Primary light battery

[306dive306]

What do you guys think a “fair/acceptable” life for a battery pack is?

To those of you guys who use Light Monkey, UWLD, BigBlue or Hollis primary, CANISTER, lights: how long did your battery pack last before burn time was reduced to half?

I thank you in advance for your helpfulness.

Cheers!

 

[tbone1004]

Lithium batteries should be disposed of when they get below about 80% capacity, they start to get real dangerous when they get much below 90% realistically.

Most of the batteries should die of old age before they die of cycles with an expected age of 6-10years depending on how you take care of them. Don't store them fully charged, don't short charge them to full, don't let them get too hot, etc etc. I have UWLD packs that are 8yrs old and perfectly fine, still well over 90% capacity.

 

[GF99/99]

Sorry little bit off subject but how to you test/check the capacity of a battery pack?

 

[Underwater Tourist]

@tbone1004 what do you think about writing a small lithium batteries 101 guide about how to store them, charge, when to throw away etc?

 

[tbone1004]

Sorry little bit off subject but how to you test/check the capacity of a battery pack?

Best way is to take the mfg expected burn time, fully charge the battery, put it in a bucket of water in front of the couch and put a movie on the TV. Note when the light goes out/kicks to dim/whatever the mfg specifies the burn time against.

@tbone1004 what do you think about writing a small lithium batteries 101 guide about how to store them, charge, when to throw away etc?

I have thought about it but would have to check with @The Chairman to get a post pinned to make for easy reference. Unfortunately with things changing as rapidly as they are in the industry it is definitely something that would have to be updated on a regular basis with regards to specific models, chemistries, etc. Also have to be careful if any of it conflicts with a manufacturers recommendation, even when those are wrong. One DPV manufacturer for example recommends that their batteries be fully charged after use for storage, said mfg used to make lead and NiMH DPV's where that would certainly be really important but that verbiage holds into their lithium battery models as well for whatever reason. Since this is the case, if you're still in warranty it could technically void a warranty claim because you didn't follow the mfg recommendation even though that recommendation goes against the entire battery industry....

 

[Lorenzoid]

Best way is to take the mfg expected burn time, fully charge the battery, put it in a bucket of water in front of the couch and put a movie on the TV. Note when the light goes out/kicks to dim/whatever the mfg specifies the burn time against.

That's how I was advised to do it. I was also told to check the voltage when supposedly fully charged. Does that make sense with a Li battery pack?

 

[tbone1004]

That's how I was advised to do it. I was also told to check the voltage when supposedly fully charged. Does that make sense with a Li battery pack?

Lithium batteries have a very flat discharge curve and the chargers push them up to a fairly high voltage for balancing but after about half an hour they settle back down as the balancing is finished. No problems checking the voltage with a multimeter but I would not try to use it for anything other than a go-nogo type analysis as the stabilized "full charge" voltage of the cell is basically anything above 4.0v/cell. If a Light Monkey pack finishes charging and has sat for any more than 15mins after the charger stopped and is anywhere above 12v it's probably perfectly fine because we don't know what the balance boards were doing and if it was discharged pretty hot it may take some current to balance everything back and 12v is still considered something like 95% for SoC.
Part of the very real conundrum is you don't always know exactly what cells are being used, nor do we usually know what the BMS is doing which makes it much more difficult than a NiMH or lead based chemistry without an active BMS that is doing "stuff" to keep the battery pack healthy.

 

[MegDiver792]

I've runpacks for many years, its all in how you care for them. Dont charge when warm, dont over discharge (roughly .5v per cell), charge at a low rate (even with BMS, because as noted, we dont how that BMS is working). My DPV batteries had monitor leads, so I could at least make sure cell blocks, remained consistent (using a hyperion charger/discharger). Dont store fully charged, etc.

 

[MegDiver792]

Sorry little bit off subject but how to you test/check the capacity of a battery pack?

basic electronics, a defined and constant current load is the best (load equivalent to usage). I have this 10A constant current load device I use. You can use a big resistor bank, but thats not constant current. Just have to make sure you dont over discharge.

 

[tbone1004]

I've runpacks for many years, its all in how you care for them. Dont charge when warm, dont over discharge (roughly .5v per cell), charge at a low rate (even with BMS, because as noted, we dont how that BMS is working). My DPV batteries had monitor leads, so I could at least make sure cell blocks, remained consistent (using a hyperion charger/discharger). Dont store fully charged, etc.

I think you mean 3.5v/cell which is when the voltage really starts to fall off and is roughly 10% SoC. Definitely don't want to let it go much below that for lithium ion.

WRT to the constant load for capacity, you do want to do it with a load roughly equivalent to its expected load if at all possible. 10a is a lot higher than most lights and quite low for a DPV which is with lights I do prefer to put them in a 5g bucket. DPV's I do use a West Mountain Radio CBA because they're quite messy to load test in real use ;-)