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Originally Posted by RedDevil
Wow! Hats off for what you've accomplished.
Did you spot weld 936 LG 18650 cells together? Eeew... what a lot of work!
Those are lithium oxide? How do you protect them?
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Thank's all.
It is not a big job with a small spot welder machine. It is recommended adding a cardboard disc on the plus pole and some isolator betwen the cells, paper, carboard, plastic, air.. I used pure nickel tabs.
I put all in 2 boxes (polycarbonate) with connectors in order to have not more then 48v when not using it. This for personnal safety. I do the same safety for the A123 packs. DC HV can kill.
Be very carrefull.
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I'm looking for a small PHEV parallel pack on my Insight, just to boost FE not go full electric (the EV motor on the Insight is too small for that anyway).
I'm thinking LiFePO4 and about 1-1.5 kWh, portable, charging at home and at work.
Any advice?
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There are two parts:
1) add cells
2) may be you will need to fool the mima system in order to use these extra energy. With a prius if you add less then 15-20A you don't need this.
For the part 2 I can't help. Have you seen what Peter Perkins have done ? on insightcentral.net or batteryvehiclesociety.org.uk forum ? He done a splendid job.
For the part 1
You have to know the min and max voltages of the stock nimh cells.
I serialy connected LG cells and of course paralled too doing a 52S18P
So this voltage is
allways lower then the A123 voltage.
LG voltage is between 220v and 175v.
A123 voltage is between 240 and 210v
Then the différence is 20 to 35 volts, 20 at the begining of the trip and 35 at the end. I add a 36v dc-dc device.
I use Meanwell HLG320H-36A. Two 240 model // is better.
This is a led driver but accept dc (127-410v) in input and give the nominal amperage in the range
18 to 36v. Excellent efficienty, no noise.
You have to be very carreful because this LG pack+dc-dc device is dc high voltage. But then heat losts are very small, say 1% power lost.
The dc-dc secondary amperage depend upon your time trip. The shorter time, the more amperage.
Insight pack have a lower voltage then Prius. So you have to check if 127v plus 18-36v will be ok or not. I think some other meanwell driver accept only 100v dc, not sure.
The meanwell device is connected:
-input on the LG cells, no matter the polarity
-output ,minus pole on top of the LG cells, plus pole on the plus A123 pole.
-minus LG pole to minus A123 pole.
Add HV fuses of course.
Connect first meanwell input and after output.
If your nimh voltage could go over LG voltage, add a diode.
You may have also to protect your nimh for over voltage.
