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BMS required for 12.8v 4s3p headway pack?

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As I learn more and decide on the goals for my EV I keep changing my mind on batteries/motor/controller. This week I'm looking hard at headway cells because of the increased performance for the same price as a TS/CALB pack but with reduced range. My commute is only ~12miles each way and I can charge at work and even the headway pack should give me 50-80 miles at 80% which is probably more than enough, and it provides 2-3x the peak power of the TS/CALB pack. And for this project power is more important than range. The Headway pack is also lighter, so I could add more cells at a later time if I needed more range.

Since I will be ordering tons of cells and probably a few extra in case I have a bad cell or two, I thought about replacing the LA 12v battery with a pack of headway cells. Maybe a 4s3p type pack that would be "charged" by the dc/dc converter. Would this need a shunting bms, or simple voltage monitoring or nothing at all?

I will be building my own bms for the main pack that measures the voltage of each cell in real time and show me the high cell, low cell and average of all the cells. I'm sure it wouldn't be too hard to extend this idea to the "12v" battery but I'm wondering if it's required? The dc/dc converter would probably be set to about 14v which is 3.5v per cell (if they're equal of course)

Remember this pack would have minimal draw unless the dc/dc converter failed or can't keep up with the load. I won't have a power steering pump, I'm switching to a manual rack, so just the usual car stuff, vacuum pump, stereo will be on the 12V line. Having no 12v battery isn't an option so it's stock or something like a headway pack.
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Please find the link. Its nothing but a rumor unless you've got some proof to back it.

I've been working with headway (buying, selling, testing) for almost 2 years now and haven't seen that once. The only time I saw one even catch on fire was ignited by a heatgun, overdischarged and shorted and it was done on purpose to show how non-volitile they are and what it actually takes to make them fail.

Lifepo4 doesn't explode, lipo does.

I seriously doubt that what you saw was a headway.
 

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HAHA, yeah I did see that.....

but that is a situation that will NEVER happen.... I mean, when are you EVER going to charge a single cell at 24V .... that's way over its rated 3.7V max charging voltage. The rated charge wattage is what, 3.7V x 60A (6C) = 222W. He was hooking to a charger that could go over 6x the voltage and 50A, and potentially charge it at 1200W.

And he Admitted he blocked the disks on one of them at least, which doesn't allow it to rupture correctly.


Lessons:
Don't overcharge a single cell at 6x its voltage.... duh
Don't block the pressure disk at the end with the screw/bolt.

Now, a cell, being used as it is designed (with proper clearance of bolts/screws) and never being allowed to overcharge in an extreme manner, will not explode.

I've overcharged these (accidentally) to 4.5V and yeah, it got hot, but never exploded. The cell didn't like it and never had the same capacity, but it did not get physically damaged in any way.
 
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