AGM battery

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Jul 19, 2003
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The guy who did the restoration of my 73 roadster suggested that I use an AGM battery (small unit with spade connectors) to save space and allow for the installation of dual Fiamm horns behind the side cover. He said he had a lot of experience using this battery type and it would work fine so I agreed.

It worked as promised, but then I let the bike sit for 3 years without running. I replaced the battery recently to get the bike running again. The new battery worked as it should, but after running around ~6 hours, the bike suddenly died. I found that the battery was completely dead. I put the battery on a Battery Tender trickle charger and it would not accept a charge so it was clear that there was a problem with that battery.

I put another battery in and checked the charging system. There was 14V at 3000 rpm with the halogen light off, and 13.5V with the light on at idle it has ~13V. So the charging system seems to be okay.

Does anyone have experience with this type of battery? Maybe the vibration led to damaging the previous battery so I'm going to install a 1/8" sorbothane mat on the bottom and side of the battery tray to help attenuate vibrations getting to the battery.


Hi mike,I run a similar battery on my '74 850, no problems at all. I think that the problem that you experienced is due to storing the battery for 3 years without charging (?), any battery standing that long will have a problem with build up on the plates causing internal shorting,I have had a battery off a bike for 2 years but on a constant "top up" trickle charge and have had no problems later. Good luck. James[/u]

Thanks for the inputs. I'm glad to hear that someone else is using this type of battery successfully. I did change out the battery that had sat for 3 years, the one that I had the problem with had only been in the bike for around 6 hours of use. Hopefully it was just a bad battery, the one that's in the bike now is working fine. Mike
There was a thread about this over on the other forum. People seem to have mixed results with these batteries. Some have run them for years with no problems, others have had frequent failures. My new Ducati came with a Yuasa AGM battery and it didn't even last 6 months. It died and would not take a charge. I had it replaced under warranty with another one. Hopefully it will last longer.

I thought I'd try one of the motorcycle-specific AGM batteries on my 750 this season. I've had the bike four years now and am still running the battery it came with, which is just a cheap wet-style battery. Surely its days are numbered.

The cheap L-A wet cells seem to last well for me. Three years and then I replace them. Yet to have a failure in nine years on my Combat.
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