[Dirt Devil]

Had a problem today, when I went to start the patrol this morning I had a flat battery, so I turned the solenoid on to connect the second battery to first but after turning motor over and letting key go as motor did not want to start the circuit breaker(100amp) between the two batteries kept tripping. Should I go higher amp with circuit breaker or is something else wrong? Not sure what starter motors draw, I jumped the circuit breaker bolts and started no problem from second battery.

Battery was flat because left amp and head unit on without realizing it for five days.:headwall:

cheers DD.

 

[drivesafe]

Hi DD, first off, is your cranking battery flat or has it dropped a cell?

Next, how long did you crank while using the auxiliary battery?

The reason I ask is that a 100 amp circuit breaker would normally handle the current needed to start a motor long enough to start the motor before tripping.

 

[Leethal]

100 amp is more than enough for everything except when you wish to join the batteries for starting or winching. Most winches draw 450 odd amps at full load, and a diesel starter probably about 150 ish at a guess.

I'd suggest perhaps leave the circuit breaker you have, but across its terminals bolt on two more cables with a manual switch between them, like those red plastic key ones for instance, which you just use on the odd occasion if you're winching or jump starting from second battery.

 

[gumflapper]

I found this in the Nissan Service Manual

 

[Dirt Devil]

Drivesafe, battery is fine, I just run it down to far, the cranking was only about four or five revolutions then slowed, this is when the breaker activated.

Thanks Leethal and gumflapper, I will give this some thought but I think I will go with the manual switch and up the breaker to 200amp.

cheers DD

 

[gumflapper]

your breaker is really only there to protect against a short circuit so a 200A would still be fine...

 

[drivesafe]

your breaker is really only there to protect against a short circuit so a 200A would still be fine...

Hi again DD and as gumflapper posted.

we often jump start other vehicles through 50 amp circuit breakers and unless we crank for a while, they don’t trip.

Could your circuit breaker be faulty?

 

[drivesafe]

BTW, is your circuit breaker a genuine automotive type.

There are different types and some have an short/overload tolerance of just 10% over the marked rate.

These types are not automotive grade.

 

[Dirt Devil]

This is the one I used.
Circuit Breaker Bulkhead 100A 100 AMP 12V 24V Suit 4WD Boat Dual Battery | eBay

I have two, one at each end of the cable (02) running from back to front as my second battery is in the rear. Only one tripped, the one closer to the solenoid under the bonnet.

You could be right about the breaker being faulty.

cheers DD.

 

[RJGU42]

Y have one at both ends of cable?

 

[Dirt Devil]

There is one both ends incase there is a short along the cable.

If you only have one at say the main battery end and you have a short in the cable from say an accident or something the cable would still get power from the rear or other battery (2nd battery) which could start a fire or burn someone as I have used 02 cable front to back.

Hope this helps explain.

Cheers DD.