Test/review of Sanyo NCR20700A 3100mAh (Red)

Sanyo NCR20700A 3100mAh (Red)







Official specifications:

  • Rated capacity: 2900mAh

  • Minimum capacity: 2950mAh

  • Typical capacity: 3100mAh

  • Nominal voltage: 3.6V

  • Charging method: CC-CV

  • Charging voltage: 4.20V

  • Cycle life: 300 cycles to 60% at 10A discharge, 6A charge.

  • Charging current: 2065mA (Standard)

  • Weight max.: 55.4g

  • Temperature: Charge: 10Ā°C ~ 45Ā°C, discharging: ~~20Ā°C ~ 60Ā°C, Storage:~~Ā°C ~ 50Ā°C




This is the new battery size that is slightly larger than 18650 cells. This cell is a high current cell with moderate capacity.










The two cells tracks perfectly and can easily deliver the rated current.




But the batteries get warm when delivering high current.



At maximum rated current they are up to 81Ā°C



In this discharge the battery is in free air, i.e. it has better cooling.















Conclusion

This battery is a very good battery and one of the best high current cell I have tested to date. At lower current there is no reason to use this cell (Instead use the NCR20700B cell), only when the current is above 10A is this cell interesting.



Notes and links

My test stations is only equipped to handle up to 30A, this means higher current must be done on other equipment.

How is the test done and how to read the charts
How is a protected LiIon battery constructed
More about button top and flat top batteries
Compare to 18650 and other batteries

The Samsung 21700-30T you tested is still the ā€œking of currentā€. :crown:

Maybe a Tesla employee will send you a pair of their Panasonic 21-70 cells for testing. :wink:

Yes, but this cell it not far behind. I am not going to do a 50A test :smiley:

I doubt it.

What I will probably need soon* is a 4 terminal rig that can do more than 40A without melting.

*I hope soon is some time away. I can fairly easy do up to 90A current draw, but I have no good idea how to make a 4 terminal battery holder to handle that (I do not have a lathe).

Nice. Looks like IR is very close to that of the VTC5A, but with a bit more capacity than the 30Q and VTC6.

You may be in need for a holder like this one, HKJ:

User AMDTrucking from the E-CigaretteForum posted these photographs of his work some months ago here: 26650 Battery Bench Test Results and New Ratings Table - page 8

You may want to send him a message.

Cheers ^:)

That look gorgeous, but are not 4 terminal and performance vice they will not be better than my original clamp design.

What about this item:

https://www.fasttech.com/p/5339401

made of solid aluminium, 4-wire design, the current wires are pretty thick.

At 50A this happens:

I had already replaced the wires with thicker wires.

Looks like there's some sort of overheating problem on the inner contact rods' plastic holders. Isn't it?

Seems an insane amount of heat is being generated around the stuff!

Custom crafted ceramic holders maybe?

Cheers ^:)

Make them or maybe even source them, (spacers/washers) out of Micarta G7 material

some info - Micarta G7 Glass Silicone Laminate & Machining Parts | Vanderveer Industrial Plastics

There is definitely being generated a lot of heat, but I do not really know if it is the holder or the battery.
The inner pin do not generate any heat, the current is virtually zero.
The battery gets hot and probably faster than my thermo sensor can follow.
The contact surface between battery and holder may also generate heat, just 1 milliohm would be 2.5 watt
The outer part may also heat at 50A, I do not now how much resistance it has.
The wire connection at the back may generate some heat.
The cable is getting warm, I uses 2.5mm2 (13 awg) (It is a bit thin for 50A).

Give the fixed position metal holder an insulating material coating, let's say a PTFE coating (rock bottom electrical conductivity, by the way). This way you can replace the plastic holder pieces with some sort of metal crafted ones, completely eliminating this problem.

Mmm, better coat both side metal holding parts, fixed and movable. Adds insulating safety while not excessively enhancing the holder's heatsinking ability, it would definitively impact cell temperature measurements otherwise (lots of cooling!).

Cheers ^:)

Notice that the inner pin has disappeared, this means the plastic controlling the inner pin has melted.

(Had updated my previous post)

Inner pin dissapeared? What's that for?

Sorry, maybe a tad philistine in these matters.

Mmmkay, maybe PTFE coated metal crafted holders (up to 327Ā°C)?

Cheers ^:)

The inner pin is used to measure voltage directly on the battery terminal, that is the idea with 4 terminal connections. Any voltage drop in the connection and wires do not affect the result.

The new Sanyo NCR2070C has been tested, and is superior to the 20700A:

https://www.e-cigarette-forum.com/threads/bench-test-results-sanyo-ncr2070c-20700-outperforms-the-ncr20700a-estimated-30a-3500mah.863425/

Wow.

That is one excellent cell.

I want to have one :laughing: