Battery maintenance tips please

[aardvark5]

Hi

I've just taken delivery of a new 36v 12.8ah bottle battery and I want to keep this one in tip top condition if possible.
I've got two eBikes fitted with Cyclotricity gear and they have served me well, both batteries have got much shorter memories for a while now and two weeks ago one of them died.

I think I remember when I had my first one that I was supposed to charge it up and discharge it 3 times, I can do this easy bu taking my spare battery out with me but does this have to be done or what is your advice for a brand new battery?

Is it best to turn the battery off when charging? I've always left them on.

Can you overcharge? It has a 6 hour charging time but I've always started charging at 5.30pm and turn it off at 8am, could this add to problems?
Would I be better charging at 11pm before I go to bed?

Any useful advice appreciated.

aardvark5

 

[Nealh]

The battery switch is wired to the bms where bms power is supplied via the last parallel group so yes you should switch on when charging. I'm sure if wrong some 'experts will put me right'. You shouldn't need to do anything special the only reason I expect they say to charge/discharge three times is to correct any voltage imbalance but really shouldn't be necessary as this if any at all will right itself after a few charges anyway.
The charge has a led red for charging and green for charged, sometimes if there is an imbalance then the charger might switch between on and off as the bms bleeds higher voltage off and then may recommence balance charging. Once the green charge led is lit it means no more current is flowing and is theoretically off although power from the mains remains to the charger.
Chargers warm up a little in use when current is flowing and charger is on, once charger stops charging and the led goes green they cool down and remain cool indicating no current is flowing.
Bms conrols any overcharge unless it is faulty, if faulty they usually fail to allow charging or discharging.
I only fully charge about 8-10hrs before a ride other wise I leave batteries sitting at 3.6 - 3.9v.

 

[aardvark5]

Thanks for that

I'll charge at 11pm before I go to bed.
The batteries do charge with the switch on and off but I'll leave it on when charging.

Another question:
When I get to work is it best to switch the battery off because I've always left them on?

Thanks

 

[Benjahmin]

I would say, when at work, turn the battery off. It's possible that when on there is power to the controller, it would only use about 4-5 watts but is a constant drain of power that you may need to get that last mile to home.

 

[Deleted member 128]

Last summer I bought a very cheap very high intensity hand torch from an eBay seller in China. Its 18650 battery broke after 10 minutes use, there was a bad connection inside and it rattled! The rest of the torch was still good value though.
I then bought, as an experiment, 2 very very cheap Chinese "UltraFire" 18650 "4000mAh" batteries, with internal protection, from a UK Ebayer and tested their capacity - 1024mAh and 968mAh ie they were rubbish.
Finally I bought 2*18650's from a UK supplier who had assembled protection boards onto Panasonic 3400mAh batteries and wrapped the packages. When I tested their capacities they were 3129aMh and 3027mAh ie a quality product. Not up to the 3400mAh specified but that's probably down to the test current I used.
My conclusions was that Chinese batteries are best avoided!!

 

[Nealh]

Any battery with fire in the name is a fire waiting to happen and they have always been poor in the rated capacity dept.
Cells are graded by the big makers cellers like NKON sell C & D and maybe some B grade spec cells on ebay they are likely to be E or F grade cells.

 

[aardvark5]

Chargers warm up a little in use when current is flowing and charger is on, once charger stops charging and the led goes green they cool down and remain cool indicating no current is flowing.

I've got it in my head over the last 5 years that even though it turns green if I carry on charging I get more miles from it
If I start charging at 5.30pm and then go into the garage at 11pm it has always turned green but I let it carry on for another 9 hours.
Are you saying that I'm wasting my time and I can turn it off at 11pm when I lock up?

 

[egroover]

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[Nealh]

I've got it in my head over the last 5 years that even though it turns green if I carry on charging I get more miles from it
If I start charging at 5.30pm and then go into the garage at 11pm it has always turned green but I let it carry on for another 9 hours.
Are you saying that I'm wasting my time and I can turn it off at 11pm when I lock up?

Yes disconnect and switch off.

 

[aardvark5]

You have been so helpful, anybody would think I haven't had eBike batteries for 5 to 6 years

One more question:
I should easily get two days commute out of the battery, would you recommend I do the 2 days or because it's L-ion it doesn't make a difference if I charge every day, it won't make the battery less efficient?

 

[Nealh]

How far is the commute and what is the voltage SOC after one commute ?

 

[aardvark5]

How far is the commute and what is the voltage SOC after one commute ?

My commute is 10 miles and (using the common calculation) I should get around 23 miles.
I only see LEDs on my computer/battery.

I've just made this and after a full charge I did 3.5 miles this morning and the Watt Meter tells me 40.76v

http://www.dmpoole.co.uk/pics/wattmeter.jpg

 

[Nealh]

The battery is 10s 4p so means cells are 3.2ah only a couple of cells likely to be inside either LG MH1 or Sam 32E both are rated 10a in my view.
I would think 23 is a min range and 35 - 42 should be on the cards during good weather and on a low Pas level. The Bms will typically have a lvc of 32- 33v so discharge isn't to deep, a really deep discharge is 2.5 - 2.8 but Bms don't usually go that low. I tend to not bother charging if above 39v unless I need the range for a longer run. As a rough rule of thumb each volt between 32v & 42v you can count as a capacity in % terms so 39v /70%, 37v/50%, 35v/30% etc ,etc.

 

[andie7]

What you need is this, they are brilliant
https://www.amazon.co.uk/dp/B005C9S0I8/ref=asc_df_B005C9S0I858073111/?tag=googshopuk-21&creative=22110&creativeASIN=B005C9S0I8&linkCode=df0&hvadid=235064608282&hvpos=1o13&hvnetw=g&hvrand=18059710675378570957&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=1007222&hvtargid=pla-416491574804&th=1&psc=1

Just ordered one for my Reactions Hybrid Pro 500. Thanks.

 

[andie7]

Just ordered one for my Reactions Hybrid Pro 500. Thanks.