BBSHD showing watts dropping under acceleration

[Nealh]

The sag is to be expected with the PF cell esp at 28a constant draw.

 

[guerney]

From what you've said about the behaviour of your bike, it works with the 500c display, and appears to work ok. Therefore if it was my bike, I'd ride it and not worry about why other displays didn't work. But I'm sure others will comment here, in time.

 

[djneils98]

From what you've said about the behaviour of your bike, it works with the 500c display, and appears to work ok. Therefore if it was my bike, I'd ride it and not worry about why other displays didn't work. But I'm sure others will comment here, in time.

I'm going to contact the people I got the HD off and see what they say

 

[djneils98]

so I tried the 950c on the BBSO2 and it errors the same so now thinking the display must have a fault. starting to hate ebike building!

 

[wheeliepete]

A few years back all 48v Bafang motors and displays worked with 52v batteries, although they did not register true voltage. Then, for some reason only known to them, Bafang started messing with firmware and that's when all the problems began. It could be that the C965 won't now work on 52v.

 

[RobAV]

From my own understanding and measurements....your suffering from voltage sag (normal...how much depends on the cells in your battery) and your 'keep current' is way to low....when you set your max current in the BASIC menu, thats the absolute limit of current draw allowed into the motor, the 'keep current' is the programmed percentage of that limit, so if say, you have 20 amp set as your limit in the BASIC menu, 100% in the 'keep current' PAS menu will be the full 20 amps, 75% will be a maximum of 15 amps, 60% 12amps, 50% 10 amps etc.....its a safeguard measure... people get this mixed up with the current decay, which is valued at 1-8 (in the PAS menu)....this value will drop the amps going into the motor. Think of driving a car.....you accelerate up to a speed with your foot pressed down, then lift off when the speed you want is reached as you don't need as much power to maintain a constant speed. And although the BASIC tab and its 9 values look like your getting full power at level 9, your not, easily checked by looking at the wattage draw in your display. And as a side note, wattage draw into the motor is not equal to the wattage out at the wheel....but its the best we can get.

 

[djneils98]

From my own understanding and measurements....your suffering from voltage sag (normal...how much depends on the cells in your battery) and your 'keep current' is way to low....when you set your max current in the BASIC menu, thats the absolute limit of current draw allowed into the motor, the 'keep current' is the programmed percentage of that limit, so if say, you have 20 amp set as your limit in the BASIC menu, 100% in the 'keep current' PAS menu will be the full 20 amps, 75% will be a maximum of 15 amps, 60% 12amps, 50% 10 amps etc.....its a safeguard measure... people get this mixed up with the current decay, which is valued at 1-8 (in the PAS menu)....this value will drop the amps going into the motor. Think of driving a car.....you accelerate up to a speed with your foot pressed down, then lift off when the speed you want is reached as you don't need as much power to maintain a constant speed. And although the BASIC tab and its 9 values look like your getting full power at level 9, your not, easily checked by looking at the wattage draw in your display. And as a side note, wattage draw into the motor is not equal to the wattage out at the wheel....but its the best we can get.

thanks - I changed the keep current to 80% but the issue of the watts dropping at full throttle (PAS9) remained. Also the watts never showed more than about 1200w (same as when the BBSo2 was connected)
Do you think the battery is the culprit? I am baffled

 

[Fordulike]

Do you think the battery is the culprit? I am baffled

I think so. As Nealh mentioned, those PF cells will sag fairly badly under high current draw.

I personally would not run a BBSHD with those cells. They work, but are likely to have a short life span.

I learnt that mistake with my first BBS02 battery pack. It had Samsung 29E cells, which didn't last particularly long. I now use LG HG2 cells, which are better suited for my use.

 

[soundwave]

if you pull alot of amps from the batt the voltage will drop/sag as the pack cant cope with that load on it and you also run the risk of it catching fire if a cell fails under load and the hole lot will be gone.

eBike Batteries

ebikebatteries.co.uk

he can custom build batts and use the right cells for the power you want to run at and not get voltage sag.

 

[djneils98]

I think I might try this battery as I don't need huge capacity and the cells seem to be able to put out a lot of current continuously https://eclipsebikes.com/lithium-ion-c-1_8/super-shark-52v-98ah-ebike-battery-samsung-25r-cells-p-280.html
Unless anyone has any other recommendations for a battery of about 12ish Ah 52v that isn't crazy money and can cope with a high current draw?

 

[soundwave]

Sony VTC4 18650 2100mAh 30A 3.6V Battery

Sony VTC4 18650 2100mAh 30A BatterySony 18650 Li-ion 3.6V Battery, Version: FlatType: NMC, Rechargeable, Continuous Discharge: 30AHigh Drain battery for Pack, Driver, Drill, Power ToolPlease Select Tabs/Tags/Tagged Option if required.Read more in product description:

www.ecoluxshopdirect.co.uk

there 30a but give jimmy a email and see what he says price wise and take it from there.

 

[Fordulike]

I think I might try this battery as I don't need huge capacity and the cells seem to be able to put out a lot of current continuously https://eclipsebikes.com/lithium-ion-c-1_8/super-shark-52v-98ah-ebike-battery-samsung-25r-cells-p-280.html
Unless anyone has any other recommendations for a battery of about 12ish Ah 52v that isn't crazy money and can cope with a high current draw?

Samsung 25R's are good cells!

 

[Nealh]

25r are 20a rated and one of the best 18650 cells in use, only the Moli 26a and the vtc5 are in the same class. All though the PF is 10a rated is sags terribly beyond 5a per cell, it is a fairly good cell for lower power at 20a or less.