Buck Converter

[dkcomm]

Hello everyone,

I bought a tiny cc cv buck converter on E-BAY. It was referred to as: "5A DC to DC CC CV Lithium Battery Charging Board Led drive power converter". It seems to be working fine, however, as with so many Chinese products there were no instructions. I connected the converter first to a variable PS and adjusted the voltage on the buck converter board. Worked just fine; a red LED lighted up. I then attached it to my solar panel (Its actual destiny.) and through fiddeling around, a blue LED lit up! Now I have red again. I attached a 300 ohm resistor to the output and everything seems to be working - EXCEPT - I haven't the faintest idea what the red/blue LEDs are for and I have no idea how to adjust the current pot. Does anyone have experience with this thing? It looks very well made and seems to work; but...

Point No.2 I recently had most unfavorable dealings with FUTURETREND01. I bought a solar charge controller from them and it arrived defective. It was listed in E-BAY as: "10A MPPT Solar Charge Controller Regulator 12V 24V Autoswitch Solar Panel #160871594102". The device would not recognize the solar panel (I connected the SP only AFTER the battery connection which it recognized.) I tried to contact the company but did not hear from them for over 3 weeks. They told me I had to return the original, defective device. Well, I have some severe physical limitations and problems, and, there is not a post office next door, and, I would have to pay the return postage which would make the thing, all things considered, prohibitively expensive. I tried to explain this to the FUTURETREND01 company and even promised to do as much business with them in the future as possible (I have to buy from somebody.) The response from them was: "We have our rules."

Just a word for the wise, I, personally, will never deal with FUTURETREND01 again. I suppose I can dig into the piece of junk and salvage a few LEDs, perhaps a working MOSFET, but other than that it will be a lesson and a loss.

Don Kennedy - dkcomm

 

[heathyoung]

OK - the cheap 'mppt' solar controller will just be a crappy PWM based one - they suck.

Your buck converter - I have seen these ones before, I'll see if I can find the instructions for them.

Here - common as mud.

http://www.ebay.com.au/itm/DC-Buck-Converter-voltage-Step-Down-CC-CV-Adjustable-Power-Supply-Module-LM2596-/171003176697?pt=AU_B_I_Electrical_Test_Equipment&hash=item27d09566f9

Chinglish translation

Battery use:
Make sure of the voltage and current of the battery you need to charge.
>Get the specs of your battery - ie. float voltage + charge current
Adjust the constant voltage potentiometer to make the output voltage same to the charge voltage.
>Obvious - stick a multimeter on it and adjust it to the float voltage you want
Use the multimeter in 10A current scale to measure output short-circuit current,and adjust the current potentiometer to make sure the output current to the expected charging current value.
>Use a multimeter in current mode and adjust the current to the charge current
Charge transfer lamp current default value is 0.1 times of the charging current(constant current value), For lamp current adjustment, please turn potentiometer adjustment;
>Set the end of charge limit pot to 0.1 X charge current (ie. set it so it goes on at 0.1 x charge current on multimeter)
Connected to the battery, try charging.
>Stick the battery on it now
(1,2,3,4 steps to connect the power module input,output no-load does not take batteries.)
>Don't set it up with the battery connected.

These do need a heatsink if you run them at more than 15W, and have a limit of 50W internally. Stick them on an anodised heatsink with arctic alumina or similar.

These aren't an MPPT, but they work better than the cheap PWM based solar chargers.

Do a search on fleabay for LM2596 - this is the IC from national semiconductor (simple switcher) that these use. Heaps of board out there, cheap, some with LED's some with voltmeters all sorts.

 

[dkcomm]

Heathyoung,

Excellent response; and quick! Many thanks.

Don Kennedy

 

[Rolfiboy]

I am currently working on a MPPT solar charger/Ballancer/BMS system.

First version currently specifications:

4 LiFePO4 cells (can be programmet via RS232 to any max cell voltage between 3-5V)
13Ampere MPPT buckconverter there will accept input voltage up to 76V
3Ampere Ballancer there will ballance every cell at the end of the charge.
50Ampere BMS there will allow to connect up to around 100 of the circuits together with each there battery pack and solar pannel to get af very big system delivering alot of amps and capacity.

Dimensions: PCB 160x100mm with LCD display

I will make a post when i have the first prototype ready and running.

 

[dnmun]

if you need a charge controller why not just send the thing back and get them to replace it. that is common practice for warranty returns so you did not get unfair treatment.

the controller may work yet if you can analyze why it went bad. but sending it back is the best course to follow unless you know enuff to repair it yourself.