Are BAK 21700 5000mAh 15A Battery (N21700CG) any good?

Ahh… I’ve been using 3 of these bad boys since last January. Great runtime. Picked up a 2 amp charger because they took a long time @ 1 amp

@raccoon city, yes, they’re pretty good.

Almost on par with the Samsung 50E3.

Like the 50E3 before it though, 15A is too high of a current rating.

10A is recommended to get full cycle life(800 cycles) without cooling.

From what i understand there is a trade off for capacity vs sustained output rate. The 5000mAh batteries seem to max out at 10A sustained. So i am suspicious about those 5000mAh 15A cells. I suspect one of those outputs is wrong.
That said i’m not the battery expert so i could be wrong.

Do you have the ability to capacity test the batteries once you get them on a charger?

Also i noticed there are Samsung E, G and other letter designations, i was not able to figure out what they meant, anyone have info handy?

I ended up buying 5000mAh Samsung 50E cells from Fasttech, they are on the way.

That said there are apparently 4800mAh 21700s that can do a few thousand cycles, next time i intend to buy those if i can find them.

The Samsung 50E2 is slightly better for the first 500mAh at 10A, but the BAK cells hold a higher voltage for the remaining discharge.

BAK is a solid brand

bench test by Mooch. he also recommends staying under 10A with this cell.

link

This actually one of the reasons the Lishen 4500mAh 21700 cell would actually be preferred for the GT FC40, since it can draw quite a bit of current, particularly as the cell discharges

I can’t comment on the cell but i can link you to a datasheet:
https://www.fogstar-wholesale.co.uk/wp-content/uploads/2021/09/N21700CG-SPEC.pdf

I’m not a battery expert either and would normally be wary of the 15A rating too but the datasheet (section 5.4.1) claims 85% capacity at 3C which is a 15A discharge so they may be capable of it, but i can’t disagree with BlueSwordM’s opinion that it will reduce battery life.

Nice to see the datasheet but a no name company’s datasheet does not carry much weight for me.
I have dealt with too many knockoffs in my time and find the big players are more honest since they can’t easily get away with making up numbers. Not to say they are squeaky clean either but the ability to hold them accountable makes them less dishonest.

@Bort, Bak is far from a no name company.

Besides, their cells have been tested a lot :slight_smile:

We have the same opinion for most 5Ah 3C cells: their 3C rating is a bit much, and we prefer to underrate them at 2C.

This is the first time i have heard of them.
BYD, CATL, Lishen, these are companies i know.

And you seem to agree with me that 3C is a bit much. Hence their datasheet is unreliable.

? No, it’s just that most of us think about that for 5Ah cell, the Samsung 50EX series, Molicel M50A, Sanyo NCR21700 5Ah, etc.

Only the LG M50LT and the Lishen 5Ah cells seem to be well rated for 15A without any real downsides to cycle life.

Again making my point.

I guess you're talking about the Lishen LR2170SD...

I could have ordered that for even less money than the BAK.

@raccoon city, you forgot the fact that it’s sold out :slight_smile:

You made a great choice :slight_smile:

Life is a school, such things happen to all of us.

Awesome.

For once I'm glad that the better item is sold out.

I got 4 of them from there also. Didn’t have any problems. Can’t use them for hot-rods.

Bak stuff is decent.
I would use them if i didnt have tesla model 3 packs to tear down for cells.
Last year a regular bought a bunch of the bak 5000mah 21700 for me to put in his harmon kardon speakers.
A cycle a day since and no capacity fade noted.

I decided to switch from Samsung 30s over to Molicel 4,200 mah 45 Amps. Not quite up there with 5,000 but much better runtime for my lights and noticeable increase in power