microprocessor car battery charger

[jbates58]

Hi all.

please excuse me, im not the best at all this electronics stuff, but i consider my self fairly knowledgeable at it.

i am looking to create a circut for charging car batteries, but basically i need/want to use the same type of circuitry and charging systems, and stages as found in a cTek battery charger. i am looking to incorporate it into something that i have invented. but after looking through the forum for hours, and having square eyes, i am lost.

i am also looking for a circuit (for the same invention) where it is basically a voltage sensitive relay, where when the voltage of A is at X volts, then the relay auto engages, and parallels both batteries; the voltages will also need to be set to a predetermind limit for cut-in, and cut-out. but i am lost as to how to make that as well. i have gotten a circuit sorted for charge time switching between the batteries, but i am looking to make an all in 1 box, that does it all. and i am happy for it to be on a PCB, as long as i can get it made and the components easily and cheaply, im after something reliable, and can be made watertight (by the use of seals or silicon) heat generation shouldn't be a problem, as i can use exterior heat sinks and stuff.

so, if that makes any sense to you, can you help?

for those that dont know what a ctek charger is, **broken link removed**

i currently own a powertech plus charger, its basicly the same as the ctek, but cheaper. here is a link to it:**broken link removed**

and i also currently use thease vsr's in my car: BLA: Boating's Leading Accessories

Cheers

Jbates58

 

[ronv]

Sounds like a micro processor job alright. I think I would start by making a flow chart of what you want to do when and at what voltages and currents, then see where the blanks are.

 

[MikeMl]

Just curious, why do you need to parallel two batteries to charge them? First problem is that if the batteries have slightly different internal resistances, then they will not charge equally. You usually have to use some sort of isolation diodes to prevent this interaction.

I would just buy two smart chargers, and leave the batteries connected in series. That way it doesn't matter what the relative state of charge of the two batteries is; each charger can do its own thing based on what its own battery is doing.