Elcat Lithium Conversion EP3: Charger woes & BMS v. 0.01

With the cells now mounted, we reuse an old project PCB to talk to the Tesla BMS measurement boards. The original Elcat charger runs into an unfortunate end, and I construct an unspeakable abomination to take its place for the time being ...
Throw money at me: / ffcossag
Music, when applicable, supplied by combatplayer.b...
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[@sarkybugger5009]

Like London busses, you wait for ages, then three come at once... That must have been an impressive pop when the PSU let go.

[@HDXFH]

Foomph

[@pjtruslow]

I love your charger you threw together. It's great to see more videos from you, you've inspired me to do some projects of my own. I recently picked up a SMT750C used, and was hoping to tear it down and adjust the float voltage through J606 with the hidden smart protocol, but it almost seems like APC fixed their battery float issues this time. It is a multi stage charge and the float voltage is about 13.55-13.6 volts per battery, after it first tops up to exactly 14.4 per battery for like an hour.

[@tigerelectronics5966]

I have been busy the last couple days so I just now finished watching all 3 videos of the elcat conversion :P I have a valid reason too lol, I actually went and bought a van myself, which I am going to convert into a little camper like your other van! :D very much inspired by you :D I have been working my ass off cleaning it up, it was a hunter's van so yeah it was kinda disgusting but thanks to some industrial degreaser and a lot of time and effort, it is now clean as new! I have almost stripped everything out of it in order to clean it, haha. I got a 2010 VW Caddy, and I happen to fit just perfectly lenghtwise in it :) it got extremely wet from all the washing, so I must let it vent out with a heater fan running inside it for several days before I can reassemble. I look forward to beginning to build the bed in it :) I think I will go to a similar design to yours, with 30x30mm square tubing, and some storage underneath, and also a fold-down table on the other side, that was a really good idea, thank you for the inspiration hehe :) Damn, I'm sorry about that charger blowing up, as it looked like it would have worked perfectly. I hope you can figure something out to replace it other than the server supplies, although I must say I absolutely love the look of them all strapped together into one giant charger :P I want to say that was a failing rectifier diode giving up it's last bit of will to work, very unfortunate. I might be able to help you find another original Elcat charger, I have a few ideas where I could ask around for one here in sweden. But I think it might be better to build or buy a adjustable high current supply from ebay or something, Maybe you could get or make a 3 phase one instead, which would theoretically allow you to charge with about 8-9KW assuming 80-90% efficiency and a 3x16A supply which is common here in sweden and also finland where you are :) The strapped together power supplies from servers amused me a lot, That's very similar to how I do things myself when things break lol, I take whatever I have and make it work x3 And yes! That feeling when something works on the first try is amazing! I got a huge smile on my face aswell! being able to monitor the cell voltages is great, at least now you can charge them to 70-80% which is a huge step forward compared to only being able to charge a little incase cell imbalances happen, atleast now you can monitor them :D I must say though, that was some pretty impressive carnage in the charger that blew. But not at all fun when it happens, considering that charger would otherwise have been more or less perfect for the needs :( I am eagerly awaiting the next video lol, when I saw you had uploaded again in a while I almost jumped up and down from happiness :) Best wishes from me here in Sweden :) I don't know if you remember me but I used to come on a lot and chat in swedish on your livestreams :P

[@FFcossag]

I do remember a "tigerelectronics" :) Good luck with your camper van. In hindsight, I'd recommend you do a wood frame bed rather than steel. Metal is sturdy, but wood is infinitely easier to finish and work with. I only went with a steel bed because it had to be removable - that van was also my work van at the time. The Elcat will remain 1-phase, and it will get a much more proper, modern charger in upcoming videos. In a way it was a good thing, because the efficiency of these original chargers is only barely 80 %, so you're wasting about 500 W as heat throughout the entire charge. If you can find old Elcat chargers, I'd be interested though. I'd like to have one original unit at hand in case I ever want to restore it to completely stock configuration in the far future.

[@tigerelectronics5966]

@@FFcossag YAY! :D I think I will build a steel frame anyways, because it makes taking it in and out of the van much easier in case I need it for transporting some larger items, unlikely, but just in case. But I'll see, I haven't made the final decisions on material choice yet. It would likely be possible to move a wood frame in and out aswell if I build it with enough support and not too heavy, but I am alone so it needs to be (somewhat) easy to take in and out by myself. I think I will make it modular for this reason :) That sounds awesome, And yeah the original chargers are not that efficient by today's standards so that's another great reason to use something better :) And yes! If I find one, I will definetely let you know :)

[@tigerelectronics5966]

Looking forward to the next episode a lot :D Watching your old VanLog and van build videos in the meantime, dreaming about having my van finished! :D Still got a few things I gotta do, I won't be home tomorrow but I am planning on rust proofing it with Biltema linseed oil based spray on sunday, and letting that dry for a couple of weeks before I do more :) Caddy's are sadly not known for lasting too long untreated, so I wanna try to preserve it to the best of my ability :)

[@twocvbloke]

When the electrickery pixies want out, they'll certainly leave their mark when they manage to escape... :P

[@FFcossag]

Yep. I had just put the car on charge and was walking away, when I heard a "fwump" noise, followed by a veritable smoke screen coming out of the cooling fan. Rarely have I moved so fast in my life, I thought the batteries were going up ...

[@twocvbloke]

@@FFcossag I bet, I've not experienced a lithium battery fire (thankfully!), but those cells, when they go, they REALLY go... :S

[@davidistesting]

I can smell that burning from here.....!

[@HDXFH]

Coming up quite well

[@FFcossag]

Thank you, the project has generally gone much better than expected.

[@WickedEngineer]

never ever played with the idea to series up pc power supplies. that might get me out of a situation in the future :D

[@Chriva]

Wow. That was one highly tuned PSU. Must've gone into complete suicide mode given the extensive damage?

[@FFcossag]

I suspect the cause of the failure was that a washer had cut into the PCB trace and severed it. Once the trace gave way completely, the output diode shorted, and it ended up with a dead short on the output. The cut trace was the weakest link, so a giant arc formed when it tried to short-circuit the battery.

[@tigerelectronics5966]

@@FFcossag That makes sense, and that explains the severity of the damage aswell heh, tesla battery VS PCB doesn't go very well :P

[@David-wh8zs]

About the back feed protection: Have you considered what happens when the v.2 charger loses power during the charge? I'd assume you'd get the same random voltage problem because the PSUs might draw different amounts of current when you back feed them.

[@FFcossag]

V.2 charger?

[@David-wh8zs]

@@FFcossag I'd call the original V.1 The new PC PSU charger V.2 And the ominous charger that hasn't been revealed yet V.2.1 or V.3 depending on how sketchy it is

[@FFcossag]

Ah. Yes, I did consider what happens when it loses power: It blows up! :D

[@SuperBrainAK]

🤣 How did you get the idea to put all those PSU's in series? I know I've done a similar thing, I made a triple output PSU with 8 Dell 90W laptop chargers stuffed in an ancient (Pentium era) 6U server PSU case. It is configured as a 2S2P 360W 39v + 2S1P 180W 39v + 2S1P 180W 39v So in theory with all but the 360W floating from ground I could wire them all in series for a 540W 118v 4.5A supply 😆⚡💥

[@FFcossag]

Ah, 4,5 A at 118 V. The most specific power supply ever cobbled together, hehe. When the Elcat charger blew, I happened to have a bunch of old PCs lying in the trash. One late, caffeine-fuelled night, I just asked myself if it could be done, so I did it just to find out. "Can you charge an EV with old PC parts?" I kind of picture myself as being lost in some desert wasteland, trapped without a charge, and forced to cobble something, anything, together in order to get out of there, hehe.

[@SuperBrainAK]

@@FFcossag Haha! Hey it didn't cost any money so why not? Certainly worth the time to learn a skill. I avoid buying parts as much as a I can when putting a circuit together. I have so many old circuit boards I can usually find what I need. I only regularly buy big mosfets (IRFP260N) and low-ESR electrolytics since most capacitors are low quality or only rated for 16v or less.

[@semifavorableuncircle6952]

I might have a few compact, efficient (~95%) and adjustable (~23-29V) 24V/40A PSU that would have a current limit that i could sell cheap.

[@FFcossag]

Thanks, but I've already sourced a new charger for it. Mean Well released a new series of very nice and surprisingly cheap 1700 W chargers, just in time!

[@tigerelectronics5966]

@@FFcossag That's more or less Perfect!!! :D

[@brookerobertson2951]

@18:41 to funny..

[@kwils6685]

I don't know exactly what information you're interested in for the Elcat but I did find in a thesis, what appears to be a wiring diagram labeled as this Subaru Elcat 1995:n kytkentäkaavio if you're interested. Nice seeing you making some content again, it's always something interesting.

[@FFcossag]

Very interesting! If it's a 494 kilobyte barely-legible PDF, then I already have it as of a few days ago. If it's anything else, I'd love it if you sent it to [e-mail] Thanks for looking no matter what!

[@kwils6685]

@@FFcossag I mailed to you, I had to send it twice, I cc my outgoing email to myself and when I looked at it the second paragraph wasn't showing??? But it is there if you highlight it. Weird!