Li-Ion vs. NIMH for canister

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wunat

Contributor
Scuba Instructor
Messages
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Location
Bangkok, Thailand
# of dives
500 - 999
Salvo currently has a range of canister with Li-Ion batteries.

Is there any concerns with using Li-Ion batteries for canister lights? Any reasons why we would want to get the NIMH instead of the new Li-Ion?

Thanks a ton!!!
 
Check the regs but if the Li Ion battery is large enough, it is considered hazardous - can't be taken on flights. I've been briefed by someone who deals in large capacity cells and there are concerns when they get large..... doubt something the size of 4 D batteries is a problem but you start talking about a motorcycle battery size....
 
webhead:
Check the regs but if the Li Ion battery is large enough, it is considered hazardous - can't be taken on flights. I've been briefed by someone who deals in large capacity cells and there are concerns when they get large..... doubt something the size of 4 D batteries is a problem but you start talking about a motorcycle battery size....

The limit is 8 grams. Lithium-Ion cells have a "Equivalent Lithium Content" that is calculated as follows. The amphour capacity of each cell is multiplied by 0.3

Example: A battery consisting of 10, 2.4 amp hour cells 2.4 x 0.3 = .72 Equivalent grams. 10 x .72 = 7.2 grams 7.2 < 8 This example battery will not be considered hazardous.

On the other hand, my current concerns about Lithium - Ion batteries centers on the effects of High temperatures on most commercial Lithium -Ion cells. Exposure to temps in excess of 60 degrees C can eventually result in dramatic failures during subsequent recharging. Consider a black battery canister in the tropical noonday sun....

There are special high temperature Lithium Ion cells, that what I use in the X scooter batteries, but they are more expensive, limited to 2.0 amphour per cell, and are generally uncommon.


Tobin
 
The main life issue between Li-ion and NiMH is the following: (which I clipped from one of Sparticle's links.)

Li-ion batteries exhibit a much lower self-discharge rate than NiMH batteries (about 5% per month compared to 30% month). The disadvantage of Li-ion batteries, however, is that their capacity decreases over time from the date of manufacture, irrespective of usage, the extent of which depends upon storage conditions: at 100% charge about 20% per year at room temperature but only 4-6% per year at typical refrigerator temperatures; at 40% charge, however, these numbers are significantly reduced to 4 and 2%, respectively. In other words, do not fully charge up a Li-ion battery pack after a dive, but wait until the night before one's next dive, and keep the pack in a refrigerator when not in use.


Some Li-ion batteries have been reported as having a life as short as 2 years. As noted above this can be overcome by storing your packs in the fridge. Personally I find this somewhat inconvenient (plus the wife would complain), so I use NiMH packs on my self built canister light.

The only other issue regarding Li-ion is their unfortunate tendency to self immolate if you use the wrong charger (or charge rate). This shouldn't be a problem if you follow the instructions.
 
bradshsi:
The main life issue between Li-ion and NiMH is the following: (which I clipped from one of Sparticle's links.)

Li-ion batteries exhibit a much lower self-discharge rate than NiMH batteries (about 5% per month compared to 30% month). The disadvantage of Li-ion batteries, however, is that their capacity decreases over time from the date of manufacture, irrespective of usage, the extent of which depends upon storage conditions: at 100% charge about 20% per year at room temperature but only 4-6% per year at typical refrigerator temperatures; at 40% charge, however, these numbers are significantly reduced to 4 and 2%, respectively. In other words, do not fully charge up a Li-ion battery pack after a dive, but wait until the night before one's next dive, and keep the pack in a refrigerator when not in use.


Some Li-ion batteries have been reported as having a life as short as 2 years. As noted above this can be overcome by storing your packs in the fridge. Personally I find this somewhat inconvenient (plus the wife would complain), so I use NiMH packs on my self built canister light.

The only other issue regarding Li-ion is their unfortunate tendency to self immolate if you use the wrong charger (or charge rate). This shouldn't be a problem if you follow the instructions.

I'm also wondering if the fridge wont cause the battery to get damp -- seems like it would. That can't be a good thing, right?
 
limeyx:
I'm also wondering if the fridge wont cause the battery to get damp -- seems like it would. That can't be a good thing, right?

Put it in a ziplock, suck out the air. Minor condensation shouldn't be a big worry.


Tobin
 
I got the Li Ion.
It is overcharge and discharge protected due to some extra electronics.
The ageing problem is effectively minimized to around 1% per year by storing the pack half charged in the fridge in double zip lock bags.
The travel limit is as calculated above and is no issue for all lights sold by salvo. Besides, security staff at airlines have yet to ask whe whether it is Li Ion and I have print outs of the battery pack with the Li content printed on it with me just in case.
Check out my previous thread about dos and don'ts with 21W Salvo Li Ion HID. I posted some links that solve the travel issue.
I am certain that the Li Ion ultimately is the more hassle free option than NimH.
I really doubt that storing it in the fridge is a major inconvenience. The pack is very small. Pop it in double zip locks and remove most of the air and the condensation issue is just not a problem. Cold air is less moist than warm air in any case.
When I use it, I remove the pack from the fridge and let it warm up to room temperature over 5 minutes before I remove and charge the pack.
If during travel there is no fridge I would not worry about it at all. Those two weeks diving in a remote location is only 1/26th of the whole year. Just store it in a fridge when you are not diving.

At only around 1% loss per year or less this is no issue. I expect to upgrade any battery pack after 5-7 years anyway.

Good luck,
Alex
 
https://www.shearwater.com/products/teric/

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