Aux Battery Swap for H8 Main Battery

[rpr]

Well, I swapped the batteries and all was fine until the 2nd or 3rd restart. Got to destination but the CEL is back on and running volts are back up to 16V.

Seems like an alternator issue. Guess I’m off to the dealer unless anyone else has experienced this and has any ideas.

Anyone know if the code readers at Harbor Freight work on these trucks? Don’t know much about code readers.

 

[Eighty]

Anyone know if the code readers at Harbor Freight work on these trucks? Don’t know much about code readers.

OBDII is standard/universal across all platforms, so it will be fine.

 

[gram10]

Proceed at your own risk. My truck is L2+, which does not come with a PCR (therefore no F52 fuse).
I went back and re-did my AUX removal to fix my previous mistakes.
Seeing as how from everything I found the L2+ trucks don't have a PCR or fuse that can be easily bypassed, I went with my original approach.

I tied both IBS from main and aux - to the negative battery terminal, in my original removal I didn't realize i tied the aux battery - IBS to the main battery IBS output, so the main battery IBS was measuring the current draw of both which is what was probably causing my charging voltage to be 14.8 all the time. This was a mistake on my part. With this new method my charging voltage is 14.4 on startup and then drops to 13.8-13.9.

I then used a 50A fused wire link to jumper N3 (AUX Battery +) to N9 (Main Battery +), and disconnected the original N3 wire that runs to the AUX + and heat shrunk both ends just to keep it clean.

Everything is working as expected, with no OBD codes, and start-stop works also (although I will keep it disabled).

I used this to tie both IBS. https://www.amazon.com/dp/B09W24MCHD?tag=ramrho-20

Until a better, proven method comes out for the L2+ trucks I'll keep using this.

Is this still working well for you?