2nd Battery not charging? (1 Viewer)

[ajinreno]

My 2nd battery keeps dying on me and I have to use a plug in charger to get it back to 12v. It seems to be happening since I had an indy shop install a new OE alternator (2000 LX470) when I was away from home. I have a Sure Power 9523a battery isolator. I tested for continuity on the isolator and it seems to be functioning with one way continuity to each battery. The secondary battery is fully charged now to 12.3, but when I start the car and it is running, it stays at 12.3 with no change. That means the alternator is not charging it, correct? Am I missing something?

The battery is a Duracell Ultra SL124MAGMDC and is 2.5 years old.

 

[saucebox]

That means the alternator is not charging it, correct?

I'd say that's correct, yeah. What does the starting battery look like when the car is running? +2.5 V?

 

[ajinreno]

The starting battery is 12.3 with the vehicle off and 14.3 when running.

 

[saucebox]

Sounds like the isolator is done for, then. You could test by swapping positions of the starting battery and house battery (charging seems like it'd move to the house battery)—if that worked, you'd know for sure it was cooked.

 

[ajinreno]

That was it...didn't realize those things could go bad. It was only a year old too!

Now I have to go do some reading to try to understand what the benefits are to using a Redarc DC charger is compared to just putting in another isolator.

Thanks for your help!