BMS Readings....YIKES!!

[DaveTM]

Originally Posted by TheCartBoy

JK has a contactor based one that goes up to 500 amps

Those appear to be for Lifepo4. Leafs are Lithium Ion.

[TheCartBoy]

Oh maybe it's not as configurable as the mosfet based ones. I've used those for li-iom batts, just set it up in the app.

[jasonojordan]

If you are looking to do 200a+ you are likely going to end up with a contactor based bms regardless of brand. I do not know of any mosfet based ones that will over over 200a continious.

[DaveTM]

Ok guys.....you're speaking way above my pay grade. I'm a retired CPA. If you wanna talk Alternative Minimum Tax and carryovers.....we can chat.

But I have no idea what Mofset means.

When ZEVA stopped he put out there what boards\parts were needed to fix or replace anything. I was successful at replacing the monitor board when it went out a few years ago,.,.,but this time it's well above my pay grade.

I looked at DALY but the reviews are not all that pretty so that brand is out.

[jasonojordan]

Daly is not a good option so you understand that correctly.

Mosfet- Its like a miniature contactor of sorts. It is soldered directly to a circuit board. They are solid state (no moving parts) so the current and electricity is routed internally using logic bit changes on the chip itself. Can not handle high amp as well due to the heat generated and its limited ability to dissipate heat.

Contactor- Old school way of doing things. Physical contact pads very large devices. These can handle higher current loads then the mosfets because they are able to dissipate the heat load better.

This is certainly not a technical explanation so much as my understanding of how they work and compare to each other toned down to an attempted level that you may be able to understand better.

https://www.bloomy.com/support/blog/...battery-safety

[davros]

Contactor- fancy way of saying big relay.

[DaveTM]

I'm searching until my keyboard keys crack and fall off (not really....but it seems that way). I can't seem to find a BMS where the "big current" doesn't run through the BMS.

And let me (again) state that I'm not an engineer....so I speak in 3rd grade language when it comes to this stuff.

On my ZEVA I believe that I controlled the amp draw with settings on my Alltrax Controller. Then I had the ZEVA BMS settings for just a bit higher. So, for example (and right now I don't have my settings in front of me) I would set the max amp draw on the Alltrax to say 400amp. Then my ZEVA setting would be say....450amp. So, if the draw exceeds 450amp, the ZEVA would trip the HV cutoff....IIRC.

At one point I thought that Sergio had a diagram of how to "work around" any BMS where the main current ran through the BMS itself....even though it was designed to do that. But I can't find it....or maybe I had a dream and it's not real.

Anyway, if anyone knows of a BMS that would work for my situation, I'd be very thankful.

[TheCartBoy]

Do you ever pull close to 400 amps? And how long would that go on for?
Perhaps you need to go find that worst case hill and monitor the current to see.

[jasonojordan]

Originally Posted by TheCartBoy

Do you ever pull close to 400 amps? And how long would that go on for?
Perhaps you need to go find that worst case hill and monitor the current to see.

From my understanding he uses the cart nearly exclusively off road in the woods. Climbing over down trees and so forth.


For reference I know when I take my Columbia Full Cab SUV off road I spike up to 300a frequently with sustained pushing 200a.

[TheCartBoy]

Hmm might be dicey to try to make it work with the 200A JK. When you draw to many amps it overheats and then you are stranded for 10 minutes while it cools down. Maybe a good time to have a smoke or a piss in the woods?