So wanted to let the community know about my experience with this controller. Since Rad went with the 13.5 Ah battery the amount of watts you can pull from this stock battery is limited to 750 Watts with the old 20 amp controller. This is actually for good reason because if you try to draw more power from this battery with the 35 amp controller it gets upset to the point the battery will not charge correctly. So whats the point in getting a 35 amp controller then. The point is finding the sweet spot which is 28 - 30 amps max draw which can be adjusted in the hidden menu of the controller labeled CH5 which I have set to 4 or 5. This video explains all the settings in the menu https://www.youtube.com/watch?v=y_NEXdUCOiY. If you set this any higher than 5 then you will have problems charging your battery after use. Prolonged use of battery at CH5 = 6 damaged my battery beyond repair. I love Rad. The damage to the battery was my fault and they still replaced the battery for me which is Rad going above and beyond for obvious reasons. If you set CH5 = 6 then the controller will draw upwards of 1500 watts which the battery is not capable of sustaining without hurting the cells.
I never use CH5 = 6 with my new stock battery because I know the consequences instead I have dual batteries the other being a 52V 19.5 Ah battery that can cope with the higher amp draw with CH5 = 6 or 7 which is way fun sport mode.

I am two weeks into owning a larger capacity battery and was thinking about maybe going further by adding a conversion kit to the front. After some thought and taking onboard your comments I don't think I will be adding a second motor, adding a second motor will increase my speed but bring down my overall range. Truth be told the upgraded controller makes the Expand very nippy and coupled with a 52V battery in parallel with the stock 48V (Date X2 battery combiner) means voltage sag is significantly reduced for power on demand making the expand feel much faster than it is. I am satisfied with my top end and with the Expand overall.

I am ready to add another motor to my Expand5 who else thinks this is a good idea?
Another thread has already tried to change out the rear motor with a true 750 watt but failed. I was very disappointed to read the thread but very appreciative of the post very informative. I have seen a kit on amazon i want but not sure of the dropout size to get, any suggestions and are we going to need additional torque arms?

So I found this device to mount my extra battery on the down tube which normally would prove difficult because of the curved design by Rad.

The battery is a 52v 20Ah and comes with two mounting screws with an option for a third which would require drilling into the frame. I actually started to drilling and stopped after getting cold feet about damaging the cables that run inside the down tube. Mounting on the down tube is plug and play using the Grin down tube bracket. You will need is a parallel connector which I got from biggamebikes and arrived in just over a week from UK to US. Additional plug and play cables are needed to connect costing $30 also from big game bikes.

OMG the difference in range is crazy but this is not fully tested yet because I need to fully charge and discharge the new battery a few more times to reach full capacity. Only running one battery at a time until I have broke in the new battery then I will run batteries in true parallel and report back. For now I get 20 miles on stock battery and 35 on new battery but the combined battery is what I wish to see here shortly. As you can imagine I am expecting way more than 55 miles. Right now I would bet 70-75 but we shall see. I should also note that I am not using the stock controller thanks to the Area13 upgrade.


Double bob bracket by Grin
https://amzn.to/3uoYMDo

Battery
https://amzn.to/3acGIpn

Dual Battery
https://biggamebikes.com/product/datex2-parallel-battery-adapter

Controller/Display Kit
https://area13ebikes.com/collections/motor-controllers-and-displays/products/radkit

I have noticed that sometimes when I put my battery to charge the charger will not change the status to charging. This is not because of a fuse issue which I have had before which is what makes this strange. After checking both fuses which are fine, I plug back in charger to battery and the lights will stay the same no charging happening............until.........just wait for it..... after around 5 mins the charger will decide to start charging which seems a strange to me. I was wondering if anyone else is having this problem? That being said this only occurs after I have ran down the battery to 15-20 % and try to charge soon after use. I am not sure but I think they may be something in the BMS that tells the battery not to charge until a cool down period goes by. I have notice this with other rechargeable devices I own that will not charge directly after use needing a cool down period. Is this normal?