Battery discharger

gicamuci

Any idea what to use to discharge a single 6V 225Ah lead acid battery so it won't take forever ? Not looking for something high-end or such, but just something I could use and maybe I would have it around.

Photowhit

Might get a 12 volt car heater, It should work at about 1/4 the rated power for 12 volt on 6 volts.

They may have a low voltage disconnect that you would have to bypass.


https://www.amazon.com/Tengcong-Portable-Defogger-3-Outlet-Cigarette/dp/B081V8QF66/ref=asc_df_B081V8QF66/

So on 6 volts it should be about 38watts, drawing 38/6=6.2 amps. Any straight resistance load should work. 

BB.

Lots of ways to address the question...

Say you wanted a 20 amp draw (10% of AH capacity)...

• V=IR
• V/I = R = 6 volts / 20 amps = 0.3 Ohm power resistor
• P=V*I=V^2/R=I^2*R= 6 volts * 20 Amps = 120 Watt power dissipation...

Find some power resistors that series/parallel to 0.3 Ohms and can dissapate >120 Watts--That would work.

So would other "non-traditional" loads... Roughly 200 Feet of 12 AWG cable laying around on a 6 volt battery will draw about 20 amps... If you have a spool of wire, re-spool in loose coils for air circulation:

http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/wirega.html

• 12 AWG wire is 1.588 Ohms per 1,000 feet (rough number)
• 0.3 Ohm load / 1.558 Ohms per 1,000 feet = 0.189 1000 ft = 189 feet

6 volt light bulbs... Here is a 40/45 Watt bulb for old cars and motorcycles:

• P=V*I
• I=P/V= 40 Watts / 6 = 6.7 Amps per bulb
• https://www.amazon.com/PROJECTOR-HEADLIGHT-TRANSPARENT-MOTORCYCLE-SCOOTER/dp/B00CAKB9NK

Get 3-4 of those bulbs for $6 each--Connect them in parallel and you have your load bank.

All the above numbers are approximate... Some things like 189 Feet of #12 AWG cable is a bit shade tree mechanic... And you should verify the actual current--And make sure the wire does not overheat.

Your battery may start at 6.4 volts charged and end up at 5.25 volts dead--So current will vary.

Neat things about filament lamps--They are sort of a constant current drain. When the filament is white hot, the resistance of the filament is relatively high. When the battery voltage drops and the filament starts glowing more towards they yellow/red spectrum, the filament resistance drops.

Of course, there are lots of electronic battery testers/load banks... Ranging from $50 to $250+... I looked around, but it was difficult to find the specification/details to see that it could support 20 amps @ 6 volts (0.3 Ohm) and 120 Watts for hours on end (some seem to indicate continuous discharge of 25% of "rated watts").

Any of this help?

-Bill

mike95490

i used to like sealed beam automotive headlamps.  When one element burned out, i had a new Load for things using the filament that was still good (usually the high beam)

Tecnodave

I have used sealed beams in the same way....also industrial filament bulbs for higher voltages, but as mentioned resistance will vary with voltage/Temperature