Upgrading low amp OEM controllers - Where to start?!

S

Slippy One

1 mW
Joined
Aug 3, 2023
Messages
12
Location
London
I just want more amps for better hill climbing.

Nothing looks like plug and play. Most controllers on Aliexpress look semi homemade and some look downright dangerous. Grin Franken/Baserunners look ideal in size and spec but I'd also have to replace screen and probably PAS or throttle, and I'm not a fan of DIY tinkering for days with such an expensive product with poor support. Grin say their stuff works with certain displays, others say no, so much conflicting advice.

What would an experienced DIY builder do? Replace everything except the motor to make sure it all works, including rear/brake lights? (kitchen sink approach)

My bike is called Engwe EP-2 Pro and is a cheap copy of a Mate-X bike with folding frame with 20" wheels and a generic 9pin clone 750w motor. Controller is a custom 48v with 17a current. Bike is great on flats, awful on any hill, even smallish ones.

I'm looking for at least a 35a controller to help climb hills better, I would assume the max amps would be for the hills, and drop down again when cruising to help battery range..

Also, apart from weird rattles at lower speeds, is there anything wrong with square wave signals compared to sine?

No idea where to start or if I should even bother at all. There's thousands to choose from.. o_O
 
I was trying to find a review that tells us if this is a direct drive or geared motor. Most of these fat tire 20: folders with the geared motor all have the same performance and climb OK on hills. I did find one where the reviewer said he could put power back into the battery, pedalling the Engwe EP-2 Pro in ECO mode. That would imply direct drive. Fast on flats, but limited on torque for going hills.

And if that's true, I think you're limited even with a 35A controller. Probably need a battery that can supply 40A too.

Yes, controllers must be used with a matching display, Most displays are $34-45 dollars, If the controller has a 9 pin motor cable, that is usually plug compatible with a 9 pin motor, but it depends on which 9 pin model. Z91 is for less than 20A. The Z916 is for 25A. I don't lnow how high it goes. I admit using the Z91 on 25A controllers, but my bikes only go that high briefly

Z91.jpg
The rest of the connectivity depends on how your bike was wired. If it uses a harness that goes to the handlebars with plugs for throttle, brakes, and display, that's called a IT4 cable and also somewhat standard. Your throttle, and display would fit. Brakes are either three pin (yellow connector) or two pin (red connector) and if your bike is different, some changes needed.

If it doesn't use a harness with modular connectors. you might have a lot of connector changes,. Messy.

KT_sinewave.jpg
s
 
My guess is that your battery will be your limiting factor, so more info on that would help. Looking at the specs for the stock battery, 48V 13Ah, it may be near its capabilities already, and certainly not capable of 35A.
 
Slippy One said:
I just want more amps for better hill climbing.
Click to expand...
What is the slope and length of the hills, worst-case?

What speed do you need to maintain on them?

What is the total weight of you, bike, and anything you carry or pull?

Those will help you determine the total power required to do what you want. You can use any of the various power calculators or simulators out there, such as those at ebikes.ca , to help do this.


That way you can be sure to get a big enough controller to do what you want, and make sure your motor and battery can handle that too.
 
Thanks to all for the advice so far. I bought 2x 48v batteries with the bike, one is 13ah, the other is 16ah which gives me a bit more range but had no idea they might not accept a higher amp controller. As for the hills, North London is mostly flat except a few steep gradients around Crouch End/Muswell Hill which my bike hates. Muswell Hill being an 8.8% gradient over 600m. I bought an 11-34T rear freewheel that has me peddling like a clown, and the motor is clearly groaning all the way up making heavy load noises. Not really looking to go fast, I can feel some assistance but it's barely there in top PAS 5 -these bikes are bloody heavy though (so am I) so maybe I'm barking up the wrong tree with this motor and controller combo. For my daily commute, I feel something might either burn out/melt or those nylon gears might round off long term. This particular bike doesn't have regen brakes - that's the Engwe Engine Pro (mine is EP-2 Pro - £300 cheaper) Happy to disassemble the entire electrics to see what connections I have to work with. Pretty sure I can reuse the brake levers, and the PAS sensor around the crank looks simple enough, new screen was expected so no problem. I'll try to find out if the generic bafang type clone is DD or geared, not much info from Engwe..

As the weight combo, I'm 90kg (200lb) the bike is a hefty 35kg (77lb) so that's probably beyond a controller fix. lol;

Downhills is no problem after upgrading to 203mm rotors and decent Shimano 375 calipers. Heavy bike that stops on a dime.
 
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Easy way to tell if a hub motor is geared or not. Spin it backwards and forwards. A geared motor has a clutch that disengages the motor so it doesn't turn when spinning forward. Should be low resistance. You will hear and feel the gears turn when spinning backwards.

I think that small direct drive motors have far less torque than your typical 5:1 geared hubmotor of the same size,
 
I was in the same boat. Looking for more torque for easier hill climbing. I have an older Ride1up 700. It's got a 48v 14ah battery with 35E cells. My stock controller was locked at 18a. I upgraded to this KT set here. Most batteries that come with premade bikes seem to have a 25a or 30a bms. So a 35 amp controller may be too much. Also, a 35 amp controller is much longer than a 25 amp controller. 12 FETs vs 9 FETs. Might have a hard time fitting it to your bike. Do some research to find out what bms your battery may have. Contact the seller, they should be willing to share that info. Would also be nice to find out what cells were used.

What I did was measure my existing controller, which was a Lishui 48v 22a, and got a new controller based on the physical size. I cut out some packing foam, cardboard could work too, to the size of the new controller to be sure it would fit properly in my downtube. Even though the controller had a 22a max, the firmware from the manufacturer locked the max amps at 18. I got the new controller and display and it fit perfectly inside my downtube. Now I have 25 amps max. I dont use the full current much, but it is helpful when I need to keep with traffic to pass road work or get to the left lane to make the turn at the light safely. I can really fell the difference between 18 amps and 25 amps. Definitely helps more on hills as well.

From the bikes listing, your motor has 960 watts peak. A 25 amp controller would top out at 1200 watts max. The motor may not care, but the wiring may. Along with the kit that I got, I did replace the phase connectors with MT60 and shortened the phase wires. The MT60 connector is rated for 60 amps and the bullet connectors I had were rated for 15 amps. Shortening the phase wires helps, even though it was only 4-6 inches. My phase wires were all jammed in the downtube and there were may=ny hard bends. Upon cutting the extra length out, I noticed that the insulation was melting at those hard bends. The hard bends in the phase wires stress the metal and restrict current flow, creating heat. It doesn't take much, but they are small wires (16awg).

Note, I did have to do some rewiring. My bike has JST connectors and I was sure to get a controller with those connectors. I used all existing components. I did have to rewire the throttle pinout. If you have waterproof (WP) connectors, this might be more challenging.

I strongly recommend accessing the controller to see what you have. Measure you existing controller size and see what connectors you have. Some of my components have water proof connections, outside the frame. The throttle, for example, has an extended wire. It's JST, at the controller, and WP at the handlebars.
 
Slippy One said:
Thanks to all for the advice so far. I bought 2x 48v batteries with the bike, one is 13ah, the other is 16ah which gives me a bit more range but had no idea they might not accept a higher amp controller.
Click to expand...
Is there a label or markings on the 16Ah battery that you could post a pic of?
 
docw009 said:
Easy way to tell if a hub motor is geared or not. Spin it backwards and forwards. A geared motor has a clutch that disengages the motor so it doesn't turn when spinning forward. Should be low resistance. You will hear and feel the gears turn when spinning backwards.

I think that small direct drive motors have far less torque than your typical 5:1 geared hubmotor of the same size,
Click to expand...
I've had this motor out of the hub many times to clean & grease the 3x nylon gears with Molykote PG75, so I'd say it's a geared hub. :)
 
slaphappygamer said:
I can really fell the difference between 18 amps and 25 amps. Definitely helps more on hills as well.
Click to expand...
That's great news! Thanks for the detailed reply, I'm generally happy with the bike as it's mostly on flats, but thought I'd need 35A or more to really feel it. :unsure:
slaphappygamer said:
From the bikes listing, your motor has 960 watts peak. A 25 amp controller would top out at 1200 watts max. The motor may not care, but the wiring may. .
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I did think this might be an issue. Cable to the hub motor is 9-pin Julet aka 9-pin HIGO. The Grin Baserunner version (L9 I think) do state they are best rated for 50a max, althoughthese controller use FOC instead of Sine or Square waves which I don't really understand at all.
slaphappygamer said:
I strongly recommend accessing the controller to see what you have. Measure you existing controller size and see what connectors you have. Some of my components have water proof connections, outside the frame. The throttle, for example, has an extended wire. It's JST, at the controller, and WP at the handlebars.
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I'll definitely buy one that fits in the frame and the connectors look like they're easy enough to wire up, although I'd still like to research the Grin Baserunner L9 V5 that definitely fits, just not sure what would work or if my battery has enough grunt to run it. Also, the Baserunner seems to use crazy amounts of continuous amps (like 40+) from reading into it, but once again I have no idea what that means using FOC signals. Here's a pic of the OEM controller from AliXpress: roughly the size of a fist.
 

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E-HP said:
I see the battery listed in a few places including Amazon. No description of the cells, but the pack is rated at 15A, for the 13Ah. I'm guessing the 16Ah may provide 19A-20A.

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OK I don't know a thing about batteries, I guess this means these batteries simply won't give me the 25+amps I need.. I don't want to buy a new battery, might be cheaper and smarter to just walk the bike up hills. Anyone know if this type of in frame/Mate-X/Engwe/Lectric battery comes in a higher amp version?
 
Will any battery that fits the Mate-X fit in your bike? I see some replacement packs on Amazon that describe what cells are being used, although not the actual model numbers, but enough info to make a decent guess. I think the 17.5Ah pack with LG cells may be MJ1 cells which are good cells. The pack is using a 30A BMS. If they are MJ1 cells, then 30A seems pretty conservative, so the pack should provide that easily.

 
E-HP said:
Will any battery that fits the Mate-X fit in your bike? I see some replacement packs on Amazon that describe what cells are being used, although not the actual model numbers, but enough info to make a decent guess. I think the 17.5Ah pack with LG cells may be MJ1 cells which are good cells. The pack is using a 30A BMS. If they are MJ1 cells, then 30A seems pretty conservative, so the pack should provide that easily.

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That's interesting, the Engwe & Mate-X frame are pretty much identical, although this Amazon ad states the older Engwe batteries are slightly smaller, they don't mention them being any different in cell spec (or maybe I missed something), therefore I think my battery might cope with a 25+amp controller.

@slaphappygamer that controller (and display combo) looks just the ticket for me size and performance wise. At that price might be worth trying out. Those Baserunner V5 aren't cheap and lack of troubleshooting support paired with their high amps FOC signal might be an expensive headache.

Doesn't anyone else use a 13-20ah battery (48v) with a high (25-35a) controller? If yes, are there any issues with pairing them like super low range, over heating etc?

Thanks in advance for anyone pointing out any obvious technical issues I may encounter..
 
Nice, just know that there will be some rewiring, with most new controllers. So be prepared for that. :)

I just saw your photo with the label of the 13ah pack. You may not be able to use the full 25amp current. It appears that that pack will only provide greater, or less than, 15amps.
 
slaphappygamer said:
I just saw your photo with the label of the 13ah pack. You may not be able to use the full 25amp current. It appears that that pack will only provide greater, or less than, 15amps.
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Oh, that's bad news for even bothering a controller upgrade. I would've happily upgraded the 18a controller, but if it means upgrading the battery etc, that's a deal breaker for me and I'll simply hop off and walk it up long hills. I feel somewhat duped by these cheap eBike manufacturers that don't mention it'll be rubbish on inclines.

If the 13ah battery can't do 25a when required, does anyone know if my 16ah battery will fare any better? Is there a calculator to work it out or is the answer hidden in what type of cells my battery uses?

I've been down many rabbit holes with various projects but I feel there's no such thing as a simple controller upgrade here and I refuse to take the bait. :D
 
It’s weird that, on the description of your bike, that it states 960 watts peak. That would be 20 amps. Your battery shows that 15amps max discharge. Perhaps your 13ah battery can provide 25 amps. Really hard to know sometimes.

If you did go with the 25 amp KT controller, with a display, you may not get the full potential of the controller, but you would get away from the manufactures fixed settings. So, you should be able to have 960 watts in your highest assist level….if you don’t already see that on your current highest assist level.

Do you see a wattage read-out in your display?
 
I'm not sure anyone knows what calculations are done by different manufacturers and governments anymore. And what does that even mean 15a max discharge?? If true, why have they used an 18a controller that apparently uses 20a to get 960w.. the mind boggles.
 
Although, I did find this Mate-X battery that fits my bike - they do a version that's 52v 17.5ah with a continuous discharge between 20-30a which means I might be in the running to install at least a 25a controller!


Although they are £206 ($260+) each, it might be worth it for the hills. Who wants to walk a heavy bike up hills anyway? lol
 
I put a Baserunner controller in a cheap ebike once. The battery's BMS indeed cut out at 20A max discharge. Had to turn bike off and on again to get it moving after hitting that.

You can program the Baserunner to have a max battery amps limit that low, though. Then the BMS won't trip, bike will just have trouble accelerating and on hills since even full throttle will never draw more than the limit.

Later on I upgraded the battery and was able to bump the max current limit on the Baserunner to 30A.

Some cheaper controllers with displays have a set of advanced settings accessible by certain button combinations. Sometimes those advanced settings include a similar current limit setting.

For underpowered controllers, if there is no limiter wire to disconnect, many people perform something called a shunt mod. Basically you modify the controller's ability to measure current so it thinks it is applying less than it is. Then it will draw more amps. Can destroy the controller, though.
 
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Slippy One said:
Although, I did find this Mate-X battery that fits my bike - they do a version that's 52v 17.5ah with a continuous discharge between 20-30a which means I might be in the running to install at least a 25a controller!


Although they are £206 ($260+) each, it might be worth it for the hills. Who wants to walk a heavy bike up hills anyway? lol
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The battery is the most important component of your system. Don't knowingly buy cheap packs made with cheap generic Chinese crap cells from AliExpress. There's a reason that one is only rated for 500 charge cycles, you get what you pay for. Make sure the cells used is listed in the description, like the 17.5Ah LG cell pack I linked above.
 
E-HP said:
The battery is the most important component of your system.
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Yes, and thanks to the Endless Sphere community I'm more knowledgeable on the system, and the limitations of cheaper components like batteries, here's me thinking 48v was just 48v volt.. (and 52, 60, 72 etc..) No!! It's all about the battery maximum discharge rate, and that's why we never see these advertised as rubbish hill climbers with 15a max BMS.

Then slap a 18a controller on a 15a entry level battery!

E-HP said:
Make sure the cells used is listed in the description, like the 17.5Ah LG cell pack I linked above.
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Always a risk, and how would I know this 52v Max Aliexpress one is what they say it is without voiding the warranty? Can cells discharge be verified with a meter?

At least these batteries fit my cheap frame exactly (double checked) alas they each come with a hefty £80 ($101) shipping fee (being batteries 'dangerous goods' of course they do), and late October delivery.. Yikes.. That's over £575 ($733) for 2x 52v batteries with a minimum 2.5 month delivery..

All because of hills! :ROFLMAO:

At least this solves my controller dilemma, without spending another fortune on 2x batteries first, my controller options are keep the factory one or nothing! Pretty easy decision then! :p

Cheaper and smarter to simply buy a new bike, as this Engwe EP-2 Pro only cost me £895 all up!

Buy cheap, buy twice! Lesson learned for sure.

Of course the real problem is British eBike laws, where if I'm pulled over by the police, the bike will be not only confiscated on the spot, but destroyed without compensation, which they're doing to all the food delivery guys here in Tottenham. Police love to pick the low hanging fruit don't they?

Even using having a throttle on a 250w motor is illegal, it's nuts..
 
Slippy One said:
Always a risk, and how would I know this 52v Max Aliexpress one is what they say it is without voiding the warranty? Can cells discharge be verified with a meter?
Click to expand...

Greater voltage drop under a given load means weaker cells less able to handle that. If you can measure the battery total voltage and the current at the same time, on a typical ride, you can note that down for various states of charge from full down to empty. When you do a measurement during the ride, then while you're stopped to note that down, measure the voltage while stopped as well, to give a comparison resting voltage done at the same state of charge.

This can tell you whether the battery is "normal", "really good", or "awful", by comparing the voltages resting vs loaded at each point, with cell data from places like Flashlight information 's battery testing section (where there are good cells and bad cells, or other cell testing data here on ES or elsewhere. (since those testing data are per cell and yours are for the whole pack, you can either multiply the numbers from their data by the number of series cells in your pack (13 for 48v, 14 for 52v, etc), or divide your results by that number).
 
Thanks @amberwolf for that detailed reply, I thought that was possible, glad to know my hunch was right.

For anyone reading this in the future, make sure your batteries have a decent amp output (20-30a+) if you want to use a decent controller to get up hills.

Part of me still wants to upgrade. Part of me says just buy a better bike and stop tinkering.. :devilish:

I could sell my current Engwe batteries to raise enough to offset the higher amps ones, then get the baserunner and compatible display/pedal sensors etc to have a rock steady, folding hill climbing 52v beast for less than $1000 bucks, whereas another bike with these features (really need folding for trains), is over £2900 (Mate-X), so I'm still £1000 better off if I do these mods instead of buying that. Plus, the Mate-X is only 48v. :cool:

Decisions decisions..
 
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