Battery died too soon

philrock · Post by **philrock** » Thu May 19, 2016 5:14 pm

Having seen many mentions of the MotoBatt MB9U battery on this forum, I bought one last year for my '66 CB77. It worked fine for a while, but after only about 5 hours of riding and a few months of sitting, it will not hold a charge - the local motorcycle shop tested it and said it's kaput.

I see a couple of reviews on Amazon from people who had the same experience. Has anyone else on this forum had the same problem?

I'm not inclined to buy the same battery again, but I'm not seeing many options. So far all I've found is a vented Yuasa, which I do not want.

Any suggestions?

Phil

jensey · Post by **jensey** » Fri May 20, 2016 2:11 am

Did you test the charcing current ? the voltage ?
If your electrics are in good shape, and you rev the bike for a longer time, the charcing currents combined with the voltage are too high for a gel battery and will reslult in "kaputt".

philrock · Post by **philrock** » Fri May 20, 2016 11:15 am

Jensey, thanks for your post.

I installed a Charlie's Place regulator/rectifier just before putting up the post above. Even right after charging, the Motobatt was not strong enough to start the bike, so I used a garden tractor battery, then switched the Motobatt into the circuit, and ran the motor for a few minutes. I never checked the charging current or voltage with the old setup or the new setup. The old setup used a silicon rectifier in place of the original selenium rectifier.

Before starting the bike with the new reg/rect, I charged the Motobatt (several times) with a regular charger. Charging current was 1.8 A. I did not check charging voltage. The indicator lights on the charger behaved in the normal manner. After charging, the battery voltage was 12.5 V.

My understanding is that the original setup was pretty weak at charging - even with the improved silicon rectifier. It seems unlikely to me that overcharging killed the battery.

Phil

jensey · Post by **jensey** » Fri May 20, 2016 3:51 pm

My understanding is that the original setup was pretty weak at charging - even with the improved silicon rectifier. It seems unlikely to me that overcharging killed the battery.

Maybe, but when the magnets of the rotor are in good shape and you ride the bike fast (highway for example), the charcing current can get to high.

However, in your case this seems not to be the problem....

Fourstage · Post by **Fourstage** » Thu Jun 09, 2016 5:52 am

This information can also be the source of some channels.