Wanting to run 2 x 36v batteries on 72v motor need help please!!


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Local time
4:49 AM
Jun 4, 2023
I have a 72V 3000W bike I built. The battery is a 72V 26ah, and does not last long enough at all. So I want to use 2 x 36v batteries, like 80-100ah. Now my question is my bike is 3000W & I keep seeing 1000, 1500w 36v batteries. I'm not seeing any 36v 3000W batteries!! I apologize now if this is a stupid question but I truly don't understand this stuff.

What size 36v batteries do I need??

Remember I want at least 80ah can someone please tell me what batteries I need & thank you in advance
Hello my name is Joe, and I built my own bike with a hub motor, 72v 3000w. " I LOVE IT!" but my battery ( 72v -26ah ) doesn't last long enough at all. So I'm wanting to use 2 - 36v batteries with them being atleast 80ah..I do not understand electricity so I'm have a hard time understanding what kind of 36v battery I need! All I see is 36v ( 750-1000-1500W ) batteries. ** CAN SOMEONE PLEASE TELL ME WHAT 2 - 36V BATTERIES I NEED TO RUN MY 72V 3000W BIKE?? ( ATLEAST 80ah ) please & thank you
Really you need to find a controller that provides inputs for two separate batteries, if that’s what you want to do.
If you took THREE of your current battery, paralleled them, you would have a 72V, 78AH battery. Do you have room to mount THREE of your current batteries? The weight would also be considerable.

To reach 72V, 80AH, using 36V batteries, you would need two, 36V, 80 ah batteries and connect them in series fashion. Don't think anybody makes such a battery, you would need to build it yourself or have it custom made. As you do not understand electricity, and you are dealing with life-threatening volts and amps, I would strongly recommend against building your own.

Do you really need a 6,000 watt battery?
No I don't need 6000W battery. It's only 3000w. I'm confused there! All I want is to be able to ride further/ longer!!! Yes everywhere I go I'm doing 40+ mph, the current battery only last maybe 15miles at the most!! When my lcd screen battery reading reaches 80% the bike completely dies! I was told that it's doing that because it doesn't have the volts left to run the bike. I'd be happy with 50ah. I was just trying to save $ by using 36v batteries instead of a 72V battery wich is ALOT more expensive. Can you tell me what 36v 50ah battery to use? 2 of them
You said you wanted a 72V, 80 to 100ah battery. That IS approx 6,000 watts. You are definitely confused. Your MOTOR is 3000 watt, that just means that if you go over that for very long, it will melt. Has nothing to do with battery measurements, you want to go farther, you need more AH.

There is no magic here, it will be roughly three times the size and weight of your current battery.


Bike should not be dying at 80% charge reading. There is some kind of calibration issue here. LVC is set too high. 80% charge should still run the bike just fine, a little bit slower. 18s, approx 72V battery, should cut off around 54 - 58 volts, I would guess yours is set at a higher voltage.

After it dies, if you turn it off, then back on, does it work for a bit?

If you would slow down a bit, and pedal a lot more, you could easily double your current range.
Yes I understand that AH is battery, but your saying 80-100ah is to much for 3000w? And the calibration part I have know idea, whatever it was out the box!! I'm curious now though, I'm going to check that! And when I first built the bike I used to be able to ride to around 47-52% battery.now 80% off, and " NO" I can't even turn the bike back on! The only way to turn the bike back on is to hook the charger back up to it then turn it back on, will only work on #1 until about 65-69% battery! Yeah I think it's quite ridiculous that I only get to use 20% of a battery! And I can't pedal, the chain kept coming off after I built it so I just took it off! I'm so sick of having to push the bike trying to find a socket to p)ug the charger in so I can atleast use #1
OK, There is NO SUCH THING as TOO MUCH ah for a motor. YOU ASKED for a 6000 watt battery, then YOU SAID that was too much, NOW you think I SAID it is too much, READ THE GODDAMN QUESTION I HAVE ASKED *TWICE*. That battery would be LARGE in terms of SPACE, and WEIGHT, the ah capacity ONLY affects range.

Now, tell me, slowly, carefully, and IN DETAIL, where you are getting these percentage readings on your battery, are they given in percentages or a voltage number? SOMETHING is very wrong with your battery, and with a unit of that capacity, and a user of your VERY LIMITED knowledge, likely this represents a very serious danger to yourself and others around you.

It is the internal BMS which is shutting you down. Likely one or more parallel groups is severely defective.

Also, where did you get this battery, did you build it, somebody slap it together in an outhouse, what?

Also, you just referred twice to #1, in reference to your battery. Explain this, clearly, in detail.

If you are not a native English speaker, try and find someone who is, or at least make a stronger effort to be clear and understandable, cause your efforts so far are not getting it done, and you may be dealing with a bomb.
One other thing not really talked about here is that the batteries you choose need to be capable of delivering 80amps for WOT operation. I don’t think there are a lot of 36v e-bike battery packs out there that have that kind of rating. They are mostly for bikes that draw less than 20amps. Remember you are wanting to run these in series so each battery is going to see that 80amp current draw. I don’t think you will find any retail 36v e-bike batteries with that capability.
I ordered the kit from alibaba. & I'm getting the battery reading right on the color lcd screen on my handle bars! It's always on the screen on left side .and I never said I wanted a 6000w battery!! I know that the bike is 3000W. All I ever said was that I was looking for 2 36v batteries around 80ah that would run my bike!! I apologize if I'm not being that clear. I'm just looking for more distance!! I found a 72V 50ah battery going for around $800. Problem is, that's about what I paid for the 26ah !! SO,,, I ask my self how big of piece of s**t can it be! I just want to be able to ride more than 10miles
Oh and when the bike shuts off it has a small red engine & reads " COMMUNICATION ERROR " Then shuts off
So, when you experience the problem you started this post for, you have a CLEAR ERROR MESSAGE on the screen, and you decided to wait until your SIXTH POST, to share this information???

Tell you what I'm gonna do. I will now allow you to jerk other people around, and waste their time.

Good luck to you.

Fix it yourself.
1st. Of all I know there is a problem with the battery, that's why " IM ASKING FOR INFORMATION ABOUT BATTERIES " that's all I have asked about, sure I am going to fix it myself, I'm going to replace the battery!! Excuse me if I'm not that educated in electric, that's what I thought this site was for! Sorry for asking for help on ur site, I'll never ask anything ever again !
For Jimbo - First, there are extremely few if any controllers with two battery inputs, second, in most cases and ALL where high power draw is needed, ONE, Single, large-capacity battery will not only last longer per individual ride, but also have a longer functional lifetime.
Not sure what your talking about, the controller, you DO NOT need a controller like that, every one I know just uses the ( dual battery connector adapter)with no issues! It's like $30
I'm sure everyone YOU KNOW does.

Now, sonny, I am going to ask you some simple questions. I need plain, direct answers. You have not done well in this regard.

First, just to see if you can handle it. Do you think you can fit something the size of your current battery, plus two more of them, on your current bike?
Oh, just to clarify. I am not interested in your opinion what battery you think you asked for, or think you need. Just answer the size question.

There will be more questions leading to solving your problem. You will answer each one, clearly and completely. Blow it, give me any crap, and you can waste a bunch of your money.
NO!! Absolutely not. But I will make 2 of them fit/work. My plan is to have a bag made by a friend's wife who is a seamstress that will hold 2 Batts side by side.and it will have the velcro just like the single ones. Use the dual battery adapter & there u go 20miles!! J/k I hope to get more than that.

You state that it used to run down around 50%. First, did it shut down then, and if so, did it have the same error msg?

Also, how long have you had this bike.

Multiple questions, big test for you. Make sure you get all three.
Not sure what your talking about, the controller, you DO NOT need a controller like that, every one I know just uses the ( dual battery connector adapter)with no issues! It's like $30
Those are for parallel connected batteries. You want to run in series. But what you want to do isn’t going to work anyway.