Hailong 48Volt 17 AH ebike battery cuts out when power is applied

[Pezza]

Hi

The battery cuts out when power is applied after a few seconds, checked voltage it is 48.3 Volts after abut 3/4 hour charge. Connected the charger to the bike directly to the charger to eliminate faults with the motor and controller. Also had a look at the wiring to the controller all OK.

The bike is a kit Bafang BBS02HD

What do I do the cells look OK cannot see any damage Voltage is OK I guess at 48Volts? Is it a temperature sensor that's gone wrong?

Do I just swap out the BMS do Pedelecs offer this service. It seems you are on your own when you buy these kits, bit of a nerd wanted to build one myself large jigsaw puzzle.

Any comments


Perry

 

[Nealh]

48.3 is about 50% charged, it should charge to 54.6v for a13s/48v batter. The battery might be unbalanced so you first need to fully charge it.

What is the batteries continuous discharge rate ?

 

[Pezza]

OK will charge fully but I think from memory it was never that much over 48V. Forgive me for asking a dumb question what do you mean when you say the batteries recharge rate do I measure that? Is it on the batteries themselves? They are 18650 2500mAh 3.6/4.2V

Thanks for such a quick reply am looking at the BMS at the moment

 

[Pezza]

48.3 is about 50% charged, it should charge to 54.6v for a13s/48v batter. The battery might be unbalanced so you first need to fully charge it.

What is the batteries continuous discharge rate ?

The battery is fully charged at 49.4V They are in banks of 10 5

48.3 is about 50% charged, it should charge to 54.6v for a13s/48v batter. The battery might be unbalanced so you first need to fully charge it.

What is the batteries continuous discharge rate ?

The Voltage is 49.4Volts It looks if there is an imbalance as you say each battery is 2500 mAh 6 banks of 10 5 in parallel plus 5 in parallel so discharge max is 32.5A is that right? school boy physics.

 

[Nealh]

The battery is fully charged at 49.4V They are in banks of 10 5


The Voltage is 49.4Volts It looks if there is an imbalance as you say each battery is 2500 mAh 6 banks of 10 5 in parallel plus 5 in parallel so discharge max is 32.5A is that right? school boy physics.

No...….
Something is very wrong if you can only charge to 49.4v.
Measure the voltage of the charger at the charger connector, plugged in to the wall socket you should see 54.6v.

Your battery for 48v nominal should charge to 54.6v max , anything less then 53.95v then it is not very well.
A 48v battery has 13 cell groups in series each one 3.7 nominal x 13 gives about 48v. 13s x 4.2v = 54.6v.

 

[Nealh]

If the battery charges only to 49.4v then it is either very unbalanced and has one or two cell groups way out of line (voltage wise) or the cells are knackered.

49.4v equates to an average cell voltage of 3.8v, something isn't right.

 

[wheeliepete]

Do you have a link to the battery you have? Continuous discharge rate is controlled by the BMS, nothing to do with the cell capacity. 2500mAh would suggests Chinese cells, so if you are running a BBSHD they are working pretty hard, which may explain your problem.

 

[Tarka]

I suggest fully charging the battery off the bike making sure the switch on the battery is in the on position.

 

[Pezza]

Thanks for the help this is amazing I have narrowed one cell bank to only 3.3V the rest are measuring between 3.7 to 3.8V.

I have measured the charger and that only reads 49.6 Volts even though the output voltage on the charger is rated at 54.6V does it change with load or is there an alternating Voltage element higher peak Voltage that I cannot read?

Anyway 64 million dollar question looks as if the battery is faulty and the charger is not giving out enough, is there somewhere I can send the battery (I have not got a mini spot welder) so that the cells are identified and the charger is changed and that they can do a power test.

In your opinion what battery should I buy in the future as it seems the battery has to work hard.

Once again thanks for your help.

 

[wheeliepete]

Your battery is most likely out of balance because the voltage of the charger is to low. It may be possible to adjust this if you can open it, post a clear photo of the inside. You will also need an old phone charger to bring up the voltage of the cell group at 3.3v.

 

[Nealh]

As pete say's first the charger needs sorting so it reads 54.6v on the charge connector.
Once that is in order the battery might re-balance slowly over a few charges 3.3v isn't disastrous and is recoverable.

 

[Pezza]

Thanks for this it is well above and beyond my expectation. Looks as if I have a bit of work to do. So an old phone charger USB type thing 5V. The rest of the charger is covered with a heat sink but I guess I could take that off but have not got and heatsink compound so I am guessing you will see that potentiometer on the left will that alter the voltage?

 

[Pezza]

Hi again Trimmed the pot and got it upto 54.5 maximum surprisingly there is a sweet spot on the pot. Keep on turning it clockwise did not increase the voltage. Anyway success so far will charge the battery again see what happens. Then test at the terminals again.

 

[Pezza]

After 2:45 hours it reads 53.2. I will try it on the bike and see what happens. It was fully on the previous charger voltage at 49.6V. Measutre charger again it is 54.5-6V now.

I guess a few charges at the new level will reset the battery I hope.

I have to put the bike together will let you know afterwards.

Thanks for your help. I did feel stranded with a bike that I could not use. Again cannot thank you enough.


Perry

 

[wheeliepete]

Anyway success so far will charge the battery again see what happens

Nice one, looks like you are making good progress. You will prob. find that one group of cells at 3.3v will remain lower than the rest when the charger led goes green. You can then use the 5v phone charger to bring them up to the same voltage. Make sure you monitor this, or the cells can go over their 4.2v max.

 

[Pezza]

Yes bike works a lot better did about 6 miles then started to cut out again as you say need a charger to bring the low cells up.

Still a lot better I guess there are dodgy cells amongst that group will have to learn to change them.

Thanks a lot for your help.

All the best

Perry

 

[tommie]

Just a couple of thoughts re. your BBSHD... (i have the same myself)
Have you checked the controller software?
There`s a couple of critical settings in there which may come into play in your case, the first two on the attachment are important.
The first `Low Battery Protect` if set too high and voltage sag sets in will cause your`cut-out`. The second `Limit current`if set high will try and pull more aH from the battery than it can provide (especially if it has some no-brand chinese cells)

 

[Nealh]

54.5v is good your meter may not be 100% accurate, now the charger is at 54.5v that is good. Charge and discharge the battery several times to give it a chance to re - balance now that the charger voltage is correct, any low cell groups might sort them selves out. Keep checking the battery voltage after each charge to see if the voltage improves.

 

[Pezza]

Hi
I managed to charge the low cells to 4.08V with a phone charger. Took the bike out today went for 2 hours gave it some heavy work loads. No cut outs at all so good news.

Will try it tomorrow thanks for all the help. I would like to ask a question do I charge the battery to the maximum or do I charge to say 90% every time to achieve a longer battery life.

Anyway fine tuning now you I appreciate that you got me out of a sticky situation.

Thanks again

Perry

 

[Pezza]

Just a couple of thoughts re. your BBSHD... (i have the same myself)
Have you checked the controller software?
There`s a couple of critical settings in there which may come into play in your case, the first two on the attachment are important.
The first `Low Battery Protect` if set too high and voltage sag sets in will cause your`cut-out`. The second `Limit current`if set high will try and pull more aH from the battery than it can provide (especially if it has some no-brand chinese cells)

View attachment 34820

Hi This screen is a laptop computer program? I think I can get all this from the display. I don't have the colour display but the basic one. I have to acquaint myself with it again and learn how to access all of this info. Now I know the output of the battery I will be better informed. Thanks for this Perry