Solar power for charging at the field - RC Groups
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Jun 27, 2016, 12:16 PM
vt_sailor
vt_sailor's Avatar

Solar power for charging at the field


Hello all!

I've been some rough calculations and it looks like batteries for this would run about $1.5 / amp-hr. I would plan on having 12V and 24V taps available able to source somewhere around 40 amps per station x 8? Stations. So, in round numbers, how many amp hours do you use in a weekend of flying? Or, if it's easier just list the packs you go through: capacity (mAh), voltage, number of times,

I'll add everything up and turn that into batteries. The solar cells and chargers are about one fifth what I'm guessing the batteries will be.

Thanks
Ray
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Jul 06, 2016, 08:20 PM
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Castel101's Avatar
Hi Ray!

It would be awesome to have solar charging at the field!

At the field I think the most I would charge @ would be 20A, two 5000mah 6S batteries @ 2C. I think that's a reasonable top limit for big batteries?

20A x 4.0V x 6cells = 480W (estimated midpoint between fully discharged and charged). For a regular flying day (8 hours? 8am-4pm) x 6 stations (assuming not all used all the time) = 480W x 8h x 6 stations = 23 KWHr . Obviously the full charging power wouldn't be used all the time... lets say 30% of the time? In between charges and not all stations will run at full use so 23 KWH x 0.3 / 0.90% (charger efficiency) = 7.6 KWHr

7.6 KWHr / 24V = 316 AH batteries in series.

I might be overestimating, not everyone will charge @ 20A and people might charge less than expected. I found this post on the forums, this guys got a system for about $1400 not including the batteries. They shared all the details, using two 120AH batteries:

https://www.rcgroups.com/forums/show...2&postcount=28

Really cool if we could do this .

Ivan
Jul 10, 2016, 02:48 AM
Registered User
OR... We could buy a nice 6000W generator for around $600.

Just sayin' :-)

Dennis
Jul 10, 2016, 02:40 PM
Registered User
For a heavy session, I came up with about 1700 watt hours for my 550 and 600 size helis, quarter scale electric plane and a couple of smaller planes.

Currently I charge at home in 30 minutes to an hour using 3 chargers than can do 110A total (at 25V) running from 2 circuits since they draw more than 20A total. I could/would switch some or all of this to field charging if that became sufficiently easy. I'm toying with the idea of a 700-size heli which could add about 500wh.

Then there are some days where I do 2 heli-only sessions with a trip home to charge in between. These days work out to about 1900wh, but could be 3200wh with a 700. In fact, this would actually encourage the 700 since you'd be making it more convenient which is something to think about in general.
Jul 12, 2016, 06:45 PM
Registered User
Beemans2's Avatar
Just another data point: I use about 1600Watt hours at 24 volts for a moderately full day of flying 2 planes and a helicopter. My maximum charge is two 5500mAh batteries at 2C that use 24 AMPS including the charger from a 24 volt supply.

Solar power at the field would be great.

Paul
Dec 15, 2016, 02:22 PM
Registered User
For my hex-copter I run through three 4S 5400mah packs in a session.