Probably a Dumb Question - Charging WITH a Dummy Cell?

[Schokokeks]

So, I got some LiFePO4 CR2 cells for a rangefinder, but I do not have a single charger that fits these.

I DO have some dummy CR123A cells (just the wire inside) as well as a Malkoff dummy (Brass center rod surrounded by plastic).

Would it be safe to charge these using the dummy cells to make them long enough to fit into the charger?

I know you DO NOT CHARGE A BARE DUMMY CELL, but if it can safely discharge through the dummy, I can't see why it couldn't safely charge through one.

I'd be running this at a low power, anyway, cause these are just a few hundred mAh.

 

[aznsx]

So, I got some LiFePO4 CR2 cells for a rangefinder, but I do not have a single charger that fits these.

I DO have some dummy CR123A cells (just the wire inside) as well as a Malkoff dummy (Brass center rod surrounded by plastic).

Would it be safe to charge these using the dummy cells to make them long enough to fit into the charger?

I know you DO NOT CHARGE A BARE DUMMY CELL, but if it can safely discharge through the dummy, I can't see why it couldn't safely charge through one.

I'd be running this at a low power, anyway, cause these are just a few hundred mAh.

When charging 16340 cells in my Opus, I always use a shorting/dummy cell together with each to increase connection quality / reliability, which is seriously lacking without that due to insufficient sliding terminal spring pressure using 34mm cells.

Not ideal, but safe, and is worth the tradeoff of increased connection points adding some contact resistance, vs the obvious poor and unreliable connections I get without them. I do use 'best practices' and clean the connections, particularly when measuring IR where every milliohm matters (so to speak).

(I assume your charger supports LFP and can charge them to 3.6V correctly)

 

[Schokokeks]

When charging 16340 cells in my Opus, I always use a shorting/dummy cell together with each to increase connection quality / reliability, which is seriously lacking without that due to insufficient sliding terminal spring pressure using 34mm cells.

Not ideal, but safe, and is worth the tradeoff of increased connection points adding some contact resistance, vs the obvious poor and unreliable connections I get without them. I do use 'best practices' and clean the connections, particularly when measuring IR where every milliohm matters (so to speak).

(I assume your charger supports LFP and can charge them to 3.6V correctly)

Yeah, it's a Nitecore D4 I keep specifically for my "weird cells," and my Surefire 16340 LFP cells, so I was disappointed they weren't long enough for the sliders.

Soshine makes a CR2 specific charger on Ali, and it's only $12, but I'd LOVE to not have to get YET ANOTHER flipping charger for lithium cells (I have 4 currently, haha).

 

[aznsx]

BTW, @Schokokeks : I've never held a CR2 cell in my hand, but I gather they're small. Do they require an unusually low charge current, and can the D4 accommodate it? Just an afterthought.....

 

[Schokokeks]

Yeah, they are quite small (think, half AA size). I can set the D4 to a low charge mode, which I do for any of my small cells (10440).

I initially got this one specifically for 10440, 16340, and LiFePO4 cells. I started with a single cell Nitecore, then one of those Xtar 2-cell charger/battery banks for 18650 and 21700.
But then 21700 become more normal, and none of these fit protected 21700 cells -_- So, now I have a two bank Xtar that DOES fit protected 21700 cells, haha.


I got my laser range finder for a screaming deal, but immediately realized that CR2 is kind of the standard size for a lot of these, and it's not great blowing $3/cell for only 850mAh.

So, as per usual, "saving money" has cost me dozens of dollars, haha.