Charging AGM house battery with '81 Chevy alternator

[SiriusGD]

This may have been asked and answered before but I can't find a scenario close to what I need. I'm new to the RV world.

I have an '81 Chevy (Mobile Traveler). I just bought it. I tested the existing house battery and it's dead as a door nail. I'm going to buy a 12v Renogy AGM 100 Ah battery as a replacement. (Is this a good battery?)

My question is this. It appears that when the engine is running, the house battery is receiving voltage from the alternator. Is this okay for an AGM? Is there something in line that would protect the AGM and how do I identify it? Would I need to do an amp test on the new battery to see what the amps are? And if so, what level am I looking for? And lastly, If I do need some sort of protection device, what would you recommend?

I know that's a lot of questions but they all pertain to the main question. Answer all if possible, please.

Thanks!

[twinboat]

It will be fine. Almost all MHs have house battery charging while running the engine.

Many have flooded acid starting batteries and AGM house batteries.

The alternator has a voltage regulator that will keep the voltages within range of your AGM.

As far as batteries, as a newbe to living on 12 volts, I would get a cheap, deep cycle, maintance free battery.

Run that for a few years, while you figure out how to not kill it, before you invest in expensive batteries.

Sam's Club sells a GP31 deep cycle battery for around $100. It has 105 AH capacity and will do what the AGM will at 1/2 the cost.

You may want to check on your onboard converter/charger. Back in the early years they were not AGM or any battery friendly.

If at a site with shore power, where you may be plugged in for days or months, it may overcharge what ever battery you install.

Since you will be on shore power for longer periods then driving, you may want to look into a 3 or 4 stage smart charger.

[SiriusGD]

Originally Posted by twinboat

Sam's Club sells a GP31 deep cycle battery for around $100. It has 105 AH capacity and will do what the AGM will at 1/2 the cost.

Thanks for the response!

Don't you have to have a Sam's Club membership to shop there?

[twinboat]

Yes you do.

Here is another place to pick one up.

https://www.batteriesplus.com/batter.../bci-group-31m

[theoldwizard]

Originally Posted by SiriusGD

I'm going to buy a 12v Renogy AGM 100 Ah battery as a replacement. (Is this a good battery?)

IMHO, not the BEST. Reneolgy is NOT a battery company. They do not manufacture that battery themselves. If you have the space, buy 2 golf cart batteries at Sams or Costco. They will store more than twice the amount of energy as that one. If you want AGM, it will cost you, but Trojan makes AGM golf cart batteries, T105-AGM. If you only have room for one battery, Trojan makes a 12V AGM golf cart battery, T1275-AGM (these are rated at 140Ah). Trojan batteries can be purchased at a solar energy store or most places that service golf carts.

Originally Posted by SiriusGD

My question is this. It appears that when the engine is running, the house battery is receiving voltage from the alternator. [B]Is this okay for an AGM? Is there something in line that would protect the AGM and how do I identify it?

The BEST solution for charging any house battery from the chassis electrical system is a DC-DC charger. Ctek, Redarc and others make them. They will "do the right thing" (prevent overcharging) and can be adjusted for different battery chemistries.

[SiriusGD]

Thanks guys! I think I'll look into buying a Sam's Club membership. Looks like I'll get my money back real quick. And I'll look into that DC - DC charging.