Internal Charger For VV Boxmod?

I would like to build a VV mod with a built-in charger. However, the only internal charging circuits I have seen are for a single batt. I have tried to search for a multi-batt charging board with no luck. Is this not a good idea? If it is possible, any suggestions would be appreciated. Thanks

Alan

 

You're going to need a balancing circuit. I've seen some interesting mods built using cell phone charging adapters, too. Might want to look into that.

 

Thanks Chaos .. it sounds like I don't want to charge multiple cells in series .. is this because the cells may be unbalanced? Perhaps I had better just continue charging batts out of the unit ???

 

Charging them in series would run all the current to the bottom battery. Bad mojo. Here's a link you might find interesting: Battery Cell Balancing Circuit Design Guidelines

 

Yeah if you charge them in series it's going to put the maximum charge into the batteries, doesn't matter where it goes, which is usually one battery which equals fire.

I have done the same as you, looking around for a way to charge 2 3.7v li-ons at the same time with a small circuit and in reality the only way I found that was anywhere near possible was to have a switched PCB that went between the batts and the rest of the guts that would be in series for the high voltage throughput until you flipped the switch which changed the battery connections to parallel which in reality isn't hard with a multiple pole switch but you would have to set it to parallel then trickle charge most likely 2 18650s with a small charging circuit that puts out maybe 250 mah.

That would just take all freaking night but it is the only acceptable and easy way I found to do it because I couldn't find a charger that was small enough to be internal that you could set to a specific voltage specification. However, there were a few exterior ones but when your looking at a 70+ dollar charging unit vs 3 bucks worth of wire/switch/PCB I would rather do a little more soldering and have something that's pretty cool.

 

I know there's a cheaper and easier way to do this, because there was that box mod that had built in charging and... Huh. Actually, that one was prob a single battery.

The other option would be an external balance charger. Once again, though, your batteries have to be running in series, not in parallel. Might want to look into playing around with Boost circuits.

 

Since I don't want to burn my house down, it sounds like removing and charging them may be the wisest way to go. However, I use FET's on some of my mods. Never thought of it before, but if I wire the FET in between the two series batts (instead of the traditional location), it would still activate the vaping circuit because when you engage the FET it will complete the circuit. However, when the FET and master switch are off, the two batts would be completely isolated one from the other. Hmmmmmmm

 

If you are only charging one battery then you can gut an old 510 battery charger and use that.

If you are wanting to charge say 2x14500s in series (7.V) at the same time then I would suggest getting a look at some of the R/C forums to see what they use on their battery packs.

They stack and parallel several of these battery cells to achieve high V and more A with longer run times and peak output. They use a higher rated balancing charger to keep all the cells at the same level and some of these chargers will detect a failing cell and warn you of it.

Maybe instead of having an on board charger you can just have the wiring on board with an external jack for this to plug into???

 

Thats what I was talking about previously hoyt, it can easily be charged with a balance charger from the exterior in the way some of the packs of Li-Pos are with RC cars, but it requires a good strong charger thats usually over 50 bucks, which hey if its the only mod you use and you wish to have it in a sealed case and run a couple wire to a connector that you can just plug in at night or something it would work out fine, but for me I just couldn't justify the 50 bucks for a charger over unscrewing a couple screws. Which is why my latest couple mods I'm working on I ordered boxes that have metal threading in the box and I can use thumb screws on it if I wished to be that lazy

 

Also, LiPoly packs have better energy density...