AVForums South Africa

Open Chat => Alternative Power => Topic started by: Bernard on September 02, 2020, 12:24:26 PM

Title: Solar panel size to charge 50Amp hour battery ?
Post by: Bernard on September 02, 2020, 12:24:26 PM
I have a 50W panel trying to charge a 50Ah battery.(half car battery size) I don't get much uptime when reading in bed with a small LED strip light and charging my phone and small 2-way radio. Panel is at 40 degrees in full sunlight facing north.

My gut feeling says the panel is too small ??

Sent from my telephone.

Title: Re: Solar panel size to charge 50Amp hour battery ?
Post by: Gerlach on September 03, 2020, 07:42:43 AM
@Bernard are you running a PWM or MPPT charger between the panel and battery?
Title: Re: Solar panel size to charge 50Amp hour battery ?
Post by: Bernard on September 03, 2020, 07:41:38 PM
It's a 20amp version of this. I think it's "PWM" ??
(https://img.bidorbuy.co.za/image/upload/v1552898751/user_images/640/3909640/190318104541_regolatore-di-carica-solare-batteria-1224v-30a-pwm-display-2-uscite-usb-2a.jpg)
Title: Re: Solar panel size to charge 50Amp hour battery ?
Post by: ingenieus on September 03, 2020, 10:01:10 PM
Some wildly mildly inaccurate math help. Or not, but let's plow ahead. 50W at 12V means 4,17A (50/12). The time to charge a 50Ah battery would be 12 hours (50/4.17). These are very approximate, not allowing for losses or the sun not not hitting the panel at the optimum angle. On the other hand, the battery will never be depleted to zero. At any rate, it looks like you will need two days of daylight to charge up that battery. I agree with your gut feel.
Title: Re: Solar panel size to charge 50Amp hour battery ?
Post by: Gerlach on September 04, 2020, 07:00:12 AM
Panel size can be a bit to small for the charge but the PWM will help with boosting it. I guess you using a normal Car battery for this setup of yours. Just remember, car battery isn't design to be cycle deep or to be discharge for long. The plates inside is thin and they start whopping inside. I guess your battery maybe took the hit there.  You need to check to get a GEL or AGM battery that is design for this sort of stuff. Other option is Lifepo4 or Lithuim but it's a bit more expensive.
Title: Re: Solar panel size to charge 50Amp hour battery ?
Post by: Bernard on September 06, 2020, 10:41:28 AM
Thanks for help guys. Now I know how to remedy this. The kit was bought from a dollar shop in George so I guess it should be the proper item and not a car battery. I do know that the guy who was helping me (standing in for the owner) was fired. He sold me lighting flex for the panel to regutor connection. I took the kit back and complained and the owner just cut off all my correct Anderson plugs and sold me heavier guage stuff.


Sent from my telephone.

Title: Re: Solar panel size to charge 50Amp hour battery ?
Post by: Bernard on November 11, 2020, 04:28:25 PM
"Solar" shop .... not "dollar" shop as shown above. lol

OK ... thanks to all above. I installed a 2nd 50W panel yesterday. ...and they have changed the connectors since I did my 1st one. They're now round, black "clip ons"

The two 50W panels in direct sun give me 18.5 volts and just over 5 Amps. The 50Ah battery must be fully charged because when I check the screen on the regulator it shows the battery at 13.8 volts and zero amps coming in. (There is no load)

Tomorrow I'm going to put on the hinges to make the 2 panels "foldable" and then get some brackets with wing nuts to fabricate an adjustable frame to get the right sun angle.

Then it's my chip amp as per Wolla.
Title: Re: Solar panel size to charge 50Amp hour battery ?
Post by: Gerlach on November 11, 2020, 08:23:34 PM
They call them MC4 connectors , the round black clip plugs  ;) glad you sorted. If you get the opportunity, get a Microcare 20A MPPT or a Victron Smart MPPT. The Microcare got n a screen that will give you nice info what the pannels doing and supplying and charging. The Victron smart got Bluetooth connect so you can connect your phone to it and you can adjust settings and pull stads.