Ok - so here's the latest...
I decided to hook up my old KT controller, to see if there was a similar connector explosion, and it hooked up just fine. This would indicate that my batteries were not the issue, and that the baserunner was again at the root of my problems...
To get a second opinion, I took a trip to Swift Bike (great bike shop in Seattle). Turns out they have a very close relationship with Grin, and helped me diagnose that it was indeed the controller that was the issue. Additionally, I guess Grin had realized and acknowledged some serious quality issues with their V4 baserunners, and have low key been recalling them.
I noticed this posted on their website very recently, on the baserunner product page -
"V5 Devices: Since June 2022 we have been reworking the V4 baserunners PCBs on hand in order to have better mosfet robustness with 48V and 52V battery packs, and also updating the Cycle Analyst plug wiring so that the throttle output is wired to Analog Input 2 (Brake1) and not Analog Input 1 (Throttle). This eliminates the need to have the 9-2 pin adapter cable to short ebrake and throttle pins to achieve regenerative braking control via the Cycle Analyst. Otherwise all wiring and plug details remain identical to the V4 units."
(https://ebikes.ca/product-info/grin-products/baserunner.html)
Bottom line - I'm returning all of my Grin products (baserunner, cycle analyst, cables, etc). I've re-installed the KT-25A controller for now, and have a KT-35A on order. I've already noticed the KT-25A is substantially better performance than the baserunner did....though i'm not sure if i ever got a fully functioning baserunner to begin with, so it may be a bad comparison.
For anyone looking into a baserunner, I would avoid for now.
I decided to hook up my old KT controller, to see if there was a similar connector explosion, and it hooked up just fine. This would indicate that my batteries were not the issue, and that the baserunner was again at the root of my problems...
To get a second opinion, I took a trip to Swift Bike (great bike shop in Seattle). Turns out they have a very close relationship with Grin, and helped me diagnose that it was indeed the controller that was the issue. Additionally, I guess Grin had realized and acknowledged some serious quality issues with their V4 baserunners, and have low key been recalling them.
I noticed this posted on their website very recently, on the baserunner product page -
"V5 Devices: Since June 2022 we have been reworking the V4 baserunners PCBs on hand in order to have better mosfet robustness with 48V and 52V battery packs, and also updating the Cycle Analyst plug wiring so that the throttle output is wired to Analog Input 2 (Brake1) and not Analog Input 1 (Throttle). This eliminates the need to have the 9-2 pin adapter cable to short ebrake and throttle pins to achieve regenerative braking control via the Cycle Analyst. Otherwise all wiring and plug details remain identical to the V4 units."
(https://ebikes.ca/product-info/grin-products/baserunner.html)
Bottom line - I'm returning all of my Grin products (baserunner, cycle analyst, cables, etc). I've re-installed the KT-25A controller for now, and have a KT-35A on order. I've already noticed the KT-25A is substantially better performance than the baserunner did....though i'm not sure if i ever got a fully functioning baserunner to begin with, so it may be a bad comparison.
For anyone looking into a baserunner, I would avoid for now.