Battery life?

[wildbill9]

I recently bought a video light with rechargeable batteries. I was told to extend battery life run them down, recharge and repeat. Is this still true?

 

[tbone1004]

no. you do not want to run lithiums below 20% and you should not charge them until the day or day before you intend to use them. storing at 100% charge shortens life *charge cycles before less than 90% capacity*, burning below 20% shortens life, and heat shortens battery life. So avoid those three, and you'll be fine.
Your cell phone appreciates those as well btw

 

[fmerkel]

Yes, +1 on what tbone said.
The info on discharge>charge was for NiMh. It is NOT true for lithium. You get no benefit at all and use up a battery cycle.

 

[BoltSnap]

no. you do not want to run lithiums below 20% and you should not charge them until the day or day before you intend to use them. storing at 100% charge shortens life *charge cycles before less than 90% capacity*, burning below 20% shortens life, and heat shortens battery life. So avoid those three, and you'll be fine.
Your cell phone appreciates those as well btw

How do you know that they are lithium batteries not NiMh?

 

[fmerkel]

A recently purchased, possibly modern, usable
video light that isn't lithium? Possible, not likely.
I'm guessing we'll be enlightened.

Note-a quick look at his recent profile posts indicates he's buying BIG POWERFUL video lights. They are not NiMh.

 

[wildbill9]

Yes.....lithium.... smdh

 

[fmerkel]

BU-808: How to Prolong Lithium-based Batteries

 

[wildbill9]

So it sounds like I need to run down the battery then store it in the freezer?

 

[fmerkel]

Depends on how long you [store] the batteries. I use my lithium batteries, then simply leave them in the basement (cool) at the finished charge level, and charge them the night before the next use. They seldom go more than 1-2 weeks. That's fine for them. I personally try to keep all lithium cells under full charge unless immediate use is probable. I don't consider fridge storage until something is likely to sit more than a month.

I also have some 18650 and 26650 that are not in the use rotation. Those get charged/discharged to ~3.7v/cell, put in vapor-proof containers, and go in the fridge. Freezing is not generally recommended. I've got a single 18650, I'm storing at 0*F in the freezer as an experiment. I know it's capacity and discharge ability PRIOR to the freezing. About 1x/month I take it out and do a capacity cycle test. So far (almost a year) it seems 'normal' and consistent with other cells from the purchase. It doesn't seem to hurt it. OTOH, there probably is not a whole lot to be gained from freezing vs. cool storage.

The 'bad thing' (besides over discharge), is prolonged full charge storage in a hot environment. That will damage your cells.

Having a decent analyzing charger makes this kind of treatment possible and is a totally worth the investment.

 

[tbone1004]

So it sounds like I need to run down the battery then store it in the freezer?

just store them at whatever they end up at at the end of the dive and it'll be fine. Charge before the dive, and you're good to go. Keep them out of the head, if you have a basement or even an inside closet that's great, but freezer isn't necessary. The cells will die of old age before they die of cycles in this type of application unless you are diving daily.

@BurhanMuntasser was an assumption since NiMH is obsolete in the lighting industry, especially on video lights that typically have a much higher draw. Even on NiMH, while they do need to be cycled, and preferably stored full, they don't have to be fully cycled on every charge *think Prius battery*