Charger for Golden motor 48v LiFePo4 lithium battery

[avantgarden]

Hello Everybody,

This is my first post here.
Wonderful forum you've got yourself

I recently bought the Golden motor 48v Magic pie motor and LiFePo4 lithium battery and I love it.
It's green and...its mean !

It came with the HP8204L3 charger.
I need to buy another charger.
The original charger has a label "Output : 58.4 v"
I measured the output of the charger (with no load) and it is about 48v.
Which charger do I need ? 58.4v or 48v ?
There are some chargers on eBay but they either have plastic cases like this one:
http://www.ebay.com/itm/48V-3A-Charger- ... 2a19b3b317

or they are metal but are smaller in size than the original. For example this one:
http://www.ebay.com/itm/120W-24V-36V-48 ... 2048839312

This is the original one which costs more than 100$.
http://www.alienbikes.co.uk/USERIMAGES/ ... HARGER.JPG

How do I know the charger I'm buying is the right one for for my battery ?
Any specific recommendations ?

[nebriancent]

the first thing you need to know about any charging system is what it is charging....(the battery)
so what we need to know to answer your question is 4 things
1 battery chem (lifepo4)
2 battery amp hrs
3 battery charging c rating
4 amount of cells in serries

without all of this information any answer givin could potentialy harm and or cause perminent damage to said battery

the information needed should be easy to obtain from any reputable battery seller (must be info from the place you bought the battery)

sooo fil us in and we can help you out

[dogman]

Either of those chargers should work for you.

Basicly, you need a "48v" charger for lithium battery. Outputs vary, but it should not be much under 56v. 60v max. Not more than 5 amps.

If you don't like Ebay, try a place like batteryspace.

Edit,, If you are in the UK, then maybe ebay is better. Batteryspace is a US company.

[avantgarden]

I have LifePo4 48V/10AH
It has the standard casing : http://www.alienbikes.co.uk/USERIMAGES/ ... 20KEYS.JPG
Not sure how many cells fit in there...

[chroot]

You can try BMS battery charger 400 watt for cheap bang for the buck and 48v 6 amp set to 58.4v (3.65v per cell for LiFePo4).

Currently, They are on sale right now for 37 dollars and here the link alloy-shell-400w-lifepo4li-ionlead-acid-battery-ebike-charger

48v usually have 16 cells

@Dogman - 6amp is fine as long as the BMS board limited up to 7 amp maximum (Ping Li told me).

[dnmun]

put it on the battery and start charging. measure the voltage of the pack while on the charger. you do not have a lifepo4 pack and the 48V or 58.4V is meaningless.

post up a picture of your pack, count the number of cells. show us a picture of the BMS, and picture of the voltmeter while attached to the pack while on the charger.

[nebriancent]

just like i said we need just a bit more to go on

[avantgarden]

Attached are pictures of my battery pack. As you can see there are 16 cells.
In the second picture you can see that peeling the blue plastic reveals a metal case on each cell.
Looks like a lifepo4 cell, isn't it ?

Output voltage of the battery during charging went from 48v (Empty Battery) to 57.5v (full battery).

Charging time is not a factor for me since I have 8 hours to charge my battery when I'm at work.
So the slower the better for the battery, right ?
A 3A charger should be enough then in my case...

Bottom line:
I think I'm getting the picture now...
"48v" is a type of Battery. Actual voltage varies based on the energy stored in the Battery. Higher energy => Greater voltage.
I think I'll buy me the 3A 58.4v !
I'll purchase something like this one (It is 3A, has metal case and will cost me only 46$ including shipping). Note that I don't live in the US so I don't have too many choices.
http://www.ebay.com/itm/320848370289?ss ... 1438.l2649

Am I on the right track ?

[avantgarden]

Here is a closeup of a peeled cell.

[dnmun]

ok, you have a 16S lifepo4 pack. the charger should be able to charge up to 58.4V and up to 60 is used on the ping chargers.

while it is open, take a close up picture of the BMS so we know which one you have. see if there is a big integrated circuit in the middle of it with 64 pins around the perimeter, and OZ590 for the label.

[avantgarden]

Dnmun,
I don't have the bike with me for the weekend.
Why do you need to know BMS values ? Please refer to what I wrote:
"Charging time is not a factor for me since I have 8 hours to charge my battery when I'm at work.
So the slower the better for the battery, right ?
A 3A charger should be enough then in my case..."

[dnmun]

while you have it open, measure all the cell voltages and write them down when it is balanced. keep track of that so you can tell what the original balanced voltages are to make it easier to diagnose the problem your pack has later.

i wondered who made this pack and the type of BMS is the clue, but in reality, i cannot imagine not needing to know. it seems like curiosity is what makes us more than rocks.

[avantgarden]

I'm an Electronics Engineer but I kind of lost you...
1. You mean to say that over time the balance gets lost ? Explain that... Does this mean that the total voltage gets lower ?
2. How are the 16 cells arranged ? Parallel ? serially ? Both ?
Do you have any drawings ?
3. When you say measure the cells, you mean each one independently taken of the circuit , right ?
4. The slower the charge rate the more it is healthy to the battery, right ?

I don't have the bike with me no and I'm curious.
Please try to answer my questions as the thread is developing. Otherwise we'll make no progress. I'm a newbie to this world but I'm a fast learner

[dnmun]

yes. the BMS will balance the cells to a voltage established by the resistor divider bridge on the analog type of BMS like the ping signalab or the others from BMS battery.

if you have the O2 micro for the processor, then it has internal voltage references established digitally, and the processor runs off the high end of the pack, along with having the TVS to protect the processor in case someone reverses polarity on the input to the pack, with a charger. but it has a longer hysteresis when the cells go to the high limit HVC during charging, so they have more trouble balancing, and the shunt current is lower too.

if you have problems later, you will have the current set of voltages that the BMS balances the cells to so if you have problems later, you can compare the balanced voltages then to these setpoints.