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Moped Battery Build
#21
8s equals 28 Volt. Are you sure ?
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
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#22
Whoops, 10s8p.
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#23
(05-01-2019, 04:35 PM)knightgreider Wrote: Whoops, 10s8p.

Still only 36 Volt. Its that what you need ?
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
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#24
To save space I made 2-36v packs. I don't know why I said 10s8p. I will be running 10s5p for each pack. Each pack will only be 15ah.
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#25
(05-03-2019, 10:20 PM)knightgreider Wrote: To save space I made 2-36v packs. I don't know why I said 10s8p. I will be running 10s5p for each pack. Each pack will only be 15ah.

Makes it only 5 times 6.5 A equals about 30 Amps max per spec.
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
Reply
#26
What do you mean? I am putting together:

2- 36v 15ah packs with Samsung 30q's (15max amp per cell) My motor draws 94 amps max. So I would be able to draw 9.4 (94/10s) amps for each series of cells right? I am wiring them tomorrow when the batteries get here.

Also, if I spot weld, could I add two strips together to increase the size of each of the pack? I got the wrong nickel strips (too thin and too narrow. If I double them to increase the surface area and thus not make the pack too hot when I run I draw a bunch of amps through it?

https://endless-sphere.com/forums/viewto...14&t=68005
Cherry67 likes this post
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#27
do you parallel the two packs or serial ?
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
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#28
Do you mean Series or Parallel? The packs are running in Series. 2+36dcV Packs = 72dcV.
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#29
(05-07-2019, 07:52 PM)knightgreider Wrote: Do you mean Series or Parallel? The packs are running in Series. 2+36dcV Packs = 72dcV.

Thats what i thought.
By serializing 2 packs of 10s5p you get 20s5p.
Nothing with ..10p.

So, current comes from 5 Cells in parallel, and with the said 6.5 Amp max (per Datasheet) you are limited to about 30 Amps.
Which will last for about 30 Minutes max under full load. In practical even less.
If you use high drain cells, as you plan, the current may be higher, but the full load time does reduce significantly, because of the higher current and the lower capacity.

(05-07-2019, 03:27 PM)knightgreider Wrote: What do you mean? I am putting together:

2- 36v 15ah packs with Samsung 30q's (15max amp per cell) My motor draws 94 amps max. So I would be able to draw 9.4 (94/10s) amps for each series of cells right? I am wiring them tomorrow when the batteries get here.

Also, if I spot weld, could I add two strips together to increase the size of each of the pack? I got the wrong nickel strips (too thin and too narrow. If I double them to increase the surface area and thus not make the pack too hot when I run I draw a bunch of amps through it?

https://endless-sphere.com/forums/viewto...14&t=68005

With this cells:
5 cells in Parallel times 15 Amps/cell makes 75 amps max per datasheet.
Time will go down to 15Ah/75 A = 1/6 h , so 10 minutes full load theoretical.
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
Reply
#30
Ok. I decided to scrap all of what I was going to do because I did not understand it fully, and now I am going to just make a single 72V battery.

I bought 120 of these https://www.18650batterystore.com/Produc...noQAvD_BwE

After researching more on the controller and motor, it looks like it has a max output of 94amps. I was getting confused as to what other people are saying in the previous threads about battery divisions for continuous output. After researching some more, I looked at the maximum output of the batteries I got, multiplied by the number of cells in parallel right? So if I have a pack of 20s8p, 8 parallel cells together at 15 max continuous output of each cell group would be 120amps? So my 8p cell group of 15amp max output should be able to supply enough of amps that the motor and controller will be asking for? Which is 94amps?

20s8p with 18ah. I am looking at this BMS, http://www.batterysupports.com/72v-84v-2...p-295.html
Do you think that will be a good choice for a BMS with my 30Qs for this mark II battery pack?

This is my first BMS and I have been researching a lot about it.

Thank you!
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