shift this with a clever charging regime (and having tried a few "magic" tablets can't endorse them either) then you're left in the position where you may well get a good Specific Gravity, and a smart charger may well indicate that the battery is fully charged, but the actual usable surface area of the plates has been diminished to such an extent that you no longer get the rated capacity of the battery.

When taking SG readings (and coloured ball types really aren't good enough) you also need to look at the acid that's been drawn up - if there is any hint of grey or black tint then you've certainly got more problems than you want ...

Get the batteries out of service - fully charge them with a proper charger and then do the 5A load test as noted above, but this time keep the load connected. If the battery can't sustain that for an hour then you have a problem (for batteries used in a "leisure" role). Then measure the SG again, making whatever temperature correction necessary and see what the indicated SoC is.
It's then simple "sums" to see if your battery has lost capacity.

For your future reference it would be a good idea to measure the voltage after the hour too - it's often rather easier to measure voltage whilst on the road than measure SG properly.

MildRed
 
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Any result to give us all some feedback for future reference???
 
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