Using Xantrex C30 to charge from the grid?

[Speo]

Hi,

I was thinking to buy a Xantrex C30 to charge my very small battery bank from the solar panels and wind generator.

On the other hand, can I use this C30 to charge from the grid (110V) if I use a transformer from 110V to 20V and some diodes to rectify to DC? So I will feed the C30 with 20V DC. Is this setup OK?

Thanks,

Speo

[Tom in NH]

You could feed grid sourced dc into the charge controller as you propose. Like you said, you will need to convert the ac into dc of approximately 14 volts or so. Using a transformer will add some inherent inefficiencies, especially if you keep the primary coil energized all the time.

You might also consider just buying an automotive battery charger and hook it up independently to your batteries with your controller also connected. You could either just plug the automotive charger in when the batteries are down or you could make it work automatically if you figure out a circuit to turn the charger on for a set period of time when the battery voltage drops below a certain point.

I developed such a circuit and used it with my solar panels and a homebrew charger made from a transformer and rectifier... but my transformer overheated one day and burnt to a crisp. I replaced the failed charger with an Iota charger and have been absolutely delighted with its performance. IMHO, Iota is the best of the best when it comes to a quality battery charger. --tom

[nothing to lose]

I had never heard of an Iota charger, thanks Tom next time I need one I will look that brand and check it out.

I second the idea of a seperate charger for grid charging. You could build your own or buy one, but I think I would keep it seperate from the Xantrex C30. If the C30 is a charge controller and your feeding from the grid, what happens when the batteries ar full charge? Does it shut off the power or send it to a dump load? Would be kinda wastefull to be dumping grid power

My mina thought is if a home built charger shorts or fries etc.. I would not want to take out the C30 with a problem. Might be unlikely, thought it could happen maybe.

Most of the retail chargers are getting into the "Smart" garbage. They monitor the battery and adjust the amps, won't turn on unless the see the battery conected etc...

Not sure if one of those would even work on a C30 or such and no need anyway. The charger itself controls the amps based on battery state of charge.

 You could build a manual charger, capacitor to limit the amps, rectifier to convert to DC, this would set the charging amps to a max limit based on the cap, the battery holds the volts down untill it reaches full charge. You have to watch something like this close, after batteries reach the charge the volts will try to climb to 120DC and fry batteries.

Normal retail charger, turn it on and forget it (if not a smart charger).

 If a smart charger, watch to be sure it does not go off because of some goofey error or a grid power glitch. That what I hate about Smart Chargers, I get random goofey errors and they shut off at times for no real reason. They won't turn on with a totally dead battery, like leave the car lights on all day, have to charge the battery first like jump start the car, then use the charger. And they turn off with any power failure of a few seconds (we have alot of those) and they  have to be manaully turned back on agian, so if not home to watch it they may turn off in the morning with a power glitch and all day they have not been charging.

 The power glitches here are often enough I plan to run my smart charger from a UPS when I get another large UPS.

I would charge seperate from the C30 in any case myself and just use the C30 for the RE charging.

[Speo]

Thank you guys,

Well, I think I will follow your suggestions and use a car battery charger.

Thanks,

Speo