This is my ongoing saga of my upgrade project.
As always , not listening to good advice ( although problems encountered could be my own doings ) I brought the 36 V 20 ah lifepo4 from Powerbattery over ebay. Delivery was prompt and the hardware looked good quality. I hooked it up to my 24V controller and off I went , top speed 20-25 mph. After about a minute or so the power cut off. I could toggle the switch off/on and keep going. But the controller was running warm/hot. So I ordered a 36V 25 amp controller from electicscooter. Hook it up but motor would just go clunk and stop. TOO low voltage ( only 27 volts going to motor BUT I still get 42V going out to the 24V controller).
So I bypassed the BMS and the motor runs well.
So I hooked the charger to the controller batt charger connection and blew up the charger! I guess you have to charge the lifepo4 thru the BMS board? I might be able to repair the charger. The switching transistor , a diode and resistor got fried as far as I can tell.
So now I plan on running the motor directly off the battery. The controller has a 31V cutoff function, And charge the battery thur the BMS.
I can't return the system because I changed a connection.
My QUESTION : Will it damage the battery running the motor directly off the battery?
appreciate any input
pat
I think you will be ok bypassing the BMS on the OUT direction from Batt->controller->motor, but re-instating it for the charging
From your figures the 27v (BMS limited) is only about 20% less than u needed, so you wont be running hugely over that self imposed limit.
Just out of curiosity, how many cells in ur LIFEPO4 pack, and the motor - was it origonally a 24v? and is it brushed or brushless. In my experience the motor has more chance of damage by over volting than the battery, Even tho Im sure the purists on here will say u may loose a few of ur 1000+ recharges lol!
I don't know how many cells the pack has. It is all wrapped in duct tape. Since the warranty is voided due to connecting new fitting/connectors I tempted to look inside.
MOTOR : BD 24V brushed
ALSO, when I bypass the BMS to the motor , the battery is delivering 42 volts to the controller and the motor runs like it did on the 36V SLA pack. So I will have to keep an eye on the motor temperature as you suggest.
Now controller is in run away mode. Getting full power thur the BMS. Plug in in and off it goes without the throttle hooked up.
Must had been the controller all along. I did arc a connection during the installation. Who knows! Since I changed some of the connections , the warranty is void. Will order a new one and carry on!
Lesson learn: Don't change connectors on stuff under warranty!
Now I'm worried about the motor burning up. Just love these home projects!
Dont worry, thats right that it should 'run away' without the throttle connected!
As these throtles work in the opposite way that u might think - (thats 0 volts on the middle (poss green lead) is full speed and 5v signal is off!)
Connect the throttle to the controller then see?
But dont drive it at full power too long as it will burn your motor out!
The new battery is most likely putting out 44v, a bit much for a bd24 controller. Get a bd36 controller, or a 48v controller from ecrazyman on ebay. You might burn out the motor running straight juice, since there will be not much amp limit, though the bms should stop it at around 60 amps. The motor can take the volts, but not in really hot weather. A bd motor will go up in smoke if run hard in over 100F weather. If you want more reliability, brushless is much better.
Many of the batteries on ebay are junk, the ones from pingbattery.com can be trusted. Chargers fry a lot, on bike kits, and ebay batteries. My theory on that is some are kinda delicately made, and can't handle the shipping bumps. I have had three of em develop loose wires, or parts moving enough to short.
Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global
Hey, I only getting ~ 25v out of the new 36V controller. There is ~40V going into the controller. It is a CT-611B9 from electricscooterparts. I think the throttle is a hall effect one. It's from the 24V bd kit from wilderness and it has magnets inside. Also I hooked up a throttle from a 24V scooter .The output is the same.
Any ideas ?
I wonder if the current is being limited- which gives a corresponding drop in voltage.
Do you still have the battery BMS in the circuit or did you take it out?
The controller is running directly off the batt. Also the ~26V measurement is with the motor disconnected. ( no load condition).
Doesnt sound right at all?
Try disconnecting the throttle how many volts do you get then. If your system is same as mine an unplugged throttle acts as full throttle?
With this controller 0 volts = no juice to the motor, 4.7V = full power. With throttle unhooked = 0 volts to motor.
Oh, well, the bike is running well with 20-25 mph pedaling easily.I've been running it 15-18 miles without decrease in power. So that's fine for now.
Thanks to all for all the input and information.
Next on the list is switching the system over to the newly acquired( garage sale brought ) full suspension bike. Man! the ride is so smooth. Should be quite an improvement carrying the 20# batt
thanks you again
Pat
Finshed the switch over to the full suspension bike. It sure rides a lot smoother. The only lingering problem is that only ~26 volts going out to the motor. I hooked up a SLA pack directly to the controller and still the same voltage. Also at full throttle the motor hums, back off a little and it runs smoothly. I didn't have this with the 24V contoller running at 36V. But I can still cruise at 20-25 mph , just a little sluggish off the line.
Thanks for sharing all the info. I'm finding it very helpful, as I have (I think I have...) a BD24 and want to put more volts through it.
Right now I'm running two 12v SLA batteries through a car horn button - no controller, as I think the one that came with it was fried.
Haven't ridden it much since I picked it up. (See the old thread "ZapGuy's electric bike") I would ride it more if it was a bit faster!
Was thinking about getting a 48v ping battery, but wonder what will melt first it if I ran one like this: the battery, the motor, or that poor horn button.
yup, you will need a new controller. If the horn button works at all, it will likely be welded shut and you better be able to reach the battery wires to yank em out. But possibly the damage you are doing to the battery will get you a bms cutoff that saves your butt.
Get either a new brushed controller and throttle from somebody who sells the kits and has parts, or a brushed motor controller and throttle from a scooter parts supplier or an ebay seller. The WE controller is 35 amp, so don't buy a 10 amp scooter controller if you want to have some power. The WE is known to usually run at 48v fine. The WE controller will plug into the throttle with no wiring to figure out, and come with the right length of wire, so it may be a bargain compared to having to make a wiring harness and get connectors etc.
Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global
My 24BD Controller ran hot on the 36V Lifepo4 batt . Using a 3 pack SLA (36V) the bike performed well usng the 24V contoller that came with the kit. A magnet came loose also using a 36V controller brought on E-bay, That controller always put out max voltage( in this case ~ 42V and the motor ran really hot. I guess the speed was controlled by amp output?