voltage drops at 2nd batt

[Jduane]

What type front batt?

Grounds?

 

[bumpingrandamgt]

Turned on the car today at lunch and both batteries are reading 13.8-14.2, really don't understand what the problem was in the first place,

 

[negolien]

Mighta have just needed time to equalize.

 

[wew lad 5,000+ posts]

The fact that they had to equalize at all is a bad thing, because one of the batteries is going to pull down the other and vice versa. Shortening the life of your batteries.

I'd really recommend getting a battery isolator or using two of the same battery, you mentioned yourself that one of your batteries is going out already.

https://www.optimabatteries.com/en-us/experience/power-source/can-i-connect-dissimilar-batteries-parallel/

in case you're trying to find one...

http://www.amazon.com/PAC-PAC-200-200-Amp-Battery-Isolator/dp/B000CEBXRS

 

[negolien]

No it's not that big a deal and and optima's are over rated. We see this talk all the time. Shortening the life of a platinum by a few months isn't a big deal. Most people running isolators do so because they run the system a lot with the vehicle off and don't want to kill the starter. If you're running a proper alt your feeding the batteries plenty of power to stay even keeled.

 

[adulbrich 5,000+ posts]

Yea, isolators are only necessary if you're running the system with the car off. Lots serious vehicle-off competitors don't even use them

 

[wew lad 5,000+ posts]

Okay yes sure you can do it, but when I get dual batts I'll be getting an isolator because I prefer to keep my batteries happy. There's no question on whether or not it's a bad thing, it's just a matter of whether it's enough of a loss for you to use an isolator or not.