Smart home sockets

[Zi55ou]

Just had an idea that may or may not be useful to some of you.
Many lights don't particularly enjoy being completely discharged so I had an idea get a smart plug (wemo smartthings and a multitude of lesser known brands available) and set it up to turn on for a few hours every week to keep my batteries topped up. That way, especially over the winter months where my diving becomes much less frequent, my batteries are kept in good shape.
Is this a good idea or not?

 

[tbone1004]

if you have NiMH batteries? good idea. If you have lipo? bad idea

 

[fmerkel]

+1 on what tbone says. NiMh is NOT, serious repeat here, NOT lithium and they should not be treated the same.

If you have a lipo driven light and there is some parasitic draw, remove the batteries if possible. Try to get them to ~50% charge, put in a cool dry place. They can go months that way without a problem.
If you CAN'T remove the battery (like Sola-at least my 1200 does), AND they DO have some parasitic draw, then a brief top up on occasion is warranted >>> meaning, you don't want them to get completely discharged. OTOH, you don't want them sitting around at near 100% charge most of the time either.

If lithium light, no parasitic draw, then treat like a bare lithium battery as above.

 

[Brian G]

Lithium Ion batteries are best stored at about 40% charged and definitely not over 80% charged.
BU-702: How to Store Batteries – Battery University

There is some concern with cheaper batteries that they will go into thermal runaway while charging so some people recommend not charging them unattended. I think this is mostly from RC car and airplane folks who are charging their batteries quickly (>2C). I seldom charge over 1C and I don't worry about that at all.

 

[fmerkel]

Lithium Ion batteries are best stored at about 40% charged and definitely not over 80% charged.
BU-702: How to Store Batteries – Battery University

There is some concern with cheaper batteries that they will go into thermal runaway while charging so some people recommend not charging them unattended. I think this is mostly from RC car and airplane folks who are charging their batteries quickly (>2C). I seldom charge over 1C and I don't worry about that at all.

It also includes some "infamous" 18650's that are cheap off the net, especially direct from China and even via Amazon now. If it's Ultrafire, BRC, GTL, some Trustfires (counterfeits), and ANY, repeat ANY 18650 battery claiming to be more than 3500mA it is probably to absolutely JUNK, and should not be trusted. If you don't have the equipment and the knowledge to do do, either acquire same, or discharge and get rid of those batteries. Those are (some of) the ones that catch fire.

Note-I'm an RC guy and usually charge my cells at 1C, but with DECENT cells (yes there is junk in RC also, plenty of it) and a GOOD charger 3-5C is quite possible, 1-3C is easy.
2C is not a problem with good 18650.

 

[Zi55ou]

Thanks all for the input think I'll use the sockets for other stuff "hey alexa turn on <insert something here>"
Thanks again

 

[fmerkel]

Yup. It's like claiming you can get 50mpg out of a Mega-SUV. You can want it to be so....it ain't going to happen.

You might like this 'revelation' about those kind of cells: Batteries with ridiculous ratings
It's weird, some of those so-called high capacity cells are literally 'dumpster dive cells' that have new shrink warp on them. Others are strange contraptions with a tiny cell inside of a jacket filled with inert junk. I would have thought it would actually be cheaper to make a REAL cell than a bogus one. What do I know it would seem.

FWIW you can get decent 18650 for ~$4-6/cell. But, you have to know WHAT to get, WHERE to get it, and often WHEN to get it (deals). It's complicated, and may not be worth the hunt for lots of people.

 

[tbone1004]

@Adiron if you're in the US, can't beat them for $6.50 they used to have the good Panasonics, but those have been temporarily discontinued due to a production constraint, but the LG's are still right up there.
Protected LG F1L 3400mAh 5A Li-ion 18650 Button Top Battery - Wholesale Discount

 

[tbone1004]

@Adiron the continuous dimming may not be a function of the battery but the light itself. Big Blue and DGX lights for example do not use a constant output driver in order to maximize burn time. So while they may start off at say 800 lumen, they don't stay there for more than a couple minutes and will fade down to say 200 lumen by the end of the burn.

 

[tbone1004]

Thanks, these are my lights I was under the impression that they'd hold a steady charge until close to the end, then again with the cheap fake batteries they're always close to the end.

mini diving video light

highly unlikely it will maintain constant output with new batteries.
If they're claiming 90 min burn using the high end LiPo batteries which are around 12wh which is an 8w draw. Real world out the front output is around 700 lumen based on that. Lower if you have longer burn, higher if you have shorter burn. If they got the 1200 lumen they claim, you'd have 45-50min burn time on the high end batteries fwiw