I have some parts that are laying around so I thought I could use them and build shed light.
Here is what I have:
- a bunch of 18650 laptop pulls (going from 2100mAh up to 2500mAh)
- bunch of 12V 10W COB leds but I thought using only 4 of them, maybe 6 tops
big aluminum heatsink
larger pcb should be li-ion charging module but I bought it so long ago that I forgot the characteristics,
smaller pcb is boost DCDC advertised as goog up to 2A but I am not so sure about that (ps. I burned 2 of them by accidentally reversing input polarity).
What I don’t know is how to make battery pack (should I go with all parallel setup or 2S3P (2S6P - higher capacity version),
how to charge that pack (especially if it is 2S) and how to protect it from overdischarging! Or maybe I should go for 4S battery
setup and use DC-DC stepdown but then I have 16.8V battery pack to charge (I don’t have 16.8+V power supply), also this are
old cells, more cells in serial setup could lead to balancing problems and I do not want to spend 20$ on a dedicated BMS!!!
So, any recommendation what to do about battery pack, charging it and protecting from over discharging?
Thanks
P.S. I also have this DC CC 9A 300W Step Down Buck Converter 5-40V To 1.2-35V
First off you need to know what is the actual Forward Voltage of the 12V 10W LED.
in first pic the larger board is CC & CV. I have a couple but forget the middle POT… Lowest current? IIRC it has to do with Li Ion charging or lowest current/voltage shut off?. Will see if I can find specs for ya. I was buying those off ebay for under $2.
Specs in link DC Converter Constant Current Voltage 5-35V to 1.3-30V LED Driver Charger LM2596
This is not a boost so you are limited to less than input voltage.
Once you get into multiple Series packs you should invest in an RC type battery balance charger.
But with that said you can get LiPo RC packs pretty cheap if they are not Super Duper discharge amps.
I have made Li Lion packs and it sucks. Especially with laptop pulls that are already half dead. They will poop out and you need to take it all apart to fix and replace that cell.
You need to have something to cut off when voltage gets too low or replacing Batts will be an endless task.
Ni-Mh Sub C cells will not care. Something to think about…
But in 2 posts I didn’t answer any of the questions or give solutions.
I thought about something similar to make use of the huge amount of laptop pulls, in the end I just ran the cobs off of an old car battery, lasts along time, very little safety risk and I didn’t need to buy or make a charging circuit for the 18650’s, build a battery pack or worry about balance charging. I just charge the car battery as required
Guys, thanks for engaging.
Whole idea behind this was to use parts that I already have and that are laying around unused for several months, without or with at least additional investment as possible. Yes, the lipo rc pack would be better but what will I do with all those liion cells then, I don’t have car or spare car battery or charger for car battery.
What I forgot to mention is that I do have Turnigy accucel 6 balance charger and one of those 1-8S lipo battery testers (which I guess I could use as a crude way of over-discharge protection by periodically testing cells).
I think that the best way would be to use 4S configuration and step down circuit, that would decrease battery pack load opposite to using boost circuits.
I just need to check if I could use 12V-4A PSU with Accucel 6 to charge 16.8V pack!…
Does that 1-8S tester have an alarm? Have seen some like that with alarm.
I have a Tenergy TB6B and have used all kinds of input supplies. Anything from a converted PSU from a Server, Bench PSU to the 12V5A block type. Oh and a Laptop 19V out from a dell. You just may not get the 5A charge but you dont need 5A on a Li Ion.
FYI: my charger uses a 5.5mmX2.5mm connector. 5.5X2.1mm is the more common but don’t fit.
Yes, it does have those two piezo horns, beeps like crazy.
I will build temporary pack (using magnets) and see how charging goes but I need to get balance connectors for accucel, don’t have those.
I am wondering how long you can get 4 10W lights to stay lit. How many P will it take to make this worthwhile. 8 hours would be my goal for it not to become a hassle.
