Optimum Battery set up for my EV scoot Spec?

jdevane5

10 mW
Joined
Nov 28, 2021
Messages
34
I have just got myself a new QS Motor 12 inch 260 (70H) 10KW V4 HUB motor (96v set-up) with a Fairdriver controller ND961200 Phase 1200A, 600a line current.

I'm building a EV scoot from scratch and looking for the optimum battery set up, I have plenty of package space for the batteries but a bit stuck on what set up to go for to get the best out of hub motor and controller.

I'm pretty new to the world of EV scoot builds, so any advise very welcome.

Also any recommendations on really handy kit for an EV build would be good (MFT's etc) also . Cheers :D
 
Here's an electric scooter for you:
https://www.walmart.com/ip/Razor-Black-Label-E90-Electric-Scooter-Kids-Ages-8-120-lbs-Up-10-mph-40-mins-Ride-Time-90W-Power-Core-High-Torque-Hub-Motor/590441042
69a2b5af-a15d-45f1-a8bb-186e589c17ce.5ff0c835a228453899b47e9fbe5ccfe1.jpeg


Maybe you could be a little more specific about what you're looking for.
 
You’re looking for at least 6-10kwh. You could use nmc pouches with nuts and bolts.
 
Thanks I have started looking at the nmc pouches, they maybe a possibility.

I'm looking to get a range of 100 miles+, so my understanding on my batteries requirements is as follows;

I need 96V in series and then a given amount of Ah in parallel to gain my range, so its all about how many nmc pouches of cells I can squeeze into my scoot package space and at the same time balancing weight and adequate cooling...

Am I on the right track, or completely left field?
 
I checked out Li-NMC 25Ah-30Ah High Power Pouch Cells which I can get from a local company, so 4 or 5 will get me
around 100Ah @ 96v = 9.6kWh...
 
What it takes for 100miles+ range depends on how you use the scooter.

The faster you go, the more power is used, just about exponentially above 25-30mph, assuming typical aerodynamics.

The more hills you have, the more power is used.

The more headwinds, same.

The more weight, same.

The harder you start from a stop ("lead foot"), same.

For typical highway speeds, you might need 100-150wh/mile or more, depending on aerodynamics, etc. Less for city street speeds, 50-100wh/mile perhaps. (again, depending on the other factors above).


Let's just say you need 100wh/mile. 100wh/mile x 100miles is 10kwh, which is around what you've got there.


Does the 100 miles include "oops" range? Meaning, for extra headwinds on some days, or necessary detours for whatever reason? If not, you might want to add another 25% to account for those possibilities.

Also, as a pack ages, it loses capacity and capability. If you really need that full range for the life of the scooter, without replacing the pack as soon as it drops below that range, you may want to add another 25% for that, just in case.

THe problem with those two things is that they add 50% more weight and volume, turnign it into a 15kwh pack that weighs 1.5x what the 10kwh pack would. If the same range can be acceptably achieved with other things, either better aero or other efficency or delays using charging stations to top up where possible, then you can avoid that extra weight and volume.


Depends on your specific usage scenario.


For the battery build, using bare pouches, you may want to look up JonesCG's threads for those.
 
I'm doing a racing street Lambretta.
I race petrol variants capable of 100mph.

I want the same with EV variant but not for racing.. :D
 
jdevane5 said:
I need 96V in series and then a given amount of Ah in parallel to gain my range, so its all about how many nmc pouches of cells I can squeeze into my scoot package space and at the same time balancing weight and adequate cooling...

Am I on the right track, or completely left field?

Yeah, pretty much. It's a bit simplified but the idea is there.
One other thing to understand is that a given amount of Ah in parallel will also give you the maximum dischage capacity of your pack. In your case, you need it to deliver at the very least 600A, which is called current discharge. There are several ways to determine wether or not your pack will be able to provide this kind of current, but in order to know that you need to know at least the following information:
-How many cells are in parallel?
-Cell individual capacity?
-Individual cell maximum current OR Discharge rate (or C-Rate) of each cell (some manufacturers will provide max currents, some other manufacturers will provide the C-rating

Lets say you have 10 cells in parallel, each of these having a maximum discharge current of 30 amps. Then 10*30= 300, your battery can deliver a maximum of 300A. Too small, you'll need at least 20 cells in parallel to match your need.

Lets now say that you have 25 cells in parallel, individual cell capacity is 1200mAh and the maximum C rating is 3C. So, 25 x 1.2 x 3 = 90 Amps. So here you'll need around 7 times more cells to reach 600A.

I recommend you to start designing your battery with these simple calculations in mind first. Current draw is what ultimately kills batteries and lowers performance, so you need the battery to at the very least match the current your controller will draw. Otherwise the voltage will sag, the battery will heat and get damaged quickly.

That means, check for a battery with the best possible discharge current, or with a very large capacity.
600A is a lot of current, not many batteries are able to deliver that without breaking a sweat. You say that space isn't an issue, but on scooters it usually is, together with weight. That is especially true if you want to get a very long range at the same time (100miles on one charge is quite a lot).

Hope this helps a little.
 
jdevane5 said:
I checked out Li-NMC 25Ah-30Ah High Power Pouch Cells which I can get from a local company, so 4 or 5 will get me
around 100Ah @ 96v = 9.6kWh...

It's now time for a little exercise:

Given the examples I showed on my previous post, can you deduct the minimum C-Rating your cells need to match in order to reach your objective of 600Amps?
:wink:
 
I use 20Ah high power pouch NMC cells in 21S5P configuration wheighting 70kg.
They are rated 8C continous discharge an 5C continous charge.

At the moment I´m drawing only 165A peak, and about 90A continous, the battery heats up 3°Celsius from full to empty.
I have my battery completly isloated (20mm foam) and with an integrated heating system for winter.
I use it as a daily driver. The ND96850 is already ordered. The 961200 didn´t fit in my scooter.
I have no fear of overheating my battery pack in summer, as I do no full power highway trips, I only want faster acceleration with the bigger controller, aiming for 16-20kw peak.

If you want to use 10kW and more for long time you should also think about a cooling option, as mentioned in Rippertons thread, espacially when you want to fast charge it afterwards (>0,5C).

A few days ago I charged a naked NMC "storage type" pouch pack with 0,5C , it heated up 10°Celsius from empty to full.
If I had installed a storage type battery I would defintly have integrated a cooling system.
 
Dui said:
jdevane5 said:
I checked out Li-NMC 25Ah-30Ah High Power Pouch Cells which I can get from a local company, so 4 or 5 will get me
around 100Ah @ 96v = 9.6kWh...

It's now time for a little exercise:

Given the examples I showed on my previous post, can you deduct the minimum C-Rating your cells need to match in order to reach your objective of 600Amps?
:wink:

Therefore @ 25 cells in parallel, individual cell capacity is 1200mAh, I would need 20C rating for 600A?
 
Dui, ni shuo de dui -Big Thanks for the battery direction -A massive help for me in the magical world of EV building :bigthumb: :D
 
dominik h said:
I use 20Ah high power pouch NMC cells in 21S5P configuration wheighting 70kg.
They are rated 8C continous discharge an 5C continous charge.

At the moment I´m drawing only 165A peak, and about 90A continous, the battery heats up 3°Celsius from full to empty.
I have my battery completly isloated (20mm foam) and with an integrated heating system for winter.
I use it as a daily driver. The ND96850 is already ordered. The 961200 didn´t fit in my scooter.
I have no fear of overheating my battery pack in summer, as I do no full power highway trips, I only want faster acceleration with the bigger controller, aiming for 16-20kw peak.

If you want to use 10kW and more for long time you should also think about a cooling option, as mentioned in Rippertons thread, espacially when you want to fast charge it afterwards (>0,5C).

A few days ago I charged a naked NMC "storage type" pouch pack with 0,5C , it heated up 10°Celsius from empty to full.
If I had installed a storage type battery I would defintly have integrated a cooling system.

That s interesting -I had not even considered an integrated cooling system for the battery...is it as simple as 12v Fans drawing air in or is it more technical? I need to check out other projects on the forum, will have a look at Rippertons thread now. Cheers
 
So battery Strategy wise I'm thinking 26S10P...LiPol 3.7v, 20C ,6000mAh..
Gone with 1200A -Is that too much?!?
I do need to check Controller Spec can handle this..

Think I'm getting the hang of spec'ing the battery now.
All learnt from this forum and the comments on the Thread -Cheers :bigthumb:

Now want to look at integrated cooling ideas and need to do a package check on the battery dimensions x 37 batteries.
 
jdevane5 said:
So battery Strategy wise I'm thinking 26S10P...LiPol 3.7v, 20C ,6000mAh..
Gone with 1200A -Is that too much?!?
I do need to check Controller Spec can handle this..

Think I'm getting the hang of spec'ing the battery now.
All learnt from this forum and the comments on the Thread -Cheers :bigthumb:

Now want to look at integrated cooling ideas and need to do a package check on the battery dimensions x 37 batteries.

It's never too much. :wink:
Too much available amps on a battery is, as far as I know, always a good thing. Means less heat, less long term damage, less voltage sag, more perfs.
So yeah, go for the highest possible amp draw you can.
That being said, careful with LiPos, they can be tricky and dangerous to work with, you need to monitor them very, very carefully. I've always avoided this chemistry mainly for this reason (but also because they don't last very long). I'm not saying not to use them, but be very serious in doing your homework before comitting to this chemistry.

The more capable your battery is, the less cooling you need. If your battery is able to throw 1200 Amps, then it won't heat nearly as much at 600. Keep also in mind that you won't draw 600Amps for a very long time, only a few seconds while accelerating. Personnally, I never used cooling on my batteries so far, it wasn't actually needed (well I'm actually building a battery air conditioning system right now, but that's mostly for fun and also to keep the battery box hot and dry during winter). If your battery needs cooling it means that it might be a bit undersized, unless maybe for some very specific use cases like track racing. So my advice here would be to not spend your time on thinking about cooling right now, maybe just leave a few spots to throw a few fans here and there later if it turns out to be absolutely necessary, that will be enough.
 
If your battery is capable of giving you around 600A peak this schould be big enough. 600Ax90V=54kW
At least ist would aim for a minimum of 400A peak, more ist better, but also more expensive.

Cooling is probably needed when you want to isloate your battery against cold weather, and heat it in winter.

If your battery is araound 10kwh , not isolated, and you do not want to fast charge( 3kW charging power and more), you can live without cooling.
 
Dui said:
jdevane5 said:
So battery Strategy wise I'm thinking 26S10P...LiPol 3.7v, 20C ,6000mAh..
Gone with 1200A -Is that too much?!?
I do need to check Controller Spec can handle this..

Think I'm getting the hang of spec'ing the battery now.
All learnt from this forum and the comments on the Thread -Cheers :bigthumb:

Now want to look at integrated cooling ideas and need to do a package check on the battery dimensions x 37 batteries.

It's never too much. :wink:
Too much available amps on a battery is, as far as I know, always a good thing. Means less heat, less long term damage, less voltage sag, more perfs.
So yeah, go for the highest possible amp draw you can.
That being said, careful with LiPos, they can be tricky and dangerous to work with, you need to monitor them very, very carefully. I've always avoided this chemistry mainly for this reason (but also because they don't last very long). I'm not saying not to use them, but be very serious in doing your homework before comitting to this chemistry.

The more capable your battery is, the less cooling you need. If your battery is able to throw 1200 Amps, then it won't heat nearly as much at 600. Keep also in mind that you won't draw 600Amps for a very long time, only a few seconds while accelerating. Personnally, I never used cooling on my batteries so far, it wasn't actually needed (well I'm actually building a battery air conditioning system right now, but that's mostly for fun and also to keep the battery box hot and dry during winter). If your battery needs cooling it means that it might be a bit undersized, unless maybe for some very specific use cases like track racing. So my advice here would be to not spend your time on thinking about cooling right now, maybe just leave a few spots to throw a few fans here and there later if it turns out to be absolutely necessary, that will be enough.


So you got me thinking and I have started looking at battery chemistry alternatives -There's a lot of choice and price difference.
I started looking at big Corps with huge Product Development budgets for EV, say like Tesla and just mimic there battery solution which looks like 18650 or similar. I'm new to batteries and want something safe and reliable that's straight forward.
Prices wise my set up as LiPO is £1300 versus £410 for 18650. Its all a balance of battery packaging, versus cost , versus battery management...Think I will check out other projects on the forum :)
 
After considerable battery reviews and looking at other EV projects right now I have gone with the following battery set up;
....27S25P....

I will use 18650's Samsung 30Q, 3000 mAh, 3.6v, Discharge 15A. That calc's to 1125A..think that will do!

So that's 675 cells....31.1 Kgs -Its a big one!

So now I'm onto the physical battery installation design, I might want to break the batteries up to distribute the weight around the Lambretta -So other than wiring, anything I need to consider going with this strategy?
 
jdevane5 said:
I have gone with the following battery set up;
....27S25P....

I will use 18650's Samsung 30Q, 3000 mAh, 3.6v, Discharge 15A. That calc's to 1125A..think that will do!

52 batteries comes in at 2.4 Kg, which does not seem too bad- I will save that weight in changes I'm making to the Lambretta panelling and components.
Cost comes in at £400 which is not bad and found a UK supplier.

So now I'm onto the physical battery installation design, I might want to break the batteries up to distribute the weight around the Lambretta -So other than wiring, anything I need to consider going with this strategy? Is it normal to break up the in-series and parallel into two battery packs?? :D

27S25P means 27x25=675 cells in total. So the weight, cost and space needed will be a "little" higher/larger than you calculated... :lol:
 
25x15=375😉
In the samsung datasheet they have listed 20A as max continous discharge.
That gives you 500A which should be enough.
31kg without housing and Connectors.
And you have to do a lot of welding.
 
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