testing the house AGM -- who can do it? (Central TX)

GreyDawg · 12-03-2012, 07:36 AM

Hi --

First, SMB-TX is not an option. My homebrew van is now officially a CCV van (new top!) and SMB-TX won't work on other brands.

Very basic question here. My van has a Lifeline 4D AGM house battery, 3 years old, installed under the side door step RB-50 style back when it was a "homebrew van. It was installed by SMB-TX.

A year ago the battery dropped to 11.5V (I had a cheap 12v digital reader in a socket, and spotted the drop one day). The van was still a homebrew, so SMB-TX pulled it, charged it, tested it and said it had about 75% capacity. Next stop was my mechanic: the van's alternator was dying, so the battery wasn't charging. New alternator, problem solved. Now it routinely reads 12.5V, but that doesn't affect the capacity, right? That should still be about 75% (165AH)?

The battery has never been equalized.

Now I want to find someone (again, SMB-TX is no longer an option) who can drop the battery and test it. And then I need to decide if it needs to be replaced. (And if I replace it, I think it must be another Lifeline to fit the current battery tray.)

Do I go to a battery place? Can they remove/charge/test house batteries? Do I go to an RV-repair place?

Even better: does anyone in the Austin area have recommendations?

Thanks,
GreyDawg

86Scotty · 12-03-2012, 07:52 AM

Just about any RV or auto repair shop should be able to drop the tray and test the battery. That shouldn't be hard at all to do, just hard to get to a frame mounted battery.

**daveb** · 12-03-2012, 08:31 AM

Ask the place if they do a timmed load test. 12.5 is iffy but not completely shot. Being that is kind of a small battery it might not be enough for you after it has lost some of its life. The trick is to test it after the battery has sat w/o a charge for a day or so. Lower voltage than 12.5 = time to replace. They may be able to equilize it back to life. If the RV shop doesn't know what that is, find another shop. Good luck
BTW, nothing wrong with an RV shop pulling the battery and taking it to a battery shop that knows how to test and equalize.
Dave

webbmac · 12-03-2012, 08:53 AM

If you call Lifeline batteries tech support they should be able to direct you to a shop in your area that is qualified to test and equalize the battery. At 4 y/o it might be worth it. I have an 8y/o Lifeline 8D that gets to 12.6v and they told me to forget about it. BTW, most battery mfgrs. say don't equalize an AGM but Lifeline says it's fine.

GreyDawg · 12-03-2012, 10:54 AM

Quote:

Originally Posted by daveb

12.5 is iffy but not completely shot.
Dave

I misspoke (miswrote?)-- fog of fatigue, I guess. Here is more accurate information. Saturday and Sunday the van was driven 1000 miles. I have the cheap 12V cigarette lighter digital meters in the dashboard outlet and in one of the house outlets.

The van has been parked, no known load on the house AGM battery, for 21 hours. New readings:

ford van battery: 13.3
house battery: 13.1

When I'm driving everything kicks up to the 14.0 range.

Does that sound healthier?

My next step is to follow the suggestions above about locating a qualified tester, and someone who can disconnect/remove the battery and vice versa.

I'm hoping that the battery is the root cause of goofy readings I'm getting on my new solar system.

Thanks!

GreyDawg · 12-03-2012, 10:56 AM

Forgot to mention that the new solar system may be adding a bit of juice to the house AGM as it sits in the Texas sun today.

**daveb** · 12-03-2012, 11:44 AM

Yes, actually it sounds fine. You don't want the alternator to supply more voltage than about 14.2. You can set your solar controller voltage to mimic or supply a slightly lower voltage to the house battery. I like between 13.3-13.8vDC but if the solar is putting out the same as the alternator it's OK just a little high for a consistant daytime charge voltage. Your charge controller is probably a smart chargerwhich helps to reduce overcharging as apposed to the alternator that supplies a bulk charge rate . One way to see if you even need to pay to have the battery pulled and tested is to throw a piece of cardboard and a blanket over the solar and let it sit for a day or so. At the start, the battery should be fully charged then no charge applied during the test. Then with the separator open, test the house voltage again. If it drops from the low 13's to 12.8, the battery is fine (100% good) and no action is needed. If it drops to 12.5, you can take it in if you wish. 12.2 = a shot battery. We're talkin standard deep cycle AGM batteries not flooded cell batteries. Hope this helps.

[Edit] those are not goofy readings, without any charging, the battery should come to rest at 12.8vDC which indicates a fully charged battery. The higher voltage is just a float charge and will reduce (even w/o any load) over several hours. I'll bet you don't even need to pull the battery

GreyDawg · 12-03-2012, 11:52 AM

Update: Just spoke to Jim at Lifeline. He also said to cover the panel, and call him back tomorrow with a new reading (actually he said 4 hours but I'll wait more like 24, per Dave's suggestion.)

Covered the panel with blanket and plywood, and both dash and house dropped to 12.8V.

He also said that a perfectly maintained battery that is 3 - 3.5 years old would be down to about 180AH capacity from the initial 210AH. The real issue is how long did it sit in the 11.x range when the alternator was bad? I don't know.

Stay tuned for tomorrow's report!

Quote:

Originally Posted by daveb

Then with the separator open, test the house voltage again..

Does that mean anything more than just having the van parked and shut off -- that opens the separator, right?

Or do I have to do something more technical?

And thanks, this is all very very helpful!

**daveb** · 12-03-2012, 12:17 PM

I just added an edit to my first post.

Pretty much yes. The float charge can make the separator stay closed until the battery reaches its resting voltage. Most separators are set to open about 12.8 volts. Sometimes mine will stay closed for several hours after I pull into camp and nothing is running in the van. My separator has an indicator showing open or closed. With the surepower pulling the gorund wire is one way to make it open but you can just turn on a light for a few minutes and that should reduce the float voltage enough to cause it to open. If the van sits overnight and no charge is applied (including solar) by morning if you see 12.8 on the house circuit you're good. Just be aware that some items in the van might pull a slight ammount of power. To do the test, you can't have anything on, which is why the only true way is to actually pull the battery. But the fact remains, if you have 12.8 by the next morning, you should have a good battery.

GreyDawg · 12-04-2012, 06:58 AM

Morning update:

Both readings (12V outlet in van dashboard, and 12V outlet on the AGM battery) have dropped to 12.5V. The solar panel has been covered for about 18 hours.

Is it weird for the two batteries to be dropping in sync? (The van battery is about 1 year old, very heavy duty.)

I'll talk with Jim @ Lifeline later today. The new solar system from AM Solar has the ability to equalize batteries, so that might be worth a try on a sunny day as a the next step.

Thanks,
Meredith