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chunker · 02-14-2019, 07:51 PM

The motorhome has been in the shop for some minor body repair and hasn't been started in several weeks. Today I went to get some stuff from it and ALL the batteries are dead. Chassis batteries showed 4.9v and got nothing from the house. Don't know if something was left on or what. Chassis batteries are 4YO so I was expecting to replace soon anyway and possibly upgrade to 6V for the house. Course I can't start or anything. Figure to jump start the generator, run for a while and see if I can bring back some temporary life to the batteries.

Where is the best place to connect to jump the generator. Cummins Onan 8kw diesel. Generator is on a slide out tray and frankly I haven't looked in the past at the electrical connections.

Jim_HiTek · 02-14-2019, 08:48 PM

I think those batts are in such bad shape that you could blow something by trying to recharge and use them. Alternator, jumper pack, powered jump start device could all be damaged by a battery that is at 4.9 volt or 0 volt.

Better to just replace them. They are ruined anyway.

One thing to remember is that when you store an RV, just disconnect the grounds. There are phantom loads on RVs brand new or built decades ago that slowly discharge the batts so removing the grounds is the best way. DO NOT TRUST A SHOP TO DO THAT EVEN WHEN YOU ASK. Get it in writing if it'll be at the shop long. They don't care if they ruin your batts, in fact seems to me that they enjoy convincing customers that they just went bad and they need to buy new ones. And that it's not their fault at all.

Rkesselus · 02-14-2019, 09:11 PM

I would start by jumping the Chassis Battery(s), start the engine and it will begin to charge everything. Also applying a charger to the House batteries will not hurt anything. If the batteries are at zero some automatic chargers may not start charging until there is some voltage in the battery. I would make all the connections directly to the batteries. Depending on what generator you have it might be possible to jump directly to the generator solenoid or the the starter itself. Jim is correct about the draw on the batteries while in storage if they we not disconnected at the battery or if you have a disconnect switch sometime called a salesman switch. Good luck Before you start purchasing new batteries I would suggest you have a load test performed if you get then to charge up to 12.8 volts or more.

chunker · 02-14-2019, 09:23 PM

Quote:

Originally Posted by Rkesselus

I would start by jumping the Chassis Battery(s), start the engine and it will begin to charge everything. Also applying a charger to the House batteries will not hurt anything. If the batteries are at zero some automatic chargers may not start charging until there is some voltage in the battery. I would make all the connections directly to the batteries. Depending on what generator you have it might be possible to jump directly to the generator solenoid or the the starter itself. Jim is correct about the draw on the batteries while in storage if they we not disconnected at the battery or if you have a disconnect switch sometime called a salesman switch. Good luck Before you start purchasing new batteries I would suggest you have a load test performed if you get then to charge up to 12.8 volts or more.

My truck might have enough battery to start the ISL but pretty sure the jeep wouldn't. Truck is the Ram diesel with 2 batteries. That's why I was ask g about starting the generator first to put some charge to the batteries. I'm pretty sure either the truck or Jeep would start it but not sure where the proper positive lead might be. I figure any ground should work. I have a load tester but of course need to hav eat batteries charged too do a proper load test. When I went out to the coach today the house battery disconnect may have been off. I'll check it tomorrow. Unfortunately I'm on the motorcycle in the morning and SURE it won't jump it.

Jim_HiTek · 02-14-2019, 09:38 PM

Many RVs the battery switch(s) (aka salesman's switches) still don't disconnect some phantom loads from the batteries.

If you plan to try to charge up the batteries with that low of voltages, you might take some restoration juice and distilled water with you and service them before trying to charge them.

chunker · 02-14-2019, 09:44 PM

Quote:

Originally Posted by Jim_HiTek

Many RVs the battery switch(s) (aka salesman's switches) still don't disconnect some phantom loads from the batteries.

If you plan to try to charge up the batteries with that low of voltages, you might take some restoration juice and distilled water with you and service them before trying to charge them.

Plan is to in the morning ride over and see what starting the generator might entail. I wasn't expecting the thing to be there this long. The shop might have the ability to jump it. I'll check. But yes I'll check the batteries but as I remember the chassis 2 are maintenance free so no water to check. I can check the 3 house ones though. If the shop doesn't have the ability to jump the generator I'll go home and get the truck, some distilled water and give it a try. Hopefully the positive lead will be easily accessible.

chunker · 02-14-2019, 09:55 PM

I did some more searching online and there are comments about jumping the generator battery. I presume that is in reference to a free standing generator not one in a motorhome. Unfortunately those comments were in a motorhome discussion but can't believe everything you read online. Maybe tomorrow will answer some questions for me.

twinboat · 02-15-2019, 05:26 AM

If your in a repair shop, that should have a battery charger to hook up for a hour or so. That should get things going for you.

If they don't have a charger, the reason to jump start the onboard generator is because its a much, much, smaller engine and will be easier to jump start with cables or a jumper pack.

It may need 100 cranking amps, not 700 or 800 CCA that the main engine needs.

Once it starts, leave the jumpers on, to support its running until the auto transfer switch engages, and the inverter/charger starts charging.

It may take a while, 1/2 to 1 hour, to get the house batteries charged enough to use them with the boost switch, to start the main engine.

funjnt · 02-15-2019, 06:10 AM

I would jump the house batteries for a bit and start gen. Then I would use one jumper cable and connect house + to chassis + and let them all charge off the generator or the house inverter charger for an hour at least. Get batteries to a safe spot and see if you can pull coach close and plug in and let charge overnight. Or run regular cords to coach and just plug in let it charge on it's own overnight.

Busskipper · 02-15-2019, 06:24 AM

Quote:

Originally Posted by drwwicks

The motorhome has been in the shop for some minor body repair and hasn't been started in several weeks. Today I went to get some stuff from it and ALL the batteries are dead. Chassis batteries showed 4.9v and got nothing from the house. Don't know if something was left on or what. Chassis batteries are 4YO so I was expecting to replace soon anyway and possibly upgrade to 6V for the house. Course I can't start or anything. Figure to jump start the generator, run for a while and see if I can bring back some temporary life to the batteries.

Where is the best place to connect to jump the generator. Cummins Onan 8kw diesel. Generator is on a slide out tray and frankly I haven't looked in the past at the electrical connections.

Either set, pick one, if it doesn't start right a way then leave jumpers hooked up to charge for an hour or so and give it an hour or so, then it should start right up.

Clean all the windows or wax the front, do something and it should charge up, the time will pass faster with a project - and it will likely take some time.

JMHO,

Or - as many say - just ask the shop to provide an extension cord and a charger to correct an issue they Likely Caused.

z3406 · 02-15-2019, 06:34 AM

Is there some way you can run an Ac extension cord to the coach? Plug the coach into external power for as long as it takes to charge the batteries with the built in battery charger. All you need is a standard wall socket and the adapter to convert that to your RV plug,Hopefully you already have the adapter.

bigchick · 02-15-2019, 07:01 AM

exactly what z3406 just posted. plug the mh into an extension cord and leave it overnight. give the converter a chance to see if it can recover something into the batteries.

you can jump start the generator using auto style jumper cables. just connect them to where the incoming cables from battery connect to the generator. once started you will have to leave them attached until the generator actually starts to output 120vac power and the transfer switch connects to the generator. at this point the converter will be making 12 vdc power which the generator can then use to continue to run. then you can remove the jumper cables.

fairway2002 · 02-15-2019, 07:15 AM

My MH's inverter/charger will not come on if battery's are dead,dead. Needs to see some DC voltage. I had to put a charger on house battery so inverter/charger would kick on. Then remover charger.

Good Luck

Jim_HiTek · 02-15-2019, 08:58 AM

My old '94 was like Fairway2002's RV in that the main battery relays wouldn't operate if the batteries were too low. So the converter would not come on. Had to jump the house batteries for an hour, then the coach batts for a half hour, then started the genset and let it run for an hour. This after servicing the flooded cell batteries.