I am working on a "best practices" document for users of the Hymotion battery. I get mine on Monday and I have heard that many people are asking questions about what they should be doing. My own electric experience is from riding my Vectrix electric maxi-scooter the past 3 months. So some of these items are based on that. If you have any suggestions to add to this list, please share them and why you think it is important. Here is the start: 1) Use an extension cord with a minimum of 13 gauge. 2) If possible at home, use an extension cord no more than 12 feet long. Try to keep the extension cord from coiling in a loop between your vehicle and the electric outlet in the wall. 3) Consider using an energy meter in your outlet in order to verify how much electricity has entered into your battery. 4) For optimum grid efficiency, consider using a programmable timer on your electric outlet and schedule your recharging between midnight and 6 am. 5) Install the Prius Engine Block Heater (EBH) in order to pre-heat your system each morning. This enables the Prius gasoline engine to avoid the warm-up running time to heat the system. 6) Install the ScanGuage II Trip Computer in order to monitor your performance when achieving greater than 99.9 MPG.
I just got the Hymotion battery owners manual. There are many items in there that are obvious. Example: Don't spill liquids on your battery. Here are a few that are interesting. 1) Do not shut off the L5 PCM while driving, except in an emergency. Shutting off the L5 PCM while driving can clear your vehicle's settings, such as cruise control, and could result in serious injury or death. That seems extreme to say that it could result in death, but those final words are included in many of the warnings on the Hymotion manual. These are not the exact words, I am writing a short version 2) Use only a contractor-grade extension cord rated for 15 amps or more
Just an FYI, I was told by Scott at Burt Toyota that a 14 gage-25' or a 12 gage-50' would work fine. I actually bought both sizes in 12 gage with the lighted end so I know I have power at the receptacle. The 25 footer staying in the garage for nightly charging and the 50 footer stays in the trunk (using it at work currently). I've had no problems with partial charges as detailed in other posts (so far), and I bought both at Home Depot. ~SVP
I think many different extension cords will work fine. The difference is really just limited to the efficiency of the charging process. If you feel one end of the plug getting warm, then electricity is not being transferred as efficiently as it could be. The rule of thumb is to use the highest gauge cord possible and keep the length as short as possible. Based on my energy meter, the Hymotion never pulled more than 10 amps and 1,100 watts. So I think a 12 gauge extension cord would be fine. I am just posting that the owners manual recommends 15 gauge.
I would like to clarify something for those of us not familiar with wire sizes. In the US the wire sizes are backwards of what most people would think. A wire size of 16 gauge is actually smaller than a wire of 14 gauge. So if the manual recommends 15 gauge, then 14 or 12 is actually even better. These would be heavier wire and handle the load more easily.
