Grinfineon 20A current limit?

[titusmc]

I have a Grinfineon C3620-NC controller (24-48V 20A) that I am using with a CA3. Does anyone know if I can set the current limit to, say, 21A using the CA3 and have it actually draw 21A? Or does the controller itself have a hard limit of 20A? If it is possible, is it relatively safe? I'm guessing there is a fairly generous safety margin built-in. Of course, if it's a hardware limit that the CA3 setting won't affect then it doesn't really matter.

Thoughts?

 

[motomech]

Well, are you going to tell us what Current Value you are seeing?
I had that very same controller W/ a CA 2.3 some years ago and W/ the Current limit on the CA off and the correct external shunt value entered into the CA, I would see peaks into the low 20's Amp range(21A to 23A). They are very peppy controllers.
What are you trying to accomplish? I'm assuming you have reviewed the CA Manual, great reading.

EDIT; Looking back over your older posts, but not reading them, I see you are building packs w/ used lap top cells?
I suspect your Current limit is with the packs or the BMS.

 

[titusmc]

Yes, I have built 6 packs with used laptop cells, but I am also building packs soon with new and more capable cells (LG HE4, Sanyo NCR18650BF). Basically, I bought the controller when I was using only the recycled cells, but since I started building the more capable packs I have been curious about how far I could push the controller (I'm already building 14S packs, which is the voltage limit, so I was wondering if the current limit is flexible at all).

I will definitely just try it out (21A limit) with the cycle analyst on my commute home today, but I figured I'd just ask anyway since if it works I'm also curious what the reasonable upper limit is (25A?). I've only yet ridden with it CA-limited to 20A, so that has been what I've seen.

 

[motomech]

Oh, I see, you are not experiencing a problem now.
I have used probably every version of the Infineon 6-FET and the version you have is a bit of an "odd bird". I think Grin only offered it a couple of years before they raised the Voltage limit. I have also used the current Grin controllers, both 20A and 25A and lastly, a Lyen Mini-Monster set at 22 Amps.
All of them on a MXUS geared mini motor with a conservative rating of 350 to 400 Watts.
Lipo, so never a concern about dis-charge rates.
The limits I experienced are more mundane than you might think, that is, how the increase effects the "Feel" of the motor and how it effects the handling of the bike.
The Lyen I used for a long time and it was the best compromise. On 12S Lipo (46V), it was just starting to "hammer" on the motor and I could feel the power pulses though the plastic gears. And, at this point the motor started to get expodentialy louder and even start to whine.
With the greater mass and` lack of gears, I would think that your 1000 W DD motor could absorb this level of power easily.
But at 1000 Watt levels, I found the handling of the frt. mounted motor to start to get squirly. At times, when the traction was less than optimal, the frt. tire would break traction and start to spin. Most of the time it is fun as long as I was ready for it.
It used to be a common practice here for folks to "solder the shunt". A rather crude proceedure of adding a lite coating of solder to about 1/3 of the shunt. With the CA, you could actually monitor the increase, usually 10 to 20 % in Current with little fear of hurting anything. Just don't let any solder dribble onto the PCB.
Over time, I moved away from these little "hot rod" controllers to controllers that are smoother and softer. I also needed PAS, as my riding is primarily assist riding and a solid LVC for the Lipo.
I sold them to my buddies who abuse the heck out of them and most them are still going, very tuff controllers. I still have the 72V/25A version, new in a box if you want to increase the Volts.

 

[titusmc]

I am definitely interested in the 72V/25A NIB controller! I was planning to buy one from Grin soon.

BTW - I changed the current limit on my CA to 21A on the ride home tonight and it did indeed pull 21A. I will experiment a bit and see what it can actually take.

What is the weakest link in the controller as far as taking more current is concerned? I thought it was the FETs, but a glance at the spec sheet makes me think they can take more current than 20A distributed amongst 6 of them... Can anyone tell me if I'm flat out wrong?

 

[motomech]

I doubt that there is any difference between the 20 A 6-FET and the 25 Amp other than the shunt.

What is the weakest link in the controller as far as taking more current is concerned? I thought it was the FETs, but a glance at the spec sheet makes me think they can take more current than 20A distributed amongst 6 of them... Can anyone tell me if I'm flat out wrong?

I think you are asking the wrong question. You really can't divorce the controller form the system and I would again ask, what are you trying to accomplish?
The rough analogy is Current is "torque" and Volts is speed(I know, very simplistic).
Assuming there is enough current for the motor to reach it's no-load speed, adding more Amps has diminishing returns.
Generally, more Amps are needed as Volts go up to allow the motor to reach the higher no-load speeds.

In answer to your specific question, I would guess the Infineons would be limited to the physical size of the shunt(s) and possibly the heat sheading ability of the controller, the phase wires and their connections.
Running too high of a speed motor forces the controller to run at Max Amps and this cond. is exacerbated anytime the motor speed falls to below 1/2 of the no-load speed(Climbing hills).
I have done all these things together and melted the phase wire connectors. A good thing as these acted like fuses, before I started to melt windings.
Bottom line, the gains you are looking for will come with Volts and the Current only in the sense of what is needed maintain the higher Volts.
This is what I have found to be true with sm. geared motors and i suspect a latge DD motor may react differently. If we keep this thread alive, I'm sure someone will chime in with more real World experience with large DD motors/controllers.

 

[titusmc]

You really can't divorce the controller form the system and I would again ask, what are you trying to accomplish?

I guess my goal is to safely eek out as much more power from my current setup as possible. I am planning a 100 mile trip from upstate NY through VT to NH and I'm trying to make sure I can climb some of the harder hills without issues. I am trying to get just enough power to keep my speed up in a higher efficiency region on 8-10% grades. I'm trying to figure out how long these hills are so I can determine if my DD hub is up to the task or if I have to get something different. I know a mid drive like a BBSHD would be best, but I like my hub motor, regen, and CA3.

EDIT: I've read that the Golden Motor 1000W hub motor I have (silver concentric rings, from eBay) can take more power fairly well, so I'm debating if a controller change or upgrade would allow me to keep this hub. I just built 6 14S8P batteries from used laptop cells that I plan to use in parallel for the trip (probably the 3 strongest), so I was hoping I could just up my current a bit instead of going to 72V and starting from scratch in a number areas (longer term, I'll probably do that).

 

[motomech]

The simple test would be to load some cargo on the bike, take it to the steepest hill in your area and go up and down feeling for what gets hot as you turn around at the bottom of the hill.
A crude rule of thumb is;
Too many Volts-motor gets hot.
Too many Amps-controller gets hot.

Controller placement can have an effect.
For both the motor and controller, if you can't leave your hand on it, it's getting too hot.

In general, big DD motors are more efficient running higher voltages(if the motor speed is well matched).
Search wesenwell's posts, he runs 72V/40A on those motors.

 

[Pwnlord187]

Interesting thread. After reading this I've added a light coat of solder to my grin 25a shunt. My question is, how would I determine my new shunt value to configure my CA with for accurate readings?
Thanks