Electrical wiring

Battery Charging
(81K pdf file)

There are 3 circuit loops:

1. Motor loop.  Begins at the + battery terminal, continues through the Main power switch then the Ammeter, circuit breaker and back to the battery.  This must be heavy gauge #6 wire, available at Home Depot etc.
2. Volt meter loop.  The circuit breaker is included in this loop so that the volt meter is disconnected when the mower is off or the meter would drain the battery.  I used 12 gauge stranded house wire.  Don't use solid wire as the vibrations will cause it to break which could be a real hazard!
3. Charging cord loop.  Power enters from the connector and passes through the Ammeter to the battery - to show charging current (the meter will read + positive).  The connector I used is a power receptacle like those on the back of computers where the power cord plugs in.  You could also just use the female end of an extension cord.

The big motor wires will be carrying up to 40 Amps and so must be 6 gauge, I recommend color coding the wire using red and black as appropriate (see my diagram).  Charging current will be up to 6 Amps so a 12 or 14 Gauge extension cord will work fine.  Wires to the Volt meter are also carrying charging current and so can be 12 Gauge stranded house wire (not solid wire - it will break!).  Since wire lengths can't be determined until the parts are all located, I began by mounting everything securely to the mower.  Vibration is an issue so I used lock nuts, lock washers or thread lock throughout to ensure that nothing works loose.

I obtained 8 #6 ring terminals from Home Depot when I picked up the wire.  They should be crimped firmly, soldered and then insulated.  I don't have a crimping tool that big, so I mashed it with a hammer!  Soldering with a 240 Watt gun takes several minutes to heat up the wire until the solder flows into the lug and fills it.  One could also use a small propane torch, but at the risk of badly melting the insulation. The final touch is heat shrink tubing - or wrapping it with insulating tape.  Try to cover up as much of the exposed metal of the lug as possible with insulation.

NOTE!  When using tools around a battery, be VERY CAREFUL not to drop a tool so that it falls across the battery terminals!  It will weld itself across the battery, shorting it out and will cause the battery to EXPLODE.  An exploding battery will spray acid everywhere and could kill or seriously maim you.  A good precaution is to wrap tool handles with electrical tape, and always keep at least one battery terminal covered with an insulator like a plastic cup.  Safety first!

I started with the small 12 gauge stranded wire to the meter, and worked my way up to the motor, breaker and battery.  I made the last connection the battery positive (+) terminal for safety, In case I messed up!  I left enough loose wire to allow for the movement of the handle.

Here are some views of the completed wiring. Note the extra circuit breaker on the right that I added.  I was concerned that I might accidentally bump the safety handle and start the mower, so the extra switch is a main power switch wired in series with the Amp gauge.