Advice for G-line Brompton kit, or new components to make the Grin kit work.

[robotron2084]

Hello, I've got the Grin Brompton G-line kit and have had various problems and I'm either going to try to get a refund/sell the kit and replace it, or mod it. For more info on my current problem you can see my post here.

Option A: Fix the current kit by replacing parts
Since I've already paid for this kit I'm wondering if there's a way to use the existing components and replace them to use another motor controller that might fix my issue, or something similar. Is there another motor controller from another brand that is better quality? I have no idea how compatible other brands of hardware is with my Grin kit. If I need to buy more than just the motor controller

Option B: Completely new kit
Looking at kits, it is very hard to tell what is junk and what is good. I have never purchased a Bafang kit but it seems like these are well recommended but the internet is full of fake reviews. The price is so low I wonder if these things are safe or quality.

Some additional context:

• I'm generally technically savvy but not an e-bike expert.
• I have a 3d printer and can design and print adapters, etc.
• I don't want to buy a cheap battery, so I'll likely build my own or buy one from Affordable e-Bike (we'll see how affordable it is with the new tarriffs).
• I'd prefer 36v but 48v for the battery is OK.
• Front drive (bromptons have a rear internal hub)
• I don't need tons of power, 500w with a max speed of 20mph is fine.

Thanks!
Chris

 

[docw009]

Make sure the 20" option on your prospective kit has a motor wound to spin fast enough to meet your expected speeds.
.

 

[neptronix]

For this kind of bike i'd go with a small geared hub motor on a lot of volts. 16-20 inch wheels inherently have good braking so losing regen isn't the worst thing in the world.

Your primary problem is that dropout width is going to be narrower on that bike, that's why you need a special kit.

Hopefully grin can help sort things out.

For option B, let us know what dropout width you're working with on the front and one of us can probably find a kit for you.
Would be nice to see a picture of the bike also.

Battery in the USA? I like em3ev still. ebikes.ca have dropped their battery prices. affordableebikes.ca has what appears to be some nice batteries but they are a tiny business and last time i talked to them, they don't know what's going on with the tarriffs. So i'm hesitant to buy and will let someone else be the test hamster on that.

 

[robotron2084]

For this kind of bike i'd go with a small geared hub motor on a lot of volts. 16-20 inch wheels inherently have good braking so losing regen isn't the worst thing in the world.

Your primary problem is that dropout width is going to be narrower on that bike, that's why you need a special kit.

Hopefully grin can help sort things out.

For option B, let us know what dropout width you're working with on the front and one of us can probably find a kit for you.
Would be nice to see a picture of the bike also.

Battery in the USA? I like em3ev still. ebikes.ca have dropped their battery prices. affordableebikes.ca has what appears to be some nice batteries but they are a tiny business and last time i talked to them, they don't know what's going on with the tarriffs. So i'm hesitant to buy and will let someone else be the test hamster on that.

I am currently looking to get a new BMS that won't die out from the regen (see the other troubleshooting post). I asked them a week ago and in general my support requests require multiple emails to get a response. Honestly I'm getting to my limit and option b is looking better all the time. Especially with this info.

Thanks for a rec on a good us battery seller. Looking at the site there is a lot of good stuff on there, too! And totally thinking about the current tariff stupidity and thinking its going to become much more problematic to get parts in general, not just canada.

The g-line front dropout is a 12x100mm thru-axle, this info wasn't easy to find, it wasn't in the manual or easily findable on brompton's site, so this is sourced from some random article online.

And agreed, while regen is cool, its not very high on the priority list.

 

[lnanek]

It's true that a motor with a clutch would provide the best protection. There could be controller only solutions that are cheaper, though.

I've seen other controllers come out with hardware v2 versions that had a freewheeling Schottky diode across each MOSFET, for example. This performs better than the body diode built into each MOSFET. So if the Baserunner controllers lack those, it might be possible to hardware mod add them. People can and do replace MOSFETs with better spec'ed ones or double up MOSFETs entirely as well.

Barring that, you could try just a different controller too. I don't know about modern baserunner controllers, but mine maxes out at 52V batteries. Needless to say, if you get a controller capable of 100V batteries, it would have stronger spec'ed FETs and capacitors for handling back EMF.

The ASI/Baserunner series has always been buggy when regen is set to zero as well and we owners often have to hack other ways to kind of, sort of disable it. It annoys me to no end that the Phaserunner Android app has no max regen voltage start setting, for example, and only has the other regen limit that breaks the stupid thing when set to zero. So I can't fix as many problems on the go with my USB on the go adapter.

I've seen other people with other controller brands that had similar problems and were just able to disable regen or running sensored or something and the problem was fixed. I think it was a Fardriver controller or something like that. So I think ASI based controllers like Baserunner just have poor handling for situations where they can't regen or the regen current would exceed the max, like a direct drive motor spinning faster downhill than it can handle. Other controllers seem to have better hardware and software protections for this case.