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Hello fawfhamilton-- I won't bore you by repeating what Overmod is telling you, except to say that he's generally correct, except on one point, that I'll try to explain below. But, I would also add that you should not set up any car battery system in an unventilated or poorly ventilated confined space (like your basement) if you ever intend to recharge (which I assume you will want to do eventually), because a standard lead-acid car, boat or motorcycle battery vents hydrogen, which is an explosive gas. It's a fire safety hazard!! If you use a battery, take it OUTSIDE or into a well-ventilated space, like the garage with the door open, away from anything combustible, before recharging it. And stand back. I've actually witnessed bad lead-acid batteries explode when they are put on the charger. And (this is where Overmod and I differ), do NOT use an automotive breaker as your primary protection. Fuses and circuit breakers must be capable of safely opening in the presence of very large currents feeding a short circuit (called the interrupting rating because the device is attempting to interrupt and shut off the current). Instead, you will need a dc rated fuse or dc rated circuit breaker and enclosure that is rated for at least 5000-10,000 Amps interrupting current (listed as A.I.C. on the device) for just a single battery, as car and boat batteries, especially deep cycle batteries, can easily provide this very high level of current into a short circuit. The interrupting current is the amount of short circuit current a protective device can take safely while it is trying to open and turn off the power to the short. Note that the "Cold Cranking Amps" usually listed by the battery manufacturer is only a fraction of the current that the battery can dump into a direct short! The reason that this issue is critically important is that electrical switching devices like fuses and circuit breakers can fail catastrophically (read "blow up") if subjected to very high currents that exceed the interrupting rating of the device. And I would definitely not recommend using automotive breakers for this purpose--believe it or not, most of their A.I.C.s are not rated sufficiently high enough to take anywhere near what the battery can put out. The biggest automotive style breakers made (usually 150-200 Amp rated--much too large for what you want to do) are designed, tested and certified to safely interrupt only 2100 Amps! The smaller automotive breakers have even much lower A.I.C. ratings. That's why automotive systems usually have either a big fuse or a fusible link ahead of all the small fuses and breakers. Therefore, I would recommend a properly sized DC rated fuse or a DC rated circuit breaker. Good news, though. Most household circuit breakers are rated for DC also and can usually take a minimum of 10,000 Amps--sufficient to handle a short circuit fed by a single car battery. Any good electrical supply house, electrician or electrical engineer who does commercial wiring design should have access to a Square D, GE or other similar catalog that lists the ratings for these breakers, and can tell you what will work. Tell them you need a 15 amp or 20 Amp breaker rated for 10,000 A.I.C. at 15 Volts dc or more. And, DO run it into a properly rated inverter and then to your power pack(s). Make sure the inverter(s) is (are) properly sized for the total watt (power) rating of your packs that you intend to connect to them, plus about 25%. Also, if you make this wiring permanent, you will almost certainly have to get a permit and meet the National Electrical Code. This, for most lay persons, means you will have to get an electrician to inatall and hook it up. DO THIS, UNLESS YOU HAVE SPECIALIZED ELECTRICAL KNOWLEDGE AND CAN UNDERSTAND WHAT THE CODE REQUIRES!! If you have any questions, respond back on this string as there are obviously several people here (including me) who are willing to assist. Adrianspeeder--good luck from somebody who has been on both sides of the lecturn in the EE lecture hall! Hit the books hard when you start and it'll only get harder from there (thought I was gonna say easier, didn't you??). But the time and effort spent are very rewarding if you continue to have an interest in the discipline. BBROYGBVGW.
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