Electric Drive Motor Retrofit

[ptsg]

Yes, forklift batteries are definitely heavy! My electric forklift that can lift 3300 lbs has a 1700 lbs 24V battery. I've restored it in the past but I can't remember the HP of the motors. The one for the drive is a 3 speed big one.

The batteries are way too expensive to replace. The forklift doesn't really worth that much. Once the batteries die, I might just convert it to diesel. It doesn't get the use it used to get a couple years a ago.

 

[MossRoad]

If you can get your hands on a Baldor motor book, you will see that the torque increased as more load is applied. The torque can increase to 2 to 3 time痴 more than running torque. Baldor shows what they call "break-down torque". The torque can increase to 3 times or more than running torque. A motor produces it maximum torque at stall speed, and this is called "locked rotor torque". The motor torque does not fall off as the load increases. This is very simple. Gas engines only produce power every other revolution of the crankshaft. Electric motors produce power every single revolution. That is why a 10 hp electric is same as the 20 hp gas this being said, a 20 HP electric motor will need some VERY high capacity batteries, and be VERY expensive to buy, then there's the recurring replacement cost.. think LARGE rechargeable lithium batteries!..

By that logic, a 2 cylinder 2 stroke gas engine rated at 20 HP should need a 40HP electric motor to replace it, because it produces power every 180 degrees. It just doesn't work that way.

 

[MossRoad]

Agreed. To have any chance of working you need to throw away the hydraulic drive motors and use electric wheel motors. I don稚 think this is a feasible project the way it is. I really doubt the wind and rolling resistance of electric car is as high as load on a powertrac and they have way bigger batteries than will be possible for this project. The electric forklifts use massive batteries. I had to take my backhoe to go unload a forklift battery and it weighed 50 percent more than the whole PT does. And probably doesn稚 use as much energy. The electric forklifts only drive around on on flat ground which with a deep gear ratio doesn稚 take much power and lift the mast. Depending on the load that could take quite a bit of power but it痴 only momentary.

I agree that electric forklift batteries are very heavy. I helped maintain electric clamp trucks at a newspaper for about 30 years. Ours were rated at 10,000# lift. We used them to stack 2000+ pound rolls of newsprint in our warehouses, and unload rail cars. The batteries were not that large, maybe 3' x 2' x 2'. The area under the hood of a PT425 is about 2.5' x 2.5' x 18", the gas engine, battery and fuel tank taking up the most room. The PT425 only weighs about 1500#. I do not know the weight of our forklifts, or the weight of our battery packs. I suspect that batteries needed to power a motor large enough to supply adequate power to the PT4255's hydraulics for any amount of time might weigh quite a bit, but nowhere near as much in our 10,000# forklifts.

I think determining the size of the electric motor needed would be the first step. Then determining how long of a run-time at load is desired. Then determining how big a battery pack would be next. After that, you could determine the weight of the batteries, then decide if the PT wheel motors could handle that much weight squatting on them, and if the center link in the articulation could handle that weight as well.

 

[MossRoad]

Yes, forklift batteries are definitely heavy! My electric forklift that can lift 3300 lbs has a 1700 lbs 24V battery. I've restored it in the past but I can't remember the HP of the motors. The one for the drive is a 3 speed big one.

The batteries are way too expensive to replace. The forklift doesn't really worth that much. Once the batteries die, I might just convert it to diesel. It doesn't get the use it used to get a couple years a ago.

View attachment 592293

I agree that batteries, purchased new, would be ridiculously expensive. I can remember 3 of our electric clamp trucks that had batteries die on them, and they sat in the basement and/or warehouse for decades before they were scrapped, because the replacement batteries cost about as much as leasing a propane powered clamp truck for several years.

 

[4570Man]

I agree that electric forklift batteries are very heavy. I helped maintain electric clamp trucks at a newspaper for about 30 years. Ours were rated at 10,000# lift. We used them to stack 2000+ pound rolls of newsprint in our warehouses, and unload rail cars. The batteries were not that large, maybe 3' x 2' x 2'. The area under the hood of a PT425 is about 2.5' x 2.5' x 18", the gas engine, battery and fuel tank taking up the most room. The PT425 only weighs about 1500#. I do not know the weight of our forklifts, or the weight of our battery packs. I suspect that batteries needed to power a motor large enough to supply adequate power to the PT4255's hydraulics for any amount of time might weigh quite a bit, but nowhere near as much in our 10,000# forklifts.

I think determining the size of the electric motor needed would be the first step. Then determining how long of a run-time at load is desired. Then determining how big a battery pack would be next. After that, you could determine the weight of the batteries, then decide if the PT wheel motors could handle that much weight squatting on them, and if the center link in the articulation could handle that weight as well.

The battery I had to move was out of a 3600 pound capacity lift and it was about 18” thick and 3’ tall and 4’ wide and weighed 2200 pounds. This battery was lead acid. A lithium battery would be better but I still doubt it would be anything close to enough. I imagine the gas motor and fuel tank and battery isn’t over 300 pounds. The electric motor would make most of that back up. How much weight do you think you could add without adverse affects? But not to worry. Just add a solar panel to the hood and then add a canopy with another solar panel on top. If that’s not enough you could put a wind mill on the top. I’ve heard people claim both of the above for electric cars. Heck, those solutions are way too complicated. Just put generators on the blade spindles.

 

[4570Man]

By that logic, a 2 cylinder 2 stroke gas engine rated at 20 HP should need a 40HP electric motor to replace it, because it produces power every 180 degrees. It just doesn't work that way.

Agreed. That’s a foolish way of rating motors that doesn’t even work. A 3600 rpm 20 hp gas motor would in theory be equal to a 3600 rpm 20 hp electric motor. The 20 hp gas motor can’t make much more than 20 hp before it stalls and the electric motor can probably produce double that much for a brief period but it couldn’t do it very long.

 

[MossRoad]

The battery I had to move was out of a 3600 pound capacity lift and it was about 18 thick and 3 tall and 4 wide and weighed 2200 pounds. This battery was lead acid. A lithium battery would be better but I still doubt it would be anything close to enough. I imagine the gas motor and fuel tank and battery isn稚 over 300 pounds. The electric motor would make most of that back up. How much weight do you think you could add without adverse affects? But not to worry. Just add a solar panel to the hood and then add a canopy with another solar panel on top. If that痴 not enough you could put a wind mill on the top. I致e heard people claim both of the above for electric cars. Heck, those solutions are way too complicated. Just put generators on the blade spindles.

Perpetual motion! :laughing:

I have no idea how much weight the PT425 chassis can handle. I know several people have or condsidered either flipping the wheels inside out to gain width for hillside stability, or adding duals to that model and found that the factory doesn't recommend it because the wheel motors aren't made to withstand that type of side load, and will develop seal leaks and quickly wear the shafts, seals and bearings. So that's one thing... will the wheel motors be able to handle the additional weight of adequate batteries.

Lead acid batteries are what we used in our clamp trucks, bulldogs, and pallet jacks. Does anyone know the cost difference between those and lithium ion? I see there are Prius battery packs out there for a little over $1000. That includes shipping, but you have to add $750 for a core deposit. No core? That means $1750 for a Prius battery pack. And I have no idea of the dimensions of that battery pack.

Toyota Prius Gen 2 Hybrid Battery Replacement | Greentec Auto

 

[SpringHollow]

The rule of thumb though is that you need twice the size gas motor as an electric motor. And that held true when I converted my log splitter to be able to use electric or gas.

Ken

 

[radios1]

By that logic, a 2 cylinder 2 stroke gas engine rated at 20 HP should need a 40HP electric motor to replace it, because it produces power every 180 degrees. It just doesn't work that way.

no, By that logic, a 2 cylinder 2 stroke gas engine rated at 20 HP should need a 10HP electric motor to replace it!..

 

[MossRoad]

no, By that logic, a 2 cylinder 2 stroke gas engine rated at 20 HP should need a 10HP electric motor to replace it!..

In all reality, a 20hp engine and a 20hp electric motor both make 20hp. Horsepower is horsepower is horsepower.