Charging questions

[Ducstrom]

This may be a question for Renogy, but I figure I'll throw it out here and see if anyone has some insight.

I have a Renogy 2000w inverter/ charger for my camper project. It has a charge output between 5-65 amps programmable in 5 amp increments. I am also planning to purchase renogys DC/DC charger with MPPT which has a max output of 50 amps and controls input from solar panels and my trucks alternator.
I will have 300 watts of solar on the roof.

Does anyone know if there has to be a transfer switch between the two chargers? Is it possible to backfeed a charger and damage it?

Also, with charging, I only have an inlet for 110v power. Does the charger need to have the charge profile matched to the source wattage available to prevent popping circuit breakers? If I am charging from the grid or a generator will I have to limit the charge rate with the charger to prevent tripping breakers?

 

[PhillySMB]

Following because I have a similar question


Sent from my iPhone using Tapatalk

 

[DiploStrat]

Simplest answer is "no". Each charger monitors the battery voltage and shuts off when its profile/program tells it to.

Someone likened this to multiple compressors attached to a single tire, each will shut off when it reaches its set point.

 

[rayra]

I'd think your MPPT would see the high volt / charge coming from you AC shore power charger as a full battery state and quit trying to push power to your batteries. And that the MPPT can tolerate the power coming from the AC.
I'd also think you don't need both inputs running at the same time, but don't think it will hurt anything and leaving both hot / on precludes forgetting to turn either one on, later.

 

[Ducstrom]

Awesome, eliminating a transfer switch and leaving both chargers on is the best case scenario.
So no worries on the charger matching the input source?
If I leave the charger at the max 65 amp charge rate at 14.5ish volts, that's 942.5 watts being drawn from the charge source. A standard north american outlet is 115ish volts and has a 15amp breaker which would supply 1725 watts. I'd lose some to the conversion from AC to DC, but ultimately even at max charge I wouldn't draw enough wattage to trip a household circuit breaker.

As far as a generator goes, do you think I could get away with a 1000 watt unit? It's pretty close to the 950 watts the charger would be pulling.

If it matters it'll be a 200 amp lithium bank that will be getting charged.

Please correct me if my math is out to lunch.

 

[rayra]

Keep in mind that in probably far less than a day your wall / shore charger has topped your battery bank and is in maintenance mode at a far lower draw / lower charge rate. That your wall charger isn't going full bore for very long. And if your panels are in full sun your MPPT solar charger should readily maintain your battery bank at top charge, with your shore power charger off / unplugged. Speaking of a parked / stored condition.
My own Suburban's PWM controller is usually in maintenance mode by 11am, after the overnight parasitic loads on my Aux battery, and that's with just a flat mounted 5Amp panel.
And now that I've installed a high-Amp alternator I'm not even worried about that.

 

[luthj]

Many chargers are not power factor corrected, so they will need 20-50% more power for the same output. Its not a terribly simple concept to explain, your best bet would be to contact customer support to see if they have an answer (not very likely though).