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  1. #1
    Senior Member teamontherun's Avatar
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    Looking to upgrade batteries

    I have a 36v 12ah (12v 12ah x 3) battery pack on my ebike and am looking to upgrade them to a lifepo4 pack. What im wondering is what 36v lifepo4 pack will give me the same range I have now with my sla batteries? The simple but wrong answer is 12ah. I know you can go much farther with lifepo4 batteries and want to cut the weight down as much as possible.

    thanks.

    (I searched but could not find how to compare the two types of batteries as it pertains to my situation.)

    EDIT: Also im looking at these batteries and the 36v batteries are recommended for 500-750watts. My bike is running a quiet 180watts. Will these batteries mess it up? I assume the controller will take care of the motor as long as my voltage is the same as the SLA batteries I am using.
    Last edited by teamontherun; 03-26-10 at 02:00 PM.
    Only God Can Judge Me

  2. #2
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    Probably a 6 or 7 AH lifepo4. 36v7AH lifepo4. It'd be interesting to test it in real life. Probably a battery that weighs like 9 lbs compared to probably the 27 to 30 lbs that you are now carrying.

  3. #3
    Senior Member teamontherun's Avatar
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    LOL right on the nose. 28lbs. Its almost comical how much it weighs. Thanks, I think im going with a 10AH battery so that I get a tiny bit of extended range.
    Only God Can Judge Me

  4. #4
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    I know. When I had SLA batteries, a 50cc scooter pulled up beside me and was like, "is that an electric bike" . I was like, "yeah". Then the stop light turned green and he pulled away from me and my batteries were basically dead so I couldn't do anything, just had to watch him go and I couldn't keep up. I was representing electric bikes in a really bad light there. He probably thought pretty badly of electric power right then because I had no power and was really slow.

  5. #5
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    Remember that LiFePo4 batteries require a BMS that will cut down your available ah's. I get 9.5 ah out of a 12 ah battery. But I can squeeze 40 miles out it which is twice as far the 12 ah SLA battery I had on another bike years ago at almost twice the average speed (10-18) and the battery weighs half as much. YMMV.

  6. #6
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    Quote Originally Posted by Mabman View Post
    Remember that LiFePo4 batteries require a BMS that will cut down your available ah's. I get 9.5 ah out of a 12 ah battery. But I can squeeze 40 miles out it which is twice as far the 12 ah SLA battery I had on another bike years ago at almost twice the average speed (10-18) and the battery weighs half as much. YMMV.
    I'm sorry but I disagree. Lifepo4 packs do not "require" a BMS. I am not saying that it's not a good idea only that it is not required. I have been running lifepo4 packs since last summer and have never used a BMS nor will I ever use a BMS. In my opinion for a small pack used on an ebike there are better and more reliable ways to protect lifepo4 packs. Without question lifepo4 is a major improvement over SLA batteries.

  7. #7
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    Quote Originally Posted by morph999 View Post
    I know. When I had SLA batteries, a 50cc scooter pulled up beside me and was like, "is that an electric bike" . I was like, "yeah". Then the stop light turned green and he pulled away from me and my batteries were basically dead so I couldn't do anything, just had to watch him go and I couldn't keep up. I was representing electric bikes in a really bad light there. He probably thought pretty badly of electric power right then because I had no power and was really slow.
    Morph old buddy...are you telling me if you have your lifepo4 packs and they were fully charged you think you could have beat the 50cc scooter? No way my friend.. Not off the line of top speed. I have my ebike and love it for what it is but I also have a scooter (250cc Roketa) and I am generally the fastest away from the light including the cars. I know your talking about a 50cc but it's pretty quick too.

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