12V Question

[millerfish]

OK so I am not to swift with electrical so I need some help.
Here is my question.
With the neg battery cable disconnected and ignition off. I put a meter between the neg side of the battery and the neg cable and read 11.5v withe the ignition on I read 12.6v. Should I have any reading with the ignition off?

 

[Ducky's Dad]

The vehicle specifics make a difference for parasitic drain. Modern vehicles will have a parasitic drain, with ignition off, of maybe 25-45 milliamps. Some vehicles might take as long as 30 minutes for the computers to mostly shut down after you turn off the key. Aftermarket stuff like alarm systems (even when off) or simple things like battery monitors (National Luna) can add to parasitic drain. An older vehicle, pre OBD, with no accessories might show zero parasitic drain. It all depends.

 

[millerfish]

Thanks verkstad/ducks dad
I set the meter to DCA it reads 1.22 between the cable and terminal. Does that seem right? FYI this is a motorcycle 97 model so there is definitely some electronics on board. The reason I am concerned is the old battery went south quickly and would be dead if left unstarted a couple weeks.

 

[lqdchkn]

You need this:

https://www.youtube.com/watch?v=KF1gijj03_0

 

[Ducky's Dad]

That is a very good video. I must admit that I don't know squat about motorcycle electrics/electronics. Except that you probably don't need to check the glove box light.

 

[lqdchkn]

Same principals apply. Either the battery isn't being charged properly or there is a drain (possibly both). IMO since the voltage is higher with the bike running it appears the charger it trying to top up the battery, thus there is a drain and the charger just can't keep up or get ahead.