Step down a LiPo battery voltage

Thread Starter

Kangaroo Jones III

Joined Dec 7, 2016
4
Hello,

What would be the most light-weight and minimalist way to step down a 6 cell LiPo battery (25.2V fully charged) to the area of 24V-24.5V.

That is, to step it down 0.7V-1.2V. The battery is connected to a device that consumes 0.5A.



Thanks.
 

#12

Joined Nov 30, 2010
18,223
The most minimalist way would be to check on the 24 volt device to find out whether is drops dead or bursts into flames if you give it 25.2 volts. (They usually don't.)
Another way would be a 2 ohm, 1 watt resistor in series with the load.
A third way would be to add a 1N4001 diode in series with the load.
 

Thread Starter

Kangaroo Jones III

Joined Dec 7, 2016
4
In case i choose the diode/resistor way - i have nothing to worry about the very visible difference in thickness of battery wire vs non-thickness of diode/resistor wire ?? i guess it's a kind of a stupid question, but the battery was pricey and it took it 3 weeks to arrive, so i'd better ask even stupid questions..
 
Last edited:

#12

Joined Nov 30, 2010
18,223
You're only talking about 1/2 amp. The wires are thick for reliability during repeated bending. The minimum wire size for 1/2 amp is 23AWG but that size wouldn't survive long term vibration. If you add a resistor or diode, be sure it is protected from bending and vibration. Their solid wire leads are much more brittle than a stranded copper wire.
 

MrSoftware

Joined Oct 29, 2013
2,027
Put a fuse, a small fuse, before the diode. The wires on the LiPo are thick because LiPo's can produce a ton of current. Please post the specs just for discussion.

For example; you've got a 6s LiPo (6 cells in series, 4.2v/cell at full charge), assuming it's from an RC toy I'll guess that it's 5000mAh capacity. If it's rated 50C, then it is rated to produce a constant 250A without damage. If it's shorted, it will make more than that. So please use a fuse. :)
 

MrSoftware

Joined Oct 29, 2013
2,027
That battery should be safe then to deliver 48A continuous, you'll get a good bit more if it shorts. One of the dangers with LiPo is they can deliver enough current to overheat internally and self destruct. Some of the smaller ones have protection circuitry, but the bigger ones like the ones used on RC toys don't normally have any protection circuitry. There are tons of videos on youtube showing shorted LiPo's, here's one I grabbed at random:

 
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