Variable Regeneration Controller

My Kelly KLS7230S controllers are capable of providing variable regeneration. To alter the amount of regeneration the controllers need a 0-5 volt signal. Most twist and thumb throttles can be used to produce this variable signal. I didn’t like the idea of adding a second twist throttle or a thumb throttle to the handlebars and wanted to utilize a brake lever instead. This brake lever will be mounted on the left side handlebar of the trike and the cable from the lever will run to the thumb throttle mechanism located toward the rear of the trike. Hopefully, this will provide the “feel” of a traditional motorcycle hand brake when the regen is activated.

Unfortunately, the “throw” of the brake lever is not quite long enough for the cable to pull the thumb throttle from the zero position to the full throttle position. As a result, the controllers would not receive a signal for maximum regeneration. To remedy this situation I needed a way to “gear up” the cable so the brake lever movement can provide a longer pull.

Photo of freewheel hub — Photo 1 – An old six speed freewheel body will be used to “gear up” cable travel from the brake lever.

To do this I am using a freewheel body from an old six speed cassette stack. (Photo 1). Note that the freewheel body has two grooves (arrows), one larger than the other. By running the incoming brake lever cable around the smaller diameter groove and the outgoing thumb throttle cable around the larger groove, the pull of the brake lever can be multiplied enough to move the thumb throttle lever from its zero position to its 5 volt (maximum) position. The six speed freewheel body is threaded onto the wheel hub allowing it to freely rotate while still being held in the proper position.

Photo of freewheel hub cut away from wheel hub — Photo 2 – Most of the wheel hub is cut away leaving the threaded disk and the freewheel body.

Only the threaded “cassette” side of the wheel hub is needed, so the balance of the hub is cut off leaving the hub disk and threads as a mounting platform for the freewheel body. (Photo 2)

Photo of back side of wheel disk — Photo 3 – The back side of the hub disk.

The hub disk is ground flat on the back side. (Photo 3)

Photo of usable part of brake lever guide — Photo 4 – And old brake lever is cut apart to utilize the guide (arrow) for the incoming cable. A normal brake lever is shown on the right and the cut down guide portion on the left.

To guide the cable from the brake lever onto the groove of the free wheel, an old brake lever handle is cut apart saving the guide (arrow) and a portion of the lever which is drilled for mounting bolts. (Photo 4)

Photo of mounting holes drilled in wheel hub disk — Photo 5 – The threaded disk base for the freewheel body is drilled (arrows) for 1/4″ mounting bolts.

With the freewheel body unscrewed and removed we can see the threaded mount of the hub disk. Two 1/4″ holes are drilled in the hub disk for mounting. (arrows Photo 5)

Photo of variable regen controller — Photo 6 – The guide, freewheel body and thumb throttle being laid out on a mounting plate.

The components are laid out on 3/16 x 3″ wide flat stock. On the left is the “guide”, in the middle is the freewheel body “gear multiplier” and on the right is the thumb throttle. (Photo 6) When everything appears to be in alignment for smooth operation, the mounting points for each component are marked and the flat stock can be cut to the appropriate length and appropriate holes drilled for mounting the guide and the hub disk. The thumb throttle is mounted on a short length of handlebar tubing which is welded to the 3″ flat stock.

Photo of variable regeneration controller parts — Photo 7 – The variable regen components attached to the mounting plate.

The components attached to the base. The thumb pad of the throttle will have a small hole drilled through the center for inserting the cable. (Photo 7)

Photo of control cables wound on gear — Photo 8 – Small bridge welds are made over each groove in the freewheel body so that the cables can pass under the weld and then be held with a crimp on the end of the cable.

To secure the end of each cable in the freewheel body groove a “bridge” is welded over the top of each groove. The cable is then inserted into the groove and under the bridge. To insure the weld does not go all the way to the base of the groove, making it impossible to fit the cable under it, a large diameter copper wire is placed in the groove while the bridge is tacked in place. The copper will not bind to the weld and can be pulled out once the weld has cooled. The cable can then be threaded under the bridge, tightened and a stop crimped to the cable. (Photo 8)

Photo of ferrule and screw used as cable stop — Photo 9 – A cable ferrule and a small screw are used to create a stop for the cable.

Note that the cable from the brake lever to the freewheel body “gear” needs to be adjustable in order to get the cable tight. Instead of crimping on the stop, a cable ferrule is used and a small screw inserted into the open end of the ferrule and tightened securely. (Photo 9)

Photo of thumb throttle return spring used — Photo 10 – An additional spring will be installed to insure the thumb throttle returns to the zero position when the brake lever is disengaged.

The thumb throttle has its own spring to return it to the zero position but to insure the throttle does not hang up due to friction in the cable or gear mechanism, an additional spring (arrow) is attached to the back side of the throttle lever. (Photo 10)