GoldenMotor.com Forum
General Category => General Discussions => Topic started by: Snookoo on October 03, 2008, 10:59:22 AM
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Hi there,
I plan to convert a 26" Mountainbike! I'm not yet sure which combination of motor & battery (lifepo4) to pick.
What's the best compromise in speed, power, range and weight?
Btw I want to keep on pedaling all time and just want to be assisted.
I plan to mount a carrier front and back and ocasionally carry some decent load.
I weigh about 150 lbs.
What would you pick?
500w kit
1000w kit
36V 15Ah 10lbs
36V 20Ah 16lbs
48V 12Ah 13lbs
48V 20Ah 22lbs
thanks for any suggestion!
greetings
nicolai
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variable.
Hilly area 1000 watts,
Flat area and need mileage 500watrs
48V 20Ah 22lbs
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48V 20Ah, I see.
Whenever I'll leave the bike I'll want to take the battery with me so it won't get stolen...
22 lbs = 10 kg is a bit heavy for that I think.
I might go with a 500W and a 48V 12Ah (or maybe 48V 15Ah) ....
I wouldn't dare leaving the 48V 20Ah battery on the bike unless I had a good cover or lockable battery case, but I don't know where to get such....
well thanks so far!
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48V 20Ah, I see.
Whenever I'll leave the bike I'll want to take the battery with me so it won't get stolen...
22 lbs = 10 kg is a bit heavy for that I think.
I might go with a 500W and a 48V 12Ah
I use a formula when calculating batteries I just add up the amp hours on each cell regardless of the over all voltage and call them distance ah (dh not real hours BTW).. All though this is not PC it works perfectly easy when chosing.
The more cells, the faster you, the further you go in the time, the more distance hours,
The more amp hours, the longer you travel, the more distance hours.
Apples and oranges...
Its only relative to the same chemistry types.
Like compare my ah SLA's, even calculated per battery works a charm, rated at 36v (3x 18ah) SLA batteries at 18 ah = 54 distance housr compared to 48v (4X12 ah) 48 distance hours. I estimated wind resistance would play a big factor and the fact that the bigger batteries handle the discharge rate way better so the 36v with the larger size make it woth while,
I feel the bigger lifepo4 even though so much different to SLA's the amp hours x by the cell number works and the bigger batteries would handle discharge better too..
Those Lifepo battries are like gold and yes if people knew what are to begin with, will steal them fast.
BTW I know little about lifepo4s because I don't own them, Id still buy the bigger ones and lock them on the bike so no one ever can remove them at all..
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Yes 48 volt 12 ah have better distance hours than 36v 15 ah.
Good choice... :D
But for an xtra 3lbs 36v@20ah I think you will go a lot further
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More Volts for more speed....
More Amps for more torque & distance.....
Easy
PS I would go for the 1000W + 48V 12AH combination....Zoom Zoom!
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i got a ping battery 36v-16amp. I should have got the next size up but couldnt really aford it. get the biggest that your money will allow,dont buy cheap stuff
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Whenever I'll leave the bike I'll want to take the battery with me so it won't get stolen...
22 lbs = 10 kg is a bit heavy for that I think.
I might go with a 500W and a 48V 12Ah (or maybe 48V 15Ah) ....
I wouldn't dare leaving the 48V 20Ah battery on the bike unless I had a good cover or lockable battery case, but I don't know where to get such....
well thanks so far!
G'day Snookoo,
I lock my bike up at the train station every day and I had thought about taking the battery with me every day, but carrying the approx 6kilos around in addition to my backpack didn't appeal, so I built a cage for my battery.
You could build your own "battery cage" like I did. See the thread http://goldenmotor.com/SMF/index.php?topic=348.msg3410#msg3410 (http://goldenmotor.com/SMF/index.php?topic=348.msg3410#msg3410) for pictures of it.
I used metal brackets meant for house building that I got from the local hardware store and cut them to size and riveted them together and mounted onto a pack rack, then spray painted black. I slide the battery into it and then close the end flap and padlock it up. I also wrap a cable lock around it and through the pack rack and wheel.
Muzza
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thanks for your input everybody.
I just seen the 48V 20A is so expensive, so I'll probably go for a 48V 12Ah.
I just will have to recharge more often, but that's ok isn't it.
With a 48V 12Ah battery, the 500W version will get me more far than the 1000W, won't it?
I feel like the 1000W version should be combined with a 48V 20Ah to make sense....
Yes, I might build s.th. like that battery cage, it's a great idea. Riveting it is good! Just need to get the tools for riveting (just rivets and a hammer that is I think)
greetings
PS: nicobie don't talk like that about my man 317537 :-[
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Dont forget.... If you are going to use 48V battery pack on the GM500W kit you will fry the controller.....replace with a GM1000W controller or best buy the complete kit, no extra recharging required, OK......Cheers & good luck.
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Yes, I might build s.th. like that battery cage, it's a great idea. Riveting it is good! Just need to get the tools for riveting (just rivets and a hammer that is I think)
No you need a pop rivet gun:
(http://img.auctiva.com/imgdata/8/0/5/1/4/0/webimg/135376574_tp.jpg)
to go with the pop rivets or aluminium blind rivets:
(http://upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Blindnieten.JPG/180px-Blindnieten.JPG)
Muzza.au
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Gutdammit I'll get the 1000W version and a 48V 20Ah battery :)
Ah a pop rivet gun, I see...
btw: I just wrote an email to goldenmotor about the rim quality problems I read about in this forum. Yao replied that since 3 months they have upgraded their wheels to double wall rims! So that downside is out the way! :) :)
now i'll get me a used 26" mtb from ebay......
thanks everybody for your help
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I agree with the better part of them here. 48v for hills once you have it you will never want to be involved with the 36v again. Had I known what I know now I would have gone straight to 48 and saved a good amount of money. Get the best battery you can afford it will likely be the most expensive part of the project and you don't want to do it twice. Foxpower makes some pretty good batteries and the last ones I bought arrived in less than a week.
http://www.foxxpower.com/ You can buy them off of e-bay also. A bit better than most of the Chinese Lifepo4s at near the same price. Nice hard case batteries and charger also. I have been running a 36v for 1200 miles with no problems at all.
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Gutdammit I'll get the 1000W version and a 48V 20Ah battery :)
thanks everybody for your help
The wife says size does count. :P lol
I hope they are great for you.
Lett us know how you go..
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Don't pay much attention to the poster that goes by 317537. He is obviously a clone with an agenda. Most likely a GM lackey.
Actually don't pay much attention to nicobie, a name I don't recognise as giving much help. Smeee aka Leslie (317537 upside down) may be hard to understand at times (probably being that he is talking upside down all the time hehe), but at least he tries to help and he has basically brought this board back from the dead as hardly anyone was posting for a while. Now I hardly post, but attacking someone who is helping doesn't help people who want it.
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Hey everybody! Right now I'm wondering if the 1000W 48V 20Ah combination is maybe a little exaggerated.
See I just read about a guy who uses the 36v 500W version with a 36V 10Ah lifepo4. He's happy with that and with slight pedaling he gets around 50 miles! That is actually all I want.
So instead of going 1000w 48V 20Ah I might go 500W 48V 12Ah, wouldn't you agree? (consider the lighter weight of the battery ;) or maybe 1000W 48V 12Ah. (I'm not sure)
PS: 1000W is more powerful than 500w of course. But will a 500W motor have a greater range than a 1000W motor using same battery??? I think so... plz correct me if I'm wrong...
thanks
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no such thing as 500W or 1000Wmotor, apparently they are the same (probably marked 500W to comply with local regulations). but the controllers are different.
I wouldn't recommend the huge 48V 20Ah batt that you were thinking of. to get an *idea* of the energy capacity multiply voltage times capacity; 48V * 20Ah = 960Wh, and that's is A LOT. for comparison, the most expensive battery that Segway offers is 400Wh.
I'd definitely recommend 48V over 36V, it'll make your rides much more fun. I'd consider 48V 8Ah enough for occasional use, but I'd go with 48V 10 or 12Ah. depending on cell type, a low Ah rating might mean a low power rating too (max amps, given a certain voltage). unless your 8Ah are very good cells, you could have cutoffs and reduced lifetimes due to excessive power demand. with 12Ah, things will go much more smooth with "low" quality cells.
now, regarding range and voltage:
36V * 10Ah = 360Wh
48V * 10Ah = 480Wh
at the same capacity the 48V batt has 33% more energy than the 36V batt. that said, it might be the case that the 48V batt will give you less range.
you see, the 48V will let you go faster; imagine it gets you 35% faster (yes, can be more or less than 33%), but using double the energy per mile that you'd use at 36V. so the 48V batt would take you 1.33 / 2 = 67% the distance that the 36V batt would; but only if you travel full speed. however if you go at comparable speeds, the 48V batt should give you 33% more range.
(controllers become more efficient when they run full throttle, so the last statement is not really exact, but it's close.)
so, with 48V 12Ah you'll have: good acceleration and top speed for fun; good range to travel (similar to a 36V 16Ah, provided that you go at 75% of max speed); reasonable cost and weight. (but if you want great range while going full speed, you might be disappointed.)
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thanks for help, happy to hear this :) 48V 12Ah should be it then!
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G'day Snookoo,
I remember reading somewhere that someone said that voltage is cheaper than ampage with batteries, so I did a quick search on ebay to test the theory and at least in once instance it was correct. I found a 36v 20ah lifepo4 for $655us and a 48v 15ah for $622us. Now working out the Wh, 36 * 20 = 720Wh and 48 * 15 = 720Wh also. This may be an over simplification and there are other factors that should probably be considered, but it does show that for the same Wh the higher voltage is cheaper. But as Lanchon pointed out you may compromise range for speed. I myself have a 400w hub (not GM) with a 36v 10ah GM battery, but if I was going to do it over again I would go the higher voltage for higher speed as I only do short commutes, about a 5k round trip a day, so range is not so much an issue for me at the moment.
Muzza.
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thanks for help, happy to hear this :) 48V 12Ah should be it then!
Just so it is not SLA batteries. A basic rule for them is that you will only get 1/2 of the rated amp hours in real use.
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they aren't, he posted this:
36V 15Ah 10lbs
36V 20Ah 16lbs
48V 12Ah 13lbs
48V 20Ah 22lbs
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You are right.
The weights are what a Lipo4 battery would be. Def not a sla.