Larger wire for Anderson SB50 connectors

[Joe G.]

In recent years, I've seen a number of top-performing teams electing to use wire heavier than the FIRST-mandated minimum of 6 gauge on their batteries and main breaker, in order to reduce resistance and squeeze ever so slightly more voltage out of their batteries. However, I haven't been able to find a source on contacts for the legally required SB50 connector beyond 6 gauge. Can anyone point me to a source for this? Or does 4 gauge work with the standard contacts with some effort?

Thanks!

[Joe Ross]

If you're careful, 4 awg wire fits in the 6 awg contact.

[cgmv123]

Anderson doesn't make SB-50 contacts beyond 6 AWG. I believe most of the teams that elect to use larger wire simply remove enough strands at the end to make the wire fit in the 6 AWG contact.

(The SB-120 connector supports 2 and 4 AWG wire. It was banned for last year (https://frc-qa.usfirst.org/Question/81/is-it-acceptable-to-use-the-sb120-anderson-power-pole-connector-in-lieu-of-the-standard-sb50-connector-when-connecting-the-robot-battery-to-the-main-circuit-breaker-and-power-distribution-board), but I think FIRST should switch to that size just because its rating matches the rating of the Main Breaker. The SB-50 was acceptable when you could only use ~10 motors. We can use up to 30 now.)

[Al Skierkiewicz]

Max et al,
The current ratings on the #6 is determined for wire temperature rise in continuous current. I suggest everyone make the calculation for the resistance of #6 vs. #4 on their own design. You will find that on a typical robot using 4 feet of wire from the battery to the PD input, the difference between #4 and #6 is millivolts at max current. This drop is far less than the drop due to internal resistance of the battery. To help you along, the resistance of #6 is ~0.4 mohm/foot. #4 is ~.3 mohm/ft.