Sorfirn SP36 protected battery suggestions

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Ilumenati
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Sorfirn SP36 protected battery suggestions

I just purchased the SP36 and would like to buy a couple matched sets of high mAh protected batteries.

I was considering the button top LG MJ1 INR18650-MJ1 from Illumen but noticed the 8A continuous max discharge limit. I would appreciate some advice if 8A would be high enough for extended Turbo use.

Thanks,

Jaidmaster
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I’m sure you have already purchased some cells, but assuming you are going to use 3 cells, then that should be plenty.
Assuming a claimed 6000 lm max output (doubt it will ever get there in stock form) with 4 x XP-L2 you are 1500 lm per led, which for this LED would be somewhere around 4-4.3A (per LED).
4.3A x 4 (leds) = 17.2A
17.2A / 3 cells = 5.73A per cell
This is just a rough estimate with a max claimed output and no losses, etc, but good enough to at least give a good idea as to cell discharge requirements?

Hope you are enjoying your light! Smile

Ilumenati
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Jaidmaster, thanks for the reply, this is the information I needed.

I ended up buying Keep Power 30Qs from Illumn, great all around batteries.

The SP36 was my first light, now I have two (and a few others) and I am very much enjoying them Smile

Lightbringer
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The cells are all in parallel, so don’t go crazy trying to find “matched” cells. Any decent cells, even mixed’n‘matched (eg, a 30Q and VTC5 and HG2), would work fine.

Umm, just make sure they’re equally charged when first connecting, though. You don’t want 2 at 4.2V and 1 at 3.6V.

Of course, it would give the best peace-of-mind to have 3 of the same kind of cell, to make sure discharge curves more or less match.

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Lightbringer wrote:
The cells are all in parallel, so don’t go crazy trying to find “matched” cells. Any decent cells, even mixed’n‘matched (eg, a 30Q and VTC5 and HG2), would work fine.

Umm, just make sure they’re equally charged when first connecting, though. You don’t want 2 at 4.2V and 1 at 3.6V.

Of course, it would give the best peace-of-mind to have 3 of the same kind of cell, to make sure discharge curves more or less match.

Just curious, what would happen when using not-similar-capacity batteries (eg. 30Q 3000mAh & VTC5 2600mAh) at the same time, assuming both start at fully-charged state? So the VTC5 will drain faster (since it has less capacity) and the 30Q drain slower?

Lightbringer
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Everything balances out to what the voltage is in parallel.

If cell A sags to 3.60V at 2A and cell B sags to 3.60V at 1A, then cell A will provide 2A and cell B only 1A. The difference will be more/less as the load goes up/down, but parallel is parallel. Voltages across each cell stays the same no matter what, as they’re pretty much all crowbarred together.

After the load’s turned off, you might end up with one cell “charging” the other as they equilibrate, but I doubt that’s much of a problem.

I think (ancient history) only NiCd has issues with being parallelled, because there’s a bit of a voltage dip as SOC increases (and the cell with higher SOC starts hogging more and more charging current). Not sure if it happens in the reverse direction as cells discharge, though.

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