LiFePO4 battery charger

Hi :

Time ago I bought some LiFePO4 batteries in China.
One of them are 48V 15AH, 16 cells in series.

The charger of this battery are very interesting because it charges each cell independently .

Here some pictures :




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The charger have 2 boards.
The first one have a rectifier . The 220V input are transformed to V DC. The DC voltage feeds each board
Each board charge 8 cells.
The board includes four black box, four three winding transformer and 8 charge circuit.
I think black board are something like a inverter that feeds each transformer primary Winding.

If somebody have experience with this kind of charger, i please post here some information.

Regards
Rodrigo

Charging each paralleled group of cells independently is by far the best way to charge a pack. It avoids the need for cell balancing that is required when you charge a series connected string of cells. Unfortunately, it is the most expensive type of charger to build and does require a good muti-contact connector for the pack.

But in many ways it is the simplest way of charging a pack. Several people have built such systems out of DC-DC converter modules used in the telecom industry. They take (usually 48 volts) in and output 3-5V. They usually have a way of adjusting the voltage to match what the cells require. The modules often show up on the surplus market for cheap. Lucent is a major manufacturer. You do need to find a way to shut of the modules when the cells are fully charged (or run them at the cell makers specified safe "float charge" voltage).

i have one of those too. what does your battery pack look like? the little black plastic box is the controller for the SMPS switch mode power supply. each stage is a separate 3.65V power supply, stacked one on top of the next up to the final voltage.

dnmun said:

i have one of those too. what does your battery pack look like? the little black plastic box is the controller for the SMPS switch mode power supply. each stage is a separate 3.65V power supply, stacked one on top of the next up to the final voltage.

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Here some pictures of battery :



View attachment 1

Thanks for describe black box. I will try to find the label of it but I think was erased.

Regards

yes, totally identical. the same BMS board and long pouches. but this one i have is 10Ah pouches (215mm long, 80mm wide and 6.5mm thick). printed with zbike.com.au on the surface but those guys don't provide any support.

this pack had a problem with the tabs cracking and breaking from metal fatigue because the weight of the pouches pushed against the end and cramped them up in the plastic box until they just burned through.

after replacing 2 pouches originally, the battery output through the BMS was shut off. i could never figure out why the BMS shut down the output, so i had to bypass the BMS for the guy to continue using it after i replaced the initial failure of the tabs on 2 of the pouches. now another 2 are bad and i had to buy it off him because it wasn't worth repairing any more.

after cutting the BMS off, all those separate wires, i found that one of the tiny wires to the BMS had pulled out of the plug so it did not make good contact, and i think that was why the BMS shut off the output FETs. really bad design, imo. plus no support any more.

what is the size of each 15Ah pouch on yours?

Size of my 15AH cells are:
246mm long, 82mm wide and 11 mm thick

The brand of battery is Huanyu (http://www.huanyubattery.com)

I foud BMS on web. Here is the web site : http://www.lt-power.com/product.asp protection board LT-PG02 model.

Now I have problems with one of the three winding transformer in charger . It are producing noise when plug into 220VAC. Also the charge ligth start running with no battery connected.

If you need contact information of huanyu, please pm me.

Regards
Rodrigo