First Ebike Battery Build (Looking for advice and help)

RedXXDuce

New Member
Region
United Kingdom
Hi all my name is Ismail I am new to the E-Bike community and was hoping to get some advice and help on the build that I am planning. This is post is focused on my battery as this will be my first time and would like to avoid screwing anything up.

Battery_Design_EBike.png

Attached above is the design for my battery pack. I will make a 13s3p battery which will be 48V and 10.2AH I am hoping this will be plenty to power the motor that I would like to purchase (https://www.aliexpress.com/item/4000056456643.html?spm=a2g0o.cart.0.0.6e203c00G8sXgY&mp=1) which is a "48V 1500W REAR WHEEL MOTOR".

The BMS that I have chosen to manage the battery is (https://www.aliexpress.com/item/33000839343.html?spm=a2g0o.cart.0.0.6e203c00G8sXgY&mp=1) a 48V BMS rated at 13s and can handle 50A working current with balance function.

Unfortunately, I am unable to find batteries anywhere else so I am either going for these VariCore cells I found on AliExpress (https://www.aliexpress.com/item/32324914059.html?spm=a2g0o.cart.0.0.6e203c00G8sXgY&mp=1) Which are rated at 3.7V 3400mah, with those figures I did all my calculations. My other option would have been the Panasonic Sanyo NCR18650GA (https://batterybro.com/products/pan...-3450mah-10a?contact_posted=true#contact_form) with similar ratings of 3.6V and 3450mAH.

I am by no means an electrician but this is what I have managed to put together and I would appreciate it so much if someone is able to take a look and advise me further. If there are any other pieces of information required let me know!

Links:
Battery cells: https://www.aliexpress.com/item/32324914059.html?spm=a2g0o.cart.0.0.6e203c00G8sXgY&mp=1
E-bike Conversion Kit: https://www.aliexpress.com/item/4000056456643.html?spm=a2g0o.cart.0.0.6e203c00G8sXgY&mp=1
Nickel Strips: https://www.aliexpress.com/item/32333149144.html?spm=a2g0o.cart.0.0.6e203c00G8sXgY&mp=1
Heat Shrink Tube: https://www.aliexpress.com/item/32605395409.html?spm=a2g0o.cart.0.0.6e203c00G8sXgY&mp=1
BMS: https://www.aliexpress.com/item/33000839343.html?spm=a2g0o.cart.0.0.6e203c00G8sXgY&mp=1
Charger (Potential): https://www.aliexpress.com/item/455606765.html?spm=a2g0o.store_pc_groupList.8148356.6.16393b94jfRpGH


 
Last edited:

reed scott

Well-Known Member
Search up a guy named greeno here on the site. He is an advanced battery builder and has put up several pics of his creations along with step by step pictorials.
 

harryS

Well-Known Member
I bought some NCR18650B's last year. They had tabs already welded on, and were 3400mah and rated for 10A discharge. (I used them to make some 3S-3P packs. ) I don't see any current ratings on your cells from VariCore. For a 1500W motor, you need 30A continuous. I think you should go at least 13S4P, maybe 13S5P to keep from stressing out your battery and killing it. I've owned packs that used GA cells. That would have been my first choice.

I've used Annpower BMS. Worked when wired up. Still working. Can't say that about some others I bought.

You got a good spot welder? I've never owned one. Just done some BMS replacements abd those 3S3P's.
 

RedXXDuce

New Member
Region
United Kingdom
I bought some NCR18650B's last year. They had tabs already welded on, and were 3400mah and rated for 10A discharge. (I used them to make some 3S-3P packs. ) I don't see any current ratings on your cells from VariCore. For a 1500W motor, you need 30A continuous. I think you should go at least 13S4P, maybe 13S5P to keep from stressing out your battery and killing it. I've owned packs that used GA cells. That would have been my first choice.

I've used Annpower BMS. Worked when wired up. Still working. Can't say that about some others I bought.

You got a good spot welder? I've never owned one. Just done some BMS replacements abd those 3S3P's.
I will go for the GA cells as they do seem more reliable than the aliexpress ones. I am assuming with the GA cells I won't need to increase the number of parallel batteries as they have a discharge rated at 10A?
 

RedXXDuce

New Member
Region
United Kingdom
Search up a guy named greeno here on the site. He is an advanced battery builder and has put up several pics of his creations along with step by step pictorials.
I have taken a look at him but as I am new to the site I'm not exactly too sure where to find his battery builds or something similar to what I need
 

reed scott

Well-Known Member
Go here:

Then click on 'POSTINGS'

He doesn't post as much as addicts like me and you can find his battery posts pretty easily. When on one of his posts just hold your cursor over his avatar and then you can choose to send him a PM
 

harryS

Well-Known Member
Cells will last longer, and stay in balance better, when not operated at max capacity on every ride. Even with the better cells, I think 13S-4P is the minimum for a 20A BMS. With 40A, you ought to go higher.
 

RedXXDuce

New Member
Region
United Kingdom
Cells will last longer, and stay in balance better, when not operated at max capacity on every ride. Even with the better cells, I think 13S-4P is the minimum for a 20A BMS. With 40A, you ought to go higher.
What if I were to get a less powerful motor what would work best with the current configuration I have as getting more cells is going to become more and more expensive
 

greeno

Well-Known Member
Region
USA
City
San Diego
RedXXDuce just saw your message so will post up reply here in case anyone else has questions if that's ok.

Is this for a commuter bike that will be used on the roads or a MTBike for off-road use?
How will you mount the battery? On a rear rack? Backpack?

Building up a 3 pack will not give you much riding time. Especially having a 1500w motor.

How do you plan on connecting up nickel jumpers to the batteries? 1.5 x 7mm pure nickel stripes have about a 4.7a optimal rating per jumper. So connect up each parallel group together and then add (3) jumpers from group to group giving you capacity of roughly 14a.
I would strongly suggest a good spot-welder. There's a guy on your side of the pond that makes the Spot-welder I used it's called "K-Weld", look him up. The spot welders from China suck.

Heat shrink tubing is ok I guess as long as you protect the battery with a padded bag. I use contact paper all around mine and then 1/4" foam board and then gorilla tape it and Then it goes in a padded bag. If A BMS ever goes bad or what ever I can just operate on it like I did in my real life ( Brain Surgeon ) before I retired. Opps got a little carried away there I wasn't really a Brain Surgeon just felt like it sometimes.

I would go with the Sanyo GA batteries with their 3.45ahr rating and 10a max discharge. I use those same batteries exclusively and have never had an issue. I think the price just went up I think I paid $5.50 ea last time I ordered.
tempImageQbT0ga.png


The BMS is good I use those same ones on most of my 30a builds. 50a is too much 30a is all you need. Go figure the one pictured above is different.
I think I have had only one go bad in all the battery's I have built. There's a company called "Vruzend" that carries those as well and they have a supplier here in the states ( Florida ) and they also have a branch in the UK. In fact I just got a couple of the 52v 14s 30a ones from there as the guys here were out of stock. Took about 2 weeks to get. Actually one of the guys that started Vruzend is Micah Toll and he wrote a book called "DIY Lithium Batteries How To Build Your Own Battery Packs" that you can get off Amazon for like $20 and I t's pretty good on explaining the basic's and I used it when I first started doing these.

The charger won't work as it's rated for 36v (10s) and your motor is 48v (13s).
 

reed scott

Well-Known Member
All hail greeno! The battery wizard. Too late now but if you were around 40 years or so ago I would have offered to be your unpaid apprentice. 🤣
 

RedXXDuce

New Member
Region
United Kingdom
RedXXDuce just saw your message so will post up reply here in case anyone else has questions if that's ok.

Is this for a commuter bike that will be used on the roads or a MTBike for off-road use?
How will you mount the battery? On a rear rack? Backpack?

Building up a 3 pack will not give you much riding time. Especially having a 1500w motor.

How do you plan on connecting up nickel jumpers to the batteries? 1.5 x 7mm pure nickel stripes have about a 4.7a optimal rating per jumper. So connect up each parallel group together and then add (3) jumpers from group to group giving you capacity of roughly 14a.
I would strongly suggest a good spot-welder. There's a guy on your side of the pond that makes the Spot-welder I used it's called "K-Weld", look him up. The spot welders from China suck.

Heat shrink tubing is ok I guess as long as you protect the battery with a padded bag. I use contact paper all around mine and then 1/4" foam board and then gorilla tape it and Then it goes in a padded bag. If A BMS ever goes bad or what ever I can just operate on it like I did in my real life ( Brain Surgeon ) before I retired. Opps got a little carried away there I wasn't really a Brain Surgeon just felt like it sometimes.

I would go with the Sanyo GA batteries with their 3.45ahr rating and 10a max discharge. I use those same batteries exclusively and have never had an issue. I think the price just went up I think I paid $5.50 ea last time I ordered.
View attachment 95989

The BMS is good I use those same ones on most of my 30a builds. 50a is too much 30a is all you need. Go figure the one pictured above is different.
I think I have had only one go bad in all the battery's I have built. There's a company called "Vruzend" that carries those as well and they have a supplier here in the states ( Florida ) and they also have a branch in the UK. In fact I just got a couple of the 52v 14s 30a ones from there as the guys here were out of stock. Took about 2 weeks to get. Actually one of the guys that started Vruzend is Micah Toll and he wrote a book called "DIY Lithium Batteries How To Build Your Own Battery Packs" that you can get off Amazon for like $20 and I t's pretty good on explaining the basic's and I used it when I first started doing these.

The charger won't work as it's rated for 36v (10s) and your motor is 48v (13s).
I have realised a few things from the feedback and I have definitely been a little stupid. The plan is to mount the battery on my mountain bike and use it for delivery work and commuting and I now realise I have no need for a 1500w motor and will now be downgrading to a 500w motor which seems to do everything I need and more, I am now also hoping the battery will become smaller and less expensive.

I have taken a look on aliexpress and would possibly like to get the 48V 500W motor (not sure what the difference is between 36V and 48V)
1628599188011.png

but this section confuses me, does it mean I need a battery that can discharge at 22A continuous? and if that's the case then would I need a 13s7p battery to work with the 500w motor? and if so then I fear it will be too big but I am not too sure about the sizes.

I am planning on getting Micah Toll's book as his videos are what got me into wanting to build my own Ebike 😂
 

greeno

Well-Known Member
Region
USA
City
San Diego
Not stupid you just didn't have a clear understanding on the specifics. All things being equal a smaller wattage motor and same size battery means two things.
Less power assist and longer range.
Changing from a 1500w motor to a 500w motor will give you three times the range as before, or 1/3 the power assist theoretically.
FWIW the 22a controller rating is on the high side for that set-up and you adding more batteries in parallel (13s/3p --- 13s/7p) will give you more range not more power.
Micah's book will explain the jumper set-up you would need on whatever design you go with.
Just an FYI
the lower the voltage with the same wattage motor will require more amperage.
Example: 48v motor at 500w
48v battery range:
100% -- 54.6v so 500w divided by 54.6a = 9.15amps
50% -- 46.8v 46.8v = 10.6amps
0% -- 39.0v 39.0v = 12.8amps

Lower voltage = higher amperage for the same wattage.
So what that means when building a battery at 48v and 500w you need a MINIMIUM of 12.8 amps current caring capacity from one group to the next (13s). The nickel jumpers you had spec'd out will optimally carry 4.7a so 4.7x 3 = 14.1a, so 3 jumpers from group to group will be fine. The Sanyo GA batteries have a max discharge rating of 10a each so theoretically you could have 30a flowing with only 3 jumpers and batteries would be rated for it. Would I do that, no you always want to build in a safety factor. Another example is I just built a 52v battery 24ahr (14s/7p) and I had 10 jumpers connected from group to group ( see pic above) meaning the most current I could ever have flowing is 30a max divided by 10 = 3a in each jumper and the material I use is rated for 6.4a, so overkill but a good safety factor built in. Less heat inside a battery is a good thing.