If you haven’t read it, please go to my post on Inverters first. We now have batteries for our bank, and an inverter to pull 120 volt AC power from the batteries (or your alternator in a mobile bank). How do we charge your batteries now?
In an IN HOME bank, we would just use a computer controlled, 3 stage, plug into an outlet, battery charger. Trickle chargers are a waste of money and will never get a battery that has been deep depleted back up to 100%. Don’t use them. The 3 stage charger will provide high current to charge the battery until it gets a fairly high amount charged, and then it will charge is at a lower current until about 90 or 95% charged, and then will trickle charge the battery which is preferred when the battery is almost fully charged. These 3 stage chargers will provide the current needed to charge a bank and then will run in battery maintenance mode to keep battery life at a maximum. This is a must for the HOME bank. Sizes of these differ greatly and should be chosen based on your battery banks.
In the miniature HOME bank (which is just a 12v marine deep cycle battery) a smaller 3 stage charger will work. You still need to use a 3 stage charger. The marine batteries can be carried from room to room with a convenient handle and run local small loads.
In a MOBILE bank, could we connect your batteries directly to your alternator for charging? It is designed to charge your battery in your car after all. Well, If you did connect your battery bank to your alternator (assuming we did not install a 2nd separate alternator directly to your battery bank with no other loads on it, which wouldn’t be a horrible idea), you would also be connected directly to your battery. What does this mean? Anything that can charge your car battery, can charge your battery bank, but that also goes for DISCHARGING. Cranking your engine goes from your bank, if your battery dies, it will drain your bank. Grounded cable to your battery bank would discharge your battery AND bank. We don’t want that. Some people come up with diodes to install that only allow electricity to flow in one direction, but not the other. A cheap and simple way to keep you battery bank charging, but not discharging, is to install a Solar Charger. That’s right, a Solar Charger. It will keep your bank charged, but will not allow it to back feed back to your automobile. Another really cool thing about these chargers is that most of them are also 3-stage battery chargers as well! Your best bet here is to have a 30 amp solar charger plugged into a cigarette lighter / 12V outlet to the battery bank. On newer cars, it will only allow your bank to charge up when the outlet is on (when the car is on), but on older cars, you will either have to unplug your bank when the car is off, or use a switch to disconnect the bank. I go for cheaper and easier is better, so just unplug it when the car is off. Keep ALL electronic devices that are connected to the battery (charger/inverter/etc.) as close to the battery as possible so you reduce the amount of expensive cable you have to run long distances. This will also keep your batteries from being damaged when a cable gets pinched.
On all of your banks, you can use a solar charger to connect a set of solar panels to your banks. Smaller panels for vehicles and larger ones for a home.
I don’t currently use a home bank… but will. I chose to start on a mobile bank to allow me power anywhere, as long as my vehicle is ok. This will allow us to help others in disaster relief. What good are all the preparations in the world, if you can’t use them to help others? What good is it that a man should gain the world, but his soul is lost? He has gained nothing.
Things to consider from this post and the previous backup battery system posts:
1.The amount of current of the 12 volt side of your system will be 10 TIMES greater than that of the 120 volt portion. What does this mean? Much bigger, more expensive cables to deal with more heat.
2.Any direct charging connection will be unregulated, kill battery life, and is a direct DISCHARGE connection. Use a charging unit to regulate this.
3.Two is one and one is none. This means that things fail. Having a backup is great. Backup means of charging your banks, multiple batteries, multiple inverters, etc. For example, you can have a 1000 watt inverter supplying all your loading needs, or 2-500 watt inverters, side by side. Both will give you 1000 watts, but when an inverter fails, one scenario leaves you with 0 watts and the other with 500 watts. Simply put, it is called redundancy.
4.Use deep cycle batteries with large amp-hours. Use batteries suited to your needs. Marine batteries with handles, Heavy GC2 golf cart batteries, and even AGM or Gel batteries are all good choices depending on your application.
5.Reduce your loading as much as possible. Heat/Cool the person, NOT the space. Light only what you need, only how bright you need it. Use LEDs. I love using LED Christmas lights and buying them just after the holidays for savings.
6.Working off of number 5, use self-powered versions over powered versions of items. I found a hand-cranked blender! One revolution by your hand made this thing spin FAST. The gearing in this this was awesome. It may not be quite what a power blender is, but it is really good for camping and a blackout scenario. Don’t use a typical coffee pot that will pull 10+ Amps from your inverter (which is 100 amps from the batteries!) just to keep the coffee hot after brewing. Use a keurig (not self-powered) pot or even better, a French press (self-powered) to make the coffee and place in a good thermos. This will reduce what you use.
7.If you can use DC adapters to power ANYTHING, like cell phones, TVs, or even electric griddles, DO IT. Inverters are 90-95% efficient, but that is still not 100% efficiency. Some gets lost in the inverter, and then some gets lost converting it back to DC, which is used for most electronic devices.
8.Some auxiliary devices that are good are an indicator light (if its on, its good), a plug in battery charging and moitoring system (Tell you voltage and gives red/yellow/green indicators, and the one on the link is REALLY cool), A good water proof breaker or fuse if you will direct connect the bank to your main automobile system this will trip if something gets grounded.
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