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From: Rufus Laggren (no email)
Date: Tue Feb 10 2004 - 00:44:07 EST
Various thoughts, mostly involving KISS (Keep It Simple Stupid) and ROI.
Electronics are wonderful, but: They cost a lot and fail more easily than most other stuff aboard. Different manufacterers' bits and pieces are often difficult to combine, even though the theory says no-problema. It sounds like you are trying to utilize what you have, which means you don't want to throw buckets of money at it, then throw more buckets next year.
Generally: All the wiring needs to be top drawer, tinned with waterproof mechanical connections, proper (or even over-) size, correct insulation (engine rooms need tougher stuff), strapped and secured so it won't move around when bashing into waves. Consider using marking tape on some of the wires so you can figure out what you did next year. Provide as much easy access as possible, add good lighting down in the bowels so you can do a good job and not re-do it later. If possible you want it to be easy to maintain water in the batteries so try to do cables and battery tie downs, box covers, work lighting, etc with that in mind. Even if you use gel-cells now, you may put in something cheaper later. Electronics and wiring s/b as high as possible, and as far away from the engine hoses and pumps as possible. Electronics boards can be shielded from spraying hose leaks with a simple piece of wood or plastic, or even just a little piece of tarp hooked over the works. If you keep the
small wiring high and out of the water, and worst comes to worst, your batteries will probably live under water for several hours and thus keep your pumps, radio, lights, and other stuff going. Grease up the battery terminals liberally to help prevent corrosion.
Basic starting: Most starter batteries seem to live 4-5 years easily with just the standard dumb engine charger. They'll live longer if you ensure they always and only _get_ the standard dumb charge. This suggests that you consider just using the standard setup and replacing the batteries whenever. This should work very well, keep it simple, and be cheap. Separate the two starter systems _entirely_, and just keep a good pair of jumper cables (custom made?) down there for emergencies; if that seems too neanderthal, wire up a simple big switch down in the engine room to parallel the starter batteries in an emergency. But the jumpers are cheaper, take less space, and work just as well. If both starter batteries fail, jumper from the house battery. Permanently wire _good_ hi-impedance (means they draw zilch current) digital voltage meters on each battery with no switches, just an inline fuse; locate them in a place of honor where you'll contemplate them each morning over your cof
fee cup (or something). If you run the meters off the "ignition" switch, you introduce at least 3 or 4 additional connections which could go bad and influence the readings of the meters. Also, you prevent the meters from reading (and alerting you) if the engine is not running. Learn how they behave. Extra fancy would be an under/over voltage buzzer/light. A dedicated meter for each bank is better, if you have the space, because it keeps the visual understanding of your stuff as simple as possible and keeps the condition of all batteries visible at all times so you don't forget one. No switches or anything else to fiddle with, either. What? You want fancy? Put a switch _under_ the panel (should never need it...) by the meters to change each meter to the other battery to check their readings, and/or in case on of them fails. But make awful sure the switch and connections are good... Want extra-fancy? Wire in a small PV panel directly to _each_ starter battery (total two pane
ls) to keep things happy when left alone for weeks or months. No regulators, no switches, just a fuse and good wiring practice, permanently installed. You don't need to hook these batteries to anything else - in particular, other chargers.
Each piece of the above system is independent, cheap (mostly), simple, and it can fail without taking down anything else. I think it will provide as-good or better service than anything else available.
House batteries: One large bank makes it simpler and allows potentially shallower cycles, making for longer battery life. But there are lots of trade-offs, one of which is the charging alternator - a huge bank can kill a weak alternator. You can read what one techno-freak (a very nice guy who has contributed a lot of research to the boating community) has done here:
Large house banks is where special chargers can pay for themselves, but again, the simpler you keep it, the less confusion, the fewer failures, the lower cost. One thing about these great elegant inverter/chargers is that most of them spew out a blizzard of RFI and wipe out radio and other stuff while they're running. Chalk it up to consumer marketing and be warned. If you can install the beast inside a grounded metal cage (copper door screen works well) you could save yourself some headache. However, they do a good job at what they do... To get the best from them, you need some bells and whistles (goodby KISS) - in particular, you need a temperature sensor installed on your battery bank. The wiring to the shunt sensor at the battery terminal is _very_ sensitive and must be done perfectly, with no extra connections to foul up your readings. You also need to visit the web site and do some inet searches and find out what little peculiarities your brand/model has built into it.
Especially, you need to find out if there is new improved software (firmware) for your model which can prevent known problems. It's not always clear whether the disease is worth the cure, but it's better to at least know what's out there. Positioning these things is a head scratcher because they can weigh a lot, need to be high and dry, handle very large battery current (200amp=very large wires), mess of compasses, radios, sometimes get pretty hot, etc, etc, etc. Some of them HUMMMMMMM.
> reversed alternator...
Sometimes things are like they are for some particular reason, and occasionally it's a good reason. Possibly mounting it that way spins it the right direction. If you consider upgrading an alternator, remember that large alternators can require special drive belts, pulleys, etc and put a serious side load on the end of a crank that may not be designed for it. It may make more sense to plan on charging with the genset/inverter. This would probably handle a single large house bank easily.
Since the genset starts to look pretty important, you may want to move some budget dollars over that direction to make service access easy and soundproof the thing really well.
I assume you know about the Nigel Calder book "Electrical and Mechnical Systems for Boatowners". It's something of a bible and in particular it details the correct way to ground the various electrical systems on your boat safely. Very, very important. Also check out the Lightning section.
IMHO (of course).
Best luck, Rufus
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