How can I convert my old battery pack to use as power source when power goes out, like for a light, little fan etc?

[alpharalpha]

I have a pack of Lifepo4 cells, still like new, just a bit bulky and I don't do the long ride I originally purchased them for so was wondering how I'd go about repurposing them to use as a power supply, just for some things like a little light, small car type fan etc? We are in hurricane season down here and if the power was to go out for an extended amount of time something like that car fan would be really useful as we can't open the windows in that situation and it gets really hot. I keep one of those 2aa battery fans that can hang off the neck, bettter than nothing, but the car fan would be better. I figure it's probably a simple transformer but can't seem to find the info on google.

 

[Chalo]

You need a DC-DC voltage converter to run 12V stuff, or an inverter to run AC household appliances. In either case, it must correspond to your battery's voltage.

 

[jonyjoe303]

you need a buck converter to lower the voltage to 12.6 volts (or whatever you require) you can find them on ebay for about 10 dollars. The buck converters have two small potentiometers that you turn, one is for the voltage and the other is for max amps you want it to put out. The ones I built I added a volt/amp led meter (about 6 dollars) so I can read the voltage/amps being used. The volt/amp meter make it easy to adjust the output voltage/amps but you can also use a multimeter.

Beside putting out stable output voltage, they can also be used as a battery charger since they are CC/CV capable. I put a small fan on all of them since they get hot when using higher amps.

buck converter with volt amp meter


here is a couple I built, for different voltages.

 

[alpharalpha]

Found them, thanks

 

[amberwolf]

you need a buck converter to lower the voltage to 12.6 volts (or whatever you require)

fwiw, 13.6v is typical "automotive 12v"s actual voltage.

(though it can range as high as 14.4-15v when revving an engine with little electrical load on it, so most stuff can tolerate that easily, and some of it even more...and some of it will operate down to 10v or so, perhpas lower, but since most of the stuff like lights, fans, etc., doesn't have internal regulators it spins faster or brightens at higher voltages, and spins slower or dims at lower voltages).

 

[Hwy89]

I just bought a 48 volt inverter for that very purpose.

 

[john61ct]

Ah capacity per cell? Tital cell count?

Atomising and reconnecting as 4S will be better, no DCDC needed

 

[j bjork]

Ah capacity per cell? Tital cell count?

Atomising and reconnecting as 4S will be better, no DCDC needed

Agreed, and if you make them in to several 4s packs you can parallel and/or series connect them to desired voltage.
Like 12, 24, 36, 48v

 

[john61ct]

If doing that then leave external connections for dwapping out BMS rather than embedding in the case(s)