48V in a 36v system

[pdonahue]

I am now running the 36V controller at 48 volts (4x12V SLA).  I'm not sure how long it will last, but it is working for now.  The only change I had to make was to add a zener diode in line with the large 150 ohm resistor feeding the 15v voltage regulator (one of two TO220 ICs on the controller board).  The zener must be enough to drop the voltage at the input of the regulator to around 48v or less.  I used two 4.3v 5W zeners connected in series.  That way the voltage is still OK when running at 36v or 48v.  A single zener of 5-10 volts and a 5W power rating should be fine.

If you want to have a correct low voltage cutoff for 48V, add a 3.5k or 4k resistor into the location marked R4 on the board (it normally has a small wire instead of a resistor.

Personally, I just added the zener and left the low voltage cutoff alone.  That means that I can use the 36V battery the same as always, and when I'm running the 48V battery I just have to be careful not to over discharge it. 

If you need more info, just ask.  I'll post again in a few days to let you know if it is still working.

Pete

[Mordaz]

If you need more info, just ask.  I'll post again in a few days to let you know if it is still working.

Hey Pete, what is the max. speed you got on 48V?  And what about its climbing performance?

I'm a bit concerned about running the motor above the specs, but I use it on a 20" wheel and get only 27 kmh max, so maybe I won't be pushing it too hard.

Roberto

[pdonahue]

Last post for the night...  I was getting a max speed of  around 32kph at 36v with a 26" wheel.  With the 48v I can easily get over 40kph, and it seems the 45kph is quite common.  I'll post the average speed from my ride to work tomorrow.

[pdonahue]

I made it to work (15km) with an average speed of 41kph.  I hit 50kph going down a couple of the hills.  Climbing I usually help out on the pedals and can maintain about 35kph without much effort.  The faster speed also smooths out the ride considerably.  You can barely feel small cracks in the road. 

The controller seems to be working fine and both the motor and controller were warm to the touch by the time I arrived.  I was drawing an average of 500-600W, and peaking at 1250W (compared with 400-500W and 1000W peak with the 36V).  Hopefully the motor lasts with the additional stress.

Pete

[myelectricbike]

More than likely you will need to replace your power leads since the insulation is most likely PVC. I am doing areplacement righ tnow using 16AWG Teflon insulated silver (150^c. I would not use 14AWG since this will overstress the windings which are stranded and equivalent to a little lower than 16AWG. I'm already thinking of designing my own high power motor for offroad and track racing with a much larger axle so I can have a bigger thru hole to accept standard 8AWG house wiring (90^c).

[weiser]

Hypotheticly, say two phase wires melt & short together while riding along...  Would that not instantly turn the motor into a very strong brake?  As in: bend the fork back, spread the fork ends, flip the rider over the bars...

[myelectricbike]

... a very bumpy instant break. Three wires shorted and you may wake up wondering why you are in a hospital bed, why there is a nurse checking your pulse and there's a bandage on your head!

[Mordaz]

Another good reason for riding a recumbent instead of an upright bike.  The low CG makes it nearly impossible to be thrown above the bars.

[weiser]

BTW I'd guesstimate a motor getting 27Km/h on 36v would get 36Km/h on 48v.

[myelectricbike]

Yes, 36 km/h with the 36 volt controller, but 48 km/h using the 48 volt controller.

[al]

I bought a 48v rear wheel kit  and it states its a 48v 800w on the hub this is good right? I ordered a 48v regen controler but im not sure what phil sent hes not the easyest to get info from and I don't read chiniese, how can I tell if its 48v its silver and looks like the bog standard one not shiny black.
Al.

[myelectricbike]

If you have 48 volts stamped on the cover with the serial number then the motor is designed to accept the 48 volt controller which you should purchase to avoid problems from circuit differences.

[Mordaz]

If you have 48 volts stamped on the cover with the serial number then the motor is designed to accept the 48 volt controller which you should purchase to avoid problems from circuit differences.

SO there's a 48V hub motor to go along with the 48V controller?  Is it a HBS-48 ?

[myelectricbike]

Not currently available as part of an ebike conversion kit or separately. Why not, you ask? When SR1156 was made law any hub motor rated over 750 watts lost its status as a consumer good, whereas the controller was not effected. The motor in question is most likely from stocks sent to the US prior to passage of SR1156.

[mustangman]

 Do like the big three auto makers did and still do! Deliberately underate the horsepower of the motor!! (in this case wattage) that way the hub motor is considered a consumer good. Give the new motor a "super-duty" or "severe-duty" designation, therfore bypassing the regulations. I believe this is the game the competition is playing, how else can you explain their motors and controllers taking 72 volts and 40 amps???