HK 8000mAh Lifepo4 packs

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midcitybikesbrla   100 µW

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HK 8000mAh Lifepo4 packs

Post by midcitybikesbrla » Nov 17 2013 11:34am

Hi all,
I've spent a few years piecing this electric cafe racer together. It is (was) a Honda XR100 kids dirtbike. Took 3 degrees out of the headtube, KX100 forks, '78 Yamaha RD350 tank, '76 Honda CR750 superbike tail, SV1000 handlebars, ZX-7 rearsets/footpegs. Registered and insured in Louisiana, then converted to electric. Currently running 4 Zippy 5Ah cell packs in a 2s2p config so 48v and 10Ah (getting 5 miles range, 52 mph top speed). Have been planning on using 6 or 8 of the 8Ah cell packs for 48v, 24/32Ah.
Image
I am not the smartest man and have flushed a lot of cash down the drain buying, and destroying, Lipo's for it and other projects. Noticed Hobby King has these big 8.4ah Lifepo4's:
http://www.hobbyking.com/hobbyking/stor ... _Pack.html
1. These are rated at 30c which is way over what I thought that chemistry is good for.
2. These are much lighter than other Lifepo4 batterys.
3. They are way cheaper per Ah than all other Lifepo4's. (this one is understandable, the HobbyKing effect i'm guessing)

So, anyone have any experience with these? Anyone have any thought or comments on using these?
I'm pulling 300amps max, using a ME0708 motor and a Kelly KDZ48401 controller.
Cheers - Travis
Last edited by midcitybikesbrla on Nov 17 2013 4:33pm, edited 1 time in total.

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dogman dan   100 GW

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Re: HK 8000mAh Lifepo4 packs

Post by dogman dan » Nov 17 2013 1:09pm

Sounds optimistic to me, 300 amps from that much of those. But maybe if you had 50-60 ah of them it would work good.

I haven't tried them, but we all know to get the most from the HK lipos, you don't run them anywhere near their advertised C rate. Sure, they can be pushed to do it, but they just aren't happy about it. Try them at 5c maybe, but I wouldn't expect them to do any more reliably.

I'd say get yourself 30 ah of 40c lipo for that thing.

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arkmundi   1 GW

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Re: HK 8000mAh Lifepo4 packs

Post by arkmundi » Nov 17 2013 3:14pm

midcitybikesbrla wrote:...I am not the smartest man and have flushed a lot of cash down the drain buying, and destroying, Lipo's for it and other projects....
Rather than make another rash battery decision, having the potential of flushing even more cash down the hole, my suggestion is to get smart. Really investigate the battery question, understand the various chemistries and manufacturers of those and what can deliver the kind of cost/performance you need to stay in the juice. Having undertaken that, and remaining tuned to the ongoing developments in the industry, I have two general suggestions to anyone doing the same:
  • calculate the life-time cost, so including the number of cycles that can be had from the underlying cells in a battery; various ways, but basically #cycles * Ah / cost
  • get the full data sheet for the underlying cells, a manufacturer statement of their test results
Obviously you can't do the former without the latter. So, for instance, my own research based commitment is to the A123 AMP20 prismatic cells, because when you plug in a number like 2000 charge/discharge cycles, you get something like:
2000 * 20ah / $70 per cell (current retail for the genuine cell) == 571 ah-cycles per dollar
Do that for any battery you're considering on buying and you'll stay on the better side of the battery equation. Best!
Last edited by arkmundi on Nov 17 2013 4:54pm, edited 1 time in total.

midcitybikesbrla   100 µW

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Re: HK 8000mAh Lifepo4 packs

Post by midcitybikesbrla » Nov 17 2013 4:24pm

I should have mentioned that distance per charge is not a consideration nor is number of charge cycles. This is a real motorcycle and first and formost it must be a hoot to ride.
Even with prismatic cells I would have to run such a large pack to get the amps I need. Battery needs to weigh less than or around 40lbs and put out 300 amps. I plan to pull 3c continuous, 10c peak. Easily done with Lipo but they are so finicky and exploisivey. These HK Lifepo4s seem to offer what I need with less potential for over and under volt problems, more charge cycles would be nice as well. A big Lipo pack has been the plan but these sound good, too good. Just hoping someone had some real word experience with these, I might try them out, if I do I will let you guys know how they work out.

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arkmundi   1 GW

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Re: HK 8000mAh Lifepo4 packs

Post by arkmundi » Nov 17 2013 4:58pm

Sorry, but there is no substitute for the data sheet, which is "real world" testing, under controlled circumstances. What you're asking for is opinion, to coraborate your opinion and so just more of the same not-smart. But whatever - its your bike & bucks.

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dogman dan   100 GW

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Re: HK 8000mAh Lifepo4 packs

Post by dogman dan » Nov 17 2013 6:12pm

I'm just saying, with any battery HK sells, you'd do best to de rate the c rate they claim. A good rule of thumb is cut the c rate in half. But for the HK stuff, maybe cut it by 4 is more like it.

So consider the 30c lifepo4. Call it 7c stuff,, maybe. 32 ah x 7 is 224 amps. And even then it may sag a lot at the full amps. 200 amps controller should work with those lifepo4's. I'm sure you can get the 3c continuous out of them.

A123 pouch cells would be great, but getting good ones might be a problem by now.

If what matters to you is amps, and light weight, then you should be looking at 50c or better lico. That you could for sure get your 10c out of.

midcitybikesbrla   100 µW

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Re: HK 8000mAh Lifepo4 packs

Post by midcitybikesbrla » Nov 17 2013 6:30pm

Thanks dogman, that is good advice about the HK lipos that I already plan on following somewhat.
Arkmondi, I will take your reply as, "I have no experience with these batteries."
If anyone has used the batteries in question please let me know, I may try them anyway.
Cheers

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dogman dan   100 GW

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Re: HK 8000mAh Lifepo4 packs

Post by dogman dan » Nov 17 2013 6:35pm

You'll have to dig for it, but I think there are some old threads from guys who did try the HK lifepo4. As I recall it, the result was, "don't expect 30 c from them"

No surprise, since we don't expect 30c from hobby kings 30c lico either. :roll:

richmpdx   100 W

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Re: HK 8000mAh Lifepo4 packs

Post by richmpdx » Nov 18 2013 10:00am

I have not used these LiFeP04 packs, but I have used other HK LiFeP04 packs. I found that when used at 4 - 5 C continuous, the packs swelled badly and I replaced them. I now use HK LiFeP04 at about 2 C continuous, certainly not more than 3 C and they seem to be OK. So I suspect that the big 8 AH packs would not be suitable for your use.

Rich

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