Tested my 1800W 48V motor/Controller with 100a shunt

[wheels]

Ok... so, as I mentioned in another thread, I purchased a lithium Ion 40ah battery pack for my smallest Campground cruiser. The 22ah were not giving the run time I had hoped for given the riding conditions(took it hunting in mud, through hills, etc). Anyways, a couple of the smarter guys(literally... not joking) on here warned against the battery pack bc of the max continuous amps, ratings vs actual, etc. So, a shunt was suggested for testing.

I ordered the shunt... wired it up and fried my first controller. Lol ****. Ok... late in the 7th inning, spare controller called into the game. Wired it up, correctly this time, and off I went with testing. Calibrating the dang display was another story. Hoping I am reading it right. Open to suggestions, if I am not.

By the way, this test was done with my 22ah batteries while I was standing next to the buggy... had it raised up on jackstands. Also, i had the highest speed set out of the three possible on the controller.

On to the goods. The max amps I saw were 5.1, which I am assuming is 51amps. Makes sense bc the wattage was showing around 160-170 range(assuming this is 1600-1700). Like I said... I dont think I had the display calibrated right. Anyways. I did several different variations of throttling, trying to get more than 5.1 amps to show.

3.2, 3.3 amps was the consistent reading when holding the throttle wide open.

Most of the spikes in amperage were limited to 4.7, 4.8, 4.9... and then, like mentioned above, 5.1 showed as the highest.

Next up will be testing while I am riding it.


Motor/controller combo I purchased:

https://www.amazon.com/dp/B07KF8M5W6/ref=cm_sw_r_other_apa_i_4Z.xEbZS3GM23


Shunt:

https://www.ebay.com/itm/163914796173

Battery I purchased:

https://www.ebay.com/itm/184160333228

And I am attaching some pictures I took during testing.

Thanks.

 

[Bgt2u]

I have the same exact motor, and controller. I have noticed that the controller that is supplied with this kit is actually underrated for this motor. You will notice that the motor is rated at 37.5A, and the maximum that the controller puts out is 33A. The Boma motors are capable of tolerating alot more current than advertised. If you are looking for all around performance, l would suggest getting a controller that pushes around 50A continuous. Otherwise, you are underpowering your motor, and are not seeing it's full potential. I am saving up for the Kelly KBS48121X. It is rather pricey, however, it is rated at 55A continuous, and 130A peak (for 10 seconds). I was also going to purchase that same battery pack that you did, however, l ended up going with 4 - 48v 10.5ah packs wired in parallel. What kind of range do you get out of your pack? I am powering two 1800w motors, so whatever you get, l should be approximately half of that. I attached a couple of pics of my creation, just for fun. https://ibb.co/FH8mJJ7 https://ibb.co/FH8mJJ7

 

[PullHorse]

I'll be curious the see the peak Amps while riding. Will the controller heat up? How long does it stay above 50?

Do you guys have the peak amp rating of this no name controller? I know it says 30 on the ad but that's gotta be continuous and that should be ok? 1800watts/48v * 0.85 efficiency should be right around there?

I'm just learning all this stuff same as you and I got a 48v 1800W Boma motor coming in. I've also been eyeing the Kelly controllers but will try a cheap one first.

I saw a controller yesterday that supported 2 motors but I can't remember which company it was or if it supported brushless. I will try and find it for you bgt2u, I should of written it down. I've just been looking at so much stuff I'm basically a zombie now.

I went with 4x 12v 22ah SLA batteries for now.

 

[wheels]

Bgt, That ride is so cool.

As for the controller, it is a necessary evil, sort of. My reasoning is that I need longer run times... the lithium can do it for me bc of the size(I am very limited in space) and ah rating. The problem mentioned in your other thread is that it is limited with ratings(continuous amps, etc) so, my current controller is actually better in this case. If I were sticking with sla or gel batteries, I would definitely consider that controller or one of them.

As for run time... it is hard to say bc I havent ridden it on pavement for a full cycle(whole battery charge). I can tell ya, it only lasted about 20mins(if that) plus or minus 5 mins when I took it hunting the first time. I went thru a lot of mud though... and it was really hilly, and my gearing was way too high.

My goal is to get 1 solid hr of run time with that lithium. By calculations, I should(hopefully). maybe.

I have the same exact motor, and controller. I have noticed that the controller that is supplied with this kit is actually underrated for this motor. You will notice that the motor is rated at 37.5A, and the maximum that the controller puts out is 33A. The Boma motors are capable of tolerating alot more current than advertised. If you are looking for all around performance, l would suggest getting a controller that pushes around 50A continuous. Otherwise, you are underpowering your motor, and are not seeing it's full potential. I am saving up for the Kelly KBS48121X. It is rather pricey, however, it is rated at 55A continuous, and 130A peak (for 10 seconds). I was also going to purchase that same battery pack that you did, however, l ended up going with 4 - 48v 10.5ah packs wired in parallel. What kind of range do you get out of your pack? I am powering two 1800w motors, so whatever you get, l should be approximately half of that. I attached a couple of pics of my creation, just for fun. https://ibb.co/FH8mJJ7 https://ibb.co/FH8mJJ7

---------- Post added at 08:00 PM ---------- Previous post was at 07:47 PM ----------

Pullhorse, During my testing, I saw the spike to 50 + amps right when I turned to full throttle from a stop... and it was only for a second. Periodically, I checked the temp of the motor and controller... not hot at all. While riding, I have checked temp periodically as well and it was always cooler than I expected. After burning up the roads for a solid 15 mins or so... it has been a little warm, but not bad.

I know how ya feel with all the info about batteries, controllers, motors, etc. I started really researching months ago and I have learned a ton on this forum and others.

I'll be curious the see the peak Amps while riding. Will the controller heat up? How long does it stay above 50?

Do you guys have the peak amp rating of this no name controller? I know it says 30 on the ad but that's gotta be continuous and that should be ok? 1800watts/48v * 0.85 efficiency should be right around there?

I'm just learning all this stuff same as you and I got a 48v 1800W Boma motor coming in. I've also been eyeing the Kelly controllers but will try a cheap one first.

I saw a controller yesterday that supported 2 motors but I can't remember which company it was or if it supported brushless. I will try and find it for you bgt2u, I should of written it down. I've just been looking at so much stuff I'm basically a zombie now.

I went with 4x 12v 22ah SLA batteries for now.

 

[wheels]

Forgot to post a pic of the Micro Campground cruiser.... which is the one I am needing the lithium for bc of limited space, of course. This pic includes my 2 seater and the micro.

 

[Bgt2u]

I do not have the peak amp rating for the controller. I would assume that 'Wheels' getting a little over 50a would be a definite, yet momentary max for this controller. I am going to purchase a shunt also, to better see what actually is going on with my system. Don't get me wrong, the little 33a (32a in the literature) controller is adequate for the motor (otherwise they wouldn't sell them together). Those controllers do get my ride up to 35.2 mph...so, not too bad. I do think though, that it is adequate at best. It does the job, however, there is room for a lot of improvement. PullHorse, if you do happen upon the dual motor controller, please let me now, as l am very interested in an option like that. Even though this is not the forum for this, l posted a couple other pics of my other unique vehicle.....l am a retired, bored, Electro/Mechanical/Structural Engineer......now, l'm moving over to electric.

 

[wheels]

Haha... awesome! I have no idea what that white beast is... but it is fantastic!!

and I agree with ya regarding the controller.

 

[Bgt2u]

Lol.....that was the point on the white beast, AKA...The "MudBug". lt started out as a Suzuki X-90.

 

[itsid]

the problem is.. with the wheels up in the air..
the system is essentialyl close to a "no load" situation..
in which case
less than five amps and less than 200Watt are actually
very plausible unscaled real world values.

Since the internal resistance indeed should be very small (0.0025 - 0.0075 Ohm depending on the amperage rating of the shunt)
And since the display has a reolution of 0.1Ohm treading zero is correct

Voltage seems to be correct (51V) and external impedance might not be too far off either (10Ohm seems plausible to me)

So IDK.. but I think I'd be happier seeing that exact setup under load to get an idea of the values you are looking for

'sid

 

[wheels]

Thanks for the input Sid... i plan on testing it under load within the next couple of days. I will report back with my findings.

 

[PullHorse]

What size fuse or breaker did you guys use to protect the system with a 48v 1800W motor on the other end? I was thinking of doing a fuse breaker but I don't want it so highly rated that it doesn't never flips off. The peak Amp @ riding without burning the controller - a bit above that?

---------- Post added at 01:01 PM ---------- Previous post was at 12:59 PM ----------

Also i'm assuming you have hydraulic brakes on that thing, did you wire those in with the controller to 'stop' the motor when the pedal is pressed or does no one bother to do that and we just assume the kids let go the throttle when braking?

 

[Bgt2u]

PullHorse, l am using 4-25A fuses (one for each batpack). I just used 4 fuses because each pack came with it's own fuse holder. Otherwise, l would have used one 80-100a fuse. If your driving habbits are NOT "full throttle" all the time, than a 80a would be adequate. That is my recommendation, however it is not carved in stone. I don't think that you were asking about my hydraulic brakes, but just incase, l did not wire them up to the controller. Just like when l am on my motorcycle, l just let off of the throttle.

 

[PullHorse]

PullHorse, l am using 4-25A fuses (one for each batpack). I just used 4 fuses because each pack came with it's own fuse holder. Otherwise, l would have used one 80-100a fuse. If your driving habbits are NOT "full throttle" all the time, than a 80a would be adequate. That is my recommendation, however it is not carved in stone. I don't think that you were asking about my hydraulic brakes, but just incase, l did not wire them up to the controller. Just like when l am on my motorcycle, l just let off of the throttle.

Thanks for the reply. For the fuse 80A seems high? Wouldn't the controller blow way before that fuse is triggered? I guess we'll find out what peak A comes out at when the OP tests it.

Thanks for the info on the brakes that's kinda what I thought. Maybe I can try and rig something with a momentary switch like I've seen in another threads if I truly want the kids brake to kill the engine. I know one of them has a tendency to use both pedals at the same time.

 

[Bgt2u]

That is a legitimate question about blowing the controller. Too big of a fuse won't protect anything. Another way to go then (even though it is slightly barbaric), is to just start with a small amp fuse. Given that everything is wired up correctly, then, l would start with maybe even a 20a, then go for a couple of high acceleration test runs (to draw max amps). If the fuse blows, go up a size, and continue doing so until it doesn't blow. Then you know that you are right on the edge of max performance and max protection. I know there is a formula to figure it out, but l am unaware of what it is.

 

[PullHorse]

That is a legitimate question about blowing the controller. Too big of a fuse won't protect anything. Another way to go then (even though it is slightly barbaric), is to just start with a small amp fuse. Given that everything is wired up correctly, then, l would start with maybe even a 20a, then go for a couple of high acceleration test runs (to draw max amps). If the fuse blows, go up a size, and continue doing so until it doesn't blow. Then you know that you are right on the edge of max performance and max protection. I know there is a formula to figure it out, but l am unaware of what it is.

Ya I just went back and looked at a thread by functional artist that sort of falls in line with this. No controller was topping out at 80A I believe and he never got above 30amp with his controller. This was only a 1000W motor though.

http://www.diygokarts.com/vb/showthread.php?t=39287&page=2

I'll be very curious to see what the 1800 comes in at on peak.

 

[Bgt2u]

I ordered, and will be installing a shunt on my 1800w dual motor set up ride. So, when l get it up and going, l will post the results. You obviously would have to cut my results in half due to the dual motors......Actually, upon second thought, nevermind, my results will be different, due to my different my controllers.

 

[wheels]

Ok fellas. I tested under load... i drove up and down my street twice. Giving throttle, letting off, giving half throttle and then letting off, jerking the throttle back and forth, etc... all kinds of different ways to try to get 50amps. I couldnt get the amps to spike above 33. And it was obvious I wasnt playing with a full deck yesterday. The 3.1 turned into 31. Something today.

I wasnt testing with a full chrge today... i was reading around 50volts. Not sure that it matters, but I am charging my batteries tonight and I will test again tomorrow after work.

 

[Bgt2u]

Yes, that 33 makes sense to me...33a is what that controller is rated at (and that probably is the max rating). So, like l mentioned before, the controller that comes with the motor is underpowered for it. You will be much happier by getting a controller with at least 50a continuous, instead of your current 33a max. The motor is rated at 37.5a, (and that is not a max rating). Your current controller is leaving your motor hungry for more power. As you probably already know, increasing your controller amps will also increase your acceleration and torque. Well anyway, keep us/me posted on your progress.

 

[itsid]

not sure tbh..

a well setup gear ratio for example can keep the motor from drawing it's maximum power,
just because it doesn't need to.

And while it's certainly possible that the controller is limited
by subpar MosFets or by an internal current cutoff

chances are that's not it..
a) the shunt measuing is usually a bit of an "expensive" gear that's usually left out on cheap controllers.
and
b) the olden days PowerMosFets are usually 20A rated.. and almost alwas used in pairs
(modern day ratings exceed 60Amps per MosFet.. 80A are quite common)
[there were 16A rated MosFets.. but those were more expensive than the 20A ones IIRC...]

And if those old cheap MosFets are used.. the motor COULD draw 40Amps if he wants to,
not without boiling some pcb traces off the board I guess (seeing how improperly the MosFets are soldered at times)... but since the only limiting factor is the MosFet itself (assuming no current cut off is in place) the spike should always equal the total amount of power needed.
(even exceeding the MosFet rating at worst)

And with that.... it might be a current regulation yes... might be 32Amps indeed
with a bit of a spike perhaps alright, but seeing the internals from some controllers lately..
I somehow doubt a proper current regulator internally..
what are the chances the chinese spend more than the absolute minimum necessary on a cheap controller?

I wouldn't want to ask to crack it open and look inside just for curiosities sake.
But if I ever come across a dead one myself I'll certainly try to get soem more insights

'sid

 

[wheels]

Sid, it just so happens that I have a fried one at my disposal. i will send it to ya if ya wanna look at the internals.

Send me a pm with your addy... as long it doesnt cost me a fortune, I will send it to ya.


I am pretty confident that the lithium battery will do fine with my setup... and this specific controller motor combo.

Bgt, i hear ya about the power starving motor. I just cant go up with the controller bc run time is more important and the lithium battery wont work with a higher amp controller. Or... am I missing something? Lol quite possible...

---------- Post added at 03:34 PM ---------- Previous post was at 03:32 PM ----------

Another thing... if this controller(the one I tested) is truely limiting to 33amps... wouldnt I be ok with a 50amp fuse? In mind, it makes sense.