Diesel Batteries/Electrical

[Felders]

I keep thinking I’ve gotten my electrics figured out and then my batteries go bad. It’s such a pain to pull the second battery out from under the chassis. For the Diesel owners, can you treat me like a child and tell me the basics for diesel RV batteries? Is there something I need to be doing to keep the charge up enough to start up after being in storage (no electricity) for 5 months?

I tried jumping off a non-diesel battery and have a little (probably too small…it was a gift) jump starter but couldn’t get enough juice to start. Took them to get tested and both tested bad.

Also, when I turn the key before cranking, my gage shows about 12 volts then after 1 minute rises to 15 volts. I’ve read this is just the glow plugs. But when jump starting today I showed less than 8 volts on initial turn and then 15. Is this any indication of 1 battery being bad versus the other? Or is this completely normal?

Also my house batteries are dead. I’ll work on them once I get the chassis batteries figured out and can get the coach home. But I’m sure I’m doing something wrong with isolating while in storage.

[Felders]

Sorry didnt give the details:

Eric Felder
2001 26RB Diesel
Texas

[Hugh]

Hello Eric,
I have a 2004 24RB with the 6.0L diesel. When I put the motorhome in storage I did not disconnect the batteries, as there is no easy way to disconnect them. After the motorhome was in storage for a couple of months or longer I always had to charge the batteries to get the motorhome started. So I crawled under the motorhome to see what I could do. I found the negative wires from the batteries went to the frame. It was just one bolt to disconnect them. So now when I put the motorhome in storage I disconnect the negative lead to the batteries and I have not had that problem since. I have planned on installing a disconnect switch for the start bank, but it has been several years and still no switch. So I just crawl under the motorhome & disconnect the negative. (Both the start batteries are under the motorhome)
My house battery bank died a couple of years ago and I upgraded to lithium batteries. I installed 2ea: 100ah Battle Born batteries. That was the easy part. The 120vac to 12vdc charger also had to be replaced. Battle Born sells everything needed to complete the change. I also added a 30 amp 12vdc to 12vdc charger for charging the house bank from the engine alternator. When the house battery bank was charging from the engine I noticed a voltage drop when the engine was idling. I suspected at idle the additional 30 amp draw was overloading the alternator. After the alternator failed I decided that I was correct. With the new alternator I also added a switch at the driver’s seat to control the paralleling solenoid. Now I only charge the house bank when I am on the highway.
I have also installed a Victron BMV 712 battery monitor. It shows battery state, plus current into or out of the batteries. It makes monitoring the house bank easy.
I have found the lithium batteries far better than the old lead acid batteries, and I am happy with the new system.
I did the installation of the new 12 volt system. It is involved, but straightforward if you are comfortable with electrical work. I have a good label maker & I label all of the wires.
As for the alternator failure, I believe it was the original alternator, and it is possible it would have failed anyway. But I think it is asking too much of the alternator to charge the house bank at idle. The cooling fan is not providing enough air flow to keep the alternator from overheating & burning up.
Good Luck!! Hugh

[John S.]

I will say it this way that the alternator is a maintainer of charge not a charging system. I know in my big class A after boon docking at night I would start my generator and let it charge the battery bank as the alternator could not charge that much without burning up. Now, when I ordered my coach that BF closed before it was built, I added and extra alternator for that very reason but alas I do not have that now. I am thinking of seeing if ford. can retrofit my current f550 to put a second one on. That said if your house batteries are way down you might do better starting the generator than trying to charge them with the alternator.