can i charge 2 lithium cells together end to end?
- Thread starter waddup
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45/70
Flashlight Enthusiast
It is not possible to charge any lithium cell, so I'm assuming you mean lithium ion (which contain no lithium). While it is possible to charge Li-Ion cells in series, you really need to use the balancing setup with your Triton. Li-Ion cells are not able to absorb overcharge, as nickel based cells are. So if one cell gets ahead of the other, you'll run into potential problems. One way they can react to overcharge, is by "venting with flame", especially LiCo cells.
So, in answer to your question, provided you meant Li-Ion cells, yes you can, but to do it safely, you need to use the balancing harness. If you don't you may get away with it, but with LiCo cells, sooner or later your going to have a big problem. As for LiFe and LiMn cells, they are not explosion proof, but are less likely to vent. Charging these chemistry cells without balancing will damage the cells however.
Dave
So, in answer to your question, provided you meant Li-Ion cells, yes you can, but to do it safely, you need to use the balancing harness. If you don't you may get away with it, but with LiCo cells, sooner or later your going to have a big problem. As for LiFe and LiMn cells, they are not explosion proof, but are less likely to vent. Charging these chemistry cells without balancing will damage the cells however.
Dave
It is a good question to ask.
Dave is giving you the best advice....but if you are using protected Li-Ion cells, and you check the ending voltage with a DMM to make sure they are relatively 'in balance' with each other (within 0.05 V), it is possible.
If you start seeing ending voltages that are out of balance (certainly if 0.10V apart), then I would stop and charge separately with balance tap leads, or if you have a way to put them in parallel while charging as a single (larger capacity) cell, that method auto-balanced them.
Dave is giving you the best advice....but if you are using protected Li-Ion cells, and you check the ending voltage with a DMM to make sure they are relatively 'in balance' with each other (within 0.05 V), it is possible.
If you start seeing ending voltages that are out of balance (certainly if 0.10V apart), then I would stop and charge separately with balance tap leads, or if you have a way to put them in parallel while charging as a single (larger capacity) cell, that method auto-balanced them.
45/70
Flashlight Enthusiast
Hey, Lux. The problem I have with charging protected cells in this manner, is that the protection circuit doesn't always work! I think PCB failure is often associated with protected cells used in multi cell lights. This has to do with the fact that many protected cells are longer in length, due to the addition of the PCB, and the PCB tends to get crushed. Something to consider, anyway.
Dave
Dave, I don't disagree with you on general rules and concerns, but with the backup checking with DMM every few charge cycles, you are going to see if this charging method is resulting in an imbalance at which time it should be stopped.
As far as crushing the PCB, the good ones (AW, Pila, Redilast) have protective rings around the perimeter to give pretty reliable support. By all means if you look at the ends of cells and they have a serious compression indentation from the light's spring/securing mechanism, I would be concerned. I have just not run into that in any of the lights I have used to date. I would be much more concerned about dropping a protected cell, where the severe impact onto a hard surface may crack the PCB/PCB component, or lead to a short from thin contact nickel strip running down from Positive terminal.
45/70
Flashlight Enthusiast
Uh, well, yeah that would do it too! I just think that many put too much faith in protection circuits. Nothing is perfect. Maybe only one in a hundred has a problem, but.....
Dave
