Ticruiser: I have been waiting over a month and a half for my replacement battery, so I know it can take quite a long time to get those replacements.

Garvie: Got my fingers crossed for ya, bud!

DickB,

Okay, I won't bypass the BMS, guess they put that there for a reason.

I used my multimeter to check the voltage present on the positive/negative contacts on the bottom of the battery (where it interfaces with the bike) on my wife's bad battery, my battery, and then my wife's new battery:

Wife bad battery:
Key off-7.4 volts
Key on-jumps to 53.4 for a second and then drops down to 22.6 volts

My battery:
Key off-7.5 volts
Key on-54.4 volts

Wife's new battery:
Key off- less than .1 volts (this battery has different labels than our original batteries
Key on- 51.4 volts (have not charged it, just pulled it out of the shipping box last night)

I did look at the MOSFETs on the BMS. I checked the voltage on each of the MOSFETs and the front three MOSFETs had a 3.3 voltage between the two leads of each MOSFET. The back three had no voltage across the leads of any of the MOSFETS. I wish there was an obvious component that has failed and I can point to it and fix it.

Do you know if there is a schematic for this BMS?

Thank you for the new BMS. I know it is an eBike BMS, but is there a lot of loss using the thin gauge wires vs the nickel strips? I would like to swap it with the same BMS if possible.

Thanks again, I am going to read about balancing now from your Wiley article!

DickB,
Thank you for your insight. My issue is not a loose tab as you have shown. I don't think the internal resistance of the multimeter is causing the errant readings from 53 to 23 volts. When I do the same operation on my good battery, there is no change.

I am actually wondering what kind of BMS I could use as a replacement. Does the BMS discharge circuit ensure equal discharge of all cells? If not, could I connect my leads to the main positive and main negative on the top of the board and run my bike that way?

Garvie,
How old is your bike? If it is under warranty, I would not crack open that battery and contact RadPower instead. Once you get a replacement, then fiddle around with it

So my wife and I rode the Going-to-the-Sun Road in Glacier National Part this June on our Rad City 4 ebikes. Most of the way up, my wife's bike just up and died. Thinking that she just drained her battery, I gave her my battery and slogged through the last couple miles on my, now pointlessly heavy and dead, ebike. When we got up to the top, I had the great idea of using the regenerative braking to try to recharge my wife's battery. It seemed to come alive on the ride down, but died again when I got to the flats and wanted a little pedal assist.
The next day, after a 12 hour charge, the battery seemed back to it's old self. But as soon as my wife used a higher pedal assist or throttle, the bike died. We got it back home and the battery pack, even when freshly charged, will only cause the display to blink on and then go right back off.
I have contacted Rad Power and, after two months, they are sending me a replacement battery. Since I still have the old battery, I wanted to know if I could repair it.

Here is my situation:
1. When I turn on the key, and push the battery level check button, the lights all come on for about a second and then turn off. If I press the button again, I only get a faint flicker before they go out again.
2. When I attach a multimeter to the positive and negative terminals, the voltage reads about 12 volts. When I turn the key, the voltage momentarily (approx 1 second) goes to 53 volts, and then drops to 23 or so volts.
3. When I open the case, everything about the BMS looks good.
4. When checking the voltage of each battery cell, they all read 4.2. All together, they read 54.5 volts.
5. The BMS is an RP1304AA model

So what is my next step? Since the battery pack is good, I would hate to see it go to waste. Is there something I am missing?

Thank you all!