Battery drains fast!

[matthewslack]

Still a question, when do you charge batweries?
Every time you get home, or when the battery goes below a certain level? What level?
Does this affect the life of the battery?

Don't run it flat if you can avoid it, don't store it long term full, just make sure there is enough charge before each journey, and when you do charge, charge fully to let balancing work.

My short commute can be done 5 times on a full battery. I normally charge every 3 days, so I am never in any doubt.

 

[saneagle]

52 X 20 = 1040W



50% of 1040W = 520W

520/17 = 30.6W per mile



I travel at 15.5mph max assisted.



Total weight of my bike + me = 93kg. My controller limit was 15A, max range was 43 miles using a 691W battery = 16W per mile. Your overall weight with bike is heavier, your controller has a 30A limit, you're travelling at a higher speed on a bike with bigger wheels than my 20" wheeled folding bike, it's new to you therefore you may well be letting the motor do most of the work (I did, still do), like I said:

The battery capacity specified is what you can get at relatively low current. The higher the current you take from it, the less useful capacity you get due to the internal resistance losses of current squared times the resistance. It's a squared relationship, so the losses accelerate upwards as the current rises.

A Samsung 21700 cell has an internal resistance specified as 0.04 Ohms. 4 in parallel would be 0.01 Ohms, and 14 of those in series would be 0.14 Ohms. The losses at 1 amp would be 0.14w. At 10 amps, it would be 14w and 126w at 30 amps.

 

[thelarkbox]

@egroover I would always recommend itead/sonoff smart devices above anything else due to the ease you can purge and replace the firmware, so you dont need to register with and rely on overseas servers that can change terms of service at anytime. Tasmota

 

[goral]

Battery charging:
Battery on or off while charging?

 

[matthewslack]

Battery charging:
Battery on or off while charging?

If the switch is for turning the bike on, and the battery charges with it switched off, then off is fine, and it probably doesn't matter.

 

[saneagle]

Battery charging:
Battery on or off while charging?

If you remove the battery, you should ensure it's switched off before re-installing.

Before you insert the charger jack, make sure that the charger is switched on.

 

[goral]

I charged the battery, discharged to 22%
From what I have read, a battery (52V) fully charged should be 58.8V
Mine is 57.7V
So well 1V below.
Does anyone have a 52V battery and can confirm that a fully charged battery is 58.8V?
Or there something wrong with mine though?
I should add that the whole charging time is about 4h from 22% to 100%.
Alternatively, maybe I should set 52V on the controller and not 48V?

 

[matthewslack]

The fully charged voltage is simple maths:

A nominally 52V battery has 14 cell groups in series, a fully charged cell is nominally 4.2V, so fully charged voltage is 4.2 x 14 = 58.8V.

Now your 57.7V is 4.12V per cell, which is probably close enough: the difference could be down to BMS tolerance, or your voltmeter accuracy.

If you want the display to do its best with battery capacity indications then it would make sense to tell it the correct battery voltage.

 

[Nealh]

If the battery reading averages out at a cell reading of 4.12v I would be a little concerned, 57.7v is well under a full charge and to me indicates a balance issue or a wonky cell group. At 57.7v the BMS isn't balancing the cells because some one are too high and one or two are too low.

If the controller thinks it is a 48v battery then your discharge could end up too deep.

 

[saneagle]

I charged the battery, discharged to 22%
From what I have read, a battery (52V) fully charged should be 58.8V
Mine is 57.7V
So well 1V below.
Does anyone have a 52V battery and can confirm that a fully charged battery is 58.8V?
Or there something wrong with mine though?
I should add that the whole charging time is about 4h from 22% to 100%.
Alternatively, maybe I should set 52V on the controller and not 48V?

First, measure the voltage on the charger's jack, then, after you fully-charged the battery, measure the battery's voltage immediately after you switch off the charger. If you still get 1v difference, leave the battery on charge for several hours after the light goes green, and check again. It's not unusual for a battery to be a bit out of balance when new, which reduces the voltage and capacity. You solve it by leaving the battery on charge.

After you've done all that and you still get 1v difference, something might be wrong with the battery.

Obviously, if your charge jack measures 57.7v, you have nothing to worry about.

 

[goral]

Charging jack 58.3V

 

[goral]

If you remove the battery, you should ensure it's switched off before re-installing.

Before you insert the charger jack, make sure that the charger is switched on.

For clarity. I As the battery is fitted to the bike, can the battery switch be in the ON position when charging?
I ask because I currently have 58.1V and when the battery is OFF the charger does not charge it lights up green.
When I switch the battery on, the charger starts to work.
Hence my question because I have a bit of confusion.

 

[saneagle]

Some batteries switch off the charge socket as well as the output when you switch off, others only switch off the only the output, leaving the charge socket live. You have the first less common type.

Normally, it makes no difference whether the battery is switched on or off when you insert the charger as long as the charger is switched on. In your case, you have the choice. You can switch off both when you connect or switch on both. What you mustn't do is connect when the battery is on and the charger off.

 

[goral]

So:
1. Battery Off
2. Charger ON
3. Connect charger to battery
4. Battery switch ON

Is that correct?

 

[harrys]

50% after 17 miles with a 1000Wh battery? That's around 25WH/mile. You must have been averaging over 20 mph, wearing bulky clothing to catch the wind.

For a slower speed comparison, my BBS02 runs under 10WH/mile at 12 mph, same as my hub motor ebikes. I've tracked it at 20 WH/mile when riding w/o pedaling at 18-20 mph, which is quite boring to me.

 

[goral]

First, measure the voltage on the charger's jack, then, after you fully-charged the battery, measure the battery's voltage immediately after you switch off the charger. If you still get 1v difference, leave the battery on charge for several hours after the light goes green, and check again. It's not unusual for a battery to be a bit out of balance when new, which reduces the voltage and capacity. You solve it by leaving the battery on charge.

After you've done all that and you still get 1v difference, something might be wrong with the battery.

Obviously, if your charge jack measures 57.7v, you have nothing to worry about.

I did as you wrote, left the battery on.
When the power supply turned green, it finished charging. The display shows 58.7~58.6 So rather correct.

50% after 17 miles with a 1000Wh battery? That's around 25WH/mile. You must have been averaging over 20 mph, wearing bulky clothing to catch the wind.

For a slower speed comparison, my BBS02 runs under 10WH/mile at 12 mph, same as my hub motor ebikes. I've tracked it at 20 WH/mile when riding w/o pedaling at 18-20 mph, which is quite boring to me.

Perhaps I was expecting something different. As I pointed out at the beginning, this is my first e-bike.
What surprised me was that suddenly from about ~90% some, it dropped to 64% over a very short period of time, a few minutes, the fact that it was uphill. This made me concerned.
However, after several replies here, including yours, I now more or less know what to expect and how to manage it (the battery) to increase the range.
For which I thank you very much.

 

[Nealh]

The % going up a hill will drop , this is known as voltage sag.
When you get to the top and ease off power one should see the % rebound .
How much sag one sees is dependant on how much current one is drawing.