150mAh vs 160mAh, interchangable?

[Craftydan]

From the comments

I'm not sure I like those boards. I'd rather use a USB charger with multiple plugs or something.

And comments on a forum are always accurate?

I see what this guy was saying, and yes, the first board I linked it probably does apply. But in the case of the board he's commenting on, I think he's spouting nonsense. That circuit is not as he describes.

you mean multiple USB chargers or one with more than one plug? There are a few that are functionally 4 independent one cell chargers (not that they're USB powered) . . . and a few 1 cell ganged chargers with an unprotected parallel interface (like the first one I linked).

The second one I linked has current limiting "fuses" that if they start to self charge they're limited to a reasonable rate -- they *ARE* supposed to be able to dump current at reasonable rates. That's a healthy function of a battery.

 

[jhitesma]

I parallel charge my 1s packs for my mini heli's with a cheap parallel cord...but I'm careful about it in that I check the voltage of each cell before hooking them up. If they're within about .05 of each other then I just hook them up and let them sit on the parallel cord until they all equalize before charging. If any are further then I discharge the higher ones until they're close and again put them on a cord and let them equalize before charging.

I basically do this by plugging the parallel cord into my volt meter and then one by one plugging the bats in to check their individual charge. It's a lot of plugging/unplugging and tedious...but beats spending 6 hours to charge 6 packs at 1S

The protected boards make it a lot quicker and easier but I don't fly my mini's enough to justify the cost of the board. Though I'm thinking about getting some fresh packs and flying them more again as I recently put one in the air after a few months of not flying them and found that all the flying I've been doing with my quads in acro mode has really improved my heli flying ability and I'm kind of wanting to get a few more heli's in the air now

 

[Balu]

Why don't the boards treat these like individual cells of a bigger LiPo? Balancing port and main connector like on a standard LiPo?

Won't the charger accept those if they differ too much?

 

[Craftydan]

Haven't seen anyone who has built a 6x1S series balance charge cable, but the wiring would be a little odd.

Most balance charger circuit layouts I've seen inject current through the main plug and siphon current off through the balance port to regulate the current going into each cell. For a charge harness like this to work, either every cell would need to be plugged into the harness or the high voltage lead on the main plug would need to be switchable between the cells, so if I plug in three cells, I plug into the three lowest positions, then put the high voltage lead into the top of the third cell.

I've got a 2x3S -> 6S harness like this, but it must have two packs connected, but I *only* need two packs.

 

[Sandhill]

Dan, how does that adapter work? I don't see any balancing mechanism and if you have differently charged 1S LiPos, wouldn't the charger just pop the full ones?

Not a problem - if you are parallel charging at say 4.18 V there is no way that any battery is exposed to more than 4.18 V, and that's as high a V as can be forced into one. As the voltage of the individual cells rise to the applied voltage, they just stop absorbing charge and nap until their friends catch up. I use the board that Dan linked second, and I just don't worry. If you do the math you'll find that even a couple of tenths difference in starting V is no prob, flying my nQX's to LVA always discharges them within a hundredth or two (3.69 typically), and they always come off of the board within a hundredth or two.

 

[Balu]

Most balance charger circuit layouts I've seen inject current through the main plug and siphon current off through the balance port to regulate the current going into each cell. For a charge harness like this to work, either every cell would need to be plugged into the harness or the high voltage lead on the main plug would need to be switchable between the cells, so if I plug in three cells, I plug into the three lowest positions, then put the high voltage lead into the top of the third cell.

Easiest way to do that would a pluggable high voltage lead that you have to put next to the last cell before charging. Another option would be "blind plugs" that just bridge the empty cells.

But there's one thing that would not work, adding a cell later while the others are already charging.

Does that work on your boards?

Or is it still better to have a single charger for each port?

 

[Craftydan]

Easiest way to do that would a pluggable high voltage lead that you have to put next to the last cell before charging. Another option would be "blind plugs" that just bridge the empty cells.

But there's one thing that would not work, adding a cell later while the others are already charging.

Does that work on your boards?

Or is it still better to have a single charger for each port?

Blind plugs and multiple alternate power connections all introduce their own issues. It's not insurmountable, but as I said, it makes the connections a little odd. With the 2x3S harness, I've got a power connector and 6S balance plug going to the charger and 2 balance sockets to the battery. Very clean, but again, it won't work for one. It must have both.

I've seen matching 2x2S harnesses, but I've yet to see a 3x2S series harness sold and I doubt I ever will -- with the 2 battery harness if I don't have two packs I can just unplug the harness and charge one directly. With a 3x2S if I only have two to charge, I can't revert back cleanly to charging two, I have to charge the two individually. with a 6x1S serial charger, not only would I need something complicated or 6 batteries . . . I can't even do away with the harness and charge the pack directly -- I'd need yet another harness to charge only one. With the parallel harness with onboard self protect I can charge 1 to 6 with no complicated setup.

I generally don't interrupt a charge cycle without completely stopping it and restarting it fresh, at which point you're back to the original problem of paralleling unblanced packs, which the "fuses" on the board should deal with.

Single charger for each pack ( in one box or just many plugged into a beefy hub) will always be the better option, electrically, but that assumes the economics are not considered.