New warning insert in MMM box: "DO THE MATH!"

[hemiblas]

Ya thats a great point. So really then we should be telling everyone to buy a battery that has a continuous rating of what we expect the surges to be. There is also a huge range on C rating. My 11.1V, 10C 5000mah truerc battery can hold 40-50A with good voltage with bursts of over 120A according to their website. My ebay 11.1V, 10C 5000mah battery can hold 10A at around 9.6V and weighs about half as much. I dont use either of these on my MMM though, but I bet the truerc battery would work fine.

I dont know if this matters, but my velineon ESC weeds out the bad batteries by the use of LVC. Its set very sensetive from the factory and on cheap batteries I get approx 10 seconds runtime from a full charge on a 10C cheap 5000mah battery before it shuts down. When the ESC pulls too much current and the voltage drops it shuts down. Shouldnt the same thing be happening on the MMM? If not maybe setting this feature from the factory so its more sensitive might help to prevent failures due to bad batteries?

[BrianG]

Originally Posted by SpEEdyBL

...You'd be amazed at how high voltage spikes can get during braking, easily twice the pack nominal voltage with bad packs. Since the the MMM and MM both have 30 volt fets this was not an issue with the MM as 3s was the rated limit.

There is a TVS on the MMM which limits these spikes to something around 26-28v.

Originally Posted by hemiblas

...When the ESC pulls too much current and the voltage drops it shuts down. Shouldnt the same thing be happening on the MMM? If not maybe setting this feature from the factory so its more sensitive might help to prevent failures due to bad batteries?

This is a double-edged sword. If you make the LVC too sensitive, it false trips all the time. If you make the LVC less sensitive to spikes, battery or ESC damage could occur. So, the LVC probably looks at the voltage over a set time and if it falls consistently below a certain value, it trips.