Questions about my second batt?!?!?

[F A T B O Y 10+ year member]

Okay i finally hooked my second battery up.

It's wired (+) of front batt, to (+) of rear batt.

(-) of rear batt is grounded to the chassis.

Sound right, yeah?

Well this morning, after leaving the batt on the charger overnight the batt was reading 10.8v. So i went to connect the front and rear batts, and my 200amp fuse blew.

Why would this happen?

I did have my amps connected, but neither would have been turned on. The radio was off.

I bought another fuse today, and now i'm charging the batt again overnight.

Why on earth would it blow my fuse when i connected the two?

Click to read more...

 

[keep_hope_alive Premium Member]

double check your connections - make sure you didn't get a battery backwards.

make sure the battery is disconnected before you charge it.

also, if the rear battery was indeed 10.8V (waaaay to low) it would have caused a large current draw from the main battery (probably above 12V). you should get the battery voltage equal before you connect them.

 

[F A T B O Y 10+ year member]

double check your connections - make sure you didn't get a battery backwards.
make sure the battery is disconnected before you charge it.

also, if the rear battery was indeed 10.8V (waaaay to low) it would have caused a large current draw from the main battery (probably above 12V). you should get the battery voltage equal before you connect them.

This is what i was thinking.

No batts were backwards, and it was disconnected.

When and why would i ever need a battery isolator, or do i not?

 

[F A T B O Y 10+ year member]

Okay still charging that big MF'er.

Can someone describe a battery isolator, and if i need one or not?

 

[bubbagumper6 5,000+ posts]

All an isolator does is disconnect the batteries when the car is off, when the car is on it does nothing (the batteries are connected normally).

Charge up your second batt, then take voltage readings of BOTH of them before you connect them. Then post those readings here.

 

[mbrooky 10+ year member]

not that it would fix your problem but i've always read to do a run from front batt - to back batt - as well. //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[bubbagumper6 5,000+ posts]

not that it would fix your problem but i've always read to do a run from front batt - to back batt - as well. //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

Meh, it depends. On some cars, the chassis ground will be sufficient, on others it would be beneficial to run a dedicated return run. However at such small power levels, I doubt he'd see that much of a gain.

 

[F A T B O Y 10+ year member]

Yeah i have the leftover 1/0 to run from - to -, but that's not my problem.

I'm going to let it charge today while i'm at school, hopefully it'll be about 12.8 when i get home...

 

[bubbagumper6 5,000+ posts]

I don't understand why it wouldn't be at 12v now...you charged it overnight didn't you? If you charge it overnight and it's still only reading ~10v then I'd say your batt is probably bad.

 

[F A T B O Y 10+ year member]

trickle charge.

 

[F A T B O Y 10+ year member]

And there is a possibility that the batt is bad...

I bought it from 1phateclipse from here. Havn't had the chance untill now to get er goin

 

[1phatclipse]

I load test every batt I ship out and I know it wasnt dead when you got it. Most batts leave here in the high 12,s none under 12.5

and thats how I get them I dont have to charge them. You shouldnt have needed to charge it before installing it!

You also said it was "3volts" when you got it ..well I just went out and put a volt meter to every battery I have , all the ones Im getting ready to ship out were over 12.6 I also checked a few others that Ive had sitting around for months that have been abused and set to the side dead and they still read over 9 volts

So how could yours have been 3volts?... I dont know what you done to it . maybe your charger is messed up or you hooked it up wrong but I know it didnt arrive to you doa at 3volts

 

[keep_hope_alive Premium Member]

any local Autozone will load test the battery for free.