the dangers of fake cells and ****fire cells in general.

[whipitup]

fooking shocking

Understatement!!

 

[Niamh]

No worries kms, I stuck it on general notices hoping as many people as possible would stumble over it. I didn't check if the link to the light that blew up and took out a coffee machine was in there but that's another one people should be aware of. Particularly in series connected box mods where protected cells and balanced cells are imo an essential item

Hi, I have a box mod which is a Jack Daniel's tin in which someone has installed a vv board (I think it is called a step down module). It takes 2 18650 batteries. The thing is it is only big enough to take AW IMRs, unfortunately protected cells won't fit. Do you think this is unsafe?

 

[gords1001]

Are the cells series or parallel wired? Ie is it 4.2v in or 8.4v in? Is the charger you use charging the cells equally?

In parallel, the cells will balance each other put, in series they wont, and "safe" chemistry does not prevent reverse charging if for example someone accidentally fitted one discharged cell and one charged cell.

The simple answer as with all things, it depends on the users care when operating the unit, take the time to find out and understand the risks and you can reduce them to a point where worry is unnecessary, if you dont know if their series or parallel post up a picture and we can probably suss that out.

 

[Tubbyengineer]

@gords101, we are comtinuosly warning people of the dangers of fake cells, to generally distrust any cell with fire in the name and the dangers of poor chargers/charging regimes, sub ohm vaping and dodgy ego's, we also have a thread dedicated to dodgy ego's with gerry rigged batteries, glad to have your photos and links here to help bash home the message...

 

[steffijade]

Hi, I have a box mod which is a Jack Daniel's tin in which someone has installed a vv board (I think it is called a step down module). It takes 2 18650 batteries. The thing is it is only big enough to take AW IMRs, unfortunately protected cells won't fit. Do you think this is unsafe?

If it's a step down board, maybe similar to this? : http://www.stealthvape.co.uk/electr...e-boards/lm2596-green-variable-voltage-module these types of boards use 2 batteries in series which will put out a voltage of 8.4volts fully charged and reduce that down to whatever voltage you set.

They are typical used with battery holders like these : http://www.ebay.co.uk/itm/Plastic-B...x-18650-Black-with-6-Wire-Leads-/110760929553 if the springs for the batteries are at opposite ends of the box, then it'll be in series (or stacked as it's sometimes referred to).

You can check the voltages of each battery to see if they're a similar range.. if they're not in a similar range, that's when problems can come. If 1 battery has a significantly lower voltage than the other 1, the lower voltage battery will pull power from the higher voltage battery.. which is a bad thing.

You say protected batteries won't fit, but have you tried different brands at all? Although batteries are often listed as 18650, they can vary in dimensions by a good few mm and you may be able to find protected ones that fit?

In my own self built stepdown mods, I use flat top 18650s that fit ok, but require a solder blob on the positive connectors in the battery box to make good contact.

If YOU don't feel it's safe, then don't use it unless or until you can source some better fitting protected batteries.. at the end of the day anyone could say it's safe or unsafe.. it's up to you to decide if you use it or not.

A general tip when using 2 batteries in series is to try and keep them in 'matched pairs' (batteries of the same brand/mah capacity and to charge them up and use them in pairs). For example, if you had 4 18650s, mark them up as 1,2,3 & 4.. use 1 & 2 together as a unit and the same with 3 & 4.

 

[gords1001]

Cheers Tubbyengineer I think the first link covers a lot of the dissection links I've seen, with the second illustrating the possible results of things gone wrong.


Sadly this message won't reach the people it really needs too, they wont make the effort to find a forum and find this stuff out. They'll continue to buy 5000mah 18650 cells from china on ebay, and tell you their xm-l torch has 2000 lumen.......then get upset when you show them what 800 lumens and a 2900mah cell does.

In the vaping world I guess it would be someone with a "cloud chaser vivi nova ego" bought on a market meeting someone like raggouri.

 

[Niamh]

If it's a step down board, maybe similar to this? : http://www.stealthvape.co.uk/electr...e-boards/lm2596-green-variable-voltage-module these types of boards use 2 batteries in series which will put out a voltage of 8.4volts fully charged and reduce that down to whatever voltage you set.

They are typical used with battery holders like these : http://www.ebay.co.uk/itm/Plastic-B...x-18650-Black-with-6-Wire-Leads-/110760929553 if the springs for the batteries are at opposite ends of the box, then it'll be in series (or stacked as it's sometimes referred to).

You can check the voltages of each battery to see if they're a similar range.. if they're not in a similar range, that's when problems can come. If 1 battery has a significantly lower voltage than the other 1, the lower voltage battery will pull power from the higher voltage battery.. which is a bad thing.

You say protected batteries won't fit, but have you tried different brands at all? Although batteries are often listed as 18650, they can vary in dimensions by a good few mm and you may be able to find protected ones that fit?

In my own self built stepdown mods, I use flat top 18650s that fit ok, but require a solder blob on the positive connectors in the battery box to make good contact.

Hi yes, it's a step down board like that one with a battery holder with springs at opposite ends. I do check the voltages of the batteries off the charger and periodically, so can ensure they are matched. I may try to find some other protected batteries as you suggest, I'm on my third set of batteries for it now, yeah AW protected flat tops didn't make contact and I can't solder, Efest protected were too long.

Thanks for replies, appreciate it.

 

[gords1001]

There are precious few battery holders that will take protected cells. Also bare in mind, protected cells are fatter due to the strip down the side and extra wrapping.

Iirc Panasonic ncr greys are one of the shortest/most slender protected cells but I'm open being corrected on tgat, you may need to look at older lower capacity cells, problem then is, you may be pushing the max discharge current of the cells. Is there room for a bigger battery holder or could shorter springs be used to give a few mm?

 

[Niamh]

There are precious few battery holders that will take protected cells. Also bare in mind, protected cells are fatter due to the strip down the side and extra wrapping.

Iirc Panasonic ncr greys are one of the shortest/most slender protected cells but I'm open being corrected on tgat, you may need to look at older lower capacity cells, problem then is, you may be pushing the max discharge current of the cells. Is there room for a bigger battery holder or could shorter springs be used to give a few mm?

I looked at some 18650 battery comparisons online, one of the graphs said AW 2200 mah where the shortest, I bought some of those from flashaholics, who knows if they will fit, if not I will investigate the NCRs.
Re the max discharge current- I thought the box would be pulling the power off the cells at 4.2 volts fully charged, then at whatever the natural voltage of the cells is as they deplete, then reducing it? So if the cells were at 3.8v the step down module would take 2 x 3.8v then reduce it to 4.3v total to power the atomizer (4.3v is what I always have it set at) Or am I completely muddled?

 

[Vern]

I thought the box would be pulling the power off the cells at 4.2 volts fully charged, then at whatever the natural voltage of the cells is as they deplete, then reducing it? So if the cells were at 3.8v the step down module would take 2 x 3.8v then reduce it to 4.3v total to power the atomizer (4.3v is what I always have it set at) Or am I completely muddled?

that is totally correct

Re the max discharge current-

and now, totally incorrect

current is not voltage