Any advantages to AGM battery for starting generator?

belfert · August 23, 2016, 11:58:51 AM

I believe I need a new battery for my generator after more than 10 years with my current battery. Is there an advantages to an AGM battery for this? I often don't start the generator for eight or nine months. The current battery I do not charge over the winter and it has started the generator after sitting all winter and spring.

Lee Bradley · August 23, 2016, 12:16:57 PM

The AGM doesn't self-discharge as fast as a standard lead-acid, it doesn't require adding water, it doesn't off-gas so terminals and box should last longer and the AGM should last longer than the lead-acid.

DoubleEagle · August 23, 2016, 12:23:00 PM

There may be an advantage, but considering the cost, maybe not. I put a AGM in one of my cars that I don't use at all during the winter, thinking that it would be okay in the spring, well no, it was dead. The alarm system monitor function used up the current. The previous maintenance-free had done okay for six years under the same conditions. When it is charged, the AGM does have more power for cranking.

bevans6 · August 23, 2016, 12:46:52 PM

AGM batteries are very good for generator use, because they retain a high output at low temperatures and retain a high charge for very long periods of time. They can also be recharged very quickly. They were used in the military to start emergency generators on aircraft, and so on. I would pick an appropriate AGM over just about any other kind of battery for generator starting.

belfert · August 23, 2016, 04:27:24 PM

My generator would not start this morning. It acted like the battery was dead. It just barely cranked before it shut off. I tried it several times. Everything is electronic so the electronics control how long it cranks.

Fast forward about nine hours and the generator cranked right up late this afternoon and started fine. It didn't act like the battery was low at all. The battery is quite old if I recall so it might be good to just change it out. In the big scheme of things an extra $80 for an AGM battery won't break the bank and is better than no power at the worst possible moment.

TomC · August 23, 2016, 08:37:40 PM

I don't bother with a separate battery for my generator. My generator is hooked in with my starting batteries (2-31's). If the starting batteries are too low to start the big engine, the generator usually will still start and I can fire up the inverter/charger to charge the batteries. Or I can simple hit my jumper relay that ties the 2-8D AGM deep cycles in with the 2-31 starting batteries. Once again-don't bother with a separate generator battery. Good Luck, TomC

chessie4905 · August 24, 2016, 03:41:02 AM

OR Tom can wrap his start rope around the crankshaft pulley and just give it a good yank....☺

jackhartjr · August 24, 2016, 04:42:15 AM

I just read a very long article about pros and cons concerning AGM batteries. It is written by a guy in Maine that services boats and sailboats, he is known as a guru in electrical systems.
The bottom line is this, even though AGM's do not discharge as quickly as other types, KEEP THEM CHARGED!
If it is a simple solar panel, or trickle charger, keep them charged!
A lot of sailboats sit out on a mooring for months at a time, the ones that have the solar panels to keep them topped off, last many years longer than those that don't!
I will try to get a link to the article!

http://forums.sailboatowners.com/index.php?threads/agm-batteries-making-the-choice.124973/

bigred · August 24, 2016, 06:27:42 AM

I had a problem with the Onan on the motor home going through batteries .For some reason the batteries would crank the geset after it had set for sometime.The polarity would reverse .Finally put a 12v deep cycle battery .So far so good !!

TomC · August 24, 2016, 08:10:57 AM

Chessie-what do you mean by that?

belfert · August 24, 2016, 08:25:37 AM

One of my thoughts on having a separate battery for the generator is I can start the generator and then use a battery charger to charge the main batteries if need be.

It would cost just as much for cables to one of my battery banks as it would cost for a new battery for my generator. One of my issues right now is I have having hernia surgery this afternoon and won't be able to lift over 20 pounds until Sept 22nd. I leave on my bus trip on the 20th. I can get someone to help install a battery, but they aren't going to be willing to crawl all over bus to install cables to one of the battery banks.

Oonrahnjay · August 24, 2016, 09:36:03 AM

Quote from: belfert on August 24, 2016, 08:25:37 AM.. I leave on my bus trip on the 20th. I can get someone to help install a battery, but they aren't going to be willing to crawl all over bus to install cables to one of the battery banks.

Hope you're feeling good soon Brian. Just takes a while. Best wishes.

belfert · September 12, 2016, 02:43:29 PM

I pulled the cover off the battery holder and turns out battery was replaced in 2014. I have my doubts battery is bad. I am going to clean the terminals and see how things go.

Oonrahnjay · September 12, 2016, 03:21:54 PM

Quote from: belfert on September 12, 2016, 02:43:29 PMI pulled the cover off the battery holder and turns out battery was replaced in 2014. I have my doubts battery is bad. I am going to clean the terminals and see how things go.

My generator battery has some phantom draw on it. Have you been keeping a trickle charger (or "battery maintainer") on it? I think that mine will drop below 50% charge in 4-6 weeks without any use or anything attached to it being turned on. I had to buy a new one in 2014 myself after the previous one was less than 2 years old. I've had a smart charger on it since then but I haven't checked it recently.
I hope that this one is OK for you. Good luck on your annual trip.

belfert · September 12, 2016, 06:27:33 PM

The battery has been left all winter every year without any charger on it. It has started every year after sitting all winter and even started first try this year. It was a few days later it wouldn't start.

The generator would only crank about a second or so before the cranking would stop. The starting is all electronic. I just hit a button and it starts by itself after a few seconds It stops cranking as soon as it starts. I have been having an issue with the oil pressure sensor shutting it down occasionally at startup. In those cases it would start and oil pressure would get up to about 25 pounds and then it shut down with low oil pressure code. The level of the oil is fine and it starts the next try after a reset.