Building hub motor bike, which batteries?

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pgt400
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Building hub motor bike, which batteries?

I ordered a golden motor 500watt hub motor. putting it on a walmart comfort bike. I've been researching batterys and it seems for this size, SLA is the way to go. I can pick up (3) 12v 12ah for $21 each. The total weight (9x3) is on 27 pounds. If I use Lifepo4's the weight is 1/2 or 13.5 pounds for 36v 10 ah.....but the cost is $500 !! SO $63 for 36 volts of SLA and the penelty is only 13 pounds??? 2 weeks without fast food can make that up! Anyway, am I missing something in the comparison? At almost 10x the price if I have to replace them more often...big deal?

andrew
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Re: Building hub motor bike, which batteries?

The price for those SLA batteries you've found is very low.

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[url=/forum-topic/motorcycles-and-large-scooters/588-fixing-my-chinese-scooter]900 watt scooter[/url]
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needWheels
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Re: Building hub motor bike, which batteries?

The key is that 12ah of SLA is not really 12ah.
You'll get 10-15 miles or so depending on temperature and how fast you go. If you drain the SLA often, you'll be replacing them often as they don't tolerate that well.

LifePo4 you can almost abuse (from what I have read). Completely drain, leave uncharged, etc. Doesn't give a darn about temperature. And you'll really get the 10ah out of it. Also, I think your $500 price is high? 36V 10AH LifePo4 from pingping is $400 shipped. Though you are going to want more than 10ah from what I have read if you do hills alot as the draw rate is too low and you'll get cut off. It's not recommended to parallel LifePo4.

I have to use SLA because I can't afford anything else, but if I had the money I'd use LifePo4 for certain. Far less hassle, far more reliable.

added: oh and 36v 10ah LifePo4 is only 8 pounds, 11x4.5x3 inches

dogman
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Re: Building hub motor bike, which batteries?

The real answer to your question lies in how far you want to go. Depending on how fast you drain them, lead batteries can give you a whole lot less than the rated capacity. To get it all you have to ride real slow. Also you get a lot less life out of lead if you can't charge frequently. If you ride to work, and can't plug in, you will wear out the pack quicker. For me, the max range of 12ah lead was about 6 to 8 miles with a brushed hub. But I allways ride full throttle. Since I needed to climb a hill for 12 miles to get home, I never made it all the way till I got a large lifepo4. If the money is no problem, get lifepo4. You'll love the lightness and the extra range. My 20ah weighs 15 lbs, so a 10 may only weigh about 8 pounds. But if you are going less than 6 miles per charging opportunity, lead batteries will work excellent. Just don't leave em uncharged any longer than you have to.

Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global

pgt400
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Re: Building hub motor bike, which batteries?

I buy the 12v 12ah units from the batteryguy on Ebay. Used in my son's ride-on with great results. I also use the 12 7ah in my quad at$12.....Yamaha wanted $80 !! Going on 3 years with it.

pgt400
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Re: Building hub motor bike, which batteries?

dogman, yes the 20 ah seems the way to go. Do you have the Ping batts or Yesa? Sam at Yesa quoted me $940 for a 36v 20 ah pack! Ping replied with "no batteries in stock and best to wait till after Olympics".

dogman
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Re: Building hub motor bike, which batteries?

Mines a Ping, boy am I glad I bought when I did. There is a new seller on ebay today, but some of the other sellers batterys weren't as well assembled as pings. If you have the money, the yesa's are considered by many to be higher quality than pings. Nowdays the best lifepo4 is the one you can get your greedy hands on.

Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global

needWheels
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Re: Building hub motor bike, which batteries?

This is speculation of course but I suspect after the olympics that LifePo4 availability will definitely go up as China allows factories resume full power (and pollution). Also shipping costs will go down because they cannot ship via EMS right now and have to use UPS because of "security".

(olympics end August 24th)

I just wish I could afford LifePo4.
I'm still figuring if I can make a NiMH pack out of sub-c batteries somehow for less than $200.

dogman
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Re: Building hub motor bike, which batteries?

I know the feeling, I have the battery, but still need to pay the bill! I suspect that a year from now I will feel like a fool for the price I paid, but this summer, many will pay more than I did.

Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global

sharkmobil
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Re: Building hub motor bike, which batteries?

I'm still figuring if I can make a NiMH pack out of sub-c batteries somehow for less than $200.

Don't do it. Small cells in NiCd and NiMh don't like the amperage the motor requires. You will kill you battery real fast. The smallest you can do with is D or better yet M cell.

You can get a 37v LiOn pack of 9Ah for about $230: http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2447

And after first month or so and losing 15 pounds you can add another 4.4Ah :)

andrew
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Re: Building hub motor bike, which batteries?

Don't do it. Small cells in NiCd and NiMh don't like the amperage the motor requires. You will kill you battery real fast.

They will handle more current than the Li-ion you posted, and without similar risk of fire or explosion. I would be extremely wary of using Li-ion cobalt cells. The pack you linked can only handle 8.4 amps.

Sub C NiMh or NiCad cells can handle about 15-30 amps continuous, and the impedance at 1 khz is similar or even lower than the D chinese cells. If you go with high quality cells, such as Sanyo, or SAFT, than the D cell impedance will probably be lower.

[url=/forum-topic/motorcycles-and-large-scooters/587-my-kz750-electric-motorcycle-project]KZ750 Motorcycle Conversion[/url]
[url=/forum-topic/motorcycles-and-large-scooters/588-fixing-my-chinese-scooter]900 watt scooter[/url]
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pgt400
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Re: Building hub motor bike, which batteries?

Yeah, I fly rc planes and helis, sub-c nimi's can supply loads of current. But I think the highest ah is 4400 now? The Tenery D cell nimi is 12 ah but I don't know the Z. I can buy 30 Tenergys for $180 (36v 12ah). I can't find a source for the Sanyo D or F cells....but they are probably very pricey. Better to get a Ping Pack when he comes back on line.

bocabikeguy
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Re: Building hub motor bike, which batteries?

Where can you buy 30 12aH D-cell NiMH for $180?

pgt400
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Re: Building hub motor bike, which batteries?

Ebay, they are $60 for 10 or $6 each. Tenergy cells, D. They also have an F Cell that is 14ah I think.

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