Second battery not receiving charge from solar panels or alt.

Submitted: Tuesday, Feb 12, 2013 at 11:14
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Hi, my sisters LC (I think it is a 1999 100 series) has the main battery + second battery for fridge etc, it has an isolator fitted and a bank of blade fuses for all sorts of things. The 2nd battery is now flat, reading 8.04v on the multimeter so we connected the solar panels but the next day the battery was at 7.8v. I have checked that there is nothing drawing from this battery and the solar panels were charging the main battery ok, do you think that it could be the isolator? Can it go open cct? I suggested she rings the previous owner as they are good friends and I believe he installed most of it or had it installed. But I know how good you guys are with helping out.
Thanks

Robyn

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Reply By: Member - bungarra (WA) - Tuesday, Feb 12, 2013 at 11:40

Tuesday, Feb 12, 2013 at 11:40
If I understand your wording correctly...you say the solar panels are charging the main battery ok...and obviously you have a multi meter at your disposal so the answer to your question is really quite straight forward for you to test

With the engine off (at least 30 mins)...allows residual charge voltage to drop
1) Read the voltage on the main battery
2) The voltage on the terminal of the isolater (the one that is direct from main battery to the isolator)..these should be the same...ie no voltage drop
3) Read the voltage on the terminal on the other side of the isolator ( the one connected to the aux battery)...at this stage this should be the same volatge as the aux battery
4) Read the voltage on the aux battery...these should be the same

Now

Connect either the solar panels (through its controller of course) to the main battery OR start the vehicle

Within 30secs or so the voltage on both terminals of the isolators should be the same...if so then the isolator is working correctly...(that is the open isolator is now closed and connecting).....the voltage on the aux battery terminals should be close to the same as well...you may have a slight voltage drop...its cable size dependant

From this you have successfully diagnosed the isolator working or not.......if is then I guess you most probably have an aux battery dead
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Follow Up By: Member - DereelGirl - Tuesday, Feb 12, 2013 at 11:47

Tuesday, Feb 12, 2013 at 11:47
Hi Bungarra, thanks for that. I will endeavour to follow your well written advice tomorrow when I have access to said vehicle. Will let you know how we get on.
Robyn
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Reply By: Member - Frank P (NSW) - Tuesday, Feb 12, 2013 at 11:46

Tuesday, Feb 12, 2013 at 11:46
Robyn,

Possibly the isolator has failed, preventing charge getting to the battery so that with continued use, or even non-use but no charge in normal driving, it has over-discharged. With your multimeter you could test for that with the engine running.

With a battery that flat many chargers and regulators won't charge them. Depending on what has happened to the battery previously, it may be unrecoverable.

A battery that low will sulphate pretty quickly if left in that state and that is usually terminal for the battery - at best there will be reduced capacity if the battery ever accepts a charge.

You could try to recover it with a charger that has a flat battery recovery program. They are usually mains powered, but I have seen some solar regulators that say they can do it. Never tested them, though. Someone else may be able to advise on brands - perhaps Ctek?

Good luck with it.
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Follow Up By: Member - DereelGirl - Tuesday, Feb 12, 2013 at 11:54

Tuesday, Feb 12, 2013 at 11:54
Thanks Frank, I did suggest to her to invest in a good 5 or 7 stage charger or take it to a battery place and have them see if it is recoverable. That will be stage 2 after we determine what caused it to go flat in the first place. I'm hoping they just forgot to disconnect the fridge the last time they used it.
Is there something they can put into their system to stop that from happening, like a low voltage cutout switch?
Robyn
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Follow Up By: Member - Frank P (NSW) - Tuesday, Feb 12, 2013 at 12:21

Tuesday, Feb 12, 2013 at 12:21
Robyn,
Most compressor fridges (eg Engel, Waeco) have low voltage cutouts built in to them. Three way fridges running on 12 volt may not.

You can add your own low voltage cutout to provide the protection you require whether or not the appliance(s) have their own.

Redarc sell one - see this link. So does ABR-Sidewinder at this link.

Cheers
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Follow Up By: Member - DereelGirl - Tuesday, Feb 12, 2013 at 12:34

Tuesday, Feb 12, 2013 at 12:34
Thanks again Frank, I thought I had seen something mentioned somewhere while reading all of the other forum questions. I will be suggesting they instal one of these devices and that will give them peace of mind.
Robyn
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Follow Up By: The Bantam - Tuesday, Feb 12, 2013 at 18:49

Tuesday, Feb 12, 2013 at 18:49
As a rule Engel fridges do not have a low voltage cut out.

There are severeal low voltage cut out relays available from the usuall suspects...jaycar stock 2 ready to go and a kit.

cheers
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Reply By: MEMBER - Darian, SA - Tuesday, Feb 12, 2013 at 11:49

Tuesday, Feb 12, 2013 at 11:49
The previous owner might be of limited help, because its what happening now that matters most. The battery could have died due to age or neglect - the charge controller may be at fault too. You need to be sure that there is no load at all on the battery when it is idle - even a small load over sufficient time will of course flatten it. A good auto electrician can quickly assess the components and operation of the setup and tell you the most cost effective way out of it - you will otherwise just be guessing and wasting time in my view.
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Follow Up By: Member - DereelGirl - Tuesday, Feb 12, 2013 at 12:00

Tuesday, Feb 12, 2013 at 12:00
Thankyou Darian I think they need to understand what they have running off that 2nd battery so they can make sure it doesn't happen again. They need to put it down on paper so they can check it each time they use it. They have less knowledge and understanding than myself so I do worry it could happen again. They only use this vehicle for their weekends away or holidays up nth so they need to get it right.
Robyn
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Reply By: Sand Man (SA) - Tuesday, Feb 12, 2013 at 18:39

Tuesday, Feb 12, 2013 at 18:39
Robin,

Regardless of anything else, the first thing your sister (or technical assistant) should check, is the voltage at the auxiliary battery, with the engine running.
After one minute or so, the dual battery controller should have activated the auxiliary circuit and a reading of around 14.2 volts should be present.

If this is not the case, the first thing to check is any inline fuse that should be present to protect to circuit from a short circuit situation.
Failing that the isolator is probably the cause of the problem. Should isolators also have a fuse which should also be checked for presence and condition.

As far as the measurement of the auxiliary battery voltage is concerned, 10.4 volts is dead flat and if a reading this low, or lower is being observed, the battery is um, cactus.

Any battery retailer can check the condition of the battery, however, if an AC charger is available, it should be tried to see if the battery will receive and hold a charge.
When being charged, the voltage reading should again be around 14.2 volts and when fully charged, the voltage should be 10.8 volts (fully charged) when the charger is removed.


Bill


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Follow Up By: Member - John and Val - Tuesday, Feb 12, 2013 at 20:14

Tuesday, Feb 12, 2013 at 20:14
Errr... Bill....

You said "When being charged, the voltage reading should again be around 14.2 volts and when fully charged, the voltage should be 10.8 volts (fully charged) when the charger is removed."

I think you meant "the voltage should be 12.8 volts (fully charged) when the charger is removed." NOT 10.8 !!

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John
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Follow Up By: Sand Man (SA) - Tuesday, Feb 12, 2013 at 22:39

Tuesday, Feb 12, 2013 at 22:39
John,

Yes, yes. Thanks for the correction John.
12.8 volts fully charged.

Cheesh! Hope I didn't confuse too many folk before John picked me up on the error.

Must have been a "seniors moment". I've been having a couple of them lately:-)

Bill


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Reply By: Member - DereelGirl - Friday, Mar 01, 2013 at 22:02

Friday, Mar 01, 2013 at 22:02
Hi All, I just wanted to let all of you that posted suggestions and advice that the car was taken to an Auto Elec and the problem was definitely the isolator. They fitted a new Redarc isolator and the battery has come back to life and is once again being charged. Thankyou all for your help.
See you all out there one day.
Robyn
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