How to test burn time on a lithium battery without damaging it?

[dray_gnv]

I've had my canister light now for more than a year. I'd like to do a burn test but I understand that running a lithium battery to zero can damage it. What's the best way to do this?

 

[ofg-1]

Check with your light manufacturer. Most lithium packs have a low voltage cutout so you cant run the voltage to zero.

 

[atestani]

The battery has protection circuitry in it for deep discharge, low voltage, high current, etc. so it will shut down if it is near completely discharged. However, you need to know if it will automatically reset when charged or if there is some procedure required to wake it up again. Obviously, you want to know this before a burn test.

 

[kensuf]

Every time you charge a lithium battery to "full" or discharge it, you're shortening the life a smidge.

You should still burn test your batteries once a year.

 

[trimix1050]

Get a Western Mountain Radio CBA IV Computerized Battery Analyzer. They work great and you can set the cutoff so that you do not harm you batteries. I have been using one for 30 years. I have upgraded a couple of times. It will give you a very good indication of what your batteries can do.

 

[Chrisk919]

Every time you charge a lithium battery to "full" or discharge it, you're shortening the life a smidge.

You should still burn test your batteries once a year.

(not a cave diver, just a computer nerd that found the thread in 'new') If we're being pedantic: lithium ion batteries have a shelf-life even if they are never used. Usually that shelf-life is about a 3-5 year timeframes before we cross that 80% of engineered capacity threshold. Obviously discharge cycles accelerate that.

 

[Hungcyon]

(not a cave diver, just a computer nerd that found the thread in 'new') If we're being pedantic: lithium ion batteries have a shelf-life even if they are never used. Usually that shelf-life is about a 3-5 year timeframes before we cross that 80% of engineered capacity threshold. Obviously discharge cycles accelerate that.

Just to be clear this means just sitting on a shelf for 3-5 years Lithium Ion Batteries will be at 80% capacity max?

 

[lowwall]

Just to be clear this means just sitting on a shelf for 3-5 years Lithium Ion Batteries will be at 80% capacity max?

In general, no. That was an early assumption, but most batteries outperform that unless they are stored under suboptimal conditions.

The largest contributors to Li ion battery capacity degradation during storage are high storage temperatures and being stored fully charged or fully depleted. Ideal is 30-50% charged and keep them under 25C/77F with cooler being better. Do this and you should expect a capacity drop off of maybe 2% per year.

 

[Hungcyon]

In general, no. That was an early assumption, but most batteries outperform that unless they are stored under suboptimal conditions.

The largest contributors to Li ion battery capacity degradation during storage are high storage temperatures and being stored fully charged or fully depleted. Ideal is 30-50% charged and keep them under 25C/77F with cooler being better. Do this and you should expect a capacity drop off of maybe 2% per year.

That reminds me.. * Runs to garage to discharge a can light in a bucket of water that was fully charged last night for a dive that got scrubbed this morning *

I knew the whole storage charge thing from my RC hobby days but I remember it being 70-80% charge has that changed?

 

[lowwall]

* Runs to garage to discharge a can light in a bucket of water that was fully charged last night for a dive that got scrubbed this morning *

Charge cycles also reduce capacity, so unless it's going to be several weeks until your next dive, you are probably better off leaving it be. Or maybe drain it to 80%? Hmmm.