Low cost BMS

[arber333]

Originally Posted by thingstodo

I'm using Leaf cells - lithium polymer - so the boards likely won't fit without some modifications.

OH, how did you get them? Were they new or used?

Well actually i use 85Ah Kokam LiPos myself so i already modified BMS to be wired 8S. I also changed code for LiPo voltage.
It works, i tested it on a single PCB, i have to test a group of 300V to see how it will work together.
I can send you PCBs. You populate sensor side and connect wire link. You can just omit transistor and everything will still work. It just wont shunt...

Oh and idea about fuse wire isnt new. Original plans have + sensor supply wire in case chip would melt. That wire burnt out in number of ocasions when i experimented/tortured it, so it works!

A

[thingstodo]

Originally Posted by arber333

OH, how did you get them? Were they new or used?

Used - I got one of the Renault/Better place packs (same as the leaf cells) from the Better Place bankruptcy, through EVTV ... 2 years ago?

I can send you PCBs. You populate sensor side and connect wire link. You can just omit transistor and everything will still work. It just wont shunt...

Great - less work for me! PM me how much you are willing to sell them for. I have 48 cans with 3 terminals each. 0V, 4V and 8V.

Oh and idea about fuse wire isnt new.

Very little that I write about is new. I read about most stuff and forget where I got the info from ... makes it hard to credit the originator! But I should make more of an effort to.

Original plans have + sensor supply wire in case chip would melt. That wire burnt out in number of ocasions when i experimented/tortured it, so it works!

So what gauge wire did you use for the 'fuse', and was it copper, aluminum, or some alloy?

I find that sort of practical stuff very valuable

[arber333]

Originally Posted by thingstodo

Great - less work for me! PM me how much you are willing to sell them for. I have 48 cans with 3 terminals each. 0V, 4V and 8V.

Huh i will have to reflect on that. My BMS is made as 8S that means 9 wires. If you connect modules so each 8V terminal is connected to next 0V terminal you need 4 modules for 9wire link yes? Since you have equivalent of 96cells that means you will need 12 PCB plates. That is some volts - 360VDC! Do you intend to connect them all in series? This BMS can support 255 cells in series

You are in luck since i also need at least 3 more PCBs. I will order PCBs and when i get them i will resend them to you OK? Ill PM you for your address and price...

Originally Posted by thingstodo

So what gauge wire did you use for the 'fuse', and was it copper, aluminum, or some alloy?

Its just PCB copper thin enough to only carry an amp or so. No need to be precise. When module shorts it draws plenty more than an amp!

[thingstodo]

Originally Posted by arber333

Huh i will have to reflect on that. My BMS is made as 8S that means 9 wires. If you connect modules so each 8V terminal is connected to next 0V terminal you need 4 modules for 9wire link yes? Since you have equivalent of 96cells that means you will need 12 PCB plates. That is some volts - 360VDC! Do you intend to connect them all in series? This BMS can support 255 cells in series

The original idea was to have all in series. I had a Netgain Industrial controller. Up to 450VDC in, programmable voltage out (was set to 190V) and max out at 1200 amps. Liquid cooled ... and broken! I killed it by not connecting the liquid cooling before doing my testing.

Now I'm looking at using an older Cougar (P&S) so it tops out at 144V and 500 amps. If I use 3 strings of 128V, I won't stress the batteries much. 32 cells is divisible by 8, so that works out nicely.

You are in luck since i also need at least 3 more PCBs. I will order PCBs and when i get them i will resend them to you OK? Ill PM you for your address and price...

I'll check out the link and see what these boards look like ...

Its just PCB copper thin enough to only carry an amp or so. No need to be precise. When module shorts it draws plenty more than an amp!

Traces .. that works!

[arber333]

Originally Posted by thingstodo

The original idea was to have all in series. I had a Netgain Industrial controller. Up to 450VDC in, programmable voltage out (was set to 190V) and max out at 1200 amps. Liquid cooled ... and broken! I killed it by not connecting the liquid cooling before doing my testing.

AH! I recommend you repair that ontroller since usually its just the IGBT and driver chip that are destroyed. Its like $100 and some skill.
I made my 3phase controller and i had water cooling working, but i burned IGBT still when i reved motor and released clutch, bam!
I simply replaced IGBT and affected driver chip together with its DCDC supply brick. Took like 2 days since i had everything on stock.

Higher voltage is way better since you need lesser cables and there are less amp losses. I used to drive 150VDC system but now i get 20% more range from same kwh. Some components are $$$ but it is worth it.

A

[thingstodo]

Originally Posted by arber333

AH! I recommend you repair that ontroller since usually its just the IGBT and driver chip that are destroyed. Its like $100 and some skill.

It would be GREAT if I could fix the controller. I just need to reverse engineer the circuit and figure out what part of it stopped - the transistor stage, the optocoupler, or the components in the big black block that I can't see into.

I made my 3phase controller and i had water cooling working, but i burned IGBT still when i reved motor and released clutch, bam!
I simply replaced IGBT and affected driver chip together with its DCDC supply brick. Took like 2 days since i had everything on stock.

Were there scorch marks? How did you know it was the IGBT? Is there a simple test I can do to test the IGBT?

[arber333]

Originally Posted by thingstodo

It would be GREAT if I could fix the controller. I just need to reverse engineer the circuit and figure out what part of it stopped - the transistor stage, the optocoupler, or the components in the big black block that I can't see into.

Oh, you have a special driver board? And the way you say it, driver chip is glued in some resin? Can you send a photo of the driver board? The one that is connected to IGBT.

Originally Posted by thingstodo

Were there scorch marks? How did you know it was the IGBT? Is there a simple test I can do to test the IGBT?

Yes when i heard bang i knew one of the motor winding coils backfired and IGBT got it all. Poor thing exploaded. Even the top blew off. Yes scorch marks were visible, but i took all 3 IGBTs off and measured them just in case.
Usually only the top transistor in IGBT is toast.
Drivers i tried with my PSU and if the chips draw more than couple mA something was wrong. With the chips i use sometimes even the DCDC converter is toast, but not allways. So whatever you find you check the pricing and decide.

[thingstodo]

Originally Posted by arber333

Oh, you have a special driver board? And the way you say it, driver chip is glued in some resin? Can you send a photo of the driver board? The one that is connected to IGBT.

The DC controller is a commercial Product - Netgain Industrial Controller NetGain WarP-Drive Classic Controller - there is potting compound on some of the circuit, or parts of the circuit.

I have no schematics. I'll get the pictures posted tonight.

Yes when i heard bang i knew one of the motor winding coils backfired and IGBT got it all. Poor thing exploaded. Even the top blew off. Yes scorch marks were visible, but i took all 3 IGBTs off and measured them just in case.

I had a big bang as well. No scorch marks visible. It may be possible that the BANG was the fuse element blowing apart? I expected there to be scorch marks, shrapnel, etc but the inside of the controller is quite clean?

Usually only the top transistor in IGBT is toast.
Drivers i tried with my PSU and if the chips draw more than couple mA something was wrong. With the chips i use sometimes even the DCDC converter is toast, but not allways. So whatever you find you check the pricing and decide.

I need to make an extension cable so that the controller is connected to external signals - contactor outputs, throttle signals, precharge voltage, etc - while the controller is in pieces. That way I can see how far the signal makes it before it stops - transistor, optocoupler, or blob.

[arber333]

Try to remove IGBT and measure it. If IGBT goes driver death is certain then dcdc power...

A

[thingstodo]

Pictures of the controller

Top, left side, main module, right side with connectors
From the left
From top left, big black blob in the middle of the frame slightly above center
From front right ... perhaps there IS some evidence of an IGBT failure ... now that I take this picture
From the right
From the front right again - less focused
From the back right, shows the capacitor