Best controller for QS138 V3 70

Crankin

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Nov 23, 2020
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Doing a 2008 CRF250 conversion. Have a QS138 V3 and em 150 controller. Aiming to get higher power from the bike than EM150 will achieve and can use EM150 on a pit bike build with smaller motor for my daughter.
So the goals I'm looking for are
over 20kw at rear wheel.
light weight ideally.
easily programmable with computer(ideally Mac).
cheap.
So far looking at
EM200 or EM 260
Siaecosys (model?)
 
I was one of the first to use the votols here but these days i wouldn’t get one, the program seems too corrupt.

QS are starting to recommend Fardriver controllers, i think a 96850 at least spec wise would be a great match for this motor.
 
I just installed a QS 138 70H V3 motor and an EM-150/2 on a KX100. The project is awesome. I get about 210A at 72V with that combination. That is about 14KW, and it rips. Plus the flux weaking allows the motor to spin up in Speed 3 (Warp Mode)
I got the motor and controller from ElectroandCompany.com, and they sell it with it programed and a wiring harness for dirt bikes/pit bikes.
They have just started offering the same motor with the EM-260, and they say they get 350A out of that. I have a 2008 YZ250F with a ME1302 and a Kelly KLS72701 controller on it that I was going to just trash the Kelly controller (Kelly Controllers suck in big power applications) and go with another controller until I talked with Austin at ElectroandCompany.com. I have on order the QS 138 70H V3 and the EM-260 controller, with the programming and wiring harness from them. That should give me about 25KW.
Check out there web site. They just recently changed the menus.
 
Here are a couple of pictures of the KX100 with The QS motor. 72V 3.2KW battery with 20S8P Molicel 21700 cells. I built it from a scratch donor bike to back to the owner in 2 months. It is an easy install after you make the motor /battery mount and build the battery. The next one should go much quicker. The owner is going to tear it down and powder coat the frame , if he can ever stop riding it. He got 23 miles of mixed track and trail riding out of it.
 

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I have 2 ways of measuring mine. I have a hall sensor current loop to a visual meter. ( https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=383480311701&_sacat=0 ) I can see 210bA. My BMS is an ANT 300A Smart BMS. It was giving me a "ShortCircuitProtect" fault at 200A and at 250A. At 300A I do not get that anymore. I don't know the length of pulse it requires to trigger, but somewhere between 250 and 300bA was sensed by the ANT.
I hope to get 350A with the EM-260.
 
I have built 3 of the KX80/100 bigwheel bikes, with the QS138 170HV3 motors and 2 have the em-150SP/2 controllers and one has the EM-260SP/2 controller. A friend is building a CRF with the same motor and EM-260SP/2, and I am building a 2017 KTM 150SX with the same motor and controller.
The controllers are very reliable at the 200A range. The program from ElectroandCompany.com is very solid, and can be customized real easily with a PC. A very easy controller to program, after ElectroandCompany.com initially programmed it.
Here is a video of all 3 KX's at a race in Hollister.
https://www.youtube.com/watch?v=-_jcmP2ECl0&t=244s&ab_channel=PaulStewart
 

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I would use a fardriver 96v 450dc 850ph amp controller on a adult size mx build.Higher voltage means less current needed thus less heat.Unlike the 96530 fardriver version that feeds the only 530 phase amps in but much slower on hard hits also no regen,so on a full size mx bike you me be wanting more.Im building a 12p26s p42 cell pack using the same controller i suggested with the intention of pushing only 360dc amps or 30a per cell (bursts)Add in 850 phase amps and a pretty light weight crf450 build so this should be a weapon :thumb:
 
speedy1984 said:
I would use a fardriver 96v 450dc 850ph amp controller on a adult size mx build.Higher voltage means less current needed thus less heat.Unlike the 96530 fardriver version that feeds the only 530 phase amps in but much slower on hard hits also no regen,so on a full size mx bike you me be wanting more.Im building a 12p26s p42 cell pack using the same controller i suggested with the intention of pushing only 360dc amps or 30a per cell (bursts)Add in 850 phase amps and a pretty light weight crf450 build so this should be a weapon :thumb:

I'm unsure about which controller you're referring to regarding the "no regen" comment. Both the 530 and 850 will regen power from the motor. As far as regen through a chain/belt - please enlighten me as to your experience with this. Thanks
I second the 850 as a good fit because of the added amps and the higher voltage. There will be voltage drop so factor that into any decision and specs to better achieve your goals/targets.
 
On the QS web site the 96530 version does not Regen(Only from what i have read) Also from experience a good battery or build should only sag voltage around 5 or so volts.The more important question if bothered with regen is at what voltage will it work from?Like the old Sabvotons some have regen BUT only work from 20s voltage range, even though with 100v caps and a 96v working voltage range.Lots of small things that have an impact on a build.
 
Im about to order a qs motor aswell and some sell with far driver and others with votol.
Is there a difference between these two? Im wondering which one to get 🤗
 
I want this next conversion(Super Soco TC Max) to be able to sit on 110-120kph for an indefinite period of time(1/2hr + ideally), whats peoples suggestions if I'm using the 90h 138? Sorry not V3 related, but theres a new V3 out that I'm guessing is 90h anyway, so this should be relevant from now on.
 
j bjork said:
Ahum, I know I have seen at least 370A drawn from the battery on my 138 70h/ em150sp combo.
That is at high rpm with a lot of FW though, but at lower rpm I had at least 300bA.

I don't understand how you can draw so much current. Wouldn't the BMS restrict it? And the em-150 has a max of 200a. Is this what how phase amps are involved?
 
I still don't understand how you can draw more amps from a battery than a BMS is set for. And how are phase amps involved?
 
Tfisher309 said:
j bjork said:
Ahum, I know I have seen at least 370A drawn from the battery on my 138 70h/ em150sp combo.
That is at high rpm with a lot of FW though, but at lower rpm I had at least 300bA.

I don't understand how you can draw so much current. Wouldn't the BMS restrict it? And the em-150 has a max of 200a. Is this what how phase amps are involved?

Why should the bms restrict anything? It can only trip and cut the connection if it thinks it should. My bms should be able to handle 600A peak, and I dont even see where bms came in to the discussion :?
If you will be running 300bA you should not have a 100A bms though..
In the manual it is max 200bA, but in reality it isnt restricted.
Yes, phase amps is involved in how much battery amps you can get, but that is an advanced calculation that I dont know how to do..
 
As you can tell by my questions, I am fairly low on the learning curve, and I appreciate what you are saying.

So the controller can handle more amps than it's rated maximum. Thats interesting and explains half of my question.

My other point of confusion is with the BMS. I thought the purpose of a BMS was to protect the battery by controlling it's output? For you to pull 370a your BMS must have a high maximum rating, like 10c.

Is it important to match the max output of a BMS with the max capacity of a controller? If they can't be matched which should be higher?
 
Tfisher309 said:
I thought the purpose of a BMS was to protect the battery by controlling it's output?
It is there to protect the cells, but it cannot control the output the way you are likely thinking. It can only turn off the entire power output, completely, or leave it on, fully. It's just switch, activated or deactivated by the readings it takes from the cells (and any current monitoring it may do--not all of them actually react to overcurrent).

So if a cell rises above HVC (full charge) it turns the charge port off. If a cell drops below LVC (empty) it turns the discharge port off. If it does current monitoring, and pack current exceeds it's limit for however long it is allowed to do so (depends on the BMS), it turns off the discharge port.

The controller is what actually modulates current within the system, and limits it gracefully and variably, rather than just shutting down completely on overcurrent.


For you to pull 370a your BMS must have a high maximum rating, like 10c.
To help you find and understand specifications:

A BMS is not rated in "C"; that would be for the cells, since a C rating is a number used as a multiplier for the Capacity (Ah) to give a current (A, Amps). A 10C capable cell that has a capacity of 5Ah could output 50A (10 x 5 = 50).

A BMS may have multiple ratings, but two typical ones would be a Max A rating, usually meaning Peak for a few seconds, and a Continuous A rating, that it can handle all day long. Some of them, especially ones meant for higher currents, may require cooling airflow thru / over them in order to operate at these ratings, and may be severely limited in capability without that, even though they may not tell you this on the seller's pages. .


Is it important to match the max output of a BMS with the max capacity of a controller? If they can't be matched which should be higher?
The BMS, first and foremost, must be able to protect the cells against anything outside their limitations. Next it must be able survive the worst-case current draw from the controller without stress or damage.

So the first step is to determine the maximum battery current your system will ever draw, continuously, and peak (and for how long it will peak, since if it's very long, that's going to end up being your continuous rating). Let's say that's 400A, just to give some big numbers in later examples below.

Once you know that, then you use cells that, in the configuration (number of parallel cells in each group) can handle that current, easily, without stress, and with some extra capability (say, 20-50% to toss out some numbers, depending on the performance and lifespan you expect from the pack) so that as they age the pack still handles the full load of the system. (and if you ever expect to upgrade the motor or controller to something more powerful, make sure you account for that when choosing the pack capabilities.) (if you use cells at their max ratings, they're stressed and will have more heating and voltage sag, and shorter overall lifespan--use cells that can handle say, twice what you need of them, and they'll have much less sag, heating, and longer lifespan, under that 400A load).

For the 400A example, then you need cells that can handle 400A, at least, preferably more. Let's say you decide to use 800A rated cell groups, and use individual cells that can handle 30A each--you need 800 / 30 = 27p or 27 parallel cells in each group. If you use cells that can handle 100A each, you only need 8p, or 8 cells in parallel in each group.

(note we haven't mentioned capacity, or Ah yet, that's essentially unimportant to the current-delivery ability, though it is related to it in that cells that can supply higher current usually have less capacity). (we alos haven't mentioned pack voltage or number of series cells (groups), as that also doesn't matter for the purposes of determining current (A). )



Then you use a BMS that can easily handle that worst case current as well, so that it is not stressed and the FETs on it don't heat up too much. If you use one that has a current detection / shutoff ability, then choose a limit that is above what the controller would ever draw (so it doesn't trip the BMS and turn off your ride), but below what the cells should ever be allowed to see.



The battery is the heart of your system, so if it cannot supply, for any reason, everything your motor and controller will ever ask of it, with as little voltage sag as possible, and as little cell and BMS heating as possible, the system will not perform as well as it could, and might not perform the way you need it to.
 
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That would be fine, not really much overkill. I use the exact BMS on my motorcycle. Bluetooth range sucks, but once you have your setting figured out, you shouldn't need to change settings much.
 
QS motor tells me a much lower battery current rating for the motor than phase current. Does that make sense?
 

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Yes of course.

You need high phase currents when the motor rpm and the motor voltage is low.
You can easily have 100A battery current and 800A phase current during a start from a standstill.
5V x 1,73x 800A (phase current)= 6920W
6920W/72V =96A (battery current) ok a little more because of the efficiency;)
The higher the rpm is the higher is the voltage at the motor. If you drive at full speed the phase current is low, around 100A, but the battery current can be 200A.
 
Yes of course.

You need high phase currents when the motor rpm and the motor voltage is low.
You can easily have 100A battery current and 800A phase current during a start from a standstill.
5V x 1,73x 800A (phase current)= 6920W
6920W/72V =96A (battery current) ok a little more because of the efficiency;)
The higher the rpm is the higher is the voltage at the motor. If you drive at full speed the phase current is low, around 100A, but the battery current can be 200A.
Isn’t the heat produced the same regardless if phase or battery current?
 
Not necessarily, because phase current is AC, and incurs much less transmission loss (doesn't need as thick gauge wire).
 
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