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Discussion Starter · #1 ·
2019 Metris cargo van
I'm a locksmith, I have a auxiliary battery and inverter I use to operate a key machine 120 volts 4 amps. Run time 5 hours per week. What size (watts) solar panel do I need to keep the battery fully charged. I live in a very sunny state.
 

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Discussion Starter · #2 ·
What if I used the 12 volt 15 amp RV plug on my console to charge the battery? Would this cause any problems?
 

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Discussion Starter · #3 ·
I spoke to my dealer, they said any electronic hook ups to the Metris would void my warranty. I guess I got to stick to a a solar solution.
 

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any electronic hook ups to the Metris would void my warranty
So, you can't plug your phone charger into the 12v socket?

And "void your warranty" is the most bullcrap dishonest pile of crap ever from any car dealer. They always claim "it will void your warranty." So, some dickhead is telling you that plugging in a batter charger will void the warranty on your transmission? Your brakes? your driveshaft? When the door hinge breaks, the sliding side door jams, the dealer will refuse to fix it because you plugged in a battery charger?

That's not the way warranties work in the USA. There's no such thing in the USA as some sort blanket "void your warranty" bullcrap.

The manual (page 230 of my 2016 Metris) says you can draw 15A from that plug. So, draw up to 15A, and there's not a gosh darn thing those immoral morons can do about any facet of your vehicle warranty.
 

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Warranty claims can only be denied if they are related to something you did; example: you don’t change your spark plugs at the proper time, and that causes your coil packs to burn out- they can deny that warranty claim.

Sensible dealers are reluctant to deny warranty claims, if they can push them through. If they push them through they get paid for the work and you are a happy customer. If they dont, you may take the work elsewhere, and they will probably never see you again.

Here’s the thing: if you have any electrical fault down the line, and it can be reasonably traced- or assumed to be from- your draw and/or external charging of the electrical system, they would have a legitimate reason to deny your claim.

I don’t know why you would want to have a solar charger and battery operated key machine wired into your van at all. If i was you i would get a solar charging mechanism, an appropriate battery, and a key machine wired in closed circuit to themselves.
 

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Discussion Starter · #6 ·
That's what I want to do, but what size solar panel (watts) do I need to keep the battery charged?
 

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Two 100 watt panels fit nicely side by side between the roof rails if they are the 42.3" x 19.5" variety shown here on my cargo van. I have them hooked up to a Goal Zero Yeti lithium battery. The Yeti's are rather pricey but allow power to be drawn while they are charging unlike most.
 

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So you're looking for 20 amp hours per week. A 100 watt flexible mono panel produces about 5 amps per hour. So that should be more than adequate to keep your battery charged with reasonably sunny weather.

 

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Discussion Starter · #9 ·
Wow, that's nice. But I'm looking for the minimum size and watts solar panel for my application.
 

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Assuming running the machine 1 hour per day, you will consume 480wh per day. Assuming 80% efficiency, you will need about 600wh from solar panel every day. That's about the daily output of my 200w solar panel during sunny days. Solar panel output varies by many factors and your panel may output more or less than mine, so my 200w is just for your reference.

The sockets in Metris have maximum 15amp output, or about 180watt. That's not enough to deliver 4 amp at 120volt that you need.
 

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2019 Metris cargo van
I'm a locksmith, I have a auxiliary battery and inverter I use to operate a key machine 120 volts 4 amps. Run time 5 hours per week. What size (watts) solar panel do I need to keep the battery fully charged. I live in a very sunny state.
So, you need 480 watts of power. You need to know the efficiency of the inverter to know how many watts feeds the inverter when the load is on. If your inverter were 50% efficient, you need 960 watts from the battery. You use the machine 5 hours so you draw about 4800 watt hours. Next, you need the charge efficiency of the battery. If it were 50%, you need 9600 watt hours from your solar array. So, it would take a 100 watt panel 96 hours per week to charge the battery if the panel is working at full efficiency. That's 16 hours per day of full sun, 6 days per week, unlikely.
Hopefully, now you can estimate your solar needs.
Conversely, a 200 Amp alternator (I think that's what the Metris has) can produce 200A X 12V or 2400 watts. If your car runs 4 hours and is doing nothing else, the battery would get charged. However, the car has other loads to serve besides your battery. If your battery were using 10% of the alternator's output, you'd need to drive 40 hours per week to charge the battery. Let's hope your inverter is more efficient than 50%. I believe my other efficiencies are about right, but I might be wrong. I hope others chime in to correct my assumptions and or calculations. Otherwise, you've shown why people work hard to avoid inverters by using 12v appliances/motors.. Inverters waste power.
 

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So, you need 480 watts of power. You need to know the efficiency of the inverter to know how many watts feeds the inverter when the load is on. If your inverter were 50% efficient, you need 960 watts from the battery. You use the machine 5 hours so you draw about 4800 watt hours. Next, you need the charge efficiency of the battery. If it were 50%, you need 9600 watt hours from your solar array. So, it would take a 100 watt panel 96 hours per week to charge the battery if the panel is working at full efficiency. That's 16 hours per day of full sun, 6 days per week, unlikely.
Hopefully, now you can estimate your solar needs.
Conversely, a 200 Amp alternator (I think that's what the Metris has) can produce 200A X 12V or 2400 watts. If your car runs 4 hours and is doing nothing else, the battery would get charged. However, the car has other loads to serve besides your battery. If your battery were using 10% of the alternator's output, you'd need to drive 40 hours per week to charge the battery. Let's hope your inverter is more efficient than 50%. I believe my other efficiencies are about right, but I might be wrong. I hope others chime in to correct my assumptions and or calculations. Otherwise, you've shown why people work hard to avoid inverters by using 12v appliances/motors.. Inverters waste power.
P.S. If you're frustrated, I understand. You keep asking the same question and no one has answered it. You may need to do a little work to research your inverter and battery in order to answer your question.
 

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2019 Metris cargo van
I'm a locksmith, I have a auxiliary battery and inverter I use to operate a key machine 120 volts 4 amps. Run time 5 hours per week. What size (watts) solar panel do I need to keep the battery fully charged. I live in a very sunny state.
seem like you already got lots of good response. I had no idea about anything solar and this guy here is awesome. He has so much knowledge, explains solar DIY build and also ready-made purchase options on his channel so somebody that is a newbie to solar can get this right. He also recently created his own blog site for more info and questions you post. Just thought I share as it helped me a lot finding my 'SolarWay":) https://www.youtube.com/user/errolprowse/featured
 

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Two 100 watt panels fit nicely side by side between the roof rails if they are the 42.3" x 19.5" variety shown here on my cargo van. I have them hooked up to a Goal Zero Yeti lithium battery. The Yeti's are rather pricey but allow power to be drawn while they are charging unlike most.
Thanks nice. Is the panels mounted to the cross members? Which model solar panel are these?
 

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Yes, to the after market cross members I purchased on ebay using my own brackets. They are a much lower profile than stock brackets and make the HQST panels invisible from below.
 

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I used flexible panels. I mounted four 100W panels using 3M VHB (Very High Bond) double sided tape. For better (or worse?) those suckers aren't coming off without a lot of work.
How are those holding up? I just wonder the day you'll have to replace a defective one or eol. the high heat of summer doesn't effect them?
 

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Yes, to the after market cross members I purchased on ebay using my own brackets. They are a much lower profile than stock brackets and make the HQST panels invisible from below.
You have a link or name of brand crossmember? I returned some I had before because they were noisy at highway speeds.
 

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