What kind of battery is recommended as the best compared to price / reliability

[T5T]

I wonder if anyone has specific recommendations where to buy battery pack that is affordable and reliable at the same time any ideas?

 (volt 38/48 - 20/15 amp)

[Hednztrüm]

I have a gm48v12ah thats been running flawlessly for 2500km(mostly in severe cold weather) not much loss in effect, I get around 37km/charge if I support with pedals on hills etc
Ive had some plans on buying ping 48v15ah

[T5T]

hednztrüm
 
Thank you for sharing your experiences.
 The reason I ask is because GM battery I have today is broken, my own fault.
 I have used this battery a few miles - after that only problems.
 The problem was - by measuring the output of the battery voltage strength was ok, when Connects to the controller, I could only measure the 0.1v from the battery even with the correct programmed controller Compared to the amp and the setting.
 So my sense was that BMS cut the power to protect the battery.
 Have tested the battery on different controllers without any change.
 I decided to desolder + cable of the  card hoping I could reset the card.
 Soldering pen touched a little touch a mosfet chip, and of course all can imagine the sparkle
 Contacted Gary, but he could not get a new  card and to contact  GM in China is a waste of time - They do not answer anyway.

[simplyfly]

Was it 36V 16Ah? If so I can supply you with a new BMS $60CAD+shipping.

[T5T]

simplyfly
I bought this battery as a 48V and 12 amp (and it is labeled as 48V see photo)
But as I mentioned in an earlier post in this forum, the battery does not show more than approx. 44v fully charged.

Then someone on the forum who said that this voltage corresponds to   a 36volt battery fully charged.
So I do     not know what is right.

Maybe it has always remained an issue with this BMS card from it was new, so charging stops before reaching ca.54v - I have no idea.
Have now purchased 10 of these on ebay:

http://cgi.ebay.com/10-pcs-STP75NF75-P75NF75-New-Original-ST-/180563501981?pt=LH_DefaultDomain_0&hash=item2a0a6c639d

Will try to replace all the fet`s  first - if it fails, I will look closer at what you have.
But anyway, I want more information on BMS card you have - is it the same type card you have as mine ?
can you post a photo ?

[_GonZo_]

Hi as per the BMS pictures is a 12 in series (12S) Li-Ion batery so:
- Nominal (medium) voltage should be around 44,4V
- Maximun voltage: 50,4V
- Minimun voltage: 36V

So if the battery never reached something like 50V looks like there is problem on the battery, BMS or in the charger.
You can check the charger just connecting it and checking the output voltage it should be around 51V to 54V
As well you can check the battery, you should check every set of parallel cells and voltage of them should be equal whit no bigger differences than 0,1V between them.
As well is posible to check the BMS but that is a bit more complicated, I posted here a way to check it and battery at the same time: http://goldenmotor.com/SMF/index.php?topic=2993.msg18154#msg18154

[_GonZo_]

By the way, answering to your question on post title the best value batteries you can buy that will last almost your life time if well treated are packs made with A123 Life cells.

[Bikemad]

Hi as per the BMS pictures is a 12 in series (12S) Li-Ion batery so:
- Nominal (medium) voltage should be around 44,4V
- Maximun voltage: 50,4V
- Minimun voltage: 36V

Gonzo, I'm going to jump in here with the correct details to avoid any further confusion:

The BMS pictured appears to be from a 48V pack, which consists of 39 x 4Ah Lithium Manganese cells, configured as 13 groups of 3 parallel cells connected in series (13S 3P).

- Stated Nominal voltage 49.4V (3.8V x 13)
- Maximum voltage: 54.6V @ 4.2V (±0.05V) per cell
- Minimum combined cell voltage: 32.5V @ 2.5V per cell (but the Low Voltage Cutoff is probably set much higher)

Alan
 

[_GonZo_]

Yes Alan, you are right.

After checking closely the BMS yes it is a 13S not a 12S sorry for my mistake.

About the minimum voltage is usually set up at 3V per cell so 39V then.

So the charger voltage should be around 55V.

[T5T]

I got the mosfet from Ebay and I have changet 1 of them (the burnt one)
Charget the battery and it give out 51.8v after resting 5 min or so to stabilitze.
Yeah better than last measurement (44v)

T5T