I have a 3yr old H-D AGM battery. For different reasons that I now know of, it has gone dead a couple of times. I have charged it back up using 12amp and 2amp combinations. Each time after I charge it, I have it load tested at the nearby Auto Parts store and/or H-D dealer. It tests fine, pulling 300 cold cranking amps. I have it loaded several times per test.

For some reason, the battery is dying on me. Is it likely that the battery is bad even though it seems to test good? Can the cells have a partial fault? I don't want to buy another battery if the problem is elsewhere. I do keep it on a maintainer, and it rarely takes more than a couple of minutes before the light goes to green.

I had the electrical system tested a couple of months ago by a qualified Indy, and he found a bad stator, so I have a new stator and regulator.

 

When is it dying on you? When you leave it a few days/weeks? When you are out riding? When it dies, is the battery discharged? That is, is the voltage low or zero or what?

I think you still have a problem here, maybe with your charging system, maybe with the battery. What is the current drain with everything off? A bad regulator can drain a battery, for example, but still give it some charge.

And I have personally never seen a battery go bad and get better again. If it's putting out 300 amps, I'd call that good, but anything is possible.

 

How clean are the posts and connections. Both battery and frame/starter. A tiny bit of oxidation does a whole lot of insulatin'.

 

My battery would/wouldn't start off and on for three weeks before I replaced mine. No rhyme or reason to pattern. Finally changed it when just after charging it that it would not start. Also the engine light stayed lit after startup till I revved it(low volts). I bought a aftermarket battery for about 60 bucks less than harley and has 350 amps. PM for location if wanted. Heat also kills batteries and it recently got fairly warm there if I am thinking right.

 

[QUOTE=Dr.Hess;5222350]When is it dying on you? When you leave it a few days/weeks? When you are out riding? When it dies, is the battery discharged? That is, is the voltage low or zero or what?

- I ride every week. If it's a short ride, then I plug in the battery tender. It dies when I'm out riding, about 2hrs out. At the times it dies, it won't even crank over the motor. I usually realize what's happening because there's not enough power to run the tach and the brake light. Those two items together kill the tachometer and that gets my attention. And by this point, if I shut it off before it dies, it won't restart. If I put a charger on the battery for 10 minutes at this point, it will fire right up no problem. I haven't tested it yet at this discharged state.

- Before I changed the regulator, the battery died, and I recharged. Then the stator turned out to be bad, so again I recharged the battery. At that point, all seemed to be working just fine.

- All connections seem to be good and without corrosion.

Are bad batteries quirky? Is it possible to pass a load test but not hold a charge for an extended time frame? Shouldn't I be able to hobble along on a bad battery once the engine is running, as long as the stator and regulator are doing their job?

 

Sounds like your stator and/or regulator are bad or not hooked up. You need to do some standard electrical system diagnostics. I suspect your battery is fine.

 

They shouldn't "die" when actually riding them. I mean the engine and accessories shouldn't act up when it's running. And yes, an old and tired AGM battery will do funky things.

I went round and round with a similar problem on a friends bike who lives way off from here. Walked them thru the tests and such, but it ended up being the stator. It would charge sometimes, especially when cold and quit when the bike got warm. Sometimes poor connections at the stator plug will do that. Sometimes a couple or 3 of the stator posts will get hot and build-up carbon deposits, causing them to short to ground intermitantly. Replaced mine recently for that problem. It checked "not grounded" but when I got it out it was. I scraped off the carbon and it checked good again, but no way I'd put it back on.

Easiest and most definite thing you can do to find the problem you have would be to wire up a volt gauge to the battery or somewhere convenient- duct tape it to the handle bars if you have to... keep an eye on it when you're riding then you'd know whether the system was charging.

Hopefully it's only the regulator and just because that one is relatively new, doesn't mean it's good... Right DR.? I should have bought stock in the regulator manufacturer for as many as I've replaced on mine.

 

I have an 03 duece I bought new, and always use a battery tender. After four years the bike would turn over slow, but would always start. After a ride I would connect the tender and in 30 minutes the green light would come on. Checked the battery with a volt meter and I had 12 volts. I decided it was time to buy a new battery before it left me stranded. Since I put the new battery in no issues.

 

Tom's battery was only taking a surface charge.

t150vej, yeah, just because it's "new" doesn't mean it can't fail. I have personally found that whenever I was eating regulators, I had an intermittant short somewhere. I could give you several examples. Just a single strand of wire poked through insulation will be enough. Finding it is usually coincidental to some other repair, but where the wires go through the fenders, into turn signal stalks, etc. is a good place to look. HD didn't even use gromits for the holes in the fenders. It's amazing they all don't melt down from that.

 

Agreed on both counts.

I have an AGM here that I use for checking small amp 12 volt stuff. It will charge to 13.8, hold 12.3 indefinitely, run an FM radio or CD player for days. Hook it to a starter on a bike - 8 volts and does not come back until it's had a deep, long charge. But I do like them for a bike, especially.

And what I find even more disappointing about HDs considering the fact there are no kick starts any more, only electric starters, they have no charge light or volt gauge on most of the models. That in itself causes more riders to be stranded and left scratching their head for answers than any other thing about the bikes....