How to make a lightweight battery

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KirstinS

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Is that your soup in the other bottle or the controller? So 2 for not much more than 2 kilo and my 10amp battery weighs 4.6kg! I wonder why commercial batteries are so much heavier? Better start looking if Aldi still have any bottles left!
They often use more cells of lower capacity (ie cheaper)

But age is amassive factor. High drain 3000mah cells or more simply didn't exist a couple of years ago

Nkon are doing Samsung 30q on a discount. 73 euro delivered for 20 cells (so 36v 6ah)
 

drummerian

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Jul 16, 2017
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Going to have a go at building one of these packs for both mine and my partners ebikes.

I am running an electricbikeconversions rear hub kit with the standard controller '36v – 15AH Max-7AH rated Fully Matched Intelligent Controller', she is running a panda pro kit which I think uses a similar spec'd controller.

I have looked in to batteries and I think with a 36s2p setup cells that give ~10amp continuous would be sufficient for both of us now and would give slightly more (20amp cont) if we wanted to upgrade controllers slightly in the future.

From that I assume going for higher mAH batteries to get closer to 36V@7ah would be the way to go?
https://eu.nkon.nl/rechargeable/18650-size/samsung-inr18650-35e.html

Or is it a better bet to go for a 3000maH but 15amp continuous cell for the additional peak?

Thanks
Ian
 

anotherkiwi

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I am thinking of a small battery and really like the Sony VTC6 - 30 A and 3100 mAh. I also like the Sanyo 20700 - 15 A and 4100 mAh.

The more Amps discharge the better in my neck of the woods.
 

anotherkiwi

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Nkon - putting 20 high Amp discharge cells in a battery for 95€ or 40 lower discharge cheaper ones in a bigger battery to get up the same hill my vote is for small and light weight powerful option.
 

cwah

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Nkon - putting 20 high Amp discharge cells in a battery for 95€ or 40 lower discharge cheaper ones in a bigger battery to get up the same hill my vote is for small and light weight powerful option.
I'd vote get the cheaper lower discharges ones. That's what Tesla did with load of ncr18650b. That way you only do shallow cycle and your pack last ages .

My 200 cells pack of ncr18650pf built almost 3 years ago is still working nicely and with good range
 

anotherkiwi

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I'd vote get the cheaper lower discharges ones. That's what Tesla did with load of ncr18650b. That way you only do shallow cycle and your pack last ages .

My 200 cells pack of ncr18650pf built almost 3 years ago is still working nicely and with good range
9.6 kg battery + 13% hill = :eek:

491€ vs 99€ also :rolleyes:
 

wheeliepete

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Nkon is still the place to go. Your choice of cells is dependent to a degree on the number of cells, current draw and the range you want. The largest capacity cells are not suitable for high current draw, but are great if you want a small high capacity low current pack. Samsung 30Q are a good balance between capacity and current or range and power.
 

anotherkiwi

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So what cells + retailer would users go for now if you were ordering. Unsure between the 3500 and 3000mah cells form Samsung (nkon )
nkon - good prices, in the EU, fast shipping

Samsung 30Q - there is 0.11€ difference between it and the 35E but the extra 5 Amp discharge is more important for me than the extra 500 mAh capacity.

Say I had a 30 km daily commute or just need a tiny battery for knocking about town with about 35 km range:

Sony Konion US18650VTC6 3120mAh - 30A - 2P10S 6 Ah battery weighing about 1 kg and cost under 100€ cells (shipped) + BMS

Or a longer commute or need for more range:

Sanyo NCR20700B 4250mAh - 15A - 3P10S 12 Ah - 184€ and about 2 kg
 

drummerian

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Thanks guys,

I think a 10s2p pack will be big enough for now, with the potential to add a second pack in parallel for longer trips.

The controllers we have are rated for "36v – 15AH Max-7AH". So I would assume that 2 10Amp cells (or even 8Amp cells) in parallel would be adequate to max the controllers output such that the controller becomes the limiting factor, therefor worth going for the 3500mAh 35e's.

Commute would be a 20 Mile round trip, using the motor for some assistance.

Have I understood the rated inputs/outputs correctly there?
 
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The controllers supply current, which is measured in amps not amp-hours. the only thing you need is the maximum current - 15A in this case. Your BMS needs a margin of 5A, and so do the cells, so you need cells capable of supplying 20A (10A each when 2P) and a BMS of 20A.
 

wheeliepete

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Have I understood the rated inputs/outputs correctly there?
You have, but it is good practice to only use 50% of a cells output ability to maximize cell life. So, if you need 15amp max and plan a 2P10s pack, it is better to use 15amp cells. Also the capacity drops as you approach the max. output, so you may find the the 30Q will give you a similar range to the 35E.
 

drummerian

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Thanks wheeliepete+d8veh, that's the advice I was after :) I know about aH vs the max output current but wasn't aware of the general rules regarding best practice and how the batteries perform in the real world.

Seems like high drain would be more suitable for my situation, rather than higher capacity. This will also allow for future power upgrades slightly more easily.

With that in mind it would appear the 30q's are currently the best value option, I'm not sure it's worth the extra for the 3120mAh Konions (+20euro)?
 

Nealh

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35E is apparently a so-so cell, 8a is about it's rating.
30Q, HG2 or VTC6/6A are the stand out cells for a 2P config.
 

Nealh

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drummerian

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Jul 16, 2017
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Starting building my own pack after being inspired by d8veh's lightweight build.

Before I commit to this is there a better layout possible (I don't think so but don't want to have missed an obvious trick!)
 

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