Thank you so much for going in to detail and explaining this clearly.
When the charger stops and displays 'Charged' the power level reader on the battery pack shows 80%. I've uploaded a video to YouTube showing this
. I did take a DC voltage reading with my multimeter, which I think showed approx 41.6V.
Typically, one thing I didn't take a photo/video of is the info on the controller unit. I'll open the casing up and check later today.
I don't have a Watt meter but happy to buy one, as it sounds as if it'll be very handy to have. Do you have one you'd recommend please?
Luke
When the charger stops and displays 'Charged' the power level reader on the battery pack shows 80%. I've uploaded a video to YouTube showing this
Typically, one thing I didn't take a photo/video of is the info on the controller unit. I'll open the casing up and check later today.
I don't have a Watt meter but happy to buy one, as it sounds as if it'll be very handy to have. Do you have one you'd recommend please?
Luke
Hi Luke, no worries about the questions, it's what the e-bike community is for.
Lots to unpack here. First of all, how do you know you are only charging to 80%? What is the final voltage of the pack?
So you probably have a 10s 4p pack with 2.9Ah cells. This is their nominal rating, if charged right up to 4.2V and discharged maybe as low as 2.5V to get that figure, at a current of maybe only 0.5A. To start with, a lot of chargers do not go to the full 4.2V, as this shortens the life of the cell. Some experts say a cell should not be charged over 4.1V to increase cell life. Yose Power chargers only charge the pack to 41.7V, so a compromise between capacity and pack life. Then, you would never want to discharge as deep as 2.5V, as it might not accept charge again after such a deep discharge. So a BMS will usually kick in at 28V on a 36V pack. On top of that, you have the controller, which is usually set up for 30V low voltage cut out (LVC).
On top of this, discharge characteristics will depend on how fast you drain the cell and the ambient temperature. High current drain will mean you will get much less out of the pack than the nominal rating. Never recharge a pack below 0 deg C, and ideally not below 5 deg C. Discharging at 5 deg C or below will reduce your battery's output.
Anyway, assuming 10 to 20 deg C for discharge at a moderate average rate of about 100 to 150W, I expect to get about 12Ah from my 15Ah pack, so about 80% of stated capacity when charged to 41.7V. If a system is working properly, that is what I would expect.
Do you know what the LVC set up is for your controller? It might be set too high. BMSs are usually set to 2.8V or so, I wouldn't expect them to be much higher than this.
Do you have a Watt meter? Can you measure how many W hr or Ah you are getting out of the pack? What is the pack voltage when the controller shuts down?