Test/review of Shockli 6x18650 7.4V 6600mAh

Shockli 6x18650 7.4V 6600mAh







Official specifications:

  • Rated capacity: 6600mAh

  • Rated voltage: 7.4V

  • Weight: 328g

  • Cable length: 55cm




This is a 6 cell bicycle pack.











The protection circuit looks like it is checking both cell groups, but without balancing.





Capacity is considerable better than rated. The over current protection will trip at loads much above 5A (This is temperature depend).
The pack was up to about 51° during my test (Measured in the pouch).









The pack can easily drive a 10W load, but 30W is a bit much (25W would probably be fine).







Conclusion

The pack works fine, but has a fairly low capacity (4 high capacity cells would give the same performance).



Notes and links

The battery was supplied by Shockli for review.

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

Is there any charger for these 2S packs you can recommend (outside of a hobby charger)? IIRC you have checked a couple of these in the past and none of these terminated. I don’t feel safe relying on the protection circuit to terminate on cell overvoltage.

I have not seen one yet.

They will not apply over voltage to the cells, they will “just” wear the cell down faster.

I’m somewhat interested in putting a mosfet for termination in the enerpower one, with the gate controlled by the green LED.

HKJ where have you measured voltage, was it at protection circuit output (P+, P~~), at cells side (B+, B~~) or at connector?
It is strange to get so much more capacity than rated, specialy when brand is not known. At 5A it is obvious cells can stand only low current up to 1A/cell.

All measurements are done at the end of my test cable that is plugged into the connector.

Thanks, this might explain quite big voltage drop at higher currents or you think it is more cells related? Shurely there is some resistance in circuit and cables, still probably not that much.

There is definitely some voltage drop in cables, connection and protection. I did not analyze exactly how much.

All the bikelight batteries i used failed after time because there is no balancing circuit.
After a couple of months there is such a large unbalance between the two sets of parallel cells that the maximum useable capacity of the battery pack becomes very low.
When i connect such battery pack to the hobbycharger (cells connected directly to the charger) , the capacity gets back to “normal” (i never had a bikelight battery pack that delivered the promised capacity).

This is because you are buying to cheap packs with low quality cells.

Come over to MTBR and see this two threads: