Page 1 of 1

battery removal with no loss of 12volts?

Posted: Tue Sep 15, 2009 3:18 pm
by FREDA MIND
hi guys,
another job i need to do is remove the battery so i can clean and rust proof the battery tray(slight corrosion present)
i need to do this without losing 12v from the car as i have no code for the aftermarket stereo.i have a spare battery and jump leads but i recall if done incorrectly you double the voltage to 24V!!!! #-o
can anyone help me? [-o<

Re: battery removal with no loss of 12volts?

Posted: Tue Sep 15, 2009 3:28 pm
by Muzorewa
You need to connect in parallel, not series. Positive to positive, negative to negative :wink:

Re: battery removal with no loss of 12volts?

Posted: Tue Sep 15, 2009 3:55 pm
by dave_aber
.... and insulate the red jump lead well........

Re: battery removal with no loss of 12volts?

Posted: Tue Sep 15, 2009 4:01 pm
by dandywarhol

Re: battery removal with no loss of 12volts?

Posted: Tue Sep 15, 2009 4:17 pm
by FREDA MIND
wow thanks for swift responce fello bongo freaks!
perfect!!!
:wink:

Re: battery removal with no loss of 12volts?

Posted: Tue Sep 15, 2009 7:55 pm
by Colin H F
Am I correct in saying that once the engine is running you can dissconect the battery and the alternator will keep everthing ticking over the same? Colin

Re: battery removal with no loss of 12volts?

Posted: Tue Sep 15, 2009 8:46 pm
by g8dhe
Its quite possible that the alternator will attempt to raise the voltage, higher than would be advisable, in an attempt to push a charging current through the battery. The alternator will have a cut-off voltage probably about 15 perhaps 16 volts - do you wish to try this out and report back to us all ?

Re: battery removal with no loss of 12volts?

Posted: Wed Sep 16, 2009 11:28 am
by Scott
newbie wrote:Am I correct in saying that once the engine is running you can dissconect the battery and the alternator will keep everthing ticking over the same? Colin
I have done this a few times when I haven't had the code available (not on a bongo mind you) I then shoved a sock over the positive lead to insulate it (un-worn sock of course) and it has worked fine :)

But as said, haven't tried it on the bongo yet as have had no need... YET! :lol:

Re: battery removal with no loss of 12volts?

Posted: Wed Sep 16, 2009 11:32 am
by Scott
this is a really clever idea tbh, but i'm not sure how it would be with split chargers, leisure batteries and re-wired fuse boxes :o

Re: battery removal with no loss of 12volts?

Posted: Wed Sep 16, 2009 11:59 am
by dave_aber
If your engine isn't running, then the split charge relay will be in the relaxed state - i.e. batteries are not connected together.

The Halfords dooberie will inject 12v into the cig socket, so that 12v will end up back-feeding the fuse box that the cig socket is supplied from, this will be either the main or the leisure battery but not both (depends how you have modified the wiring to take advantage of the leisure battery).

So, if the stereo and the cig socket are on the same battery, and thus on the same fuse set, then the halfords dooberie will keep 12v going to your stereo and keep the code.

remember that there are normally 2 supplies to a stereo, permanent 12v (for memory, security code, etc) and switched 12v to run it normally. If you have each feed off a different battery then you would need to be clear about what is going where first.

Re: battery removal with no loss of 12volts?

Posted: Wed Sep 16, 2009 1:13 pm
by FREDA MIND
thanks guys , top stuff!!!! :)
rick