Cave Diving Backup Lights / Rechargeable Batteries

[kensuf]

Hey Jim, what do you mean by "short burn time"? 30 minutes?

I'm still using old non-rechargeable batteries for my backup lights, but could see making the leap sometime in the future.

 

[Capt Jim Wyatt]

Hey Jim, what do you mean by "short burn time"? 30 minutes?

I'm still using old non-rechargeable batteries for my backup lights, but could see making the leap sometime in the future.

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....

 

[inquis]

If you're looking for a charger (e.g., to get a storage mode or capacity measurement), be aware the CX2s use *protected* 21700s. Make sure the charger explicitly says that it will do protected ones, most cannot.

 

[tbone1004]

Fast Forward: I have been using rechargeable batteries in my backup lights now for about a year. I have been happy with them overall. All of the batteries are lithium of some type or other. I have a variety of chargers for these batteries.

I burn tested one a few days ago after making sure it was fully charged and got poor results, dim and short burn time. I charged it again and burn tested and got good results, bright and long burn time.

My questions are:
-> Should these batteries be cycled periodically and if so how often.
->Are all lithium battery chargers created equal? If not then how do you decide which ones to stop using?
->If you are not going to use them for a few weeks at what state of charge should they be stowed?

The key is that many chargers are really sketchy and are best disposed of immediately after purchase. Most of the ones that come with backup lights are like that. Do not store lithium full, it's bad for them, but their self-discharge is so low that every 3-6mos put them on a test cycle and you're good to go. They should not need to be cycled as they have no memory BUT most of the chargers that come with these backup lights are utter garbage so you don't actually know if it was fully charged to begin with....

If it looks anything like this one, just trash it.

This one is ideal. It has selectable charge rates, has a battery test mode which will fully charge, fully discharge, and fully charge the battery and report back the capacity. For NiMH batteries it has a refresh mode which will cycle them a couple of times and will be fine.

 

[tursiops]

The key is that many chargers are really sketchy and are best disposed of immediately after purchase. Most of the ones that come with backup lights are like that. Do not store lithium full, it's bad for them, but their self-discharge is so low that every 3-6mos put them on a test cycle and you're good to go. They should not need to be cycled as they have no memory BUT most of the chargers that come with these backup lights are utter garbage so you don't actually know if it was fully charged to begin with....

If it looks anything like this one, just trash it.
View attachment 765708

This one is ideal. It has selectable charge rates, has a battery test mode which will fully charge, fully discharge, and fully charge the battery and report back the capacity. For NiMH batteries it has a refresh mode which will cycle them a couple of times and will be fine.

MEDIA strikes again. No link except on mobile devices.

 

[tbone1004]

MEDIA strikes again. No link except on mobile devices.

It's something with adblocker and Amazon specifically IIRC. Since I am a supporter I have ads disabled through scubaboard and the adblocker paused on this domain and haven't had issues.

From another vendor, should go though.

Opus BT-C3100 Charger/Battery Tester

This is the Opus BT-C3100 v2.2. This is identical to the BT-C3400 that some other vendors are selling. This is the most full featured charger we sell. It can do all kinds of stuff in addition to just charging batteries, including testing and cycling them. This product is for advanced users...

liionwholesale.com

 

[inquis]

@tbone1004, I don't believe that will charge Jim's 21700s or has a storage mode. I would go with an XTAR VC4 Plus OR VC8. ETA: one can manually stop charge/discharge at 3.7 V for storage purposes.

 

[tbone1004]

@tbone1004, I don't believe that will charge Jim's 21700s or has a storage mode. I would go with an XTAR VC4 Plus OR VC8. ETA: one can manually stop charge/discharge at 3.7 V for storage purposes.

For backup lights they aren't ever really being "stored" though I did just check and mine won't hold 21700's. Xtar is a good call though, just make sure it is the Plus or S because the regular VC4 doesn't have a test mode and that's critical for backup lights.

 

[sprockjohnson]

The key is that many chargers are really sketchy and are best disposed of immediately after purchase. Most of the ones that come with backup lights are like that. Do not store lithium full, it's bad for them, but their self-discharge is so low that every 3-6mos put them on a test cycle and you're good to go. They should not need to be cycled as they have no memory BUT most of the chargers that come with these backup lights are utter garbage so you don't actually know if it was fully charged to begin with....

If it looks anything like this one, just trash it.
View attachment 765708

This one is ideal. It has selectable charge rates, has a battery test mode which will fully charge, fully discharge, and fully charge the battery and report back the capacity. For NiMH batteries it has a refresh mode which will cycle them a couple of times and will be fine.

This. The cheap chargers will sometimes charge a bit but most of the time seem to turn their little charging indicator LED from red/ orange to green and the battery is not charged. Put them in a decent charger (typically one with a digital readout like the one above) and the battery will get a real charge.

 

[inquis]

For backup lights they aren't ever really being "stored"

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

make sure it is the Plus or S because the regular VC4 doesn't have a test mode

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.