House battery getting fully charged?

[SameGuy]

I bought a used LG camper last year. It has electrical system with shore power and a group 31 battery maintenance free Energizer battery which the previous owner said was about 2 years old. He said the trailer connection did not have a charger and neither did the shore power and that he just charged the battery when he needed to with a regular car battery charger. The camper just has lights and a Propex heater. I've been out for 7 days at most and never run low on power. I didn't like the idea of charging the battery with my low buck regular 2/10/50 Sears charger every time I got home so I connected a little cheap Battery Tender Jr. charger to it to keep it maintained. This charger supposedly puts out .75AH with a 4 step charging system
http://batterytender.com/battery-tender-junior-12v-at-0-75a.html
On occasion it would take a few days to top off my battery which wasn't really an issue.

I just picked up a 50qt ARB fridge and after testing it inside the house on 120v for a couple days I took it out to the truck and camper to give it a run out there. When plugged in the only battery protection setting it would run on was LOW. It would start on MED but go off in less than a minute.

This led me to put a multimeter on the battery and I was surprised to see it was only at 12.2 volts. The Battery Tender Jr. had been on the battery for over a week with the battery having no use. With the charger connected I was only seeing 12.4 volts at the battery.

I figured that the little charger would be ok for my needs charging the group 31 up, albeit very slowly but I am starting to think it is not capable of charging a battery so large. Does anyone know if that little charger can charge a 100AH group 31 deep cycle battery all the way up, or is it just getting to be time to replace that battery? Seems like a shame since it powers my lights and Propex heater without issue.

 

[dwh]

That charger should get it fully charged. It'll take probably two hours per every amp*hour the battery is down, so a 100ah battery down 50% will probably take AT LEAST 100 hours to get back to full.

I would say that the battery is shot and not holding a full charge.

But really, .75 amps per hour is a maintainer or a charger for a small battery. For a bigger battery, that charger will take so long that the battery will get a bit sulfated every time you have to recharge it. Get enough sulfation and it won't hold a charge, or won't hold a full charge anyway. Which sounds like about where you're at right now.

I recently picked up a Stanley (Baccus) BC1509 15a battery charger at Lowe's for 50 bucks and it's doing a surpisingly good job of charging. I bought it just to play with its desulfation mode. I hooked it up to an old battery I had laying around to use for a core. The battery was at 8.4v and would only charge up to 10.4v and wouldn't hold that for long.

After a few 24 hour desulfation sessions it'll now hold at 11.4v. It won't fully revive a truly screwed up battery, but it DID improve that old beater that was completely toast. I figure once I buy a new battery for my camper, doing a desulfation on it once and a while will probably get a bit longer life out of it (I abuse and destroy batteries habitually), which is why I bought that particular charger in the first place.

You'll probably need a new battery, and you really should get a decently sized automatic charger.

 

[SameGuy]

DWH, thank you very much for the information. Very well explained. I just ordered a new charger with a desulfation mode and more power so I will see what that does for the old battery that is there. If it helps it get to full charge then I will be thrilled, if not I will at least have a good charger in place for when I get a new battery in the spring.

 

[dwh]

If it works, post it here. One reason I was pleased when I spotted that one at Lowe's and saw it had desulfation and was cheap, is that there is really very little "real world" data on the net about whether or not desulfation actually works and for years I'd been wanting to try it for myself, but didn't want to spend a lot just to test it out.

Of course, all the manufacturers say it works, and they all say their method is the best, but I've only seen one actual more or less scientific study about it (which was done years ago by - I think - a battery company, and they said it helped) but after that I couldn't find the damned report on the net anywhere.

Reviews on the net usually run 50/50. Half, "Amazing! It worked so well, I turned a papaya into a battery that ran my whole house for a year!", and half, "It's crap! I hooked this thing up and Japan crashed into New Zealand!"


The fact that it actually did do something was good, and the charger actually being a decent charger for 50 bucks was icing on the cake.

 

[CaliMobber]

Yea its hard to say how that battery is doing. Let us know after a good charging what happens.

After looking into chargers and battery life Ive learned its really really hard to find a trully good battery charger that gets up to 15v. most will only get as high as low 14's and thats just not enough for most batteries. They will charge but will only be like 80% charged when it says 100%.

Handybob realy opened my eyes to what batteries really need.If you have not read his blog yet http://handybobsolar.wordpress.com/

Ive found the optima charger is the best deal on a charger, they are kinda expensive for most people but you know the old saying buy quality once or buy low quality a few times.


http://www.optimabatteries.com/en-us/shop/charger/digital-1200/

 

[4x4junkie]

If you use the desulfation mode on your charger, disconnect everything else from the battery so that just the charger/desulfator is connected to it.

IME, the added capacitance of other wires connected to the battery drastically impedes the high-frequency pulses needed to effectively desulfate a battery (this is probably why there are so many mixed opinions out there about desulfators if you were to research their effectiveness... Many people I suspect don't bother to remove the battery from the circuit, some even going as far as to say doing so doesn't matter, which isn't the case).

As long as lead-sulfate hasn't been shed from the plates (don't drop or impact the battery!), the water level (or moisture level if AGM) is good, and it can maintain at least 12 volts without a load on it overnight, you should be able to bring back a goodly amount of lost capacity to a battery that's been sitting around for awhile not-fully-charged.


To the OP:
You might want to hook up a harness from your camper (trailer?) to the truck so that the battery can be charged via your alternator (through a battery isolator if desired). This should mostly eliminate having to fuss around with an external charger, and will be a lot better for the battery as well. The most important thing if you do this though is to use big enough cable & connectors so that you'll have good current available from your alt (#1/0 gauge welding cable would be the minimum I'd use... #2/0 even better. This might sound like overkill, but any more than a 0.5V drop from the alt to the battery will cause a considerable loss of charge current, lengthening the time required for it to reach a full charge. With the engine typically only being ran for a few hours at a time you want to make sure it charges up as fast as possible).
The other option is to go solar. 150-200W of solar power should be able to power the furnace (it's blower fan), your 12V fridge, and a couple LED lights pretty much indefinitely. Solar can keep the battery fully charged while the camper isn't being used too.

 

[dwh]

If you use the desulfation mode on your charger, disconnect everything else from the battery so that just the charger/desulfator is connected to it.

IME, the added capacitance of other wires connected to the battery drastically impedes the high-frequency pulses needed to effectively desulfate a battery (this is probably why there are so many mixed opinions out there about desulfators if you were to research their effectiveness... Many people I suspect don't bother to remove the battery from the circuit, some even going as far as to say doing so doesn't matter, which isn't the case).

Another known issue is that the desufation pulses of some desulfators can interfere with the function of some MPPT solar charge controllers. Reports are sketchy and rare, so no one really knows yet exactly what the cause of the problem is.

But that's just another good reason to make sure that everything is disconnected while desulfating.

However, disconnecting everything might not be required - depending on the desulfator. Battery MINDer now sells a dedicated desulfation unit for vehicle batteries. It hooks to the battery and does desulfation whenever the engine is running. It operates a bit like a smart battery solenoid - detects charging voltage and then starts doing it's thing...no charging voltage, it shuts down. So with that unit anyway, you don't have to disconnect anything.