Help with the Details

Newb to ebikes but I am an old guy with pretty good mechanical understanding.
First build and I am having trouble understanding some of the details about how things work.
Already have the bike, a steel framed Mongoose Terrex...and I weigh about 220 lbs.
Leaning towards a 12T MAC IGH (prewired with temp sensors) in a 650B wheel from em3ev with an infineon 12 FET 3077 controller, CA-3, and a 14.7 ah/14S6P -25R triangle battery pack. Bike is going to be ridden off road 90% of the time and if I can do 20 mph on flat ground, I'll be happy.

Questions...please explain, I am trying to understand not just get a Yes or No answer and Thank You!:

1. What controls the maximum amperage that can flow to the motor? Is it the battery and/or the battery management system (bms), the controller, the CA-3, the throttle, or can all of them be reprogrammed or used (throttle input) to control the maximum amperage?

2. What parameters are programmable within/about my infineon 12 FET controller and should I order the "EB3 Infineon Program Lead" with my kit?

3. em3ev is recommending a 9 FET 3077 (maximum) since the 12 FET will be hard on the MAC clutch but my concern is that it (9 FET) will also limit the amperage if I need to climb a steep hill for a very short period of time. The 9 FET should allow about 1,500w max and the 12 FET should allow about 2,000w max. If I am careful with my throttle input when starting from a stop, is my rational for going with a 12 FET reasonable or am I going to destroy my clutch and cause premature wear on my planetary gears?

1., 2., and 3. are my biggest issues at this point but I am sure answers will lead to more questions.

Thanks for any and all input.

Bullfrog said:

1. What controls the maximum amperage that can flow to the motor? Is it the battery and/or the battery management system (bms), the controller, the CA-3, the throttle, or can all of them be reprogrammed or used (throttle input) to control the maximum amperage?

Click to expand...

Taking these components one by one:
Battery - the battery itself won't limit current; you need to make sure one of the other components will limit current to a value that won't damage the battery. 6p of 25R can deliver a lot of current safely - probably 100 A or more. So no problem there.

BMS - this will limit the current, but in an unpleasant way. It will completely shut down and you have to physically disconnect the load before it will reset. The limit should be specified by the vendor.

Controller - this limits the current by regulating the voltage that makes it to the motor. Nothing shuts down, it just limits the power available.

CA-3 - this basically limits the same way as the controller, but it's easier to program, and has some features that give it more flexibility.

Throttle - this doesn't do anything to limit current directly.

So basically you want a BMS with a limit that will keep the battery from being damaged, you want a controller with a limit lower than the BMS so the BMS doesn't shut down, and you want to set your CA-3 with a lower limit than the controller so you can take advantage of the CA's flexibility.

2. What parameters are programmable within/about my infineon 12 FET controller and should I order the "EB3 Infineon Program Lead" with my kit?

Click to expand...

Not familiar with this, sorry. But next answer may be relevant.

3. em3ev is recommending a 9 FET 3077 (maximum) since the 12 FET will be hard on the MAC clutch but my concern is that it (9 FET) will also limit the amperage if I need to climb a steep hill for a very short period of time. The 9 FET should allow about 1,500w max and the 12 FET should allow about 2,000w max. If I am careful with my throttle input when starting from a stop, is my rational for going with a 12 FET reasonable or am I going to destroy my clutch and cause premature wear on my planetary gears?

Click to expand...

Since you're using a CA-3, I'd just go for the more powerful controller and set your limits with the CA. Start out conservatively, and increase the limits as you get more familiar with how the system is performing. I think the CA can even be programmed specifically to minimize the takeoff jolt, but I'm not sure.

Welcome!
Yes, CA3 can do torque/power throttle function too, and amp rollback based on temps. I'd go with the 12 fet, and get a spare clutch and gears in case you wear them out fast. I'd also get the program cable as it is very handy to also tweak the controller settings for battery and phase amps, 3 speed switch settings, and voltage settings for various batteries. It is somewhat redundant with the CA, but worth adding in case you end up wanting it. I primarily use my controller to do all that, even though I'm missing out on amp rollback and the other throttle types.

Thanks for the help....one thing I forgot was that I don't plan to have any torque sensing device in place so my bike will be purely throttle with whatever pedal power I want to contribute. I just wanted to keep it as simple as possible.

Thats fine. In reference to my mention of torque or power throttle, it's a special function of cycle analyst v3 and it's still for throttles- it sort of changes the 'mapping' of the throttle so the degree of twist can correlate to power rather than speed. Otherwise, 'speed' throttles are usually standard and work linearly with speed- twist half way and the controller tries to get the motor up to half speed, using all available power. Torque/power throttle would respond by giving you half the max power with half of a twist, more like a car or motorcycle.

nutspecial said:

Thats fine. In reference to my mention of torque or power throttle, it's a special function of cycle analyst v3 and it's still for throttles- it sort of changes the 'mapping' of the throttle so the degree of twist can correlate to power rather than speed. Otherwise, 'speed' throttles are usually standard and work linearly with speed- twist half way and the controller tries to get the motor up to half speed, using all available power. Torque/power throttle would respond by giving you half the max power with half of a twist, more like a car or motorcycle.

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Can you explain this more to me ? I'm having an argument with my father (?) who doesn't believe me when i tell him I need to use 100% throttle to ride my ebike at my desired speed (20 mph). He says ' you dont drive a car flat out everywhere - be more careful and feather the throttle blah blah blah."

I thought my cruise control restricted the current to maintain a given speed but this is wrong - now i have a CAv2 i can see the Amps range from 1 to 40+ depending on the gradient. So how does my bike determine what the maxium motor speed (RPM i guess ?) - is this a function on how many Volts are in the pack at any time ?

Standard ebike throttles control speed, not directly power. Different from a car. Specifically the throttle controls the effective voltage the motor sees (which ultimately controls the motor's speed). The current is a function of the battery voltage and back EMF from the motor which is based on how fast it is turning, as well as the system resistance. If the motor is turning slowly and you advance the throttle fully the current can go very high, stressing the torque ratings of the clutches and gears. It is very hard to always control smoothly. Settings in the controller can help this, or using a CAV3, though it reacts somewhat later (depending on various settings), so there may still be very high but short torque events.

The best way to control motor current is with a programmable controller that measures motor (sometimes called phase) current. Unfortunately most controllers don't measure it, they estimate it, and can be less than precise at controlling it. Controllers that do measure motor current are somewhat more deluxe and costly, but they do a better job and often have the torque type throttle control that operates more like a vehicle throttle.

So, to go full speed requires full voltage and full throttle (with the usual speed controllers).

I would suggest following em3ev's advice on his products if you want them to hold up. Paul has more experience with these motors than almost anyone that you are likely to talk to, and he's the one you'll be getting any warranty service from. Get some experience under his guidance, then later make changes as you wish. Gearmotors don't need 2kw to climb quite well. If you really want to climb trees you may want to look at mid drives, smaller wheels or dual motors. If you want the gearmotor to last you will want to limit the peak power to a safe level as he recommends.

Well it has been a couple years and I have been running my 12T MAC in a 29" rim with a Hookworm tire that is 750mm OD along with a 14s6P battery with 25r cells and an Infineon 12 FET (3077) controller. The controller came programmed to 40A battery and 112A phase...which is EM3ev's max recommended.

Has anybody programmed their Infineon 12 FET (3077 FETs) to more than 40A/112A...and had it survive without any problems ?

I am considering programming to something like 50A/140A but I don't have enough experience to know if that is too much for the controller to handle.

Thank You for any insight.

I have an 12 fet 3077 controller from em3ev that I've programmed to at least 60A batt and 120 phase (might have had it up to around 140-160). From what I remember (using a different controller now) it worked flawlessly on a 5T 205mm 35mm leafmotor (26"
rim) hub with minimal heat. Programming it beyond its rating would probably void any warranty etc... from em3ev. Your performance may vary, just keep an eye on the heat. You may want to replace the phase cable connectors with something like an XT150. My Anderson 45PPs melted a bit.

In case your weren't aware, you are supposed to using current levels of something like 50% of the desired current with these controllers. It is outlined in a document from em3ev.

pwd said:

I have an 12 fet 3077 controller from em3ev that I've programmed to at least 60A batt and 120 phase (might have had it up to around 140-160). From what I remember (using a different controller now) it worked flawlessly on a 5T 205mm 35mm leafmotor (26"
rim) hub with minimal heat. Programming it beyond its rating would probably void any warranty etc... from em3ev. Your performance may vary, just keep an eye on the heat. You may want to replace the phase cable connectors with something like an XT150. My Anderson 45PPs melted a bit.

In case your weren't aware, you are supposed to using current levels of something like 50% of the desired current with these controllers. It is outlined in a document from em3ev.

Click to expand...

Thanks PWD....great to know somebody has been there before me . For anybody programming their infineon controller, the number in the program is one half of the actual number that the controller provides at peak output. EM3ev pointed that out when I was questioning programming my 18 FET 4110 controller.

I plan to actually punch in "25" and "70" in the program which will provide "50" and "140" during operation.

Interestingly, the 3077 FETs are rated for 120A each on the spec sheet provided by the manufacturer...but at some point the traces on the printed circuit board and "other" components in the controller may exceed their limits before the FETs do. Another potential problem is the phase wiring...both coming out of the controller and going into the motor...I think mine are both 4mm copper stranded so they should be OK for intermittent use at 50A battery current. My battery to controller uses a XT90 so I should be OK there.

Thanks again :wink: .

Keep in mind that in these cheap common controller designs (whcih go all the way up to Sabvoton, Kelly, MQCON, and beyond), the powerstage doesn't do current sharing very well between FETs. So the higher you go, the more likely there is to be a difference between one fet and the next in the same phase, great enough to bring that FET past it's abilty to handle it, and POW, then all the current flows thru the other FET(s) in that leg of the phase, and POW (POW POW) etc.



So pushing things harder than the max a trusted vendor recommends is probably bad for reliability.

(pushing things even that hard may affect reliability--any form of "hotrodding" almost always decreases reliability, though you can get lucky for a long time...right up until you don't. ).