Electrified Yard Equipment Hauls Grass

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[AmpEater] spent the summer converting yard equipment from internal combustion to electric power. The conversions run from a relatively tame Wheel Horse, to an insane Cub Cadet. The Wheel Horse lost its Kohler engine in favor of a hydraulic pump motor from a crown forklift. 48 volt power is supplied by MK lead acid gel cells. An Alltrax 300 amp controller keeps this horse reigned in.

On his Reddit thread, [AmpEater] says he is especially proud of his Cub Cadet zero turn ride on mower. For those who aren’t up on lawn implement terminology, a “zero turn” means a mower with zero turning radius. Zero turn mowers use two large wheels and tank style steering to turn within their own radius. We bet this style mower would also make a pretty good robot conversion, however [AmpEater’s] zero turn is still setup for cutting the grass.

After pulling the V-twin motor the 48 volt Motenergy ME-1004 was put in place. Batteries are 3 x Enerdel 48V 33 amp hour lithium ion packs. The packs are wired in series to provide 144V nominal. Right about here is where our brain started to melt. A 48V motor on 144V has to mean magic smoke, right? This is where the motor controller magic comes in.

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Upgrading Cordless Drill Batteries to Lithium

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Cordless power tool battery replacements are expensive: you can easily spend $100 for a NiCd pack. [henal] decided to skip nickle-based cells and cut out the middleman by converting his old cordless battery packs to inexpensive hobby lithium cells. These batteries appear to be Turnigy 3S 1300mAh’s from Hobbyking, which for around $10 is a great bargain. As we’ve explained before, lithium batteries offer several advantages over NiMH and NiCd cells, but such a high energy density has drawbacks that should be feared and respected, despite some dismissive commenters. Please educate yourself if you’ve never worked with lithium cells.

[henal] gutted his dead battery packs and then proceeded to prepare the lithium replacements by soldering them to the cordless pack’s power connectors. To keep charging simple, he also branched off a deans connector from power and ground. After cutting some holes in the pack for access to the balancing connector and deans connector, [helan] went the extra mile by soldering on a DIN connector to the balancing wires, which he then securely glued to the side of the case.

We’ve featured lithium power tool replacements before, and these Turnigy packs pose the same problem: they don’t appear to have any low voltage cut-off protection. Check out some of the comments for a good solution.

Makita battery pack repair

[Rob] grew tired of his Makita power tool battery packs dying so he figured out how to repair them himself. The video after the break walks us through the process which starts by cracking open the case. Inside there is a controller board and a battery of ten cells. [Rob] has pinpointed these battery failures to just the first cell, which is confirmed by measuring the cell voltages with a multimeter. The first cell in the demonstration battery reads zero volts and needs to be replaced. For some reason he’s got heck of a lot of these cells on hand, at the end of the video he shows off a massive block of them that provides one half of a kilowatt-hour of power.

To complete the resurrection he removed the control circuitry from the integrated PCB. It seems that the microcontroller on the battery’s PCB monitors it and bricks them when it thinks the life of the unit has ended. By hacking a charger he can now balance-charge the altered battery packs and get more use out of them before they hit the landfill.

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