Buying Ebike kit, will these batteries work?

Marcelo99RDZ

1 µW
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Hi! I'm thinking of buying a conversion kit and a battery for my MTB, It would be my very first step into ebikes and I would like some advice regarding the amps (I don't want my house burning down!)

I'm planning on buying this kit(1500w motor 45a controller):

https://www.aliexpress.com/item/32476876343.html?spm=a2g0o.cart.0.0.3bdd3c00bGsO9y&mp=1

Looks good for me, they do offer a kit with an included battery in the usual plastic housings;

https://www.aliexpress.com/item/33010620925.html?spm=a2g0o.cart.0.0.3bdd3c00bGsO9y&mp=1

(that's the same kit but with a 52V 12.8Ah battery)



I don't trust it as much though, that's why I plan on buying an EM3ev jumbo shark battery, this one:

https://em3ev.com/shop/em3ev-52v-14s5p-jumbo-shark-ebike-battery/

Here's my question, the kit comes with a 45A controller, and in the em3ev battery site they specify the amp tolerances for each type of cell they put in their batts:

Panasonic PF: ~29A Continuous, 38A Max Burst Current

Samsung 30Q: ~38A Continuous, 55A Max Burst Current

LG HG2: ~ 44A Continuous, 55A Max Burst Current

Samsung 35E: ~25A Continuous, 34A Max Burst Current

Samsung 25R: ~40A Continuous, 55A Max Burst Current



Let's say I get the 35E, will it overheat due to the controller being rated at 45A? or are the tolerances from the battery higher than stated due to their series and parallel configuration?

Or should I just get the kit with the battery from the aliexpress seller?, they claim they use the Panasonic 32BD battery, anyways thanks in advance!
 
em3

battery bro talks about the Panasonic bd and how the chinese use b or c grades of these cells

https://batterybro.com/products/panasonic-bd-ncr18650bd-3200mah-10a

45 amps from 5p is 9amp discharge per cell. limits options to 25r,30q or hg2

hg2 datasheet showing lifecycle
https://www.nkon.nl/sk/k/hg2.pdf

you going to use regen?
 
https://endless-sphere.com/forums/viewtopic.php?t=104145#p1520999

HG2 better for high power and longevity, comparable to VTC6.

Not saying 25R is bad though if it's lots cheaper.
 
Marcelo99RDZ said:
...are the tolerances from the battery higher than stated due to their series and parallel configuration?

If anything the current rating of batteries is overstated. Lower current ratings for cells generally means higher internal resistance, which is the spec that really matters because heating batteries up reduces their life. Using resistance it's easy to calculate heat, which doesn't dissipate so easily inside a plastic housing with an insulating air gap between the cells and the housing. Since lithium batteries will supply the current you ask for even if it means committing suicide, so as batteries heat up their internal resistance increases too, which means even more heat.

As we head into colder weather in the northern hemisphere, that doesn't mean keep your batteries in a sub freezing garage in a effort to start your ride with an ice cold battery, since lithium batteries don't like the cold either.
 
Here is the Question? Should he buy a battery that peaks at 45A-50A and can be ran continuous at what 20A-30A.

With a 45A controller my battery of choice would be 40A continuous and peak above the controller rating and limit the power to 44.9 or lower.
 
John in CR said:
lithium batteries don't like the cold either.
Sure they do, when stored, not in use.

They must be warmed up for charging, hot for high rates is best, and perform better discharging when warm too.

But warmth generated internally from the chemical reactions from within, always indicates shortened lifespan.

For many use cases some is inevitable, but lowering the C-rate / adding Ah capacity is worth striving for when possible

 
john61ct said:
John in CR said:
lithium batteries don't like the cold either.
Sure they do, when stored, not in use.
They must be warmed up for charging, hot for high rates is best, and perform better discharging when warm too.
But warmth generated internally from the chemical reactions from within, always indicates shortened lifespan.
For many use cases some is inevitable, but lowering the C-rate / adding Ah capacity is worth striving for when possible

I don't think sub-freezing temps are recommended for storage, and "hot" is certainly not ever best unless you don't care about life and just want to charge at as high a rate as possible. In fact you're cautioned against charging when hot or even quite warm, ie let them cool down after use before recharging (again not talking about very cold weather here)....Heat is our enemy...always.
 
you live in mexico, i run 4p of 25r at 45 amps in my trike and in the summer if its 25 to 30 celsius outside the power flows out of the pack really well, the pack likes to be warm in the high 30s.
 
If you **must** charge at very high rates

and ambient temps are say 20-25°

then there will be much **less** hit to longevity if the cells are pre-heated, and well over 30° is no problem.

Going over 2-3C in sweater weather or below results in **much** shorter lifespan.

Down anywhere near freezing, can render instant scrap.

Much lower / slower charge rates required if you can't warm them up.

And none of this is talking about internally generated heat, that is always an indicator of stress, lost cycles compared to cooler operation.

And heat is always the enemy of longevity in general, storage or low C-rate operation, colder the better
 
Thanks to everyone who replied, I will be sticking with the em3ev Jumbo shark with either the Smsng 25r or the LG HG2 (though the HG2 pack is out of stock, so I might wait a while!) I'll try to update whenever I start my build :D

Shipping to Mexico is hell, USPS equivalent here (Correos de Mexico) is really, really bad for anything that's not a letter (they open everything and 50% of the time packages never arrive), so I'll recieve them in an US address and bring them back home, lets hope that goes well!
 
goatman said:
you going to use regen?

While I know the basics about regen braking, I don't actually know how to set it up or if the kit I want even supports it, i'll look it up, how would it affect the batteries? I imagine it has something to do with the max charging A rating, right?
 
Hi Marcelo99RDZ,
I have the same pasion 1500w kit and I did order the 52V EM3ev Jumbo Shark Battery with the 25R cells the advice of EM3ev. The battery wil arrive coming weeks and I am very curious how it goes together!
 
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