Alan
I have a policy of only discharging only one bank in a day. I keep a bank available for emergencies. It is rare that have to switch banks before I get a chance to recharge. If I need 100AH/day, I need two banks with that capacity.
As I’m sure you know, it is bad for a battery to completely discharge. If you want your batteries to last a few years, you can’t discharge them completely. I switch battery banks when the voltmeter shows a 12.0 volt reading under a moderate load (approx 5A). This is about 50% discharged. It is also very difficult to bring a battery up to 100% charge. Even the smart regulators drop off after a timed period. If you get your batteries up to 90% charge, you’re doing well. This means that I’m only getting 40% of the rated capacity out of the battery bank. If the bank is rated at 220AH, I can only get about 88AH out of it. That’s close to what I use on a daily basis without refrigeration. The largest consumer is lighting, but the television, radio, and electronics take their share.
On a related subject, I went on a cruise last month with my daughter. It’s the first time I went on something that large. I really enjoyed it. I particularly enjoyed watching the crew maneuver the 950 foot ship in and out of the slip without tugs. We shared a dinner table with a guy who works for a light bulb company. He’s an engineer who is working on LED lighting. I had a chance to discuss what is going on in the industry and got a lot of good information. He said that one of the challenges he has is finding a way to dim the LED bulbs. They have a new replacement bulb that sets different light levels by quickly toggling the on/off switch. Another challenge is finding a way to make a point light source. He said that current LED technology is about on par with the efficiency of fluorescent lighting. This surprised me since I was always under the impression that LEDs were more efficient. I didn’t get a chance to discuss where the power was lost, but I suspect that
it is
in the current regulation circuitry. Bulb life is drastically shortened if too much current is consumed. In an installation such as a boat where the 12v source varies by so much, it is difficult to get an efficient regulation circuit. This is interesting, since I’ve been evaluating the value in replacing some of my fixtures with LED lamps. It may be more practical to replace at least the overhead lamps with fluorescent.
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Rich Carter
Original message
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