Lipo for the Currie USPD

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circuitsmith
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Joined: 11/21/2006
Points: 31

I've been running my LiPo system for the 24V Currie for a couple of weeks.
I'm using Hobby King 3s and 4s 5AH Turnigy packs configured 7s3p 15AH.
Fits in the Currie box.

BMS schematic and PCB attached.

Uses an Arduino Nano microcontroller.
Here are initial limits I've set:
High cell V charge cutoff: 4.25V
Low cell V charge disable: 3.0V
Low cell V discharge cutoff: 3.2V
Low pack V discharge cutoff: 24V (3.4V per cell)
Low pack V discharge warning light: 24.5V
Charge to 29V (4.15V per cell)

Schematic doesn't show 0.25A PTC polyswitches on the balance lines and 9A PTC on each string output.
Parasitic drain is 100uA. PWM Shunt balancing during charging to 20mV. Shunt current ~400mA max.
The PCB has 6 jacks for the balance connectors.
Pack weight 8.5lb.

Questions or suggestions welcome.

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IBScootn
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Joined: 01/03/2011
Points: 232
Re: Lipo for the Currie USPD

I would use a HVC of 4.15V instead

__________________

Motorcycles:
2011 ZEV Trail 7100, 84V, 60AH, 75+mph, Cycle Analyst, TNC throttle, modified charger. 800 miles so far.
2010 ZEV 6100, 72V, 40AH, 60+mph; Cycle Analyst, LED head lights, 3 Cell Log interfaces, TNC throttle and faster charger added. 8100 miles so far.

Big EV Grin. :)

circuitsmith
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Joined: 11/21/2006
Points: 31
Re: Lipo for the Currie USPD

IBScootn wrote:

I would use a HVC of 4.15V instead

Sorry, I did revise that to 4.2V.
The charger stops at 4.15V per cell average.
The 4.2V is for an individual cell, which would only happen if there's a problem with the balance circuit.
The cells never routinely go over 4.15V +/- 20mV

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