Video of 48v20ah Lifepo4 battery, 3 pieces?

cgokey

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Below is a video of someone pulling out a 48v20ah Lifepo4 Battery bought on ebay...
https://www.youtube.com/watch?v=JFjeLcLPSM4
That thing is a monster size...

What is that computer attached to the battery for?
 
It looks like the "computer" is the BMS which stands for "battery management system". Basically the BMS makes sure the cells within the battery remain balanced, there is a wire from each cell (or group of parallel cells) to the BMS so it can monitor the voltage of each cell in the battery and "bleed" off current to balance the cells. It also prevents the battery from being over-charged or over discharged. A few people refer to a BMS as a "battery murdering system" because the BMS itself draws a small current from the battery so if you leave the battery laying around for long enough this small current will eventually flatten and thus murder the battery!
 
leew said:
It looks like the "computer" is the BMS which stands for "battery management system". Basically the BMS makes sure the cells within the battery remain balanced, there is a wire from each cell (or group of parallel cells) to the BMS so it can monitor the voltage of each cell in the battery and "bleed" off current to balance the cells. It also prevents the battery from being over-charged or over discharged. A few people refer to a BMS as a "battery murdering system" because the BMS itself draws a small current from the battery so if you leave the battery laying around for long enough this small current will eventually flatten and thus murder the battery!

So it is only attached during charging? It doesn't have to be installed on the bike! right?
 
No, the BMS should be permanently attached to the battery, the only time you should disconnect it is if you are going to put the battery into long term storage.
 
leew said:
No, the BMS should be permanently attached to the battery, the only time you should disconnect it is if you are going to put the battery into long term storage.

So that is monterous lifepo4 pack? What about these that they sell on ebay:
http://www.ebay.com/itm/48V20AH-Li-ion-LiFePO4-Battery-Pack-and-BMS-Charger-For-Ebike-Free-Shipping/191893423984?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36861%26meid%3De703e319445e4022b0a39b825baf4844%26pid%3D100011%26rk%3D1%26rkt%3D10%26sd%3D191892564119

s-l400.jpg

Do these come with a computer too? Or are they now built into the battery pack somehow? I don't see that third piece (battery, bms computer, and charger).
 
cgokey said:
leew said:
No, the BMS should be permanently attached to the battery, the only time you should disconnect it is if you are going to put the battery into long term storage.

So that is monterous lifepo4 pack? What about these that they sell on ebay:
http://www.ebay.com/itm/48V20AH-Li-ion-LiFePO4-Battery-Pack-and-BMS-Charger-For-Ebike-Free-Shipping/191893423984?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36861%26meid%3De703e319445e4022b0a39b825baf4844%26pid%3D100011%26rk%3D1%26rkt%3D10%26sd%3D191892564119



Do these come with a computer too? Or are they now built into the battery pack somehow? I don't see that third piece (battery, bms computer, and charger).

Yes, the description says "One Special 16 cells PCB with balance function is installed with battery pack to protect battery from over charging, over discharging and over drain ".
it is most likely built into the main "block" in that instance.

All LiFePO4 batteries should be used with a BMS, if you just put an unprotected LiFePO4 battery on an ebike and then ride it until it runs out of power, the battery will most likely get over-discharged and thus be ruined.
 
Looks similar to one of those cheap ass V POWER Lifepo4 packs. Notoriously poor. Lifepo4 18650 cells don't hold a lot of capacity, so they are large compared to NMC types.

That is the biggest bms box I ever saw though. I thought the one on my cheap ass NMC pack was huge.

In lifepo4,,, 48v 20 ah is generally too big to carry easily. 48v 15 ah about as big as bikes can handle, on top of a rear rack.
 
The BMS looks like it's in a generic IP56 "adaptable box", it's possibly the smallest such standard box which the BMS would fit in, with a load of wasted space inside the box, the "carbon fiber" looks like that fake stick-on stuff.
 
If you want a LiFePO4 battery, PING seems to be the recommended supplier, they use pouch cells rather than 18650.
I have just ordered 2Kwh of PING for my upcoming build.
www.pingbattery.com
As said above and on various areas on the forum, avoid vpower, they are shite.
 
Pings are lifepo4 pouch cells, which means the connections tend to be more reliable. decent quality cells, that tend to last. I rode many thousands of miles on my pings, in 2008-2012.

To carry on a bike, the size to get is 48v 15 ah. Fits in small tool boxes, larger tunk bags, and weighs just about the max you can stand to put on top of a rear rack. 48v 20ah ping is too big unless you have a cargo bike. 48v 10 ah is about the largest size that will fit in a triangle bag.

Get the upgrade charger.
 
I decided to order my PING with the default charger omitted, I have ordered a Cycle Satiator instead.
 
leew,

"I decided to order my PING with the default charger omitted, I have ordered a Cycle Satiator instead."

You won't be sorry. I have five, 5 amp Chinese chargers, 45 volt, and 58.8 volt (two are now dead). I have always used them paired, for 10 amp charge rate. The oldest has done over 500 charges. My Satiator has replaced them all (soon to be joined by a second, for 10 amp parallel charging).
 
Sounds like leew did. Pings a decent lifepo4 pouch cell, if you can deal with the larger size and weight, of a pack that can stand some amps. discharge pings at 1.5c max for best results. They do hate a 3c spike.

No telling now, but the ping bms used to max out at 5 amps. But you just can't beat the satiator, especially if you are going to do an on board charger.
 
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