Hi, I have a fairly new battery, less than a year old, and it doesn't hold any charge anymore. The other day I was going for a ride and found the battery completely flat. Checking the various fuses and where the load went I found the biggest current draw to be a temperature gauge I recently fitted. Anyway, battery was completely flat and my Optimate wouldn't charge it. Eventually I put the battery from my Honda parallel to the BMW one and got some charge into it, but I never got it above 3.5/4 Volts. When connected on its own after that to the Optimate it just didn't charge it, although it regarge the Honda one easily.
Anybody got any idea what's wrong with the battery and any possibility to resurrect it? Thanks!

Hi Rene,
Best chance to resurrect it would be to check the electrolyte levels if you can top up with distilled water if required and then connect it to a cheap non electronic charger capable of smacking it with about 3 amps at 14 volts and leave it on for 10 hours or so. If that will not bring the voltage up I suspect it may be kaput sadly.

Your temperature gauge should not draw anything at all when the ignition is off as it should be powered only when the key is in the run position. Only loads for the battery in the resting key off position should be the the clock and any bike alarm you have installed and that should be minimal.

I have resuscitated batteries that will not hold a charge (i.e. they charge up OK and then over a day they self discharge back to flat on one or more cells. That can be done by draining them and then refilling with water, violent shaking drain refill with water shake and drain until no more crud comes out with the draining, then put the acid back in and charge.

That gets the sludge off the bottom which is responsible for the shorting out of the plates in the cells. BUT it is messy and splashes will get everywhere and will rot your clothes, clean up around the work area with cloudy ammonia and tip a tablespoonful into the rinse water and do a rinse and spin of all clothes you wore in the washing machine, that will neutralise any residual acid.
Regards,
Jeremy

Hi Jeremy, many thanks. I guess it'll be 'shaken, not stirred' then. Cheers, Rene.