Reddit reviews SMAKN 2 Wire Green Dc 4.0-30v LED Panel Digital Display Voltage Meter Voltmeter

A resting battery should read 12.6 volts, give or take. As the downvotes on some of these comments would imply, this 'give or take' isn't that big of a deal... but it is.

A car battery is made for starting. These batteries are designed to push out a ton of amps (called cranking amps) just for a few seconds. There's a big difference between a car battery and, say... a marine battery. A marine battery is made to run electronics (such as your navigation, sounder, bait well, etc) while the boat is off. This requires amp-hours. These are called deep-cycle batteries. In a deep cycle battery, 'about 12 volts' would fly. In a car, the 'about 12' should really be "about 12.6 +/- a couple tenths of an amp." So, 12.3-12.6 would be okay if your starter is good... but not 11.8. That would probably not crank the car over.

Just make sure your starting elements are in good shape. Alternator, Battery, Starter, Etc. Quick Troubleshooting Guide:

• A resting battery should read 12.6 volts. Any less than that with everything off means you have an issue
  
• A battery with the car on should read 14.3. Anything significantly less or more means you have alternator trouble.
  
• A starter should "tap tap tap" very rapidly. A bad starter means a battery that will have to work harder, and it goes on from there.
  
  There's a lot more to it than that, but that'll give you the basic idea.
  
  If you're seriously concerned, get one of these. Run some wire through the firewall to the battery. Red to red, black to black with a toggle switch in between. You could know your voltage on demand! The more practical solution is to keep doing what you're doing... start the car every once in a while. Even a few minutes is enough for the alternator to give the battery some juice!
  
  Have a Harbor Freight near ya? There's almost always a coupon for a free multimeter. It's not bad either! I wouldn't trust it for serious stuff, but for free it's great to get your feet wet with and keep in the glovebox for the just-in-case. Good luck!

I'm sorry for your situation. Check out renogy.com, they are one of the best DIY solar retailers around IMO. Their sales and technical support is also excellent -- I recommend live chatting or calling them to discuss your needs.

Here is a 100W folding suitcase kit. You would only need a 12V battery and 12V inverter to complete it.

This inverter is 500W, pure-sine wave (you want to avoid modified sine) and includes cables to connect to the battery. I would not go higher than 500W on the inverter since the higher the wattage, the higher the self-consumption.

A car battery will work if you cannot obtain a deep cycle but they have to be very careful to not discharge it too deeply (no more than 20% DOD/12.5V for conventional flooded battery) or they will destroy it quickly.

You will also have to educate them on electrical safety and how to operate an off-grid system. You may want to send them a small digital voltmeter display and print out a 12V state of charge table for them to reference (like this one) to avoid deep discharging.

PM me if you have any more questions.

Do you already have the solenoid? I really recommend a Relay isolator instead.

Looks all good but I'm not sure why your solenoid it connected to your fuse box? I would just connect your auxiliary battery to it.

For the ignition source I used my car stereo for that it isn't much power so the amperage should be okay for it.

Edit: Some additional info after having time to look stuff over more.
I would get a simple reader like this.

You'll need at least a 4 gauge wire for the starter to the isolator with it being 80amps.

Are you getting a fuse with a ground connecter? if not theres no need for a grounding wire from the fuse box as each item being powered will just need to be grounded.

Everything else looks fine tho I'm not totally sure on some of those wire gauges for the items outside of the isolator, I use 12 or 14 for most of my items; lights, fan, usb charger, sink pump.

don't sweat it. if you just use the topper that comes with it (or things like it) you'll be fine. but what you need is a way of checking your battery's voltage because you don't want to discharge the battery below 3.5-3.6 volts. i have VV mods that tell me, but i found it was a lot easier to just pinch it between the wires on a voltmeter like this one: http://www.amazon.com/SMAKN-4-0-30v-Digital-Display-Voltmeter/dp/B00B689UGA/

just hold the black wire against the - terminal on your battery and the red wire against the + terminal and check the reading.


you'll also want a better charger than the one that it came with to prevent overcharging. if you get a voltmeter you can check the batteries as they come off the charger as well. they shouldn't read over 4.2v (i generally get 4.15-4.18).