First build, need some help

Zephyr117 · Oct 29, 2018

I'm not using any of the below parts any more, please refer to my most recent post for my questions concerning those. Thank you!

Hi all, I'm building an electric bike and have some questions. my main concerns are in bold
I'm going to be using this motor https://em3ev.com/shop/5kw-qs-v3-rear-direct-drive-hub-motor/ it's rated for 5000w
and maybe two of these batteries, I may move to the 48v version https://em3ev.com/shop/36v-super-shark-ebike-battery/
I'm going to be running a 60A controller, and either 72 volts or 96 volts. I was thinking about getting either two 36v or two 48v batteries and wiring them in series to achieve the volts I need, but if each battery has lets say 14.8Ah and a 30a amp rating, will the amp rating double if I run two batteries in series or stay the same? I don't want to run a 30a battery on a 60a controller, but if it doubles then it's fine.
Also, I know with 15ah I'd be getting a short range but I'm fine with that. What I want to know is will it still work with a 5000w motor. I've seen some people say "You need this Ah for this motor" but I never understood why. Is range the only concern?

If two of the above batteries in series won't work, does there exist a reliable 72v battery with a ~60a rating in the $500-$600 range?

Thank you for any and all help, I rode one of those lime e bikes recently and instantly knew I wanted one for myself, I hope to join you all on two wheels soon

xiteamxi · Oct 29, 2018

Zephyr117 said:
Hi all, I'm building an electric bike and have some questions. my main concerns are in bold
I'm going to be using this motor https://em3ev.com/shop/5kw-qs-v3-rear-direct-drive-hub-motor/ it's rated for 5000w
and maybe two of these batteries, I may move to the 48v version https://em3ev.com/shop/36v-super-shark-ebike-battery/
I'm going to be running a 60A controller, and either 72 volts or 96 volts. I was thinking about getting either two 36v or two 48v batteries and wiring them in series to achieve the volts I need, but if each battery has lets say 14.8Ah and a 30a amp rating, will the amp rating double if I run two batteries in series or stay the same? I don't want to run a 30a battery on a 60a controller, but if it doubles then it's fine.
Also, I know with 15ah I'd be getting a short range but I'm fine with that. What I want to know is will it still work with a 5000w motor. I've seen some people say "You need this Ah for this motor" but I never understood why. Is range the only concern?

If two of the above batteries in series won't work, does there exist a reliable 72v battery with a ~60a rating in the $500-$600 range?

Thank you for any and all help, I rode one of those lime e bikes recently and instantly knew I wanted one for myself, I hope to join you all on two wheels soon

if you put them in series the ah and amp draw rating stays the same , parrallel would make them addup.

that battery is rated for 40A 40ax36v=1440w you can run that motor just dont expect to see 5kw.

2 in series 2.8kw

e-beach · Oct 29, 2018

EM3ev is offering a 72v battery. Why aren't you purchasing that battery?

Zephyr117 · Nov 2, 2018

Hey guys, I'm going to building an ebike that I want to run at 72v x 80a 5760w
These are the parts i'll be using (unless one of you can direct me to something better for a similar price)
72v 20ah 40a cont. 80a burst battery
https://www.aliexpress.com/item/72v...lgo_pvid=bfe289c6-5528-4020-b229-7fcd00f74699
50a cont 80a continuous controller
https://www.aliexpress.com/item/KUN...M3cISkCcbVEdxd0NkRhoCIroQAvD_BwE&gclsrc=aw.ds
QS 5000w Rear hub motor
https://em3ev.com/shop/5kw-qs-v3-rear-direct-drive-hub-motor/

I got a couple questions, the battery and controller are rated for 3000w and I dont expect to be running my system at any higher than that except during passes and accelerating, can that battery and controller handle almost double the rated watts or is that a misleading spec?
Also, what are the main disadvantages to buying on aliexpress? I could easily spend double on each part on luna but i it ok to buy on AE?

Finally, are there any incompatibilities/bottlenecks between those parts? I'm probably goingto solder some XT90's for the batteries to the controller but that's about it

Thank you for any and all help.

Zephyr117 · Nov 2, 2018

not sure why my new post is in my old post, but these are the new parts im going with after some research.

mark5 · Nov 3, 2018

Zephyr117 said:
Also, what are the main disadvantages to buying on aliexpress? I could easily spend double on each part on luna but i it ok to buy on AE?

The disadvantage of buying a battery pack from China is what about repair if it goes bad? Do you expect to be able to ship a defective battery pack back to China?
If you search for "aliexpress battery" you can find useful past discussions on buying a pack from China.

Topics get merged together for several reasons:
1. So people won't waste their time and effort replying to your first topic after you've changed your mind and created a new one.
2. Combining your first topic preserves any useful background info you may have supplied. Then it's all in one place for easy reference without having to page back and forth between your previous and current topics.
3. Some people might create new topics whenever they have a new question about their build. Better, though, if they're all in the same place.
4. So everything is in one topic for any future search.

Zephyr117 · Nov 3, 2018

Yeah, that makes sense. I've been looking for an american battery with the same 72v spec for a similar price but I haven't had much luck. Only one I've found is one from Lunacycles that's been out of stock for a while. The main thing i'm wondering is if those three parts together are incompatible in any way.

First build, need some help

Zephyr117

1 µW

xiteamxi

100 mW

e-beach

10 MW

Zephyr117

1 µW

Zephyr117

1 µW

mark5

100 kW

Zephyr117

1 µW

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