BigBlue overcharging battery pack?

[Rick_C]

A buddy just purchased a BigBlue TL4800P dive light. This light uses a battery pack with four 18650 3.7v Lithium Ion batteries. The light includes a "smart" charger. I recommended that he monitor the voltage when doing his first charge and test.

Anyway, the voltage reading after removing the battery pack when the charger turned green was 17.45v. That equals 4.3625V per cell. I've always read to never charge 18650 3.7v batteries past 4.2v. Should this be a concern?

 

[fmerkel]

Maybe.
There are 4.3v 18650 cells. He needs to find out if he has a newer version. These are not common but they do exist and are becoming more common.
FWIW, there is no problem undercharging these cells to 4.2v. They'll last longer. 4.25v is within spec for normal 18650.

OK, went hunting: It's a protected pack. The protection.....should....prevent over charging.
4800-Lumen Tech Light | Bigblue Dive Lights
They do not specify the cells other than 18650:
Battery Cell 18650 x 4 | Bigblue Dive Lights

Until proven otherwise, I'd suspect overcharging. I'd contact BigBlue pronto.

 

[Rick_C]

Maybe.
There are 4.3v 18650 cells. He needs to find out if he has a newer version. These are not common but they do exist and are becoming more common.
FWIW, there is no problem undercharging these cells to 4.2v. They'll last longer. 4.25v is within spec for normal 18650.

OK, went hunting: It's a protected pack. The protection.....should....prevent over charging.
4800-Lumen Tech Light | Bigblue Dive Lights
They do not specify the cells other than 18650:
Battery Cell 18650 x 4 | Bigblue Dive Lights

Until proven otherwise, I'd suspect overcharging. I'd contact BigBlue pronto.

My buddy sent a picture of the battery pack he received.

 

[tbone1004]

please be careful, those lights have a tendency to explode.... May want to find a better charger....

 

[fmerkel]

14.8/4=3.7 > those would seem to be standard 18650.
Safe option > replace charger, charger + pack, or entire light. How that goes depends on the dealer and/or BB.
Much less safe option > watch it like a hawk and stop charging when it gets near the wanted voltage. (not recommended). Or, get a hobby charger and it should be charged correctly. Chances are the stock charger is lame (really common), as well as possibly defective in this case. The BMS SHOULD have prevented overcharge so I wouldn't trust the pack either.

FWIW, I personally hate packs like that. They have you over a barrel when you need a replacement. The pack ($92) is 4-5x what the individual cells are worth.

I've personally dealt with several commercial diving packs where the battery management system (BMS) screwed up and rendered the pack unusable by choking down the upper and lower limits. When torn apart ALL cells were fine by capacity and performance testing. I actually re-built one (3S4P-12 cells) heater pack using the same cells but put a balance tap on it and it gets charged with a hobby charger now. It works fine and you can check the individual cells. I do the same with my personal canister light. My 2S2P packs cost me ~$5.

 

[BDSC]

please be careful, those lights have a tendency to explode.... May want to find a better charger....

This is the first I’ve heard about this. Are the lights exploding when in use? When you say they have a tendency to explode, that says to me it happens quite a bit. Any serious injuries?

 

[tbone1004]

This is the first I’ve heard about this. Are the lights exploding when in use? When you say they have a tendency to explode, that says to me it happens quite a bit. Any serious injuries?

during or immediately after charger.
Not quite a bit, but has happened several times
Yes to serious injuries. One of them fairly recently almost died. The canisters don't have proper pressure relief built into them and the shrapnel when it quite literally exploded missed his femoral artery by a few mm's. Several surgeries and still recovering almost a year later.

 

[BDSC]

during or immediately after charger.
Not quite a bit, but has happened several times
Yes to serious injuries. One of them fairly recently almost died. The canisters don't have proper pressure relief built into them and the shrapnel when it quite literally exploded missed his femoral artery by a few mm's. Several surgeries and still recovering almost a year later.

Got a link to this accident? I’ll be going to DEMA in November and I’d like to ask them about it.

 

[tbone1004]

Got a link to this accident? I’ll be going to DEMA in November and I’d like to ask them about it.

the lawsuit is in process so there has not been any formal published accounts of it and there won't be until the lawsuit is done.

 

[BDSC]

the lawsuit is in process so there has not been any formal published accounts of it and there won't be until the lawsuit is done.

OK.

I just did a google search on “Big Blue dive light explodes” and not a single link to any type of incident showed up. I would have thought if someone almost died there would be some sort of account about it.