New panel strange readings

I just bought a solar panel from Harbor Freight Item number 9500 It is rated at 12/18 volt's but when I put my meter to it, it measures 44.xx volt's . I measured the amps and it measures 6.x My question is what could cause such a high measurement? This is my first panel so it may well be something I am doing. I set my multimeter on DCV 200 for volt's I reset my meter lead on10mA and the dial on 10A to get my amp reading. Any help would be greatly appreciated.

Specifications
Features Solar Panels in a Portable Folding Design

For Charging 18V through 24V Batteries, Charging Indicator LED,

Blocking Diode to Prevent Draining, Four Different Adaptors

Overall Dimensions 26 1/2” L X 20 1/2” W x 3/4” T (open position)

Output 400 mA Maximum

~24 V Direct Sunlight, ~17.5 V Indirect Sunlight

Power Cord 10 ft. Length, Two Way Insulated Plug

Weight 9.7 lb.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,708 admin
    Re: New panel strange readings

    It sounds like your meter battery may need replacing? Or are you doing the voltage and current measurements correctly (10mA reading and leads connected to 10A range???)?

    I could not find an Item# 9500... Just an Item# 90599 45 Watt Solar Panel Kit.

    The specifications you are listing look to be a mix of several different sets... One of a 45 watt "12 volt" charging system (above), and another of a 5 watt portable battery charger.

    Do you have a link to what you purchased?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New panel strange readings

    Harbour Freight strikes again! :p

    A panel capable of charging a 24 Volt battery could have a Voc of 44 Volts. That's something we need to get carved in stone around here:

    Every solar panel has three Voltage ratings;
    Nominal system Voltage (12, 24)
    Voltage Open Circuit (20, 35, et cetera)
    Voltage @ Maximum Power (17, 30, et cetera)

    You're probably reading the Voltage Open Circuit, because that's what you get if you put a DVM on a panel that isn't connected to a load.

    400 milliamp output? That's 0.4 Amps. How were you getting a 6 Amp reading?
  • System2System2 Posts: 6,290 admin
    Re: New panel strange readings

    sorry for the typo, item number 95000 my meter is also from Harbor Freight and is new . I am use it on an open circuit, (no Load) so the reading is believable. The meter i am using has a 20mA setting. I want to use it to charge a 12 car battery for lights in a trailer. May need to rethink the whole thing. Thanks for you input.
  • icarusicarus Solar Expert Posts: 5,351 ✭✭✭✭
    Re: New panel strange readings

    Just fyi, a 40ma panel will likely BARELY keep a 12 volt car battery on float. It is way too small to provide any meaningful charge into a battery that you are actually using for anything.

    There is a standing condemnation of most Harbor Freight solar stuff. It is mostly junk, useful mostly for toying with. Some here have gotten a start in PV with HF stuff, only to move on to "real" solar stuff.

    As long as it's cheap, have fun, but beware of spending any more money on this system. Consider the "ready, fire, aim" syndrome.

    Welcome to the forum and good luck with your project.

    Tony
  • BB.BB. Super Moderators, Administrators Posts: 29,708 admin
    Re: New panel strange readings

    OK--Here it is...

    Assuming it can charge an 18 volt electric drill at 24 volts and 0.4 Amps (400 mAmps), then it is a:
    • Power=V*I= 24 volts * 0.4 amps = 9.6 watt or so panel
    Not a very large panel--but if it meets your needs for charging a portable drill--that is fine.

    It may e possible for you to measure upwards of 44 volts--That panel would be capable of charging upwards of 34 volts DC or so:
    • P= 34 volts * 0.4 amps = 13.6 watts
    In general, you want to match the Vmp (voltage maximum power) point of the panel such that it will be a bit higher than the charging voltage of the battery pack.

    For example, a 24 volt Lead Acid battery bank should be charged around 29 volts. With controller and wiring voltage drop, plus hot panels don't output quite as much voltage--for a 24 volt battery bank, the panel Vmp should be around 34-35 volts or so.

    Unfortunately, the website does not have much technical information for this setup...

    Is there something (other than the cordless drill) that your are trying to charge?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New panel strange readings

    Car batteries are generally around 100 Amp hours, and won't even notice the output from this panel. Its 44 Voc would be sunk to battery Voltage level, and its rated maximum 0.4 Amp output will be meaningless.

    Even one of these http://www.canadiantire.ca/AST/browse/4/Auto/SolarPortablePower/SolarEnergy/PRDOVR~0112020P/Sunforce%252BSolar%252BPanel%25252C%252B1.8W.jsp?locale=en which is meant to maintain a car battery is really insufficient. You really need about 15 Watts to do this properly. More if you want the panel to actually recharge the battery.
  • System2System2 Posts: 6,290 admin
    Re: New panel strange readings

    I'm on my way back to Harbor Freight, now where did I put that receipt?

    Thanks guy I how someday I'll be as helpful as you have been.
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