The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: thrang on July 03, 2015, 07:45:57 AM

Title: parasitic battery drain
Post by: thrang on July 03, 2015, 07:45:57 AM

Hey all. I've not had the LS out for a month, (10 day holiday to the canary islands and lots of commuting on the 1200) anyway just rolled her out of the shed before the National tomorrow and the battery is flat as a pancake. Normally it would have been on a trickle charge but we had some work done on the house while we were away and the builders turned the eleccy off, and did not reset the trip for the shed power.

Anyway does anyone know of a way of testing which circuit is causing the drain. I know its not  the satnav power hook up as that's powered off the ignition switched live and the only other live power hookup is the GPS tracker I have fitted.

Ta.

Title: Re: parasitic battery drain
Post by: donbmw on July 03, 2015, 08:07:09 AM

Hook your volt meter between one of the battery terminals and the lead removed. Make sure your meter is set up for mil amps. Start unplugging one thing at a time an see what the draw is on your meter. First place I would check is the diode board. Every time I have had the same thing on one of mine the diode board was the it. Have been not been using the stock board for over them years now and have not had a battery drain issue with the better after market board.

Don

Title: Re: parasitic battery drain
Post by: Bob_Roller on July 03, 2015, 08:34:14 AM

Do as Don says to check for a small current draw .
I've seen the '  GEN ' light glow very dimly if a diode fails .
If you don't find any parasitic draw, check out the battery .
How old is the battery ???
Serviceable type, or sealed ???
If you have a serviceable type battery, check fluid level in the cells .
You can also have  electrical ' leakage ' between the battery terminals from conductive deposits on the battery case .
Set your multimeter to low volts DC scale, place one probe on a battery terminal and the other on the battery case away from the metal of the other battery post and see if you have any voltage reading .
If you do, use baking soda to remove the electrolyte deposit on the case .

Title: Re: parasitic battery drain
Post by: thrang on July 03, 2015, 09:47:16 AM

Thanks Don & Bob! I'll test it once the battery (new last January when I finished rebuilding her) has charged up, but I'm going to take a punt that its probably the diode board as it was second hand OE board (from the spare parts doner) when I fitted it.  

Title: Re: parasitic battery drain
Post by: Bob_Roller on July 03, 2015, 02:56:04 PM

Also, a trickle charger is not a good idea if it is left connected to the battery for long periods of time .
It keeps charging regardless what the battery voltage is, a battery maintainer is a better choice .

Title: Re: parasitic battery drain
Post by: thrang on July 03, 2015, 04:39:27 PM

Just tested the diode board and with everything off It's drawing about 0.5volts, so I'm guessing there is a duff diode in there. I'll order an upgraded replacement from Motobinns.

My trickle charger is a maintainer type Bob- a tip I picked up here a while back.

Thanks again gents!

Title: Re: parasitic battery drain
Post by: mrclubike on July 03, 2015, 06:16:54 PM

Quote

Just tested the diode board and with everything off It's drawing about 0.5volts,  

A drain would be measured in amps or miliamps
Not sure what you mean by this
If you hooked up the multimeter as Don states .5 volts would not  mean much.
If you have  a .5amp draw then that is a definite drain on your battery

Here is video on YouTube that may be of some help
https://www.youtube.com/watch?v=WJHcuuv-OtA&feature=youtu.be