Cave Diving Backup Lights / Rechargeable Batteries

[Whitrzac]

Get the vc8, not the USB one.
4x of the bays can do storage/testing/etc. The other 4 are charge only.

It's not much bigger than the vc4

 

[Capt Jim Wyatt]

Roger all the above....!!!!

 

[Wibble]

Store lithiums at around 50%. Some chargers have a storage mode which is super useful. Otherwise, around 3.7V. I killed a number of lithiums in the past by storing them at full charge.

One of my MacBook Pro laptops is pretty much permanently connected to the power supply and hasn't moved in over two years as it's connected to a monitor, etc. MacOS has turned off the charging to the battery and keeps it around 70% charge to "protect the battery life".

 

[ACHiPo]

Oh, the joy of living near cave-country. Yeah, I can see that feature diminishing in importance, lol.


The VC4S isn't large enough for protected 21700s. The VC4SL does, so perhaps the "L" stands for "long. I agree on the test mode.

Oh great, another rabbit hole!

 

[kensuf]

It was less than 30 but after a full cycle was about 60. This is a single cell light with an XSTAR 3500 mAh/ 18650 Li-ion in it.

The best backup lights I have are two Dive-Rite CX2's which can be used as a primary for cavern dives.

Take a look at that light....

Yeah, I've had a CX2 for about a year. It's a great cavern/ocean primary.

 

[Manatee Diver]

I still love my CX1s. Even went so far as buying two back ups after DR discontinued them.

 

[ACHiPo]

Yeah, I've had a CX2 for about a year. It's a great cavern/ocean primary.

I got my CX2 a few weeks ago and am quite impressed. It will be my primary ocean light. I'm looking for good batteries (and I guess now a fancy charger/storage system) to swap in while others are charging.

 

[Underwater Tourist]

@sprockjohnson @tbone1004

so i got a second-hand lx20+ and it arrived with 4 xtars 3500mah 3.6v 18650 batteries and xtar mc4s charger

to best preserve the batteries i must:
-not store them fully charged, nor discharged (store with 50% ish charge)
-once a year run a discharge test to confirm that they hold 90%+ (below this threshold the batteries get dangerous (what might happen exactly, overheating?))
-is the mc4s charger good enough or its best a get a fancier one?
-should i remove the battery block from the light alltogether when stored?
-any other important steps i missed

Thank you

 

[Manatee Diver]

-should i remove the battery block from the light alltogether when stored?

If it uses the same battery carrier as the HP50 just turn it around, that is the travel position.

 

[rjack321]

Store lithiums at around 50%. Some chargers have a storage mode which is super useful. Otherwise, around 3.7V. I killed a number of lithiums in the past by storing them at full charge.

Fast charging isn't good for them. I usually charge 4 once, so the amps top out at 0.5 or 1.0, which is reasonable.

About yearly, I run mine through my charger's capacity test. There's no "refresh" for lithiums, though (like the Ni-MHs of old). I wonder if your first burn test just had poor contact for some reason.

Can confirm that storing them full (and in hot spaces) kills li-ions. My dog walking headlamps barely hold a charge anymore. For primary lights and suit heaters I try to store them discharged (aka less than 100% but I don't agonize over 40 vs 65% etc)

Backups are a challenge since I rarely use them, my current plan is to rotate my cave diving backup cells into my dog walking headlamps every 18-24 months and just live with the shortened life from sitting in my backups at near 100% charge for months at a time. I could throw them in a bucket and partly drain them, but for $15 in 18650 cells I'd rather just rotate them into non critical roles.