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Old 05-20-09, 07:06 AM   #1
The Big Wheel
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Which battery should I go with?

Ok so I have narrowed my decision to two choices. I will be using one of these batteries with the ampedbike 500w rear hub motor.

48V 15ah


or

36V 20ah

Both batteries weigh exactly the same and are the same size and there is just a $15 difference between them.

I guess I have to chose between speed or distance. But the distance is only 5 miles (if 1ah=1 mile of non pedaling). If I pick the 48V battery I will get to where I am goinga bit faster, but if I go with the 36V I will be able to go a little bit further. By the way, I like to pedal, so it's not like I am going to turn my bike into a scooter or moped, I just need a little bit of assistance.

Any advice on which one I should go with?

Say the 36V battery is only good for 21-23mph tops. If I am at WOT at 23mph, would this somehow be not good for the battery, to be running at max?
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Old 05-20-09, 09:19 AM   #2
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If you go with a 48V battery on a 36V kit you risk the possibility of damaging the controller and other components. Although I've heard about people running a 48V battery on the Amped kit, I wouldn't risk it. I'd go with the 36V battery... just my 2 cents...
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Old 05-20-09, 09:23 AM   #3
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I heard the guy who makes them over engineered his kits so 48V should be fine. He recommends the 36V for legal reasons (so the bike will not go over 20mph).

But I'm still unsure which one to go with...
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Old 05-20-09, 10:30 AM   #4
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If you think 48 volts is too much, a lot of the guys at ES are running theirs at 72 (with appropriate controller).

How about getting two 36 10 ah and running them in parallel for range and in series for speed? I would just go for the 48 15ah and be done with it.
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Old 05-20-09, 11:09 AM   #5
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I think I should go with the 48v 15ah as well but I keep changing my mind. The bad thing (or good thing) is the ping batteries last forever, 3000+ cycles so whichever battery I buy it will last me a long time.

I'm not too sure if I need two 36v 10ah and making them 72v, that would be way too fast I think.

Anyone on here own a 36v battery? Are you satisfied with the speed or do you wish you went with the 48V battery? I think I need to buy the right battery the first time because if I end up buying another one it would defeat the whole purpose of going car-free and saving money.
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Old 05-20-09, 04:54 PM   #6
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With the 48 volt battery, you could also keep the throttle light or limit current with a cycle analyst to increase range. I'd rather have the option to go slower later on rather than not having the option to go faster.
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Old 05-20-09, 06:18 PM   #7
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With the 48 volt battery, you could also keep the throttle light or limit current with a cycle analyst to increase range. I'd rather have the option to go slower later on rather than not having the option to go faster.
Right. What Snowranger said.

The total watt/hrs contained in either battery is essentially the same. If you self limit top speed (and hills), to the same performance your 36V/20 battery would ordinarily have, you would go just about the same distance with the 48V/15.

Batteries will drain at ever higher rates as speed increases, or as hills get steeper, assuming you're running on motor only.

I'm also with Ecowheelz, it may be costly overvolting your set-up at some point. Usually no problem on flats but on a steep hill with high amp draw. You don't want to pop your controller FET's, or whatever magic stuff they use these days.

But I'd go with the 48V/15, cuz that's what I run.

Last edited by wernmax; 05-20-09 at 06:26 PM.
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Old 05-20-09, 07:05 PM   #8
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Your other tread mentioned you wanted to get a folding bike with 20" wheel. Therefore, your only option is 48v or higher in order to get the speed & torque that you want from your other tread.
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Old 05-20-09, 07:32 PM   #9
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Your other tread mentioned you wanted to get a folding bike with 20" wheel. Therefore, your only option is 48v or higher in order to get the speed & torque that you want from your other tread.
Thanks for all of the info, I am going with the 48V 15ah battery.

I decided to go with the bike I already own.

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Old 05-20-09, 09:10 PM   #10
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I had a 36V ping battery on an ampedbikes 500 watt motor and a 48V ping battery. I prefer the 48V, but I live around a very hilly area. I find that I use the full range of throttle positions with the 48V even though it can go a little faster. It just means more freedom.
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Old 05-21-09, 07:56 AM   #11
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Nice mountain bike! I hate to see such one of the wheel out of the whole wheel-set being replaced with a hub motor that do not matches up however.
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Old 05-25-09, 07:08 AM   #12
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Don't expect 3,000 charge cycles if you drastically drain batteries to their max discharge every use.
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Old 05-25-09, 09:18 AM   #13
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I have never seen where that 3,000 cycles came from. I believe they are just made up -a guess based from the testing of the A123 batteries but even that test was done at low amp levels.
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Old 05-25-09, 09:33 AM   #14
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how many cycles can I expect? I thought it was 1,000-3,000+. After 1,000 cycles the battery keeps like 80% charge and after 3,000 cycles it's at 70%?
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Old 05-25-09, 09:54 AM   #15
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That's the theory. I doubt any of these Chinese companies, other than Dewalt has done the testing.
1000 cycles takes a long time to test.

I don't always ride to work but if I did everyday, it would take over 4 years from now to reach 1000 cycles.



Oh and 5 mile trips will not drastically discharge that battery. It will hardly put a dent in it.
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Old 05-25-09, 09:01 PM   #16
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I run my bike at 36 volts and 20 ah and at 72 volts at 10 ah. 30 mph is top speed at 36 volts and 53 mph with 72 volts. However, if I simply cruise along at 20 mph, the overall energy draw is about identical. Both setups are limited in acceleration simply by the controller/motor internal resistance. I seem to peak out at 80-90 amps under hard acceleration.

So, I'd rather have the ABILITY to go fast but not necessarily use it. I'd rather have 400 hp under the hood than 200 hp. Doesn't mean I have to use all 400 all the time. I also have a variable voltage controller - 36-72 volt so it gives me more voltage freedom.
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