BMS modding for more current

Batteries, Chargers, and Battery Management Systems.
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ElectricGod   1 GW

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20S smart BMS v2 upgrade

Post by ElectricGod » Jul 30 2019 1:04am

I pulled up the HY3410 mosfets and moved them over to the C- buss. I had a bunch of AOT290 mosfets that I pulled off a dead BMS. They already had the center legs cut out of them which was exactly what I needed for the BMS. I left all the copper reinforcing where it was and then added wire to both sides of P-. The original .004 ohm .5w shunts came out and were replaced with 10 .005 ohm 2 watt shunts. I'll need to reset the shunt value so it reads current correctly.

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Dui, ni shuo de dui   1 kW

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Re: BMS modding for more current

Post by Dui, ni shuo de dui » Aug 06 2019 2:27am

agniusm wrote:
Jul 29 2019 11:38pm
Can someone explain to me, whats the point of this? I buy small bms'es, fit 10 usd relay, positive from the pack, negative from bms p- to drive coil and i switch controller ignotion to positive.
Discharging through bms mosfets is just another waistfull thing that subtracts from overal efficiency.
In this case it seems to me that you won't have current discharge control, since the current won't pass through the BMS. So basically your BMS will only manage cells voltages.
Also, your relay will need electricity to stay close since you need to feed its coil. I'm not really sure that is more efficient in the end, a proper BMS doesn't heat at all (well at least mine doesn't), and the inefficiency isn't constant, since it will only happen under discharge, while the relay will need current 100% of the time your ride will be on.
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agniusm   10 MW

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Re: BMS modding for more current

Post by agniusm » Aug 10 2019 1:05pm

Well, your discharge is controlled by your controller and doing it twice has bo benefit. Relays consume power but you only need tiny one and the levels there are miniscule. You are also adding another point of failure in your circuit. Just saying. There are no motorbikes or cars that are made to discharge trough bms and extra cost is just ridiculous. Better invest that 100 extra on branded reliable western bms.

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ElectricGod   1 GW

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Re: BMS modding for more current

Post by ElectricGod » Jan 08 2020 3:58pm

agniusm wrote:
Aug 10 2019 1:05pm
Well, your discharge is controlled by your controller and doing it twice has bo benefit. Relays consume power but you only need tiny one and the levels there are miniscule. You are also adding another point of failure in your circuit. Just saying. There are no motorbikes or cars that are made to discharge trough bms and extra cost is just ridiculous. Better invest that 100 extra on branded reliable western bms.
Thank you for your opinions.
These BMS's are already pretty good as is.
I just make them handle more current.
Reliability isn't really an issue with them.
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ElectricGod   1 GW

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Re: BMS modding for more current

Post by ElectricGod » Jan 23 2020 12:23pm

I've psoted a lot of stuff on modding several smart BMS's.
The ones that use the cute elephant app have an LCD.
I thought I'd get a couple of them to try out.
This would supposedly eliminate the need for a phone app or the USB/PC app.

I have to say...do NOT waste your time. This is the dashboard screen.
All the other pages of data are even worse than this.
Since I can't read squiggly, I don't know what is what.
I've gone through all the menus looking for something to select or change and maybe get an idea what things do.
It appears that you can't change anything via the LCD...disappointing!
Assuming it uses settings from the BMS, you should see the battery at nearly full.
There's zero documentation for the LCD so I'm 100% guessing at functions.
It has a connector labeled speed, but what you connect it to is a mystery...maybe a motor hall?
Doesn't matter really as none of the screens list kmh or mph or RPM.
This was a waste of money!

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XB-502: viewtopic.php?f=10&t=83302&p=1222730#p1222730

Currie scooter: viewtopic.php?f=35&t=83830&p=1227407#p1227407

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