Factory battery ongoing issues

[Jmitchelltfo]

Try manually resetting the BMS. The truck does track the age of the battery as a variable and the manual reset procedure makes it think it got a new batt and changes its behavior. No reason a 12.7+ voltage should be triggering a service charging system.


I bought another battery tray off ebay for $50 delivered as it was unknown territory cutting into the tray itself to make that fit. LFP battery life can degrade quickly if charged below freezing which is why I've not really suggested people to go LFP aux route due to the varied winter conditions seen across the US. That battery is touching the lid -- its fit is tight, but the lid closes / snaps in. if it was 1/8th inch taller it wouldn't close.

You could use an H8 if you pull the battery isolator out of the battery tray and just leave it chilling next to the battery under hood. The wires are sufficiently stiff to keep it in-place. Wouldn't be hard to secure it if desired -- I didn't try. The LFP affords me a 'free' 25ah worth of reserve capacity before the under hood AGM starts to get consumed which is quite considerable. Can't speak to the long-term effects of this arrangement though. Keeping the AGM at 100% is supposed to have long-term negative effects but I'm not sure when they'll show up. It's only used for starting the ICE while moving in hybrid mode so even if it degrades to 70% health it still might not show up.

Running two Audison amps with 1/0 wiring will probably be taxing on the factory battery. I was hoping to run an upgraded battery and had already considered the H8 option when my H7 needs to be replaced. I will also be replacing my aux battery and live in the Ozarks, so we don't have frigid temps very often (had maybe 30 days below 32 F last winter).

TL;DR I'd just like to run a reliable auxiliary battery that has some increased aH capacity. I don't really care if it is lithium or AGM, I just want it to last several years and be as reliable as possible. If that costs a couple extra bucks and takes a little bit of modification to fit, I'm ok with it.

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[HammaMan]

I've got a 2ga run back to my D5.1300 that's connected to the BCMC at the same point the underhood AGM's 8ga wire joins the party. Both the DC/DC converter and the aux batt's feed are on the same bus in the BCMC's terminals. IMO going to the under-hood AGM is a bad spot for a load like that as it's all going to be feeding back over fairly small but short wires as well as taxing the battery isolator. The DC/DC is water cooled and rated at 220 amps and delivers all of the power for the amp. When I get my truck back I'm going to probe various parts of the electrical system with the amp doing its thing to check for transients. I'd considered putting a small bank of ultracapacitors onto the bus as well for transients but I didn't see even a .1 volt delta on the scope (likely the LFP doing its thing).

For grounds I ran 2 8ga wires that combine in a block, 1 about 4' in length running to the frame and the other just under 3' long to the cab where the aux batt connects to it. The 2 8ga runs have less resistance than the 2ga run to the BCMC. The peak theoretical droop at 120 amps on 14.2v should be just ~.4v and I just haven't seen that. This as measured on a scope, not a voltmeter. The LFP has energy to feedback at 14.2v whereas the AGM does not. Voltage would have to droop way down to 13 before it could contribute anything. We'll see how the LFP handles this winter bringing its lifetime up to 1.5 winters before I could suggest it. It's neither heated nor has low-temp charging protection in it. That could lower its theoretical life from several thousand cycles down to hundreds if charged below freezing. Tests on them aren't mixed nor partial such as it sees in the truck.

Right, that's my understanding too and aligns with what I typically see. Was curious though if this dip on wake-up would trigger the "charging system service soon" message if it happened to go below 12.4 (ish) volts? It seems to do that pretty regularly so I'm not certain it would.

I wish I had a better indicator of when it was going to happen or what is causing it. Everything seems normal to me, and it occurs so sporadically.

No, no value greater than 12v should phase the truck. You may have another issue. Double check you fuses being fully inserted. Do you have anything on your OBD port? Verify your battery terminals are secure and clean.

 

[DadBald]

No, no value greater than 12v should phase the truck. You may have another issue. Double check you fuses being fully inserted. Do you have anything on your OBD port? Verify your battery terminals are secure and clean.

Good questions - I do have an OBDLink MX+ bluetooth scanner in the OBD port. I've tightened the battery terminals. I recently tapped into a fuse under the hood for my ped sounder defeat device, and I noticed that all of the fuses are pushed in like halfway. I can push them all in further by maybe 3/32 inch. This problem started when I replaced the battery though, and I didn't go in the fuse box until several weeks later. Perhaps one has worked slightly loose in the 3 years the truck has been around...

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