Jumping starting batteries.

[SaltLife]

Trying to move to a different site and the starting batteries don't have enough juice. I knew that and have the onboard charger hooked up the last couple days during daylight hrs.

Well, it won't start. Even with the house battery jumper.

I want to try jumping with my jeep. Since it's dual batteries, do I hook it up like a single, or, one cable on each battery?

Even started the generator to give more boost.

Thanks

[DavidM]

The house converter will not typically charge the chassis battery when the converter is on and powered either by shore or generator. The Trick L Charger is a separate device that can be added that does that.

Don't know what you mean by jumper? Maybe you mean the battery boost switch that temporarily hooks the coach batteries to the chassis battery to help with a discharged chassis battery. That should have started it.

Your Jeep probably has two 12V batteries wired in parallel: pos to pos and neg to neg. If so connect the jumper to one pos and one negative and try it.

My guess is that either you haven't connected coach to chassis battery yet, or both systems are dead, or the chassis battery is bad and won't hold a charge, or......

Oh you said you started the generator. These generally take their starting current from the chassis battery which means it might be good but maybe too low to start the main engine.

Need some more info to help further. Measure the chassis battery voltage. Then try either connecting the coach to the chassis battery either with the built in boost switch or a jumper. Measure the voltage. If both are less than 12V then both are dead. Then hook up your Jeep and measure the voltage with the Jeep's engine running. Should be 13 or so. Then try to start.

David

[powercat_ras]

There are two chassis battery connection insulated stud points and a chassis ground stud point on the side rail of the chassis on the passenger side behind the steer wheel.

Never have used them but it appears that the bottom one is going to the starter.

[SaltLife]

What a fiasco. Starter batteries discharged, jumped with house batteries while generator was running. House batteries drew way down and couldn't get 1 slide in....

Either something is drawing down the starters, or they're shot. Only sat 4 a month....

No idea the age of the starters. No date, probably old.
House are new.

[Goodspike]

Sitting for a month is a long time.

[SaltLife]

2 more weeks to go. I think I'll keep them connected to the onboard charger

[creativepart]

Are you confident they can hold a charge? Can you remove them and use the Jeep to take them to an auto parts store for load testing??

[SaltLife]

Originally Posted by creativepart

Are you confident they can hold a charge? Can you remove them and use the Jeep to take them to an auto parts store for load testing??

I don't have confidence at the moment. We bought the rig about a year ago. Prior to that, i dont think it was used much in the last 5yrs. We're the 2nd owners. I could bring the batteries in, but, I'll probably wait until I get home in a little over 2 weeks. I'll just keep the tender running.

[creativepart]

And, when you can't start your MH after two weeks of charging... what is your plan then?

[SaltLife]

Heading home to the nothwoods. Batteries should be fine. They will only sit idle overnite......

[SaltLife]

May need AC so I'd have to run the generator. Then I could rehook up the charger.

[dickb46]

Something you could, or should do.
Check the battery connections. Put a volt meter across the positive terminal on the battery and the wire connected to that terminal.
Measure voltage. If there is any voltage reading then your connections to the batteries are bad.
Clean them.

[SaltLife]

I've had the 1.5 v on board trickle chager connected for a week. They're maxing out at 12.8v

[creativepart]

Originally Posted by SaltLife

I've had the 1.5 v on board trickle chager connected for a week. They're maxing out at 12.8v

Take them off the charger. Disconnect the power. Let them sit until tomorrow and then put a volt meter on them.

[SaltLife]

Originally Posted by creativepart

Take them off the charger. Disconnect the power. Let them sit until tomorrow and then put a volt meter on them.

I'll do it, but I'm pretty sure it will drop. No indication on how old they
are, probably will replace them this summer.

[NeilV]

Originally Posted by SaltLife

I'll do it, but I'm pretty sure it will drop. No indication on how old they are, probably will replace them this summer.

If they are bad they will usually start dropping the moment you take them off the charger.

Here in Florida after sitting for a year the batteries would be considered bad if they were not being charged every 2 weeks or on some sort of float charger.

Its asking a lot of a 1.5 Amp trickle charger to restore the engine start battery in a diesel pusher. 12.8 volts with the charger running could still a little low on some float chargers many of which put out around 13.2 volts. Even if they do not drop to 10 volts in short order that is no guarantee that they won't drop below that when under load which is why the Autoparts stores will use a small load tester to check batteries.

This load tester is less than $20 at Harbor Freight and works quite well:

Note too that the house battery chargers that came with those 2003 and earlier motor homes were notorious for boiling your house batteries dry. Many would have changed it out with a Progressive Converter/Charger with the Charge Wizard that cycles through full, float and desulfating charging of the house batteries.

[SaltLife]

Let them sit for about 11hrs, dropped to 12.4. I would have expected more. Either they're not holding a charge or there is a draw somewhere. I'm on the road and will check it at home...

Meanwhile, I'll keep the charger runnning until we leave in a week..

The onboard charger is meant only for the starters. Only ones the clips can reach....

[creativepart]

Originally Posted by SaltLife

Let them sit for about 11hrs, dropped to 12.4. I would have expected more.

Yes, but... 12.4v is only 75% state of charge.

However, keep in mind the difference between a fully charged battery and a dead battery is about 1v.

Perhaps only one battery is bad - but it doesn't really matter. If one battery needs replacing you'd really have to replace both. Perhaps, test each one separately and put the charger on only one at a time?

Which brings up a point... are you charging them with both charger alligator clips on one battery or one clip on the most positive battery's positive post and the other clip on the most negative battery's negative post?

[SaltLife]

One on each..

[SaltLife]

Well, the bats are charged to 13.1v. Seem to continue to climb......