I have a Schwinn stealth 1000. Runs great on Lead batteries. I recently received a Chinese 36V (gray taped) lifepo with BMS hanging off the side. I added connectors and charged it with the incleded charger, monitored charging amps with clamp. and volts while charging (Stopped at 41.5 or 43 at v times), so with the new batt after charging the red light flashed, tunred off, the green and red turned on after about 4 hours, etc. In short, who knows. On to the bike.
I put the pack into the Schwinn, and the witch on, I rolled the throttle and blip, stop. Hmmmm. I reset th power switch, got green light, throttle, roll on, blip...stop.
Put the bike up on crate, rear wheel off ground and got the wheel turning. Then put it down on ground, same thing, green light on throttle, roll on blip stop. Took batt outm tried charger, charged for a awhile, had 41.5, back in bike, same problem.
Question: Seeing as the wheel will turn fast when off the ground, what is the likely problem? Lead acid batts that came out are fully charged at 39.9. Too much volts at throttle? IS there a mod or does this whole thing with the battery swap not make sense. It cost 400+ with ship.
I thought I heard of a mod to a resistor or diode that will make control volatge from throttle less sensitive? I also hear that 48v is possible, so is that not my problem>?
Any help greatly appreciated, or I will get rid of the Lifepo for a song. GO back to SLA. Boy did I spend some time on this today!
pingbattery or a different vendor?
The problem you're likely having is the BMS shuts down the system at a too-high amp draw. It's meant to protect the battery. What current or wattage is the battery rated for?
The difference between the wheel in the air, and the wheel on the ground (with you sitting on the scooter) is the power required to make the wheel move. It doesn't take much power to spin the wheel while it's in the air.. put it on the ground with someone sitting on the scooter and it takes a lot more. Obviously enough to go past the max power the BMS will allow you to have.
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
That Stealth 1000 doesn't free wheel, does it? I was going to suggest that your try kicking the scooter up to 2-3 mph before hitting the throttle. It could be that the initial amp draw of starting from a dead stop is causing the BMS to kick out. For that motor you will probably need a 15ah LiFePO4 pack at a minimum.
Yes, thanks, it is a 15AH pack, and is probably fine except for an overly conservative BMS on the discharge side. I did try rolling forward, but this did not help. It sure runs great with the wheel off the ground and I can put my boot against it and brake it pretty hard!
I wish there was a way a dummy like me could mod the pack, and I would probably pay good money to have it done, if I knew who or where, rather than ship it back.
Again, if anyone wants it, I'll take 250 and I will pay ship/ It has a 3 amp charger. If anyone knows who can mod the pack to work with teh schwinn 1000, please let me know.
My suspicions and others pointed to the BMS on the load side being too conservative, and shutting down the circuit under load. This was the problem. The Stealth 1000 may be 1000W, but almost never exceeds 15 amps - even that's an overstatement. It's more like an average 10-12, and very max peak is 23 Amps up at hill, and only at the start.The rates and max discharge for this LifePO battery is 15 and 30, respectively. I think for this light scooter we are right in the sweet spot, and the BMS on the load side is overkill, as all the cells are going the in same direction on discharge.
So, thanks to Andy and my own suspicions, I took a risk and moved Batt - to the common controller side (the BMS and Batt / charger are Pos common). The BMS will still balance the cells, and I will never discharge this pack much.
The scooter is now wow at 40+ volts for more miles than I ever rode on SLA. It maintains top speed for miles, unlike the SLA, and pulls like a devil up hills. This was a $400 experiment with shipping, and I would not do it again - the stakes and inconvenience factor are too high to deal with China. I think this company is OK, though, and the communications with them was civil and efficient. Next time, I will buy domestic and deal with guys like Andy, that add value and expertise. Thanks again, all who helped. Thanks Andy!
Thanks much for keeping us posted on your progress. I'm glad you were able to find a solution and use the battery.