Need a circuit to charge a 12V 2Ah battery with 24V 5A dc generator output

AnalogKid

Joined Aug 1, 2013
8,485
Build or buy?

TI, Linear Tech, and Maxim make both switching and linear battery charger control chips. A really smart charger circuit starts out in a low current constant voltage mode to bring a deep-discharged battery up to a safe charging level, then shifts to constant current mode to pump in the watts, then shifts back to constant voltage mode for trickle charging to keep it topped off. Most chargers use only 1 or 2 of these stages.

ak
 

ian field

Joined Oct 27, 2012
6,539
Build or buy?

TI, Linear Tech, and Maxim make both switching and linear battery charger control chips. A really smart charger circuit starts out in a low current constant voltage mode to bring a deep-discharged battery up to a safe charging level, then shifts to constant current mode to pump in the watts, then shifts back to constant voltage mode for trickle charging to keep it topped off. Most chargers use only 1 or 2 of these stages.

ak
Trucker's supplies do 24V to 12V adaptors for running things like 12V portable TVs off the truck 24V system - a neat little solution, but it'd need a bit of modification to make it suitable for battery charging.
 

Zeusameow

Joined Jun 27, 2016
1
I'm in almost the same situation. I have a 12V car battery that measuring 11.2v and my car will not start. I have a cordless drill battery which is 18V, can't I quickly top up my car battery without damaging anything??
 

ian field

Joined Oct 27, 2012
6,539
I'm in almost the same situation. I have a 12V car battery that measuring 11.2v and my car will not start. I have a cordless drill battery which is 18V, can't I quickly top up my car battery without damaging anything??
You can buy made for the job lithium jump start packs.

A columnist in one of the electronics magazines tried one - he deliberately run the car battery flat by leaving the headlights on. He found that one unit wasn't enough, but two were. You can probably buy one that will start a dead flat car...........if you've got deep pockets.
 

tcmtech

Joined Nov 4, 2013
2,867
I'm in almost the same situation. I have a 12V car battery that measuring 11.2v and my car will not start. I have a cordless drill battery which is 18V, can't I quickly top up my car battery without damaging anything??
You could go and get a proper automotive battery charger being your 18-volt battery maybe has 1.8 Ah of power in it and to get your vehicle battery up to the point where it can start the engine might require 5X that amount of Ah to recharge it.
 
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