# New to electric motors and the former and need advice



## Shades251 (Sep 9, 2015)

Ok just a little history on me. I am a diesel mechanic by trade, and have just start working on forklifts, and been introduced into electric lift systems. Well this has led me into wanting to build something electric. 

OK so now the information I'm looking for is what are the average torque output specs on an eclectic lift truck? And RPM for said motor?

What I need is high torque. I can regear to get my needed RPM, I just have to know what to gear up to. I also need to be running no more than 36v to keep battery weight down. 

Any info is greatly appreciated.


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## major (Apr 4, 2008)

Shades251 said:


> Ok just a little history on me. I am a diesel mechanic by trade, and have just start working on forklifts, and been introduced into electric lift systems. Well this has led me into wanting to build something electric.
> 
> OK so now the information I'm looking for is what are the average torque output specs on an eclectic lift truck? And RPM for said motor?
> 
> What I need is high torque. I can regear to get my needed RPM, I just have to know what to gear up to. I also need to be running no more than 36v to keep battery weight down.


Hi Shades,

A couple things:

Gearing doesn't change power. So if you gear to increase RPM, you decrease torque. Always holds: Horsepower = Torque * RPM / 5252 where the torque units are pound-feet.

Battery weight is not strictly dependent on voltage (just to a small degree). Battery mass or battery volume depends on the energy and type (chemistry) of the battery. So for a Lithium Iron battery, you can find an energy density specification in kiloWatt-hours/pound (kWh/lb). That number along with the energy needed for your mission will determine the battery weight. How the cells of the battery are sized and configured will determine the voltage.

major


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## Shades251 (Sep 9, 2015)

Thanks major.

As far as batteries I was just going to use 12v deep cycle batteries. I have seen this setup in forklifts and it is me t to last up to 8 hours. 

As for the motor depending on application I need to be somewhere between 35 and 100 footpounds, at 3000 to 6000 RMP. 

Now for the first build I need to be between 40 and 60 flbs and 3000 rmpand I'm trying to see if this is possible. And where or what I could find an old motor in.


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## Shades251 (Sep 9, 2015)

Ok so I thought I was onto something bout I finally Google enough and found them.

I am trying to make an electric boat motor. 

Gas is insane. And I do alot of hunting. So if I can make it work (which I have now found others who have) I could have pretty much the same speed boat but no gas cost and way way way quieter.


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## puddleglum (Oct 22, 2008)

I suggest you spend some time reading the forklift motor thread at the top of this section. There is a lot of good info in there but there is a lot to go through. Welcome to the forum. I'm sure if you are willing to wait you will find something that you can use come through your shop. I've found a few now. Keep in mind, everything on a forklift is heavy and lead is heavy. I don't know how big your boat is, but I'm guessing you'll be weight limited. I haven't seen many elecric forklifts with 12 volts that will go 8 hours on a charge either. forklift manufactures don't seem to publish many specs but I think you can come close if you compare similar sized motors for sale for EV use.


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## Duncan (Dec 8, 2008)

Hi Shades
40 ftlbs x 3000rpm = 23Hp = about 17Kw - that is quite a lot for continuous output,

My forklift motor is 11inches diameter, weighs 102Kg and is rated at 10Kw continous

Also 17Kw for 8 hours is 136 Kilowatt hours - that is about $60,000 worth of batteries

100ftlbs at 6000rpm is 114Hp - 85Kw
For 8 hours that is 685Kwhrs - a small fortune!

How much power do you actually need?
You are NOT going to be able to have a "planing boat" with 8 hours endurance using electric
But a displacement boat going at less than hull speed is possible


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## Shades251 (Sep 9, 2015)

puddleglum said:


> I suggest you spend some time reading the forklift motor thread at the top of this section. There is a lot of good info in there but there is a lot to go through. Welcome to the forum. I'm sure if you are willing to wait you will find something that you can use come through your shop. I've found a few now. Keep in mind, everything on a forklift is heavy and lead is heavy. I don't know how big your boat is, but I'm guessing you'll be weight limited. I haven't seen many elecric forklifts with 12 volts that will go 8 hours on a charge either. forklift manufactures don't seem to publish many specs but I think you can come close if you compare similar sized motors for sale for EV use.


I was thinking more along 36v. Most electric pallet jacks are 36 or 48v are are ment to run 8 hours on one charge. I don't need constant 8 hours but I need more than 20 minutes.


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## puddleglum (Oct 22, 2008)

In 10+ years as a forklift tech I have never seen a power jack that is more than 24 volts. Are you in Europe someplace? I know they tend to run higher voltages there. Anyway, there are jacks that may run for 8 hours, but the small jacks with 2-12's wouldn't likely run steady near that long. More importantly, power jack motors aren't designed for anywhere near the power output or the speed you are saying you want. Duncan is absolutely right, what you say you want is absolutly unrealistic to get from a power jack motor and 3 deep cycle batteries, Sorry to say. Here is a link to a Impulse 9 which is similar to a motor you might find in a counterbalance truck or maybe a large stand up reach truck. http://www.go-ev.com/images/003_09_ImPulse_9_SpreadSheet.jpg You can see that it will produce around 50 lb/ft at 3000 but it's at 72 volts and 360 amps.
Have you done all your power calculations, do you really need all that power continously? how long do you really need it for? I'm not trying to discourage you, maybe you don't actually need what you first said and you can accomplish what you want to do with less power.


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## Shades251 (Sep 9, 2015)

Ok then. I need to be able to plane out and drive down the water 20 maybe 30 minutes. And get back to the boat ramp. And have the battery capacity to double the if something came up. I'd like to be able to run 20 maybe 25 mph.


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## Yabert (Feb 7, 2010)

Shades251 said:


> Gas is insane. And I do alot of hunting. So if I can make it work (which I have now found others who have) I could have pretty much the same speed boat but no gas cost and way way way quieter.


What you want is feasible and with relatively cheap parts (used forklift parts).
And the fact you are freshly introduce to electric drive system isn't a problem. Many people here can help you to design a simple system.

I suggest you to start by sharing more details about the boat you desire to be electric (model, weight, ...).
Don't hesitate to share picture.


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## Shades251 (Sep 9, 2015)

I do not know how to post pics the boat is a 1976 tennessee volunteer. I do not know a weight. Factory the boat had a 35hp gas engine, remote steer. It is 14 feet trihull. By the time I got the boat it was bare hull. I have a 2 stroke 9.5hp. The engine is way under power for the boat. I use the boat to do a lot of hunting. So I thought it would be awsome to run electric, since gas is so high. And electric motors are so quiet. I have seen a couple of these conversations online.


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## puddleglum (Oct 22, 2008)

I'm afraid I know very little about boats and calculating required power. Try looking through here. http://www.evalbum.com/type/BOAT/ Seeing what others have done should give you a rough idea of what kind of performance you can expect with the type of conversion you want to do and/or how to size your components to get where you want to be. Good luck with it.


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## Shades251 (Sep 9, 2015)

Ok guy so I think I am going to try to use an ac set up first. Just because I have almost all the parts that I need.

So the parts are off of an ewp pallet jack.
I have a controller, bdi, and tensiometer. 
I will have a motor, contacter and key switch next week.

I do not remember all the part numbers, but the controller uses a zapi hand set. 

The problem I am having right this second is, with the controller the motor has all the low end torq I could need but does not have the top end rpms I need. I do not know how fast it is turning but I don't think it is turning at 45-6000 rpms I need. So is there a way to reprogram the controller to speed the motor at at full power?

And just to clear up a past comments the pallet jack that is dc with 4 12 volt batteries is a clark. And I will get the model number later on.


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## puddleglum (Oct 22, 2008)

All EWP Clark pallet jacks are 24 volt and I think they are sep-ex. The ewp45 usually had 4 6 volts in series but someone may have done a 2S 2P arrangement, the ewp30 had 2 12's IIRC. How are you testing it and at what voltage?


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## Shades251 (Sep 9, 2015)

Haven't tested it for my use as a boat motor yet. And we will be running 24v. I just was wondering if you could reprogram the controller to have a higher ac out put. So the motor will turn faster


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## Duncan (Dec 8, 2008)

Shades
Why do you want the motor to turn faster?

You are going to be power limited - so you will need the most efficient way of applying that power to your boat
That basically means driving a big prop slowly


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## puddleglum (Oct 22, 2008)

You are going to be voltage limited at 24 volts. the controller progarmming isn't the problem the motor never needs to run that fast in a power jack and the the system isn't designed for that speed. I'm sure it can't be done without raising the voltage and changing the controller. Keep in mind that system is only is only going to produce about 1.3 hp continous and maybe 6 hp peak. What Duncan suggested might work or you could try speeding it up through gearing. If you gear it up you will reduce your torque though.


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## Shades251 (Sep 9, 2015)

A 30 hp gas engine turns 6000 rpm with a 1.92 to 1 which means the prop is turn close to 3000 rpm.


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## puddleglum (Oct 22, 2008)

Had a look at the service manual for the EWP45 and something isn't adding up. It is showing a Curtis sep-ex controller. Can you please confirm what Jack these parts came off of and I may be able to find you some specs.. You may be able to get the motor to turn 3000 rpms (not sure), but I still think it will be low on power.


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