Electric tongue jack

Philski · 05-20-2018, 09:03 PM

My jack works fine as long as I am hooked to the tow vehicle. But will not work at all on trailer batteries. Have you seen this before? TIA

GHen · 05-20-2018, 09:28 PM

Not sure, but most have an in-line fuse between the batteries and the jack. But that doesn’t explain why it why it works off the Tow vehicle.

nddan21 · 05-20-2018, 10:01 PM

Quote:

Originally Posted by Philski

My jack works fine as long as I am hooked to the tow vehicle. But will not work at all on trailer batteries. Have you seen this before? TIA

Yes. Same issue. It was the fuse.

OdiN1701 · 05-21-2018, 12:45 PM

Quote:

Originally Posted by GHen

Not sure, but most have an in-line fuse between the batteries and the jack. But that doesn’t explain why it why it works off the Tow vehicle.

Might bypass the fuse when it's hooked to the tow vehicle. Fuse only between trailer batteries and the jack? Not sure how it is wired but that would explain it.

RichR · 05-21-2018, 03:21 PM

When that fuse blows it also prevents the tow vehicle from charging the trailer battery. Dumb, dumb, dumb! I took the jack wire off from that hookup and took it directly to the battery. It took about three feet of ten gauge wire, a ring connector, a butt connector and a couple cable ties.

If you have the Lippert tongue jack it has a 20 amp automatic breaker built in.

Philski · 05-21-2018, 03:46 PM

I have the FIC 3500 jack. Italso has a resetting internal breaker. It has a (good) inline fuse. Also has a 30 amp ATO fuse that I found blown. Thanks for your help!

RichR · 05-22-2018, 11:45 AM

Quote:

Originally Posted by Philski

I have the FIC 3500 jack. Italso has a resetting internal breaker. It has a (good) inline fuse. Also has a 30 amp ATO fuse that I found blown. Thanks for your help!

The 30 amp fuse is the one that both the charge line and the jack are connected to, the battery is on the other side. The charge line and jack are directly connect to each other. So when the jack blows the fuse that prevents the battery from being charged. A 30 amp automatic breaker could also be a good replacement for the fuse. If the fuse is blown there is no way to know when the battery isn't being charged.

You may also like: