2nd batterys not holding charge

[guzzla]

I run a tripple battery setup in my 80s with 1 battery for winching and starting and 2 others in parallell for all other accessories. Charging is regulated by a redarc solinoid. I have 2 volt meters in the cab wired in to each terminal on the redarc so i get reading of the starter battery for 1 gauge and the other gauge reads the other 2 patteries wired in parallell.

Ive run this setup for about 18months without incident but lately ive been needing to use the battery bridging button to turn off the alarm as the 2 second batteries appear to be draining down to 10v or less just sitting there during the day and it will do this even if the alarm isnt activated or any other power drawing item is connected. upon turning the ignition off after driving for a short period both gauges read about 12>13v.

The redarc charge light comes on when the engine is running to show its charging and I can hear the relay switch to isolate the main battery when it gets to 11.5v and the main starter battery is holding charge without incident.

Im not really clued up with using a multimeter though I can only deduce that since they seem to be getting charge but not holding the 2 second batteries (optima 75amp rc yellow top and dominator 100amp rc yellow top) are stuffed. These 2 batteries use to run the 80L engel non stop without recharging for 4 days but now they cat hold 12v over night. My alternator was reco'd about 18months ago.

Edit: I forgot to mention that these batteries have copped a hiding from
regular discharges to 8v or less during extended camping trips etc.

Your help is much appreciated.

[drivesafe]

Hi guzzla, if you have a 240 volt battery charger, try removing both auxiliary batteries and charge them separately although I suspect both batteries are stuffed, you may be lucky and find only one is stuffed and is discharging the other.

The fact that you have been taking these batteries below 10.5 volts it’s probably safe to say they are probably both stuffed.

BTW the Redarc should isolate the batteries way before the voltage gets to 11.5.

Cheers.

[guzzla]

Thanks drivesafe,

I was under the impression that being a deep cycle battery i could discharge them as much as i like without consequence for atleast 200 times though it seems about 50 times is more realistic. Still better than a wet cell battery though.

I have the redarc set up so it isolates the main battery but not the other 2 so I could draw past 11v and get a bit more out of them on longer stays.

I will put them on a 240v charger and see what happens but it looks like my greed has been rewarded with an expensive lesson.

[turps]

I had a very basic dual batt set up in my old GQ. It just had a terminal switch for isolating things.
But I had times when I would forget and leave the batts connected all the time. One of the batts started to die and it would make the relative new batt play up also. Worked out which one was stuffed. Replaced it and didnt have anymore problems for about 3yrs. Then same thing. Replaced the dieing batt and it worked well again.

[drivesafe]

Hi turps, as long as you find and remove the faulty battery quick enough there shouldn’t be a problem but if you don’t separate the faulty and good battery soon enough, you will, in a very short period of time, have two stuffed batteries.



Hi again guzzla, you need to be very careful of the info supplied by battery manufacturers.

The info will be correct BUT this info is based on tests carried out in temperature controlled pristine laboratory conditions, not exactly the same kind of conditions one would expect to find under the bonnet of ANY vehicle.

Also, no battery should ever be taken as low as what you are doing and if you have the room, a couple of larger 120 A/H wet cell batteries with a low voltage cut-out device would probably be better and would be MUCH cheaper.

Don’t be dazzled by all the hype surrounding AGM batteries. Much of their supposed advantages over wet cell batteries is actually BS

Cheers.

[turps]

Don’t be dazzled by all the hype surrounding AGM batteries. Much of their supposed advantages over wet cell batteries is actually BS

Cheers.

The last batt I brought a month or so ago. The bloke said the same things about those spiral wound Optima's. I was going to price them to put in my ute. But he was saying the dollar value just isnt there.
I ended up with one of those maintenance free batts. So far so good. But its not very old either.
I do like the terminal options that they have though.

[guzzla]

took it to battery world and he put a meter on it. Both were reading under 12v and were only drawing about 70% or max AH.

I decided to get 2 trojan 130AH wet cell batteries and I'll fit them up tomorrow. Doing the navrun this weekend so they will get a good charge and test run.

Cheers all for your help.