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Originally Posted by cart213
I've been pondering whether or not I could get away with using 6s A123 cells on a MM. I know that's a lot of voltage (19.8v nominal), but I haven't heard of anyone frying a MM due to overvoltage yet :036: , so I wonder how much is too much? Didn't rtsbasic say that he was going to try 16 cells (19.2v)?
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Haha, this is what I've been planning to do for a while, but I've been keeping it under wraps. :) Problem is my Triton v1 charger only charges lipos @ 2A, so I'd have to get another charger (for wait forever), and the SPT are ~$20ea for the A123 cells. Plus I'd have to redo my batt trays as the M1s are so wide. so plans have been on hold.
However, I've been doing some more testing with the MMax, and I successfully ran it with 16 cells last night. I had been using 15 for a little while with no issues, so decided to go for it. Nice. Two critical factors I am looking at; peak and discharge voltage. W/ the NIMH I am saying a high 1.45V/ cell, so 16 cells=~23.2V Very high, but obviously this drops very quickly after a little discharge. From graphs I've seen, I'd put loaded V @ ~1.1V/cell (depending on batts), so ~17.6V.
The M1 cells peak @ 3.7V/cell, and look like they drop to ~2.7v/cell under a 40A load. => ~16.2V for 6s, but only peak @ 22.2V.
The numbers are very loose, so don't get to hung up on them for exactness, but I do think the MMax would easily run 5S M1, and even 6S M1 with care. I am also thinking it would run 5s lipo (if peak =4.2V/cell, ~3.3v/cell loaded.) This actually looks the best situation as peak voltage is only ~21V, but under load the voltage should be about the highest. This is the plan I've been leaning towards lately (getting a 2S and 3S and saddling them) vs the M1 cells for ease of fit and charging.
I have some more testing to do, it was only a few speed runs and some bashing, but nothing blew up. If it does nuke, its only $50 to fix for any reason. Temps stayed very low, ~100F Esc, but it was only 59F outside. Don't know how it would fare 90+F in summer.
@BrianG, checked the manual, and it does talk about 4s so that would be ok IMO. I was thinking about my Mtroniks or some other esc I believe that had some wierd spec of 12cells/ 3s lipo.
@Cartwheels: I've never seen that w/ mine after ~2mos of use... Maybe something w/ yours in particular or your setup? What motor?