RC-Monster Forums - View Single Post - Home-brew battery measuring station

BrianG · 01.24.2010, 08:46 PM

Sikes: Like J57ltr said, 3 x 56 ohms is not nearly low enough. My design called for between 30 x 3 ohm resistors in parallel (0.1 ohm total), and 60 x 3 ohm resistors in parallel (0.05 ohm total). Each being rated for 50w and mounted on a heatsink, would be enough to dissipate the power.

J57ltr: Since the MMM is a BL ESC, there are no braking FETs. I imagine braking in brushed mode is done the same basic way as it is in BL mode; use PWM to short the phases, and in between the PWM pulses, put the inductive energy back into the battery. Although, you can disable the brakes in the ESC when used in this way, so it wouldn't matter either way.

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BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	01.24.2010, 08:46 PM Sikes: Like J57ltr said, 3 x 56 ohms is not nearly low enough. My design called for between 30 x 3 ohm resistors in parallel (0.1 ohm total), and 60 x 3 ohm resistors in parallel (0.05 ohm total). Each being rated for 50w and mounted on a heatsink, would be enough to dissipate the power. J57ltr: Since the MMM is a BL ESC, there are no braking FETs. I imagine braking in brushed mode is done the same basic way as it is in BL mode; use PWM to short the phases, and in between the PWM pulses, put the inductive energy back into the battery. Although, you can disable the brakes in the ESC when used in this way, so it wouldn't matter either way.