jhewitt3476

New Member
Upgrading batteries for ebikes

a possibly complicated question, so I'm going to separate it...

My objective on my ebike project isn't power or speed, but distance, without overpowering the motor or having to purchase one or two EXTRA batteries.
I want to get a 350w hub kit, but the "recomended" batteries are only just enough to run it and then for not very long distances, so......

#1 : can I hookup a 36v 20ah battery to a 10a battery controller ???

#2 : will it damage the controller

I ask these questions because NOWHERE on the internet can I find any answers, yay or nay, I wonder because most other battery operated dc electrical devices can run off of a battery that has more ah than it needs as long as it is the proper voltage.

I'm asking for first-hand knowledge answers please, not assumptions or speculations, because I am NOT a well funded person and I can't go replacing the battery, controller or motor every year because somebody talked big and convincing, but didn't actually know first-hand or has had direct contact with another person who attempted the same thing. this information should also be of great benefit to lots of other ebike riders or those who want to ride.

Thank You for any help
 

George S.

Well-Known Member
A controller has a 'system' voltage, and you are talking 36v. So the motor and controller are 'set up' for 36 volts. The complicated stuff is amps. We know the voltage, but the motor can draw almost any amount of amps. The limitation is heat and electronic components, that sort of thing.

A 10 amp controller generally means it will not draw more than that. The general idea would be to have the controller limit amps, not force the ebike rider to think this out.

Amp hours is a measure of capacity and, by itself, doesn't matter much. More is more, less is less. What does matter is that big battery packs can let you draw more amps simply because they are bigger, so each cell works less hard.

You can buy a battery with a large capacity and nothing really changes. The voltage matters. You want the system voltage or something that is within the range of the controller.

So,

1) Stay at your system voltage
2) figure your controller is set to limit amps (may be programmable, probably set at factory)
3) More capacity at the system voltage is just more capacity, more amp hours

There's a lot of information out there, but it is spread around.

Note: One amp hour, 1AH, is drawing one amp for one hour. A 10 amp hour battery lets you draw an amp for 10 hours. A 20 amp hour battery lets you draw one amp for 20 hours. Ebikes typically draw 10 amps, something like that. So one hour versus two hours.
 

jhewitt3476

New Member
yes sir, but that was the jist of my query, would a controller for a set volt and amp allow me to put a larger battery (20ah) of same voltage in but still only draw enough to make the motor function but twice as long as a 10ah battery would allow,

I live in Mayberry (Satsuma, Al) and want to get to Mobile and back, a good 18mi one way to my specific destination, but as I am not ga rich person (or even adequately funded) purchasing a second/spare battery would be out of my range, plus the added weight of a second battery would reduce the range also, I plan on pedaling, but one larger capacity battery is cheaper and lighter than two+ adequate capacity batteries,

I need to know, can it be done and if so, how is the best way to do it ???
:)
 

jhewitt3476

New Member
the tech specs are appreciated fully, I just don't want my first (and only) ebike experience to be a costly flop or a wasted one, I never believe advertised ranges anyway since rider weight, road conditions, weather conditions and even bicycle condition affects it greatly, that's why I was going to max out at 350w motor (36 or 48, not sure yet), but wanted a battery that could get me out and home again in one trip
 

jhewitt3476

New Member
I see lots of kits with the motor being various wattage and a corresponding battery, but the running time seems to vary, one company's 1000w w. batt runs about the same length as another's 500, it's all proportional, but some offer a kit only but let you select a battery, it gets very confusing
 
Yes you can put higher volts but i wouldnt over do it because it wont work anyway and if it allows u to do so u can burn the wires. For example i have a 48v 1000w 20ah hub motor and i am currently running 5, 12v 7ah wich makes 60v 7ah on it and i have not had a problem but then again i throttle less then most people. I peddle and throttle continuous. I tried adding a 6th battery to make it 72v but my motor didnt move at all. So your controller is probably set to higher volts from factory but not by much.
 
I see lots of kits with the motor being various wattage and a corresponding battery, but the running time seems to vary, one company's
1000w w. batt runs about the same length as another's 500, it's all proportional, but some offer a kit only but let you select a battery, it gets very confusing


Yes but thats because the ampere hours are the same. The mph will vary
 
yes sir, but that was the jist of my query, would a controller for a set volt and amp allow me to put a larger battery (20ah) of same voltage in but still only draw enough to make the motor function but twice as long as a 10ah battery would allow,

I live in Mayberry (Satsuma, Al) and want to get to Mobile and back, a good 18mi one way to my specific destination, but as I am not ga rich person (or even adequately funded) purchasing a second/spare battery would be out of my range, plus the added weight of a second battery would reduce the range also, I plan on pedaling, but one larger capacity battery is cheaper and lighter than two+ adequate capacity batteries,

I need to know, can it be done and if so, how is the best way to do it ???
:)


Yes because your bikes run time is based off of the capacity of your battery. So if you use a 48v 7ah battery you will not see more then 5-6 miles on average with a 200lb body on it like me. If you weigh less then u will go probably just a few miles more because 7ah is very small. Now 20ah at my weight i can probably do 25-30 miles so just do the math
 

Alex M

Well-Known Member
#1 : can I hookup a 36v 20ah battery to a 10a battery controller ???

#2 : will it damage the controller

I ask these questions because NOWHERE on the internet can I find any answers, yay or nay, I wonder because most other battery operated dc electrical devices can run off of a battery that has more ah than it needs as long as it is the proper voltage.
Old topic. For the sake of clarity, and perhaps - education: there is no yay or nay because you can't compare AH and A. There is no such thing as "more AH than {device} needs". AH is a capacity, storage - think of it as the size of a car gas tank. More gas in the tank - longer range, there are no other consequences.

OTH, A is a current, this is like a rate of gas withdrawal from the tank to motor. Amps rating of controller is like a diameter of pipeline from tank to motor, 20 A controller will let you draw more fuel each second from battery than 10A controller IF motor needs more. So...

#1 - Yes, because controller (pipeline) doesn't care about battery AH (amount of gas in the tank). However, voltages of battery, motor and controller should match.
#2 - No, because the pipeline (controller) doesn't care about AH number (size of tank). It is the motor that could damage the controller. If motor will demand more A (gas flow) than the controller (pipeline) can let through, the pipe would burst on seams. Or some fuse will blow. OTH, there is no punishment for over-sizing the pipeline diameter (i.e. controller A rating).

This is of course a simplified picture. Unlike a car tank, a battery is sensitive to how much fuel (A) you withdraw every second, it doesn't like giving too much A, so the A demand of motor would not exceed the A limit of the battery. NOT the ah capacity - but the A limit. AH capacity doesn't matter, it only makes your range longer and bike heavier.
 
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I have 6 lead acid batteries i need 48v and 20ah but i know it wont work with 6 batteries so can i create higher "ah" and "volts" with a series parallel connection of the 6 batteries? If so please show diagram even if its drawn on paper and let me know what would the new volts and amp hours be?
 

Alex M

Well-Known Member
can i create higher "ah" and "volts" with a series parallel connection of the 6 batteries?
This is what happens when they don't teach Physics in school, giving a combined course of "Science" instead :)

Series add volts, parallel add A and AH.

Series 4 (7AH , 12V each) will give you 7 AH , 48v.
Another series 4 will give you another bank 7 AH, 48v.
2 of these banks in parallel will give you 14AH, 48v.

Verdict: to achieve your goal of 20AH, 48V, you need total 8 batteries, not 6. Though it will be 14 AH, not 20.
 
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Awesome. Thank you. Ok so i would connect both banks of 4 in series and then connect parallel right? Ok so where will i connect it in parallel because i have seen different parallel diagrams. I understand the series for both banks i just need the parallel connection for proper installation. Thanks
 

Trail Cruiser

Well-Known Member
Awesome. Thank you. Ok so i would connect both banks of 4 in series and then connect parallel right? Ok so where will i connect it in parallel because i have seen different parallel diagrams. I understand the series for both banks i just need the parallel connection for proper installation. Thanks
I started my ebike days with lead acid batteries more than ten years ago. 8 lead acid batteries would be close to 70 pounds. Not practical at all. My ebike was 24v 12ah (2 12v in series) and that was close to 20 pounds. If I need to have longer trips I carry a spare battery which is ridiculously heavy. I would rather look for a lithium 48v 12-20ah range which is very light compared to lead acid. I suugest you use the original 4 batteries and carry a spare if you need to ride on longer trips.
 
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Trail Cruiser

Well-Known Member
Upgrading batteries for ebikes

a possibly complicated question, so I'm going to separate it...

My objective on my ebike project isn't power or speed, but distance, without overpowering the motor or having to purchase one or two EXTRA batteries.
I want to get a 350w hub kit, but the "recomended" batteries are only just enough to run it and then for not very long distances, so......

#1 : can I hookup a 36v 20ah battery to a 10a battery controller ???

#2 : will it damage the controller

I ask these questions because NOWHERE on the internet can I find any answers, yay or nay, I wonder because most other battery operated dc electrical devices can run off of a battery that has more ah than it needs as long as it is the proper voltage.

I'm asking for first-hand knowledge answers please, not assumptions or speculations, because I am NOT a well funded person and I can't go replacing the battery, controller or motor every year because somebody talked big and convincing, but didn't actually know first-hand or has had direct contact with another person who attempted the same thing. this information should also be of great benefit to lots of other ebike riders or those who want to ride.

Thank You for any help
18 miles trip would require approximately 360 wh (at 20 wh/m). Three 10-12 ah lead acid batteries would suffice. 36 volt setup tends to provide longer range than 48 volts for the same battery capacity. If your ebike does not have pedal assist mode, then you have to add a PWM controller to efficiently control your output and connected in between the battery to the motor . You dial the exact consumption so you can have enough power the whole length of your trip.

http://www.ebay.com/itm/Universal-DC10-60V-20A-PWM-HHO-RC-Motor-Speed-Regulator-Controller-Switch/172624953809?_trkparms=aid=222007&algo=SIM.MBE&ao=1&asc=20150313114020&meid=2ace7e7580ab4f27b3eb752ea56240f9&pid=100338&rk=17&rkt=30&sd=122601803398&_trksid=p2141725.c100338.m3726
You have to fully open the throttle when using the PWM controller to be efficient. Partial throttling is the least efficient way of using the battery.

Or you can set the throttle as full open all the time and then use the PWM controller dial as your new throttle.

You also need a voltage meter to know the exact state of charge of your battery.

http://www.ebay.com/itm/Mini-DC-0-100V-Battery-Level-Voltage-Monitor-Indicator-Meter-Voltmeter-Red-ZS/180458654927?_trkparms=aid=555019&algo=PL.BANDIT&ao=1&asc=41451&meid=0fa162e7578f4b50bbc5e2eb7830379c&pid=100505&rk=1&rkt=1&&_trksid=p2045573.c100505.m3226

So get a pedal assist version with built in battery gauge and you don't have to go through all this hassle.
 
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I already have 6 batteries 2 more wont hurt. This bike flies with that weight. But i am going to just sell them and get four 12v 18ah batteries instead wich will be 40lbs but in the mean time can i use these 6 batteries and create 36v and higher ah in series parallel connection?
 

Trail Cruiser

Well-Known Member
I already have 6 batteries 2 more wont hurt. This bike flies with that weight. But i am going to just sell them and get four 12v 18ah batteries instead wich will be 40lbs but in the mean time can i use these 6 batteries and create 36v and higher ah in series parallel connection?
Yes. it would provide lower speed than the 48 volt but longer range.
 
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Ok 2 more questions.
How much less speed. Its going close to 30 now? Also how do i do series parallel connect can you show a diagram? Or drawn out picture please?
 

Trail Cruiser

Well-Known Member
awesome! so in this diagram I see the 36v but what would be my ah? just to recap I have six 12v 7ah batteries.
That would be 36 volt 7ah or a 252 watt-hour battery. At a 20 wh/mile realistic battery consumption, your battery should have a range of 12 miles with PAS (less miles with throttle).

Edit:
I apologize for the mistake on my quick response and then forgot to include the parallel circuit. That would actually be 36 volt 14ah or a 504 watt-hour battery. At a 20 wh/mile realistic battery consumption, your battery should have a range of 24 miles with PAS (less miles with throttle).

I am guessing that the 6 batteries weigh 30+ pounds.
 
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