Bench Test Results: iJoy 40A 3750mAh 21700...hugely overrated but better than NCR20700B

[Mooch]

While the test results are hard data, the conclusions and recommendations I make based on these tests are only my personal opinion based on my criteria for setting a rating. Carefully research any cell you are considering using before purchasing.

Testing cells at their limits is dangerous and should never, ever, be attempted by anyone who has not thoroughly studied the dangers involved and how to minimize them.

If the cell has only one current rating number on it, or if it only says "max" then I have to assume that the company is stating that the cell can be discharged at that current level in any way, including continuously.

Cell photos: https://imgur (dot) com/a/t6nlk
(Sorry for the split link but direct links to Imgur do not display properly)


Bottom Line
This cell has “40A” on the wrap which is far, far above its true rating of 24A. It's capacity is also exaggerated and averages only 3650mAh for the three cells I tested.

I have spoken to iJoy though and they have agreed to rewrap the cell using more realistic ratings. I will retest when the new wrap is available.

There was a greater than typical variation in the capacities of the three cells I tested. It almost appears that there is no grading by capacity for the cells coming off the assembly line. It would take several days of testing to determine the true capacity rating of this cell but the 3650mAh rating I am giving it is close to its true rating.

This cell is outperformed by the 40A 3000mAh iJoy/Ampking/EBAT/Efest 20700 which hits harder and runs just as long at moderate to high power levels. I recommend using this cell at power levels of 50W or less to help prevent voltage sag from giving you early weak/low battery alerts in a regulated mod.

This iJoy cell does outperform the 15A 4000mAh Sanyo NCR20700B cell though.

This cell is not a rewrap of any other 21700 that I am aware of. I am rating this iJoy cell at 24A and 3650mAh.

While I am extremely disappointed with the degree of overrating of this cell by iJoy I am glad that they are willing to rewrap it with more realistic ratings.

The two cells that were tested were purchased for that purpose by me.


Continuous-Current Test Results



Pulse-Current Test Results



Comparisons against Sanyo 20700 cells



Comments

• At 0.5A continuous this cell delivered about 3600mAh to 3700mAh, depending on the cell. I am rating it at 3650mAh.

To see how other cells have tested and how hard you can safely push them, check out these links: List of Battery Tests | E-Cigarette Forum

 

[Tonee N]

Thanks again Mooch.[emoji106]
I'm really glad that Ijoy responded to you, wish the other companies would fess up and do the same.

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[sonicbomb]

I have spoken to iJoy though and they have agreed to rewrap the cell using more realistic ratings.

That your word carry's that kind of weight makes me happy. You tell them.

 

[Heartsdelight]

Thanks again Mooch!

 

[Barkuti]

Looks like a great middle ground cell at 24A and 3.6+Ah. From my safety and lifespan standpoint I'd avoid using it above 17A continuous (max current rating × ½√2), halving cell thermal stress. This is about in line with Mooch's conservative 50W recommendation, though I believe it should be good for a lil more in practice (regulated mods shouldn't be cutting off above 2.8 - 3V/cell).

Cheers

 

[Heartsdelight]

But the Sanyo NCR20700B is still good for under 45 watts, .40 - .80ohms right? Single battery use on the Geekvape Aegis mod? Thanks!

 

[Mooch]

But the Sanyo NCR20700B is still good for under 45 watts, .40 - .80ohms right? Single battery use on the Geekvape Aegis mod? Thanks!

Your coil resistance doesn't matter when determining battery current, just the wattage setting.
45W is pushing it, and your efficiency won't be good, but you can use the NCR20700B at that level.

 

[Heartsdelight]

Your coil resistance doesn't matter when determining battery current, just the wattage setting.
45W is pushing it, and your efficiency won't be good, but you can use the NCR20700B at that level.

Huh? Just to clarify, you are saying that the Sanyo NCR20700B's are good to use for 45 watts & under? But it's efficiency won't be good?

Thanks for all you do & answering batteries are all so confusing

 

[Mooch]

Huh? Just to clarify, you are saying that the Sanyo NCR20700B's are good to use for 45 watts & under? But it's efficiency won't be good?

Thanks for all you do & answering batteries are all so confusing

Correct.
There are safety limits, performance limits, and recommended performance levels. They can blur and overlap.

The B's will survive high wattage vaping, work badly at lower levels, be acceptable at even lower levels, and perform well at even lower levels than that.

 

[Heartsdelight]

Correct.
There are safety limits, performance limits, and recommended performance levels. They can blur and overlap.

The B's will survive high wattage vaping, work badly at lower levels, be acceptable at even lower levels, and perform well at even lower levels than that.

Thanks for clarifying

 

[rob33]

Either they improved the battery or just left the 40a wrap on for mainstream sales

 

[stols001]

Thank you Mooch

Anna

 

[Barkuti]

A little oddity, found this cell in one of those AliExpress stores. I thought it may as well be this cell in its OEM wrap since it is a chinese breed, don't you think?

This one is for you to see how it is advertised.

I wonder which OEM features these wraps.

Cheers my dears

 

[Mooch]

A little oddity, found this cell in one of those AliExpress stores. I thought it may as well be this cell in its OEM wrap since it is a chinese breed, don't you think?

This one is for you to see how it is advertised.

I wonder which OEM features these wraps.

Cheers my dears

Possibly! Probably a lot of similar cells out there though. Too bad the sticker prevents a part number search.

 

[EODPaul]

I just picked up a pair of iJoy's 21700 batteries, and the ratings marked are as follows:
"3750 mAh,
25A Continuous,
40A Max Discharge."

Looks like iJoy kept their word and changed their ratings.

Thanks Mooch!