Reader Interactions


      • My ebike came with 36v 11ah battery and manual says 36v 10ah recommend. I want to upgrade to 13ah . And the controller overflow current protection is 12ah+1. Does this mean it’s limited to 12ah+1 our it can increase no more then 12+1ah. I’d like to use a 13ah 36v battery.

      • My eBike is 48 volts and has 21 amp hour battery, its motor is 750 watts. I get twice the distance at ten mph as compared to 30 mph at top speed. The speed determines the wattage draw by the motor and has the biggest effect on distance. I see the word “range” used allot and was educated to believe range is the point that one can safely return home, range is half the total capable distance.

    • A while back, I ran my 18v weed whacker using an old 36v ebike battery by running it threw a voltage controller. I set the controller to 50% (or up to 60% if I want to overclock it) and can mow down weeds all day. I got to wondering if I could do the same to my ebike. If I bought a 72v 20ah battery and stepped it down to 36v, would I get twice the range/capacity (essentially making it a 36v 40ah battery) since I’m drawing half the current?

  1. Your explanation on electrical terminology is very good, & appreciated. My wife & of 43 yrs are retired recently, & if we can afford it we would like to get one of the ‘Pegego’ Electric Tandem bikes this summer. Have been catching bits of news here & there on types of batteries that may be available. The voltage would be in the 48-volt arena, and will need one that will take us as far & long as possible. We live in an area that has mostly flat roads & small knolls and rises. No big hills. Lithium-ion/phosphate. Lithium-manganese. And latest one is Hyrogen/extended range battery. Would the latter one be the best for us? It seems to be the latest hi-tech option & we need to know how expensive & dependable as well as safe it would be for us. The Dutchman and the Mrs.

      • The Pedego Tandem is in stock and selling out fast. It has the same proplusion system as the Pedego Interceptor – 48 Volt Motor, Battery, Controller and Throttle. For extended range, the best solutions are 1. Carry and extra battery and/or 2. Carry a charger with you. The 48 volt LifePo4 battery is 10 Ah and should take you 20-30 miles per charge with minimal pedaling. With 2 batteries, you can go twice as far. Call us anytime at (800) 646-8604.

  2. thank you.. nice explaination… now another question. i have an e bike and love it… i also have a scooter/bike and i need new batteries. 4 12v 12amp. and i am having a hard time finding them here in san diego. everyone wants me to bring in the batteries i have. why cant they just tell me if they have 12v 12a batteries. then i have to connect them. is there one battery that will take the place of 4????

  3. I just bought a new 48 volt, 20 amp hour LiPo4 battery from China for my bike. I charged it with the provided charger. After charging, it is up to 60 volts. Is this how much it should have?



    • Hi Garen, Normally a 48 volt pack would be in the 52 volt range when fully charged. That pack does seem to be a bit high. Check with the store or manufacturer who you bought it from to see if they think that is strange.

      • Exact Pete, we at the workshop the 48V batteries when fully charged give between 52 and 54 V.
        Above it is surprising, the BMS does not work well, danger !

  4. Thanks for spending the time to educate. I own a GT004 green power bike that I bought thru Craiggs List. The guy does not return my calls. I have been trying to find a maintenance manual to service it but have not had any luck online. The closest service area is too far for me and I call them but they also are not returning my calls. their number is 718 200-6967. Anyway I hope my info facilitates someone. I know that they are in Flushing, ny which is in the borough of Queens. I got through one time but haven’t been able to since. I need to service my brakes. If anybody has some ideas or info please share it with me/us. Thanks again for this blog. Great stuff!

    • Are your brakes not standard bicycle brakes? May I suggest you watch Park Tool’s YouTube channel and search for brake adjustment.

  5. This is really over simplistic. One thing that I think you should have talked about is that the higher the voltage is,the more cells you need and the easier it crosses your skin. The more cells you have, the more points of failure you have. Ideally, you want 4 separate cells for a 48V bike that are not packaged in a “battery” (A battery is a group of cells). What can happen in a sealed “battery” is one of the cells can become discharged and then have their polarity reversed causing that particular cell vent and to become permanently damaged it’s capacity permanently diminished, which causes the problem to happen more frequently. By have 4 separate 12v cells, they can all be charged independently and replaced on an individual basis based on the condition of the cell via the smart charger. You can also use the charger to make sure all 4 cells have the same charge (if one is diminished) which will keep that bad cell from venting again until you can get a replacement. Also, having higher torque at the low end (with higher voltage) causes much more heat in the motor at the high end. Higher voltage does reduce the thickness of the wiring needed both on the bike frame, controller and the windings in the motor, but like I said, these thinner wires will heat up faster when going very fast or climbing a hill.

    Batteries are incredibly complex and there are entire books about batteries. The same battery can go 20 miles one day, 18 the next and 22 the day after that.

    • Hi Chris, Thanks for the detailed info. And yes batteries are very complex. My goal with this post was to convey the basics of batteries for people who are new to e-bikes.

    • No thanks, Chris. If your 4 cells give (nominal, not actual) 48V, then you’re using lead-acids and clearly off the 21st-century standards. Not even NiMHs even. Furthermore, multi-cell strings push the problem back to the BMS computer, an entirely solvable problem. Cell balancing- bottom AND top- should be standard in any BMS worth buying today.

    • I think we have a failure to communicate here.

      eBike battery packs use small Lithium cells, typically called “18650,” which are slightly larger than AA cells in size. Their voltage output depends on their state of charge but the output is nominally 3.7v. A typical 18650 cell can deliver about 2.5 Amps of current for about 1 hour, or 2.5Ah (2.5 x 1).

      Since one cell is good for 3.7v, battery makers line up 13 of them, tied in series, giving a nominal voltage of 3.7 x 13 = 48v. Then, to get more current capacity they tie up 4 banks of such cells, so the current capacity is 2.5A x 4 = 10 Amps of current. And most cells can reliably deliver about twice their rated capacity, so a typical eBike battery can deliver about 20 Amps for short periods.

      Now the TOTAL capacity of a finished battery pack is measured in “Watts.” Since watts = voltage x current, our finished assembly is rated at 48v x 10a = 480 Wh. This means it can deliver 480 watts for one hour, or 240 watts for two hours, and so forth. The peak current output is generally 20 amps, so full-throttle operation delivers 48v x 20a = 960 watts, or a bit over one horsepower. A typical hub motor may only be rated at “500 watts,” but it can easily absorb 960 watts for a short period of time.

      By the way, it’s called an “18650” cell because it measures 18mm in diameter and 65mm in length.

      • Very good details Riredale, I add a fairly simple little comment for buyers new to E-Bike. We in France use the following technical rule: 1 Watt/hour is worth 4 kilometers in normal use on flat ground. So for a 48V-14Ah battery or 672Wh you can estimate a range of approximately 672:4 = 168 kilometers on exclusively flat terrain with low assistance. I personally am on a winter cycling course in Spain with experienced couriers, on my Scott 48V/14.5Ah, I do 115 km but at high speed, and lots of big climbs.
        sorry for my English and my conjugation mistakes, long live cycling and be careful on the roads !

  6. I have a 48v 20amp hour LiPo4 on my bike that I’ve rode about 15-30 miles a day for about 45 days. The farthest I’ve ridden it on a charge was 44 miles before it cut off. I am very happy with it. It has always charged up to 60 volts and then went down a little after about one mile of riding due to surface charge. However, when I took it off the charger today so I could go for my ride, it had 67 volts. After I rode it for 15 miles, it was finally down to 53 volts which is where it is usually at after only about 5 miles. Can someone explain to me why it is now charging up to 67 volts?

  7. Hello all.!!!
    I am looking for a Big, Stout Electric Mountain Bike that can handle me. The one I just bought for 375$(cheap I know.lol) I BROKE!! I am 6ft 5inches and 310lbs. I need one of these as I have an injury from years ago that stops me from Hiking like I like to do. I am looking at the Busettii 60 Vortex. Can anyone out there tell me about the Vortex, the Busettii Company, if they are a Good, reputable Company and or where to look for what I need. Thanks so much!!

  8. hi, are there any open source Battery Management Systems that are suitable for users to alter the performance etc of an e bike. that work with all providers systems?

  9. I have 2 mini electric bikes one of which appears to have a battery which will not charge I have heard it may be asleep. It is 24v 6ah and I can’t seem to find a replacement. Is it ok to use a li-ion battery of different ah value. Pretty sure motor is 230W. Thanks for any help.

  10. i live in hilly NE PA, w/a heart condition and bad feet, and back so i bot a heavy recombant but am limited to a flat rd along a river, I also weigh 270 lbs and need to loose wt, so i’d like to expand my area and distance of riding. to do this i have to conquer many hills. hence i see a front wheel kit w/48v-1000w 470rpm kit requireing a LI, /lead acid/ or NIMH batterynominal capacity not less than 17Ah to be compaatible w/kit
    Is this available, safe, and legal,…. i’d like to go far..thanks, my hart depends on it!! where can i get battery.

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  12. I have a 750 to 1000 watt hub motor
    ,48 volt 15amp battery.
    The current controller is 26 amp.
    Can I replace controller to a 1000 watt 38 amp.
    My old controller went bad.

  13. I was wondering if I could get an answer here since I haven’t been able to find an answer anywhere else I have a kit which has a controller that is a thousand Watts 60 volts and goes up to 32 amps I have a battery that’s 48 volts a thousand watts and a motor that’s 48 volts a thousand Watts and I was wondering if this controller can work and all the way if anybody can answer this question I would appreciate it very much thank you

  14. I was wondering if I could get an answer here since I haven’t been able to find an answer anywhere else I have a kit which has a controller that is a thousand Watts 60 volts and goes up to 32 amps I have a battery that’s 48 volts a thousand watts and a motor that’s 48 volts a thousand Watts and I was wondering if this controller can work with my battery and hub motor if anybody can answer this question I would appreciate it very much thank you

  15. Well done but I do not complete agree with “ A higher Newton-meter rating equates to better uphill performance”. The torque can be specified to 1000 Nm and still the bike is not moving and the manufacturer do not specify when the max torque is delivered. It is the power in W that is needing to move the bike 😉.

  16. I am looking to power my awning with a DC tubular electric motor. It is a 12V, 66W,5.5 amp motor. It turns at 8 rpm and accordingly develops 36 Nm of torque.
    What would be the likely specs for a lithium ion batter pack to power such a set up.

  17. It’s important for voltage to be the same, so you’d likely want to look at a 12V battery – but otherwise, I’d recommend talking to an awning specialist!


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