an other DIY electric supercharger

Yeah, you could, but those prices make my wallet cry. It'd literally be cheaper to get a high power inverter and run two DC supplies in parallel (the supplies I'm using are variable 0-48 volts at 10 amps). Of course I wouldn't do that - there are too many losses and too many parts, but I'd probably look at something like this:

www.ebay.com

1800W 40A DC-DC Current Boost Converter Constant Voltage Current Power Converter | eBay

Output power: 1800W. It is very powerful. (the power of the 48V input and fan can reach around 1800W). Temperature coefficient: 50% load. to boost the original battery after charging, equivalent to an electric car charging treasure.
www.ebay.com

That's an 1800 watt boost converter (chinese watts, of course, so consider yourself luck to get 1,000 watts out of it), but it can charge my pack certainly fast enough. In fact, for $30, I might just buy one now...
 
99% of BMS simply try to keep the batteries between a certain voltage range .. they are NOT chargers.. you can not simply give them a random voltage or current and expect the cells to be charge to 100% SOC... you can you something like Alex has just posted but still it would ALSO need a arduino to monitor charge voltage and current and take the appropriate steps to charge them correctly ( this is what im planning to do )
 
Last edited:
@WB projects I just watched your latest video

I feel like you haven't run the theoretical numbers to workout about how much electrical power you'll probably need and therefore what components you'll need. Brgwarner has a great tool that you can use to get an idea of the power you'll need ..
1) What engine size do you have
2) What is it's redline
3) What PSI do you want at redline.

In your video you have a 24v 50amp BMS .. 50amps is WAY WAY WAY to low you'll need hundreds and hundreds of constant current amps to get any meaningful power (BOOST) out of such a low Voltage.
 
MkngStffAwesome said:
@WB projects I just watched your latest video

I feel like you haven't run the theoretical numbers to workout about how much electrical power you'll probably need and therefore what components you'll need. Brgwarner has a great tool that you can use to get an idea of the power you'll need ..
1) What engine size do you have
2) What is it's redline
3) What PSI do you want at redline.

In your video you have a 24v 50amp BMS .. 50amps is WAY WAY WAY to low you'll need hundreds and hundreds of constant current amps to get any meaningful power (BOOST) out of such a low Voltage.
Click to expand...
the BMS is not part of the discharge circuit. im almost 300A of current
 
It is meant to be part of the charging and discharging circuit. Otherwise it can't save your battery from over or under discharge, which is the point of having a BMS
 
It's going to be difficult to find a BMS that can handle the currents we're talking about (at least in my case). I plan on setting very specific charge voltages and letting a balancer keep the cells balanced. If you're not going to have a constant current/constant voltage source, then you could use a balancer and have a relay triggered at a particular charge voltage cut the charge before going over; as for pulling too much voltage out of the pack, you could have another voltage switch cut power to the contactor so if the voltage gets too low, you can simply cut the power to the electric turbo. In my case, neither one of those should ever be an issue, so I'm primarily just worried about keeping things in balance.
 
found this "smart BMS" with some unclear descriptions ... but looks like worth a look? :

Jk 1a/2a Active Balance Battery Protection Board Smart Bms 14s ~ 24s 100a 150a 200a 300a 400a Phone App Lifepo4 Li-ion Lto 16s - Buy Active Balance Battery,Protection Board Smart Bms 14s ~ 24s,14s ~ 24s 100a 150a 200a 300a 400a Product on Alibaba.com

Jk 1a/2a Active Balance Battery Protection Board Smart Bms 14s ~ 24s 100a 150a 200a 300a 400a Phone App Lifepo4 Li-ion Lto 16s - Buy Active Balance Battery,Protection Board Smart Bms 14s ~ 24s,14s ~ 24s 100a 150a 200a 300a 400a Product on Alibaba.com
www.alibaba.com

similar/same with more spec details:
www.aliexpress.com

95.99US $ |1A/2A Active Balance Battery Protection Board Smart BMS 14S ~ 24S 100A 150A 200A 300A 400A Phone APP Lifepo4 li ion LTO 16S 20S|Battery Accessories| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com
www.aliexpress.com www.aliexpress.com
 
AlexLTDLX said:
That's a good idea. Sorry, WB Projects. We'll let you get back on track with your build. Any updates?
Click to expand...
haha no worry! the updates is that I ordered a new BMS and still argue with the first seller to have a refund! 3 of my cells look damaged 😥 long story short, I dont know if I allready explain but the bms balance the cells perfectly for couple minutes of charging. But when I go back and test if all going like I want but the voltage drop A LOT compare to 5min earlier and keep going down even the power supply unplug. the BMS discharge the cells 5,6,7 with nothing pluged! don't know if its a coincidence that the 3 middle cells goes bad. anyway the chinese sais the BMS is in protection mode.. I will try with the other BMS that comming in
 
Ahh, the joys of dealing with Chinesuem. Sorry to hear about all that. I finally had to put my foot down with the people I bought my balancer boards last night. And that's also why I'll likely avoid buying from Aliexpress from now on - there's very little protection for buyers. In my LiFePo4 car battery with 4 100ah cells, three were fine but 1 was low at 96 ah. I just had to accept it. I am also discovering my balance board does draw down my batteries more that I think it should; but I'll have to do some testing to be sure. I can wire a switch to the balance board to turn it on and off. Maybe I'll have to do that...

I'd suggest charging up your cells individually (I know, that's time consuming - it'll take you like a week), then see what voltage they "settle" at. Mine seem to settle at 2.6 volts when charged to 2.8 volts. Could be they just need a few charge/discharge cycles, I dunno.
 
AlexLTDLX said:
Ahh, the joys of dealing with Chinesuem. Sorry to hear about all that. I finally had to put my foot down with the people I bought my balancer boards last night. And that's also why I'll likely avoid buying from Aliexpress from now on - there's very little protection for buyers. In my LiFePo4 car battery with 4 100ah cells, three were fine but 1 was low at 96 ah. I just had to accept it. I am also discovering my balance board does draw down my batteries more that I think it should; but I'll have to do some testing to be sure. I can wire a switch to the balance board to turn it on and off. Maybe I'll have to do that...

I'd suggest charging up your cells individually (I know, that's time consuming - it'll take you like a week), then see what voltage they "settle" at. Mine seem to settle at 2.6 volts when charged to 2.8 volts. Could be they just need a few charge/discharge cycles, I dunno.
Click to expand...
I currently charging them individually 🤞
 

Great video! I had a few thoughts - first of all, I like how compact and well laid out your setup is. I think you're really close to some actual boost. First thing I noticed in the video is it looks like your power cables may be CCA (copper clad aluminum). Keep in mind, while you can use CCA wire and cable vs pure copper, you need to go up in cable size - I'd two AWG sizes up to be safe. I could be wrong, but most car audio stuff is CCA because thick cables "look cooler" and they're cheaper. I use high-quality welding cable. Best cable for the $$.

Also (I may have mentioned this before), if your motor is "chugging" and not running right, then most likely your motor cables are too long. I made the exact same mistake and had the same problem. And I have 3 long 4 gauge welding cables in a box no longer doing anything to prove it. I saw the first comment on your video and agree with the guy about this. What I don't agree with is the power cables thing. Those CAN BE long, but you'll need a low ESR capacitor bank right next to the ESC to smooth out power spikes. And then you'll need a power resistor to slowly (like over 3 seconds or so) charge up the capacitors before you turn on the power directly, because otherwise the capacitors will appear as a dead short to the battery and you'll get a massive spark that will destroy your power switch or relay pretty quickly. RC guys use small resistors, but after I thought I came up with this idea in an automotive application, I discovered that ALL HYBRID and ELECTRIC CARS do the exact same thing (I said that in all caps so you wouldn't miss it - this is getting a bit long; my apologies).

Watch this guy's youtube channel and see how any of the hybrids or electric cars' control modules work - they all have capacitor banks right at the ESC, with power resistors that charge up the capacitors first:

In fact, if you watch his videos, you'll notice that virtually all electric cars have not only capacitors in their ESCs (though in EVs they're called inverter units), but the ESCs are all right next to the motors. Hope this helps.
 
of course all of this help and I really love all the info that can help me! I don't want anybody take it personnal if they think I don't lisen or anything! I really considered all of this and I explain myself in the video. I talk with MGM and they will help me with datalog and programming the ESC to be perfect. I told them the problem of "long motor cable" and they said to me that 7' of wire should not be a problem. they proposed to facetime me when the time will come to put all of this together! before I was ready to put it in the car, I've been able to make it work without to much "chugging". like 80% less chugging. I may think is a little bit of fine tuning but I don't know with their ESC if this will help. because even when I did my bench test, I have chugging with the motor and bettery verry clost to the ESC. Anyway I know there's solution with all the infos on here if I still have problems ! I will keep you all update!
 
I wanted to more understand this topic and the debate is all over internet! but I found this. this make sens to me, what do you think? ""The AC component is low frequency, harmless. There are no switching spikes in/on the AC current, the motor side, the motor inductance already takes care of that. Just a light current ripple due to switching. The DC side however, the battery side, has spikes but the input capacitors take care of that. However, when the battery wires are too long, the capacitors have a tough (read: warm, hot and short) life, hence the necessity of extra capacitors in that case.""
 
You must log in or register to reply here.
Top