so I bit the bullet and decided to try the lithium replacement cells.

they showed up today, and since there's almost no info on using them in these trucks, I figured I'd start a thread in hopes it shows up in searches for anyone that has questions. good or bad, we shall see

my truck, it's a 2011 yukon denali 4wd with 135k on it. had it about 6 months. I knew the battery would need replaced so no biggie, seemed kinda cheap really. Older truck but I find myself enjoying driving it more than I thought I would but it's mainly a soccer mom mini van with a tow rating for me at least that's the idea, while I daily the volt and weekend the vette.

​​​​​​so far I've changed the headlights, I dislike the factory yukon lights, i went with the Morimoto LED lights. they are a drop in DOT replacement made to look like the next model up. that's there thing, like they make c6 corvette lights that look like c7 lights, stuff like that. makes the truck look less dated to me, expensive at 900$ but the ebay stuff is just awful. I've replaced the fog lights with bi-led projectors as well. all wired so they go high beam with the headlights. very nice light setup for the middle of nowhere dark roads while keeping a crisp cut off to not bother any oncoming traffic. the AFM is always a bad thing on these trucks. this one still worked, and the engine looks very clean inside and runs well for what it is but I've turn it off with hptuners, and pulled the intake to do the mechanical bypass as well. still would like to ditch the factory exhaust someday for something turned for mid range scavenging now that I don't need to worry about the v4 drone. I saw a thread on a forum somewhere where a guy put a new intake air filter housing and duct, he said it picked up a few mpg. I'm not sure I believe it. but I still kinda want one haha

I'm sorta a mechanic my trade, but maintenance mechanic, not a flat rate shop guy. did electronics school stuff years ago, but forgotten all of that haha. so I don't deal with repairing the latest and newest cars. all my stuff is older. we do have some electric equipment, with more on the way and just now switching to lithium in the next batch. older stuff is still huge lead acid batteries. so I have access to some decent equipment to test out any questions. but nothing to crazy like meggers. so I can't test the internal resistance or anything.

all 20 packs showed up in good shape and packed well. box said 69lbs on it. all tested at 16.29v unloaded with my cheap home volt meter.

my oem pack has officially took a bad turn in only the last few weeks, I'm sure it was hurt, but it fell off a cliff. I need to get a log of the old. pack before taking it apart, if I can even get it to auto stop one more time but quick glance today on my phone with torque showed over a 2v difference between some cells and that was just idling engine running with the ac on. I'd say none that pack is useful lol. they do offer a program now to return your old cells for recycling, I believe you get back a little more than what shipping costs. so that's nice of so, I thought I might set the oem stuff aside incase there's a failure but they seem to far gone for that. if these fail or give me trouble warranty doesn't cover I'll just have to order some used prius stuff and let it eat them alive in a few years use haha.

the lithium cells themselves say 16v and 7AH. I thought I had seen 6500ma in one video of a prius install. not sure if that's new. or different for the trucks or just a sticker. I don't really wanna open one at this point to check, but I will open one if there's a good reason down the road.

so basically any questions along the way, any tests I can run to get some info out there, cause to be fair. basically every one of these trucks needs a new battery by now or very soon. and man do they run like crap with a failing battery pack. gm should probably have just shut the trucks down much sooner than they do before you damage something, it can't be good for it.
I usually keep my old beaters around a good long time, and from what I read these trucks are way harder on its battery than the prius is. might be a good torture test for them and I can try and log stuff along the way.

I'll add some pics along the way. this should be interesting.

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This will be a great test of these modules. The GM hybrids use these batteries way more aggressively than they're designed for, and it will be interesting to see how these hold up.

 

just who I was thinking of, besides the load test when the ac on I'll get a log of soon, wanted to grab a better scanner from working hoping for a faster refresh. anything else I can do. to get some useful data?

I think you'll get a laugh out of how bad this pack is now haha.

 

If you're measuring 2V at idle, I wouldn't bother. I don't find any of this funny. The pack management is so bad, it's a crime. On the rare occasion I get one, I don't even bother anymore. When 38 modules test at ~600mAh and the ends get as high as 1500mAh, it's not worth the effort.

Beyond NiMH used in hybrids, I have pretty extensive battery experience including the LFP chemistry used in these Lithium modules.

You didn't ask for my opinion, but I can't help it. I'm going to be blunt. I regard the product as woefully deficient. Max braking in the vehicle will ROUTINELY push these modules above recommended voltage regularly.

Due to the absurdly flat voltage curve of LFP, I expect the initial performance will be exceptional. The downside to that is the system will utilize a much larger % of the total capacity. Use more capacity, and you shorten cycle life. Lastly, NiMH has more robust high temp longevity, and the cooling system of the GMs are known to be marginal at best.

If you drive this thing like an SUV in a hot climate, I'll poo my pants if these things show no signs of degradation after 1-2 years. If you drive them like a Prius in a mild climate, they might last as long as a new NiMH pack.

 

yeah, I'm good with it, no worries.
it's more of a let's see how this works kinda thing. my thinking is eh, go buy a oem battery and I know it will be dead in what, say 80k miles at most? I keep stuff a long time, my 96 has 325k on it so my guess is I'll have it long enough to kill a new oem pack too.
I did ask if anyone had run these before in a suv that he could point me to, he gave me a dudes email with the dodge version of these. he said it's been a few years and running good. but who knows what that means, and maybe dodge did a better job with the battery management.

my wife drives it much harder than I do, she's got a lead foot. I can keep it from bucking to much, she drives it and it struggles badly as is. so it will get driven as a normal truck, and south tx. so it's not the hottest, but I'd say it's a hot ish climate. since you have experience with these type of cells, any thoughts on what kinda Temps would be to hot or cold for them while driving? just something to an eye on with tq.

if these fail miserably in 2 years, I won't be upset. less then 2 years we'll see how good the warranty is. got some road trips planned and hopefully some towing of a car trailer with it.

I am curious about the battery cooling mods. kinda annoying I can't adjust fan speed with hptuners the radiator fan in other cars is super easy to adjust. these trucks almost no support for the ecm and zero for any other module. don't really want to mess with the system to see how it holds holds of stock cooling, but also I do. enjoy modding things, so if there's a simple way to add some cooling, be hard not to.

 

quick log with torque just for the heck of it. it was actually driving pretty good today after sitting a day. 2 days ago it was really bad, even in M4 mode it didn't seem like it wanted to charge up the soc at all, total battery voltage in the 260 range and oddly all the Temps were sitting at 94deg. this time they actually got some temps in them and were showing more assist than I've seen in a while. weird. it is crazy how much better these trucks feel when the battery is helping, when it's struggling they are super laggy. feel like a 90s turbo car before boost kicks in. I guess that's part of over using the batteries and all

your post about max voltage got me thinking, so quick Google search, which I know isn't alway reliable. shows these type of cells being happy fully charged at 3.5-3.6v but will accept up to 4.2 but anything beyond 4.2 will damage them. my quick math, 4.2v x 5s = 21v per module. with 3.6 x 6s = 18v. I've not seen over 18v but I have also not gone down say a long mountain road to top out voltage. it does leave me wondering where the top is. I get there's a max charge rate too, usually 1c from my understanding if you have them on a charger, with them being 7ah and I've seen 50amps charging for short burst under braking.


OK enough babbling, I need to get these swapped out over the next few. days.

 

I've seen 70-90A charging on Prius depending on state of charge. I don't recall charging on the GM, but I recall 220A on a medium-hard launch (traction drive + engine start).

They're 5S, not 6S.

I've seen over 20V.

3.65V is a healthy limit. A lot of cycle degradation occurs at 4.2V. It's a pretty steady worsening from 3.65 to 4.20. Above 4.20, and the electrolyte breaks down.

Plus, If you charge LFP below freezing, you plate the lithium to the terminals permanently reducing capacity. You can get down to about -20°C with Yttrium doping of the cells, but I don't know if they use that.

Had they made an effort to spoof the BCM so that the car would manage the LFP as it needs by simulating NiMH values, I would be telling a completely different story, but they would need a different system for each model car. They took a short cut and went with drop-in.

 

batteries are in.. it was definitely needed, from the first crank it fired off much cleaner if that makes sense. I'm sure a oem battery would have been the same thou too, so that's not specific to these.

the factory battery had nickel plates bus bars, I didn't know they did that. they still had a decent amount of corrosion on them thou. I replaced them with new bars and nuts that jack from Nexcell recommended, and used a thin layer of No-Ox-id grease on everything. it's like a conductive Dielectric type of thing, he said he's been using it. so figured it can hurt.
also once I cleaned off the green stuff, the 2 crimped thermals that run to the battery safety plug. they offer a solder service for the prius stuff, so I went ahead and did mine too. probably won't make any difference, but I was there and have a huge soldering iron I haven't used since rc battery thermals haha. mainly wanted to make sure I wasn't the cause of any failures.

anyways, quick test drive, truck felt great. will drive it for a week and then do one of the torque pro load tests just to see and have a base line. long term will be interesting.







the cooling system for these batteries just looks bad. holy crap lol. mine had hair in the grill and between the cells themselves. no clue how it gets there, there's hardly any airflow and it's completely hidden behind plastic stuff. I was going to back probe the fan wire and see what kinda signal was being sent to it and returned from it with a scope, but honestly it's crap. fan runs off like 20g wires, there's no hope for that thing mod wise. I thought it was basically a under dash blower motor, it's not at all.

anyways here's hoping these last a while and become a decent alternative to stuff like green bean type referbs, that while have a good warranty on paper, I've seen some posts where they only warranty them when like a prius gets a red circle of death, where on these trucks gm has coded to allow such horrible batteries, you have a hard time proving the battery is ready to be replaced under warranty. but that's just what I've seen in comments, I've not bought anything from them.

 

yeah, 5s. typo saying 6s.

I'll look to see what kinda voltage I see while driving around. gives me something to look for.

 

Wouldn't hate a Torque log... maybe blocks 1, 5, 10, 15 and 20 along with current and SoC?