DIY Electric Car Forums banner

2521 - 2540 of 2569 Posts

·
Registered
Joined
·
7,791 Posts
The pump motor rating is S3, 15% on-time. Drive motors are S1 (IIRC) rated, one-hour. It is not uncommon for a short duty cycle rating to be twice the one-hour rating on the same motor.
Also, the drive motor is likely rated at lower RPM making it a better candidate for increasing power by raising voltage.
Regards,
major
 

·
Registered
Joined
·
57 Posts
Thanks Major!!! With it being a 4kw drive motor, what kw or voltage could a person push them? I'm going to see the guy Thursday and he said he would give me a good deal.Anything I should look out for besides commutator wear, brushes etc. Should I rather just take as many pics of everything and post here and then based on what you say go from there? Remember is most likely going to be in a Leyland or bullnose mini. Perhaps something else but will be less than 2000lbs. The smaller the car the more I save on weight which equals less batteries which at the end of the day is the biggest cost.
 

·
Administrator
Joined
·
6,238 Posts
Thanks Major!!! With it being a 4kw drive motor, what kw or voltage could a person push them?
I have a 10 Kw Hitachi motor - 48 volt and 200 amps
And I'm feeding it 1200 amps and 340 volts

But that is a wee bit extreme
If you have both of the drive motors you can afford to abuse one and keep the other as a spare

"Saving on batteries" - maybe - but for a car wind resistance is at least as important as weight and my car (with dreadful aerodynamics) eats about 20 Kw at 100 kph despite only weighing 800 kg
 

·
Registered
Joined
·
57 Posts
I have a 10 Kw Hitachi motor - 48 volt and 200 amps
And I'm feeding it 1200 amps and 340 volts

But that is a wee bit extreme
If you have both of the drive motors you can afford to abuse one and keep the other as a spare

"Saving on batteries" - maybe - but for a car wind resistance is at least as important as weight and my car (with dreadful aerodynamics) eats about 20 Kw at 100 kph despite only weighing 800 kg
Woah thats quit a bit of power! Not a bad idea on getting x2 of the 4Kw drive motors.

Major also thanks for your comments, what you say makes sense. I'll have a look at the drive motor and some other motors.

Just on a side note, look what I found on my current 8.5kw "Prestolite" motor. Your thoughts? Those RPMS look lower than my bench test. I am not sure which one is mine but the KKDF one looks exactly like mine with the same stats and the LNAQ just has a generic pic but same 8.5kw stats too.

*KKDF*
https://detail.en.china.cn/provide/p111075435.html
Specifications
8.5kw, 48V, 290A, 1450rpm, S3-15%, Series

*LNAQ*
https://detail.en.china.cn/provide/p111075535.html
Specifications
8.5kw, 48V, 238A, 1665rpm, S2-10min, Series
 

·
Registered
Joined
·
7,791 Posts
:confused:
*KKDF*
https://detail.en.china.cn/provide/p111075435.html
Specifications
8.5kw, 48V, 290A, 1450rpm, S3-15%, Series
This conflicts with the table of specs on your subsequent post which gives 1520 RPM, S2-5min, and Separately Excited.
For motor rating specs, the RPM indicated is what the machine develops at rated load. For series wound motors, the no-load RPM is theoretically infinite, realistically limited by its self loading due to friction and windage. That's the reason no-load tests are run at low voltage.
It is uncommon to see a lift pump motor with a SepEx winding, but could be part of a variable flow system. A couple of things make me suspect it might be a SepEx or custom wound. There is a third terminal, in the comm end casting. You do not connect it for your no-load test. Typically on a series wound motor, on the no-load test, when you touch the battery leads to the motor terminals, there is an inrush current. This happens very quickly. This high inrush current (sudden) causes quite a sizeable torque pulse, usually enough to roll the motor on the bench, or in this case, lift one side of the bracket. I don't see that on your test. Relatively speaking, you have a slow smooth acceleration. This might indicate that the field excitation is low.
Regards,
major
 

·
Registered
Joined
·
57 Posts
Wow mind blown Major. Yes there's a bit of conflicting info on the web, to make matters worse is it looks like this Prestolite Asia place is out of business as I cant even load thier web page. I had to use a web tool that finds old offline copies of websites from previous years and try get that table.
So would you still say this 7.2 inch motor is not suitable for a 1200 lbs car? Obviously with forced air cooling strapped to the commutator end?

I went to look at the 2 drive motors from the same forklift today and they are tiny! I took alot of pics of many things as I can for you guys but I doubt these have any use even in a motorcycle. What's your thoughts? I really wish I could find a motor for this little mini.

Thanks again to you and the other guys commenting. I read everything but sometimes need to go away and do more research to ensure I've understood what you say. Thanks for your patience. Attached are the pics of the drive motors.8cm diameter or 3 inches lol.
 

Attachments

·
Registered
Joined
·
7,791 Posts
That last photo shows a terminal in the comm end casting as well, the one with the blue insulated ring terminal still on it. So maybe it is for the bwi.
So on my previous post, the bit about lack of starting torque, if a series motor, could be due to a badly drooping battery, where the voltage falls on its face during the inrush.
That size drive motor is common for dual drive forklifts.
major
 

·
Registered
Joined
·
7,791 Posts
I give advice and opinion on motors, not applications. Too many variables. Besides other members willing to do that part. Check out the EValbum for the size vehicle and desired performance.

If the motor turns out to be SepEx or "special" wound, then I suggest not using it due to controller availability. Before disassembly, run the no-load test with a voltmeter across the motor terminals and the scale visible in the vid so the droop, or sag, can be seen during the inrush.
major
 

·
Registered
Joined
·
7,791 Posts
Not too drastic of a sag. Again, I noticed no torque jerk on the motor. Usually they jump when the cable makes contact.
I'd be happy to look at the motor guts.
major
 

·
Registered
Joined
·
57 Posts
Thanks skweeks. So find a other then. I weighed my mini today... 1200lbs it's tiny. I was really hoping this motor could propel it without overheating.
 

·
Registered
Joined
·
48 Posts
Thanks skweeks. So find a other then. I weighed my mini today... 1200lbs it's tiny. I was really hoping this motor could propel it without overheating.
Is that 1200lbs stripped? With battery weight etc I imagine your finished weight will still be below 1600lbs. This motor world probably power it to NEV standards. That is, an under 40 mph grocery getter like the Dynasty IT vehicle. Using a transmission would be a must also to provide the starting torque. Motor selection is based on preferences, design, and end goals. If your set on using this, it will put the car in motion just not as good as a bigger more torquey motor.
 

·
Registered
Joined
·
57 Posts
You right Skweeks, with this Corona issue it's a bit difficult to shop for motors at this point. That's the loaded weight, it's actually about 1300lbs or 611kg with motor and gearbox and all equipment, I need to make this skinny lady skinnier. I've attached some pics for you.
 

Attachments

·
Registered
Joined
·
14 Posts
Good night everyone
sorry I'm new to the forum and I was reading thru this thread 1/3 of the way (80 pages) to try to find info on a general guideline or a chart on forklift motors and application for cars/weight

I HAVE A SUGGESTION, and please don't get me wrong
I think this will be very helpful for future DIYers

so there are thousands of different DC motors from forklifts drive and pumps and I see people posting pictures of motors from ebay and local forklift salvage yards and asking if there are good for their X or Y application
I understand that not all used motors have their tag and the size and will only be the way to go on these

I see a lot of focus been done on the size of the motor, but I don't trust this 100%, for example;
motor X=9'' diameter 14'' long can only be 7kw
motor Y=8'' diameter 12'' long and can be 9kw

if your motor has a tag or you know what forklift it came from you can search its specs

my idea is that if the more experience members can do a chart like
cars
1,500 to 1,800 pounds - 6-7kw 5-6hp
1,900 to 2,100 pounds - 8-9kw 8-9hp
2,200 to 2,500 pounds - 11-14kw 13-15hp
.
.
.
.
maybe an excel sheet with reference to recommendations on battery volts hook ups for +RPMs, volts x ah for range/weight, etc.…….

just trying to help
 

·
Registered
Joined
·
14 Posts
Ok guys, I have reached the 250th page, and I am going to add to this previous summary that I found :)





I will add, motors with female splines are not easy to couple to your drivetrain, and the consensus among the experts is to not use them. Hence the comment above on the drive motor being prefered: it will likely have a male shaft, be variable speed, be reversable from the outside of the case (so that it can be matched to the direction your transmission turns), and be heavier duty (1 hr continuous duty cycle at its rated power - it will handle much more for shorter bursts).



Regen is hard to implement with DC motors, and probably not worth the hassle.



Also, the easiest motor type to use is going to be series wound, which can be identified by 4 large terminal posts on the outside of the case, likely marked A1/A2 F1/F2(or S1/S2). A multimeter will read nearly zero resistance across these sets, as they will have very heavy windings. Smaller electrical connectors can be brush-wear-indicators, or temperature probes, not all motors will have them.





SEP-EX or separately excited motors are more complicated, but can be used with the right controller (do your homework before going this route). They will have smaller windings for one pair of terminals - so looking at the coils on the inner sides of the case (stators), expect to see copper wires the size of pencil leads. There will be a measurable resistance on these posts, and the terminals may be smaller.


Shunt wound will have 3 sets of terminals, 2 with low resistance, and 1 that reads higher like a sep-ex. Maybe not the best choice for a complete beginner.



Advancing brushes is done by removing the commutator end of the motor and re-drilling the holes to allow for the new position. You can tell that a motor has neutral timing by checking to see that the brushes line up with the center of the stator coils.



Bring a multimeter to check the resistance of the coils, and that there is not an electrical path from the studs to the case.



Plan on doing a 12 volt test: bring a 12 volt battery, jumper cables, and a third jumper of some sort. You will need to bridge either of the A terminals to either of the S terminals, and then connect your battery to the remaining studs. Swapping one of the jumpered studs reverses the direction.


If the forklift motor is still attached, have a look at post #2478 - it will give you an idea of what you might be up against.



Also, I want to give a huge shout-out to the experts that made this thread into the diamond mine that it is (you know who you are :cool:) Hopefully I have not added too much to the overburden!
thanks great info
just posted a request for like a chart info ''rule of thumb"
but them I started reading backwards and ran into your post

one question (newbie):
why do you suggest drive motor and not the pump motor??
whats the difference
 
2521 - 2540 of 2569 Posts
Top