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Old 08-20-2011, 07:30 AM   #5003 (permalink)
Greg Fordyce
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Join Date: Nov 2009
Location: Scottish Borders, Scotland
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Quote:
Originally Posted by jpirkola View Post
Paul and everyone.

It's been a while since I posted, it's the old can't breath in high humidity and temperature thing. A bit better now. We built the controller from the kit we bought from you and it works a treat.

I originally was going to put it on my EV conversion international Cub Cadet garden tractor. That idea got slightly side tracked.

The controller now resides (temporarly) on top of the scratch built (Called an ultralight modified) 1/4 scale pulling tractor with a 160 volt battery of 150 Headway cells (50S 3P) I'll attach a couple of photos. The tractor has a 13 inch GE motor and needs more amps.

Now on to the questions, right now the controller is limited to 511 amps. we have heard that people have safely run these controllers at up to 700 amps with a change in the softwear on the chip. Have you heard of this being done. If so could you put me in touch with the person(s) who have done this.

I have been out of touch because of health ptoblems, but I did hear that you were either in design phase or production for a High amp controller. What is the status? Will it be available in a kit form?

I'll be posting a you tube of the first complete run of the Big 13. If you watch the end you will see that it just ran out of amps. We have the RTD explorer log of the run if your interested.

Jim
Hi Jim, looking at your tractor I suddenly had a thought about your Headway cells. I am going to assume you are using the 16ah 40160. I found some specs for them on the web.
Quote:
Headway LifePo4 40160S 16AH

Nominal Capacity: 16AH
Nominal Voltage: 3.2V
Max Charge Voltage: 3.65V
Cut Off Discharge Voltage: 2.0V
Charging Method: CC/CV
Max Charge Current (Continuous): 5C (80A)
Max Discharge Current (Continuous): 10C (160A)
Cycle Life: 2000 Cycles 1C 80% DOD
So you have 3 cells in parallel for 48ah which at 10C is 480 amps. At 500 amps you are already over the max discharge current. Also when you parallel cells you can't be certain that all cells will share the current equally so you need to derate the max discharge current by some value (I am not sure by how much though). Another thing to notice is that cycle life is stated for 2000 cycles at 1C. I will be interested to see how the headways hold up to that abuse. But maybe since you are using them for racing (ie, only intermittently) and not daily driving they will be fine. I was talking to someone recently who had tried running Thunderskys at around 5C and was getting cell failures in as little as 200 miles. Please let us know how your cells hold up to the abuse. The only other Headway pack I know of being used in a car is Damien's aka Jack Bauer. This is also a relatively small pack at 48S4P if I remember correctly. How's your pack doing in your bmw Jack? It will be interesting to see how well these small packs hold up in daily use.

Greg
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