Higher pinions = safer MMM's? Or no? Someone's lying....

[shaunjohnson]

jeff,
i tryed to look at these voltages yesterday but the eagle tree V3 wont log quick enough to really log the voltage spikes from breaking.

all of that aside, therefor the super low gearing, low KV and super high voltage guys, if they are running low quality packs then they should use mechanical breaks and disable the MMM's correct?
therefore there is no regenerative voltage.

i think this thread has taken it too far, too many seemingly big brains here and not enough balls to go test it ourselves!!

from what ive seen, my revo only demands 70A from my cheap turnigy when i give it the beans, but i rarely do that cause it's scary
it's all about the breaks isnt it, too many voltage spikes and pop goes the TVS.

[J57ltr]

Your right the Eagle Tree is slow 10 times a second is way too slow to pick this up inless you just happen to catch this. The only other data logger I have will only measure at 240 hz which is better (but isn't exactly small and needs to be connected to the computer at all times), but I think you need something in the 1K range to see this. I have several O-scopes, but they are all old and don't have a way to capture information (been thinking of a chassis dyno for some time now).

I also don't have a RC this large my stuff is 1/10th scale or I would find a way to test it. I don't even have a MMM becuse of all the problems I have seen. I will get one, but I think I am going to wait a little longer.

The way I see it ( I don't have schems in front of me to study the exact circuits so I have to guess based on what Patrick says and my knowelege of electronics). If the voltage rises enough to cause the damage to it then the power is only kept in check by the batteries. One question to Patrick I have is how much internal resistance is too much?


I don't agree that the thread has been taken too far, as it invites interaction between the actual manufacturer who gives good information and helps us as a group understand the working of the system on a better level. I also don't see this as arguing I see it as a discussion.

Jeff

[shaunjohnson]

eagle tree can be set to below 1 second if needed i think...deffo not 10secs though!!
there is a TVS in the MMM to protect the FETS from the voltage spikes i think.
large voltage spikes are caused by the battery not being able to absorb the charge and hence the ESC has no where to dump the power, then the voltage rises and blows the TVS off sometimes.
then the next time the TVS is needed, it inst there, so the FETS suffer.
i'm not a castle teach but this is what i believe to be happening.

getting an MMM is a good move but you need to run good batteries period!!