Martin it is largely academic if an Edison type bulb is 100% current source. When testing a lipo between 4.2 and 3.1 V or a lead acid between 14.7 and 10.7 it is good enough (tm)

Reply to
Jan Panteltje
Loading thread data ...

Off a 220V line, the difference in charging current between one and two car batteries in series is just 3%.

In the bush, that's a pretty cheap, rugged, calibrated current source.

Cheers, James Arthur

Reply to

Indeed, Martin, I once used a small incandescent bulb as a rough constant current regulator for a string of red LEDs running from a 12V battery on my bike.

The bulb was mounted on the handlebars and normally ran dull red. This was a useful indication that the rear lights were on, and also provided a battery charge indicator - it would go out when the battery needed charging but the LEDs were still operating.


Reply to
Syd Rumpo


Probably a good load for measuring reserve capicity for a lead acid.

Lipo or li-ion may be another thing, they usually run a converter which keeps constant power. Which means increasing current as voltage drops.

It depends upon the application.


Reply to
Martin Riddle

On a sunny day (Fri, 27 Nov 2015 10:33:53 -0500) it happened Martin Riddle wrote in :

No the other Martin, sorry because I lost the original article, then remembered his words about arguing in school about it, so just wanted to reply.

I got some new RC lipos (single cell) and need to measure some discharge curves. I found that using a 12 V car headlight works just fine (on a 3.8 V lipo). But need a low voltage cutoff to protect the batteries from getting damaged. Bit over 2 amp, simpler than a heatsink with some transistor. And then to log the voltage every minute... until cutoff.

Reply to
Jan Panteltje

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.