Author Topic: Solar panel size to charge 50Amp hour battery ?  (Read 264 times)

Offline Bernard

  • Trade Count: (+1)
  • AVForums Grandmaster
  • *****
  • Posts: 2,955
  • Stereo .... what stereo ?
Solar panel size to charge 50Amp hour battery ?
« 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.


Offline Gerlach

  • Trade Count: (+8)
  • AVForums Grandmaster
  • *****
  • Posts: 2,074
  • Far Far away there was a land that was far away.
Re: Solar panel size to charge 50Amp hour battery ?
« Reply #1 on: September 03, 2020, 07:42:43 AM »
@Bernard are you running a PWM or MPPT charger between the panel and battery?
Good drivers have dead flies on the side windows. (Walter Röhrl)

Offline Bernard

  • Trade Count: (+1)
  • AVForums Grandmaster
  • *****
  • Posts: 2,955
  • Stereo .... what stereo ?
Re: Solar panel size to charge 50Amp hour battery ?
« Reply #2 on: September 03, 2020, 07:41:38 PM »
It's a 20amp version of this. I think it's "PWM" ??

Offline ingenieus

  • Trade Count: (0)
  • AVForums Super Veteran
  • ****
  • Posts: 1,192
Re: Solar panel size to charge 50Amp hour battery ?
« Reply #3 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.

Offline Gerlach

  • Trade Count: (+8)
  • AVForums Grandmaster
  • *****
  • Posts: 2,074
  • Far Far away there was a land that was far away.
Re: Solar panel size to charge 50Amp hour battery ?
« Reply #4 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.
Good drivers have dead flies on the side windows. (Walter Röhrl)

Offline Bernard

  • Trade Count: (+1)
  • AVForums Grandmaster
  • *****
  • Posts: 2,955
  • Stereo .... what stereo ?
Re: Solar panel size to charge 50Amp hour battery ?
« Reply #5 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.