Charging time question

[Gyrophoenix]

Hello,

A thought exercise for the electric Gurus amongst us. Here's the set-up:

Eight 12 volt 300ah lithium batteries in parallel. They are connected (via charge controllers with a max rating of 200 amps and dual 4,000 watt inverters) to a 12 volt solar array producing 2,000 watts (167 amps). If the batteries are discharged to 50% overnight, how long will it take for the batteries to be fully charged (assuming nothing is discharging them) from the solar array?

Thank you.

 

[Isaac-1]

Wow that is a big bank of LiFePo4 batteries, I only have a pair of 200AH 12V LiFePo4's.

Assuming an actual 167 amps continuous peak output (which is unlikely due to panel tilt, clouds, etc.)

8x 300 = 2400
X 50% = 1200AH
1200 / 167 = 7.18 hours of peak solar output, which is about 2-3 hours more than you can typically expect out of those panels if they are flat mounted on clear summer day.

 

[Gyrophoenix]

Thank you!

 

[HueyPilotVN]

You beat me to it. I was also going to say 7.12 hours assuming no load on the batteries.

I have 1200 amp hours, (4 300 Amp hour lithium) and 1600 Watts of solar which produce about 140 amps,

Your solar input will also vary at different time of day and conditions of the sky'

If your Invertors are also chargers, then much less time if you turn on and add shore power or genny the next morning.

 

[Isaac-1]

There will also be other factors, like conversion losses in the MPPT solar controller, etc. So take the above as a ballpark figure.

 

[solarman]

Hello,

A thought exercise for the electric Gurus amongst us. Here's the set-up:

Eight 12 volt 300ah lithium batteries in parallel. They are connected (via charge controllers with a max rating of 200 amps and dual 4,000 watt inverters) to a 12 volt solar array producing 2,000 watts (167 amps). If the batteries are discharged to 50% overnight, how long will it take for the batteries to be fully charged (assuming nothing is discharging them) from the solar array?

Thank you.

this is a joke, right ?
even the diy forums wouldn't tell you to setup like this..
ah well, joke or not here are your figures.

12*300*8*50% = 14.4 kW/hrs of discharge
if you really have 2000 Watts of production then depending on your location and
panel orientation,you could have 6 hours of peak harvest.
with charge controller efficiency of 90% and battery charge efficiency of 95%
then recharge time will be in the order of ( 14.4kW / ( 2000 * 90% * 95% ) is approx 8.5 hrs

if you have 2000 watts of panels, not 2000W production, then real production will be less, closer to 85% of 2000 ..so now your recharge time will extend to something like
14.4kW / 1700*90%*95% is approx 10 hrs

 

[Gyrophoenix]

Thanks. Actually I have 2,400 watts of solar panel, so the 2,000 watts in the set-up description was already lowered by 20% to be realistic. I'll be adding another 1,600 watts of panels next year. That definitely should be enough....

 

[Tulecreeper]

What are you trying to power?

 

[Tulecreeper]

Double...

 

[Gyrophoenix]

I guess best described as the most boondock friendly Class A ever created. It's an HR Scepter. The roof has twelve 200 watt panels, and the trailer roof will have another 8 panels (hooked into the coach system with an umbilical). Uses 5 charge controllers (4 panels to a controller), eight 300ah lithiums, and has two 4,000 watt AIMS inverters. Shouldn't need to use the generators too often. Pretty much be able to stay off the electric grid.

 

[Tulecreeper]

I guess best described as the most boondock friendly Class A ever created. It's an HR Scepter. The roof has twelve 200 watt panels, and the trailer roof will have another 8 panels (hooked into the coach system with an umbilical). Uses 5 charge controllers (4 panels to a controller), eight 300ah lithiums, and has two 4,000 watt AIMS inverters. Shouldn't need to use the generators too often. Pretty much be able to stay off the electric grid.

Avoiding the tax man, eh.

 

[Utclmjmpr]

My thought would be,, how much time will it take to PAY FOR all that compared to "on the grid".??.>>>Dan

 

[Tulecreeper]

My thought would be,, how much time will it take to PAY FOR all that compared to "on the grid".??.>>>Dan

I guess it doesn't matter how much, if you're trying to avoid Guido and Tony.

 

[Gyrophoenix]

To paraphrase the Capital One credit card commercial... "Not having to worry about electrical hookups or burning fuel in the generator... Priceless!"

Seriously, we're going to be involved in supporting SAR groups all over the country, most likely visiting some locations where hook-ups are not available. When we go in to help after a natural disaster, the power grid may be down for days, even weeks. In those circumstances, being self-sufficient is critical.