Clark TW25B Battery help

[k_kindig11]

I recently bought a Clark TW25B 24v forklift. It has a weak battery in it and since I just use this a couple times a month at my house for 10-15min at a time, I decided I would just pull the normal 24v battery out (12-85-15 battery) And put two 8D 12v commercial batteries in series in it to create 24v. The 8D batteries are meant for combines, tractors, etc as they are 1725 amp batteries that weigh 130 pounds each. Obviously not the correct application, but in theory should work. I actually have an older 36v forklift that I use 3 of these exact batteries in and it works without issue. My dilemma is, when I hook it up to my 8D batteries in series, the lift and tilt work great, but my drive does not. It doesn’t make any sound at all. Plug it back in to the original forklift 24v battery and it works (but is really weak due to the failing battery). Why would connecting these two 12v batteries in series run the lift and tilt, but not the drive? I also went as far as using four of these batteries - two sets connected in series, then connected the sets in parallel to create 24v and double the capacity. Still same result - no drive. Any thoughts?

 

[k_kindig11]

Here is a picture of my “bench test” of the 4 connected together in series and parallel. Batteries are at full charge and new in june 2020. All the same specs. Also attached is a diagram of how they are connected to correctly create 24v and double the amperage

 

[Jonas302]

Check the connectors up on the forklift looks like the red wire coming out of the plug is on the negative terminal

 

[Delmer]

Maybe check the voltage on the forklift side of the connector while it's trying to move? maybe a loose connection somewhere? I know they have a minimum voltage for the drive motor (sometimes?). I'd think a pair of those batteries would be plenty, my experience is two half decent marine starting or deep cycle batteries will run something like that, two new starting batteries should have no problem. Double check the voltage at the controllers, or at least at the forklift side, and see what's happening.

 

[k_kindig11]

Check the connectors up on the forklift looks like the red wire coming out of the plug is on the negative terminal

I bought a 350 to 175 amp adapter online and someone made the positive side black and the negative side red. So yes by color it is incorrect, but it’s actually connected correctly.

Maybe check the voltage on the forklift side of the connector while it's trying to move? maybe a loose connection somewhere? I know they have a minimum voltage for the drive motor (sometimes?). I'd think a pair of those batteries would be plenty, my experience is two half decent marine starting or deep cycle batteries will run something like that, two new starting batteries should have no problem. Double check the voltage at the controllers, or at least at the forklift side, and see what's happening.

I will check the voltage at the lift tomorrow when I get a chance. I haven’t had a chance to take the lift apart to get to the controllers but I will see if I can figure that out as well

 

[TD24]

As an aside.. The battery is your counterweight for that truck. With it removed you have no capacity.

 

[lantraxco]

May just need one cell in your OEM battery, now it's been thirty years but way back in the stone age, the battery repair guy could pull one cell and replace it, not sure they still build them the same, with links between each cell.

 

[TD24]

May just need one cell in your OEM battery, now it's been thirty years but way back in the stone age, the battery repair guy could pull one cell and replace it, not sure they still build them the same, with links between each cell.

Agreed. Battery shops and dealers get hands on batteries that will not run a full 8 hour shift,
but will do 2 or 3 at capacity. Find an industrial battery dealer and shop. Weight and adequate run time for his operation, win, win.