18650 protection circuit

[racerx_]

I recently got myself a DGX 600 light from dive gear express (https://www.divegearexpress.com/lights/backuplt.shtml)

It came with an 18650 battery and I was looking for a second battery to have on hand. I located one at a local electronics place, but it was shorter and the guy said it was because it didn't have the circuit in it that the original battery has, which I suppose is the protection circuit. i'm kind of new to this so a couple questions:

1) what happens if you run the light without a circuit in the battery?

2) is this protection circuit a standard thing? as in, any battery with a protection circuit will function the same, or is this something that's been specifically tweaked by the light manufacturer to get a certain output from the battery for their light


thanks in advance!

 

[lemke]

I haven't tried it, but using a non-protected 18650 could have some ill effects... the protection circuit "controls" the charging and discharging of the battery. And, the LED driver on the torch may be designed to be used with a protected battery only. Personally, I wouldn't... but I am curious if it would work.

 

[BugHunterNY]

Even if you get a battery with protection circuit - check with manufacturer. I exploded a battery which should have been fine in my light - and Big Blue can't tell me why it happened. They did replace the light though


Sent from my iPad using Tapatalk

 

[lemke]

Stick with Japanese brand batteries (eg. Panasonic). Stay away from China brands or anything with "Fire" in the name.

 

[MRTdiver]

... I located one at a local electronics place, but it was shorter and the guy said it was because it didn't have the circuit in it that the original battery has, which I suppose is the protection circuit.

How much shorter? a couple millimeters? ok then

Protection circuits come in different varities. But mostly likely if you get a Li-ion w/protection circuit it will have overdischarge and underdischarge protection.

So for example, if you were using your dive light with a protected 18650 and the battery drained down to ~2.5V it will simply shut off. The protection circuit shuts off the cell because it hurts Li-ion cells if you drain it beyond recommended values.

Another example: In the charger the cell may stop charging at ~4.27 because of the protection circuit. That way the cell is not over charged.

I personally don't use protected 18650/26650s many times. Because when I go cave diving (a very dark place :cool2 it is more important that the dive light stay on rather than the battery being preserved.

Here's more than you wanted to know about protection circuits: HKJ

 

[racerx_]

Thanks for the replies. So basically you guys are saying yes.. And no. Hahaha

Protection circuit sounds good for my use and to prevent overcharging.. I can find stuff like this but still not sure if the circuits are all the same:

http://m.ebay.com/itm/2-PANASONIC-N...-18650-NEW-PROTECTION-PCB-JAPAN-/370925377492

 

[scubastingray]

If you get a smart charger it should prevent overcharging though.

Personally I prefer non-protected, especially because protected ones don't fit in a lot of lights.

 

[Polari]

If you get a smart charger it should prevent overcharging though.

Personally I prefer non-protected, especially because protected ones don't fit on a lot of lights.

Protection circuit doesn't help for protecting against short which can cause explosion?

 

[MRTdiver]

Protection circuit doesn't help for protecting against short which can cause explosion?

yes, some do protect against shorts. e.g. this Panasonic 18650 w/Seiko protection circuit.

It was also stated in the longer info doc. from HKJ. Just control F and search for "short"

Like scubastingray said the protection circuits add length to the nominal 18650 cell.

18 = 18mm width
65 = 65mm length (see pic )
0 = a cylindrical shaped cell

So an 18650 cell is just in name only (nominal). When you add the protection it gets longer.

 

[racerx_]

MRT..

The link isn't valid. Could you repost it?