13.9v with engine running. Too low? Just installed an isolator

[nobb 10+ year member]

Hi,

I just installed a battery isolator so that I could put a deep cycle auxiliary battery to power my carpc and audio equipment for extended periods with the engine off.

Before, my system voltage was 14.5v with the engine on. But after installing the diode based isolator, there is a voltage drop and now with the engine on, both batteries are only "seeing" 13.9v. So I am just wondering if this is ok? I always thought that at around 13.8v is only a trickle charge, whereas you need a little over 14v to fully charge a depleted battery.

Can someone confirm that 13.9v is good? Will be be enough to fully charge up my auxiliary deep cycle if it is depleted?

Thanks.

Click to read more...

 

[SethPhillips 5,000+ posts]

Hi,
I just installed a battery isolator so that I could put a deep cycle auxiliary battery to power my carpc and audio equipment for extended periods with the engine off.

Before, my system voltage was 14.5v with the engine on. But after installing the diode based isolator, there is a voltage drop and now with the engine on, both batteries are only "seeing" 13.9v. So I am just wondering if this is ok? I always thought that at around 13.8v is only a trickle charge, whereas you need a little over 14v to fully charge a depleted battery.

Can someone confirm that 13.9v is good? Will be be enough to fully charge up my auxiliary deep cycle if it is depleted?

Thanks.

im usually idleing at 14.1... so i guess it's not bad..

 

[bad @SS chevy 10+ year member]

i idle at 13.9-14.2

 

[jer_stud56 10+ year member]

It shouldn't be bad. How are you checking the voltage? a DMM? If it's based off a car deck or your dash, I wouldn't take that to complete trueness of voltage. They're usually both off a little bit. If you're not using a DMM, check that out first.

 

[denali804 10+ year member]

Thats not bad voltage. A diode based isolator will show a little bit of a drop. Check out http://www.hellroaring.com and take a look at his bic isolators he makes. I used one for about 2 years and the thing worked great and i had pretty much no voltage drop. The engineer will spend hours of time on the phone with you prior to even purchasing the product. I think his name is Mike Hines. I have one of them around that i need to place in the for sale section at some point. good luck.

 

[nobb 10+ year member]

Thanks for the replies. I am using a DMM by connecting the leads to the battery posts. So this is exactly what the battery is seeing. I know those Hellroaring isolators are supposed to be really good, but I rather not have to uninstall what I already have if possible.

 

[MikeyB 5,000+ posts]

Im sure even temperature could affect a batterys voltage, but you should be fine. Dipping below 12v is when your going to be running into problems.

 

[Pioneer~Saturn 5,000+ posts]

With that voltage you're fine