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Battery Boost Not Working

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TXheat

RVF VIP
Joined
Jan 6, 2021
Messages
283
RV Year
2003
RV Make
Holiday Rambler
RV Model
Endeavor
RV Length
38
Chassis
Roadmaster
Engine
350 Cummins
TOW/TOAD
None
Fulltimer
Yes
The battery boost is not working batteries got drained and tried waiting a good long time for it to show charging from the boost and it did not charge, I have had to put the batteries on a charger. I checked the ausillarynstart fuse and it’s fine. I’ve narrowed it down to the relay solenoid in this picture. I read in another forum, that if you hit the solenoid with a hammer it might free up because they tend to get stuck, I tried that and no change, I went ahead and ordered a replacement and I’m hoping that this is reason the battery boost isn’t working. Has anyone else had an experience with that and it being related to the relay solenoid? Thanks.
 

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How old is the battery and what is its current state of charge? If too low, some recharging equipment can't do much to get it started charging.

Rick
 
How old is the battery and what is its current state of charge? If too low, some recharging equipment can't do much to get it started charging.

Rick
 
As far the age of batteries there is a 9/23 sticker so not that old, there 2 in parallel sitting at 11.8 V got them on a charger at the moment.
 
Last edited:
I not sure I am thinking og the same switch. Many coaches have a boost switch which temporarily connects the chassis and house battery
Irs in the event the chassis battery is too weak to start the engine. Is this the switch to which you tefer or do you have a special charging seitch?
 
I not sure I am thinking og the same switch. Many coaches have a boost switch which temporarily connects the chassis and house battery
Irs in the event the chassis battery is too weak to start the engine. Is this the switch to which you tefer or do you have a special charging seitch?
Yes that's the switch that I was referring to and the biggest reason that a battery boost would not be working is because the solenoid will usually stick or get damaged if the battery boost is used persistently, that's what the manual says anyway. So the batteries have been on a charger for some time now currently sitting at 12.78 and that's with the cutoff switch on, also tried an engine jump start feature, that the charger has It's a 15 amp charger and it did start, but two things, 1 It didn't continue running It died and two there is a warning light by check engine and the check engine light came and went, so there is a Cummins diagnostics port on here and so I went ahead and I bought a Cummins diagnostic scanner on Amazon should be arriving on Friday, to find out what the heck is going on. In the meantime any insights? This seems to have gone from bad to wors, once I know more I'm most likely going to bring in a professional because I'm probably over my head if there's a engine related issue. Thanks


over my head depending on what the verdict is.
 
I know that in my case there is a minimum voltage for battery boost to connect. Don’t quote but I believe it is somewhere around 11.5 volts.
 
The first stage in troubleshooting a battery powered system, is knowing and fixing any battery issues.

A 15A charger is a trickle charger so plan on a wait.

Boost won't do much if the coach chassis battery has problems. Other than drain the house batteries.

Separate the batteries, not an option if you want to know they are good, and the drain is coming from the rest of the circuit.

You can fiddle around with your time, or grab the meat! Should be self explanatory!
 

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