Battery Tender Question

[drewsss]

Did a search and couldn't find an answer to this one...

I have two batteries in parallel. First one is the stock 12V lead acid battery, and the second is a 12V dry cell (Stinger SPV35, 525a) mounted in the back to drive two amps, two subwoofers, etc.

http://www.sonicelectronix.com/lp/pla-car-batteries-power-cells/spv35?utm_source=google&utm_medium=cpc&utm_campaign=PLA&affiliate=googpla&scid=scplp3599919&sc_intid=16772&gclid=CJC_heHVns4CFcNefgod3CQEnw

Also had a breaker installed to separate the circuits when it's parked for long periods of time, so they won't draw on each other.

Question is: can I use my Battery Tender to charge both 12V batteries at once, knowing that one is lead acid and the other is a dry cell?

A poser question for sure, so maybe D6666 will swoop in with some...comments. But I welcome useful advice from anyone else.

Thanks,
Drew

[Sam Goldfarb]

I am guessing that you have the two batteries wired parallel as if they are in series you would have 24 volts!

https://www.batterystuff.com/files/manual-product_instructions_waterproof_800.pdf

[drewsss]

Yes, you are correct. I just noticed that error and just corrected it. Thanks for catching that.

And thanks for those instructions. They are the same ones I got with the Battery Tender, but they don't specify whether or not I can charge both of these types of batteries in parallel.

[EZ 2B Green]

The fact that they wired in parallel and in your vehicle means that your charging system is already charging both batteries at once. If it hasn't been a problem in your vehicle and it has been installed that way for a while, you are probably not going to have any trouble with a battery tender. The tender basically does what you charging system does but at a much slower rate.

[drewsss]

The fact that they wired in parallel and in your vehicle means that your charging system is already charging both batteries at once. If it hasn't been a problem in your vehicle and it has been installed that way for a while, you are probably not going to have any trouble with a battery tender. The tender basically does what you charging system does but at a much slower rate.

Just spoke to technical support at Deltran, and they recommended against charging both batteries at once. Since the charging amperage is basically cut in half (from 1.25a to 0.625a) when two batteries are in parallel, it would be overworking the Battery Tender excessively. So, looks like I'll use the breaker and only charge the main battery by itself. Thanks guys.