an other DIY electric supercharger

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WB projects

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Hey guys, super happy to see all of this! I raise my glass to Alex and his child for this forum! I start this journey this winter with a friend showing me the torqamp. I have this idea in life that I will buy it if I can't make it. so I start from scratch not knowing much on the turbo science, I just know how it work that's it. long story short, I have the chance to be a machinist and having a twin brother who know electronic a lot. So the two head combines I'm sooo clost to put it in the car! if you want to se something more in details, I can make video for you on YouTube! so there's how it look like
I will try to figured how the forum work it's my first time. thanks to alex who want to see me here!
 
Welcome! I'm glad you signed up! I'm really looking forward to your progress. One thing I wanted to know watching your video is what are the specs on your batteries?
 
AlexLTDLX said:
Welcome! I'm glad you signed up! I'm really looking forward to your progress. One thing I wanted to know watching your video is what are the specs on your batteries?
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two pac of 12s in parallel 2.9ah each. 75C of capacity! should give me a couple minutes of boost! tonight I should crank it to 100% will post a short clip here see if my esc blow up 🥴😂
 
AlexLTDLX said:
Looking forward to seeing that. Where did you get the batteries?
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get a lot of my stuff on alibaba! don't know if you are familiar with this website but there's A LOT of stuff. yes they have cheap wish stuff but you can find a lot of big brand and company
 
That's where I got my LiFePo4 cells for my "car battery." I don't think I'd order from alibaba again. One of the cells is about 6% weaker than it should be (94 ah instead of 100) and it took forever - like 4 months - to get here. At least I got a good deal - I think I paid $170 for all 4 cells or so.

When you do your testing, keep an eye on voltage drop - I'm curious to see how much drop you'll see. If it goes too low, you might hurt the cells; but LTO cells are very resilient - you can drain them down to zero a couple of times with minimal negative effects. And if you have a clamp meter for current, that's another good measurement to take. If not, here's an affiliate link to one that's a little better than the one I use - and cheaper (meaning, if you do buy one and you use this link I get a couple of bucks): AC/DC Clamp Meter - of course, don't feel obligated to buy it, but if you need one, that's a pretty solid choice.
 
thanks a lot, I will keep an eye on this! my brother have this clamp im pretty sure! I will try to film all of this!
 
well good news, don't have a lot of info for you but I've made my first test on 60%. the water cooling système for the ESC is incredible! the ESC stay icy cold during my ≈1min test. The issue I see is my 8awg wire may be not enough because they start to get warm. If I compare this to my little bench test with 6" of wires vs all my système with 6' of wires, I feel no drop of power. I will test in the future if I have a big voltage drop. For what I see, I'm pretty sure I will reach my goal!
ps. I wich I could post video here but I don't know if I can 😅
 
For a video, I think you'll have to post a youtube video (could be unlisted) and put the URL in your post.

I'm always using an online voltage drop calculator to figure out cabling losses with various combinations of cables. This is a good one:

Voltage Drop Calculator

Wire / cable voltage drop calculator and how to calculate.
www.rapidtables.com www.rapidtables.com

That's why knowing your loaded voltage and current draw is valuable. You want to minimize voltage drop while still being reasonable in wire size. I'm very much looking forward to seeing your setup running with some data!
 
yes my brother use something like this! I will make a video tomorrow and asking my questions there! and you will see the set-up 🤘
 
If it's your BMS you can bypass it and the batteries will be ok for short tests - just don't let them get too low - but that's one of the beauties of LTO cells - they're not as sensitive as LiPos.
 
AlexLTDLX said:
If it's your BMS you can bypass it and the batteries will be ok for short tests - just don't let them get too low - but that's one of the beauties of LTO cells - they're not as sensitive as LiPos.
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I did some short test but I never get the chance to full charge them. by the time I want to charge it all the way, the BMS stop charging after couple of minutes and doing some weird thing. so now, I have unbalance batterys and they are verry weak 😭 I had the chance to test it for a couple minutes before the BMS die, but I've not do all the test I wanted to look at. The ESC really look perfect, the water cooling is insane! I first thoght that my ESC blow's up even if it's stay cold. because the BMS have an app with the cell phone that gave you all the infos about the cells. On the app, all the cells was good but nothing goes ON. five minutes before the super charger blowing air like crazy and now nothing. so I grab my volt meter and the battery was dead. I reopen the app and it shows nothing. so I start the car to charge the battery and it work but for couple minutes like I said, but still nothing on the app. sorry it's hard to explain but now the BMS not charging anymore and no data on the app. So im pretty sure my ESC is still good but I need to order an other BMS quick so I can try the electric supercharger before the end of the summer 😂
 
I said my BMS "blow up" but no smoke or nothing, just stop worcking.. do you have a knowledge of good BMS? all I see is aliexpress and alibaba BMS. I maybe want to have a bigger BMS even if I was charging it under the specs.
 
I can't find a BMS to handle my power needs. So I'm just using balance boards during charging. But to do my tests to find the strongest cells, I charged the cells individually to 2.8 volts per cell, and stopped charging when the current dropped to about 80 mA. When my electric turbo is in use the batteries will never get low enough to get damaged. The BMS cuts power to and from the batteries when the voltage is either too high or too low; it also balances the cells. A balancer will just keep the cells balanced. But since I won't be charging my batteries to full capacity anyway (full capacity right after charging would be 78.4 volts @ 2.8 volts per cell; and the cell voltage drops down to about 2.6 volts per cell after sitting for a bit after charging, where it stabilizes - which is still 72.8 volts total). My ESC will only handle 68 or 70 volts max (68 per the guy I've been talking to over at APD; 70 according to the documentation), so at most I'll probably only charge to about 2.5 volts per cell. That's the beginning of the "stable" part of the discharge curve anyway.

In your pack, at 12s, the most you'll get is around 31 volts. I would suggest a balance board and a variable power supply to charge your pack, while monitoring current draw with a clamp on ammeter, staying below the max current for the supply (and gradually turning up the voltage to keep the current up until you hit 31.2 volts).
 
AlexLTDLX said:
I can't find a BMS to handle my power needs. So I'm just using balance boards during charging. But to do my tests to find the strongest cells, I charged the cells individually to 2.8 volts per cell, and stopped charging when the current dropped to about 80 mA. When my electric turbo is in use the batteries will never get low enough to get damaged. The BMS cuts power to and from the batteries when the voltage is either too high or too low; it also balances the cells. A balancer will just keep the cells balanced. But since I won't be charging my batteries to full capacity anyway (full capacity right after charging would be 78.4 volts @ 2.8 volts per cell; and the cell voltage drops down to about 2.6 volts per cell after sitting for a bit after charging, where it stabilizes - which is still 72.8 volts total). My ESC will only handle 68 or 70 volts max (68 per the guy I've been talking to over at APD; 70 according to the documentation), so at most I'll probably only charge to about 2.5 volts per cell. That's the beginning of the "stable" part of the discharge curve anyway.

In your pack, at 12s, the most you'll get is around 31 volts. I would suggest a balance board and a variable power supply to charge your pack, while monitoring current draw with a clamp on ammeter, staying below the max current for the supply (and gradually turning up the voltage to keep the current up until you hit 31.2 volts).
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yeah I see! I talk to the guy right now for the BMS. I never talk about the set up but I have a step up in the car to charge the battery while I drive. The BMS with 2 port (1 for charging and the second for discharge) is hard to find yes. so I use it only for charging
 
I haven't even started building anything to charge my packs while driving yet - not until I get the rest of the system perfected. But keep in mind you can't really draw more than 1200-2000 from even high output alternators. But keep your charge rate around 500 watts, and you should be fine. I'm looking forward to your next tests!
 
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