Dual Battery Gremlins

Torq

Observer
Primary Battery:

Factory 2017 RAM Power Wagon Battery



Secondary Battery:

Bosch 151R340B

CCA: 335A

CA: 400A

Group: 151R





Battery Isolation: National Luna

Wired in Configuration 1:





I read this - lots of interesting issues, but didn’t see one like mine:






First failure: I installed the secondary battery, National Luna split charge system (config 1), and some camping lights mounted to the roof rack immediately prior to a trip through Arizona and Utah, which involved a lot of high speeds on washboard roads. I have the battery sitting on one of the divider platforms, and after some of the rougher roads, it dropped down a few inches into the deep section of the RAMBOX. The battery was ruined after the first trip, and I first thought it was from the impact of falling. I brought it to the auto parts store just to confirm; it held 0 charge. I later determined there was a faulty ground for the secondary battery. There was less than 12V from (+) to (-), and there was excessive impedance between ground post and chassis ground point. Found a new ground point and battery was reading 12V. I’m not sure if that was the cause of the original failure or not, but I found it in the course of the installation of the new secondary battery.



Fast forward 5-6 months and I had a second failure: From the install in December, everything (which was just LED rack lights at the time) seemed to run fine. I checked a couple days ago and there was 0 charge (0V) on the battery. During diagnostics, I found there were no indicator lights on smart solenoid, and the remote won't enable manual linking, although it gives the audible report after holding down the winch override for 3 seconds. I reset the solenoid by disconnecting the black wire coming out of it. Still no change.



Trying to determine why it might have failed, I’ve thought of the following:



  • Between DEC and now, I've run winch. Can high current hurt a small battery? 100A fuse between the primary and solenoid seems fine
  • The secondary battery is significantly smaller than the factory RAM battery. Could the high charging current from the alternator hurt the secondary?


In both cases the secondary battery was chosen for the dimensions. I’m housing it in the RAMBOX which, other than the failed batteries, has worked great so far. The battery, relays, and switches all mount great in the RAMBOX, especially with the dividers.



Note: pictures are from the first battery install, which was a slightly different group size.


DSC_0618.jpgDSC_0617.jpgDSC_0615.jpg
 
If you are USA based.

I’ve had very good luck using the Hellroaring isolators. Their isolators are solid state, do not use diodes, have next to zero voltage drop. The company also returns phone calls. Located in Montana. Been building solid state isolators for over 20 years.

https://hellroaring.com/
 

Torq

Observer
If you are USA based.

I’ve had very good luck using the Hellroaring isolators. Their isolators are solid state, do not use diodes, have next to zero voltage drop. The company also returns phone calls. Located in Montana. Been building solid state isolators for over 20 years.

https://hellroaring.com/
Hellroaring looks like a solid company. I had a good experience with my first National Luna setup in my last rig. Worked pretty flawlessly until water got into the control circuitry so I tried it for a second go round. Not sure if the National Luna is the issue this time or not...

Would appreciate input from anyone with experience using these smaller batteries. Even if the solenoid failed, I wouldn't expect the secondary battery potential to drop to ~0V.
 

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fratermus

FT boondocker
Could the high charging current from the alternator hurt the secondary?
The battery will only take ("accept") what it wants, so having too much current for it is not an issue.

Sounds like two batts and the isolator have all failed, right? Maybe excessive heat or vibration? AGM like the bosch are typically tolerant of vibration because of their internal construction.
 

Torq

Observer
The battery will only take ("accept") what it wants, so having too much current for it is not an issue.

Sounds like two batts and the isolator have all failed, right? Maybe excessive heat or vibration? AGM like the bosch are typically tolerant of vibration because of their internal construction.
Just the National Luna smart solenoid and the secondary battery have failed. Primary seems fine.

I thought that it might have been vibration that killed the secondary battery the first time around, but now with the replacement secondary battery dying and the national Luna dying, all with only highway driving, I can't imagine vibration plays a role.

Sent from my G3123 using Tapatalk
 
Last edited:

MOAK

Adventurer
A lot of folks don’t care to wire it all up the old fashioned way but that’s exactly how I do it. I use a Blue Sea manual switch. The only failure point would be me, forgetting to switch it on or off. Years ago I was in -35f up outside of Halifax. The company truck I was in had 6 house batteries to run the bunk heater and lighting. I woke up around 4 Am, cold, really cold. I got all my winter gear on and walked about a mile to a hotel lobby. Called service and they had to tow the tractor to a shop to get it running again. Lessons learned? For my personal vehicle, manual switches do not fail. For company assigned power units? To the dismay of management I refused to adhere to the “no idle” policy when in cold weather. Yea, popping the hood and manually turning that switch is a pita, about as much of a pita as checking my fluids each day.
 

Torq

Observer
Well, I owe an update.

I went ahead and replaced the failed battery and the NL smart solenoid and monitor started working again. Secondary battery has been healthy for 3 weeks. The odd thing is, that none of the indicator lights on the smart solenoid worked and the manual battery link didn't work until I replaced the failed battery. Makes me wonder if the smart solenoid has a feature to protect the primary battery against a drained battery even when the manual override feature is engaged.
 
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