Sorry for the long delay in posting. Been busy on a couple projects, one of which will be a nice original project for this site.

So on to today’s post. Some smart dude somewhere at some point in time said knowledge is power, and this post is a tribute to that. Every novice prepper quickly finds solar panels on the list, and that is great, so you run out and buy 300 dollars worth of cells, a battery and a charge controller, stick it in the basement and forget about it. (I have yet to buy cells, but they are on the list.) That is probably where most average people stop thinking. Well I was thinking about it one day, and realized that if SHTF and it suddenly became hard to get even the most basic tools, if you don’t have those tools, you won’t have those tools. Now thinking about a really bad situation, say EMP, everyone around will quickly be scavenging car batteries and jerry rigging plenty of things with what little working equipment is left. Not only that, but it will quickly become apparent that when dealing with 12 Volt car batteries, every amp counts, so if you don’t know what your pulling you will quickly be left with a dead battery. Most people happen to have a multi-meter around but thats a pain in arse for real world jerry rigging, you have to hold it in place and don’t get a good feel for normal usage.

So I started hunting on ebay and found a cheap analog panel meter and some really cheap battery clamps. Now I can easily meter my power usage and leave the meter in place to see normal usage easily. The one I bought went up to 20 amps. I should probably get two more, one with a smaller/finer range and one up to say 100 amps. While I was at it, I also bought over a dozen of the clamps for less than 5 bucks. These are very cheap items that could be very useful as trade items with neighbors. The dinky ones are only good for 15 amps, but your not going to be pushing around lots of amps with some solar cells. In addition I bought a slightly larger set good for 100A.

When doing a test one day during a winter power outage, I wanted to see what my little inverter could power from my car and also wanted to charge my wifes and my cell phone. I had bought one of those cheap 3 way splitters from ebay and tried plugging everything into that. I quickly found that the inverter would cut out when I hooked it up this way. The wire in the 3 way splitter was way too small. So I got on ebay and found some cheap 12 Volt car female receptacles for a couple bucks. They were really cheap and were of fair enough quality that I was able to wire them up with 16 gauge extension cord wire and it seems really solid. So now I can attach and run multiple devices to a car battery. Good thing to have.

I also wanted a finer meter that was easier to read. Specifically I wanted this to keep an eye on a small floating charger I have that keeps my deep cycle battery topped off. This small charger has worked great, but the problem is, that if the charger fails the indicator led is back fed from the battery and stays on and will eventually run your battery dry and kill it. So I searched Ebay for a digital panel meter. I found a cheap one from chine for just over 10 bucks. Then my experimentation became annoying. Once receiving the unit and the shunt (a shunt is a low resistance, resistor that sets up a voltage difference which is measured by the amp meter.) I put it together in a small project box with a power switch. I also added a 12V linear regulator to give the unit clean power, not sure if it was needed, but I did it anyways. After doing all this I plugged it in, and promptly fried the meter. This mistake was technically my fault, but I slightly blame the crappy chinese ebay page. On that page they had pictures of the correct way to hook the unit up. I had looked at them when buying the unit, but the links were broken a month later when I received the unit and went to install it. Thinking it didn’t matter, I hooked it up with the shunt on the positive leg of the circuit, as some may guess that fries the meter. So I ordered a replacement, and a month later re-wired it correctly. Then I became really annoyed when I could not get the unit to zero out. The closest I could get was -1.3 volts by adjusting the adjustment pot. I tried hacking it a bit to  change the range of the adjustment pot, but that didn’t work out to well. Evidently this pot doesn’t just zero the unit but also adjusts the scaling. Ugg… In addition during my testing I discovered the unit does not track actual amps that well. At 0 amps it reads -1.3, with 0.45 amps going it read -1.8 amps, then with 6 amps going across it read -6 amps. So the overall story here is: you get what you pay for. I am still trying to get the eBay seller to send me a new meter. So this meter stinks, but it will at least tell me if the charger is working. I don’t leave the meter one, I just flip it on once a week or so when I turn on a small ham radio I have hooked up to the battery while working in the garage. If you have any better suggestions for mega cheap digital panel meters, leave a comment.

So all these little things are shown in the picture below and while this isn’t mind blowing stuff, if you don’t have them you will wish you did. They are just little tools that can be bought mega cheap on ebay, but could be very valuable when every amp on the battery must be carefully managed after the SHTF.

Meters and Clamps

Float Charger

Update: After thinking about it, I should probably just add a small power diode to the charger to prevent the indicator LED from being back fed.