Self Jump w/ Isolator (1 Viewer)

[Overlander 80]

Just finished up a dual battery install and I am wondering how I would execute a 'self jump'. Do I just run jumpers from one battery to the other or do I need to disconnect the isolator so I don't fry it???? Other options???

As always I greatly appreciate the advice.

 

[robmir]

Just finished up a dual battery install and I am wondering how I would execute a 'self jump'. Do I just run jumpers from one battery to the other or do I need to disconnect the isolator so I don't fry it???? Other options???

As always I greatly appreciate the advice.

The cheap way: just a jump cable between the positive posts since you already have a common ground and NOTHING will happen to the isolator

 

[mobi-arc]

yep...

 

[Lka1988]

The cheap way: just a jump cable between the positive posts since you already have a common ground and NOTHING will happen to the isolator

yep x2

 

[Overlander 80]

Great - thanks guys!

 

[Overlander 80]

Dare I ask what the "not cheap" way to self jump would be....

 

[george_tlc]

Great - thanks guys!

Heavy duty (high current) switch or relay/solenoid with heavy wire between the two positives of the batteries. With the manual switch you would pop the bonnet and flip the switch to make the circuit. With the relay you could have a switch in the cab to flip that would provide power to engage the relay/solenoid to make the circuit.

The suggested self jump scheme has the potential risk of disaster if one battery is pretty flat, the other fully charged and you have hydrogen gas floating around the batteries. Since you already have a ground path on the two batteries, the moment you make the last jumper cable connection to the positive there will be some largish sparks and possibly followed by a largish explosion of the battery.

THIS CAN HAPPEN - a mate was grinding near a battery that was sitting in the garage - some sparks went to the battery and BOOM - battery exploded covering things in acid and battery shards...

That's why when jump starting a second vehicle you hook the positive leads first, then you hook a ground lead to the donor battery negative and FINALLY hook the other end of the ground lead to the flat battery vehicle's engine or chassis. This provides the best jump start current AND keeps the spark away from the battery.

cheers,
george.

 

[Overlander 80]

Heavy duty (high current) switch or relay/solenoid with heavy wire between the two positives of the batteries. With the manual switch you would pop the bonnet and flip the switch to make the circuit. With the relay you could have a switch in the cab to flip that would provide power to engage the relay/solenoid to make the circuit.

The suggested self jump scheme has the potential risk of disaster if one battery is pretty flat, the other fully charged and you have hydrogen gas floating around the batteries. Since you already have a ground path on the two batteries, the moment you make the last jumper cable connection to the positive there will be some largish sparks and possibly followed by a largish explosion of the battery.


THIS CAN HAPPEN - a mate was grinding near a battery that was sitting in the garage - some sparks went to the battery and BOOM - battery exploded covering things in acid and battery shards...

That's why when jump starting a second vehicle you hook the positive leads first, then you hook a ground lead to the donor battery negative and FINALLY hook the other end of the ground lead to the flat battery vehicle's engine or chassis. This provides the best jump start current AND keeps the spark away from the battery.

cheers,
george.

Interesting and a little scary. So what would cause hydrogen gas to be in the immediate area? Welding? I have a heavy duty marine switch that I am going to connect between the positives. No need to ground the switch since both batteries are grounded - correct? Thanks.

 

[robmir]

Hidrogen is only present when you ARE charging a battery. Once you stop charging and let flow some air in area the hidrogen will dissipate.

And regarding the cheap way, I installed the heavy duty switch used by the truckers in their big rigs to disconnect the battery, to parallel both positive posts, but if you have to open the hood already as is my case, a jumper cable will do the job fine but again remember if you were charging a battery, once you stop, just wait until the hidrogen is gone !!!!!

 

[e9999]

the H2 issue is, I imagine, much less significant if you have a maintenance free battery, no?