Hello All, first post here and I thought it would be helpful. I have a Yale/Hyster Walkie Stacker I bought used. It had low hours and the battery seemed good but I had no idea what I was getting myself into.

After lifting several loads I got Alarm AL06 that could be reset by cycling the power. Eventually I learned that it meant that the battery was too weak. I learned that industrial batteries have to be watered. I looked inside the gelled battery packs and it looks dry. Tried adding water and that worked for a while until the other day when it died lifting a load. It started smelling like rotten eggs (sulfur) and I saw that one of the cells was brown and burnt on the inside. Called a tech and he told me he could replace the cell for $400 but it likely wouldn't work. Recommended replacement with a reconditioned pack for around $3000. Yikes.

I read the battery specs and realized that the walkie stacker just needed a 24v DC source. I thought I could wire two 12V deep cycle marine batteries in series to get 24v. This means wiring the positive end of one battery to the negative end of another and then to use the existing unused terminals as the "bigger battery."

Disclaimer: This information is just for educational purposes and is not meant to be repair advice. I am not a forklift tech. If you choose to do the following it will be at your own risk.

Went to Costco and got the two largest marine deep cycle batteries - the group 27DC which has a capacity of 88 amp hours. After taxes and fees they were about $115 each. Then I went to the auto parts store to pick up 2 gauge battery cable to wire from the positive end of one battery to the negative terminal of the other for $15.

Got back to the walkie stacker, took off the cover and tossed it aside. This allowed me to set the batteries on top and not have it slide around too much. I managed to take the existing 1/0 awg power cables off of the existing dead battery. I then set both batteries on top of the dead battery and wired up everything. Turned the key and the battery gauge was at full bars. After using it for a bit I felt like I got a brand new machine. That thing felt so much more powerful.

After load testing it I had to figure out how to charge it. I could connect a regular car battery charger to each battery individually and charge them that way but it was inconvenient. I took a look at the existing onboard Colt Charger and found documentation that it could be set via dip switches to charge lead acid batteries. The charge rate can be set via dip switches as well. I took it apart and found that it was already set to charge lead acid batteries - that was probably why the original gel battery died.

Anyways, this is perfect for our needs. We only use the thing for 15 minutes at a time. The original battery has a capacity of 255 amp hours. The new batteries have 88 amp hours each but since they are wired in series it's still effectively 88 amp hours at 24V. The original battery is good for probably 6 hours out of an 8 hour shift so the new battery will probably last 1/3 of that or 2 hours.