Some electrical and electronics research

I’ve spent quite a while today researching various electronics and electrical stuff.  Here are few findings.

My house battery bank is 4x Trojan T-105 6V 225 amp-hour golf cart batteries connected in series-parallel for 450 AH @ 12V.  My starter bank is 2x T-105s.  These batteries seem to be universally well-liked and relatively inexpensive, although the fluctuating price of lead has made that less the case recently.  The previous owner felt it was sufficient to plop all the batteries in a crawl space just aft of the companionway, beneath the forward part of the cockpit.  They are not in any kind of a battery box, and they’re loosely covered by a flap of rubber to prevent short circuits.  Needless to say there is a spaghetti of all kinds of wires occupying the space, not to mention plumbing, as the main water pressure pump, watermaker, and even some fuel hoses are all in the same space.  The batteries really need to be in good boxes to isolate them from all this stuff and minimize collateral damage in case of an acid leak.  At first I thought I’d go the DIY route and build a couple plywood boxes sheathed in fiberglass, but after some futher pondering I really don’t have either the tools or workspace to do so and probably it’d end up costing me more than just buying some manufactured polyethylene or polypropylene boxes.  I haven’t been able to find anything with quite the dimensions I want for, say, 2x T-105s per box, and the selection in Singapore is probably pretty limited, but hopefully I’ll be able to find something close enough.

While I was at it I whipped up a quick battery charge percentage graph using data from Trojan, which I’ll maybe laminate and put next to my voltage display.  It’s just slightly nonlinear:

Before I got into all the battery stuff I was doing more AIS research, and I remembered it’s kind of pointless to go AIS shopping unless I have a “maritime mobile service identity” (MMSI) number.  In general you’re not even allowed to walk out of a shop with an AIS transponder without having the shop pre-program your MMSI, because of the potential for abuse.  Unfortunately I don’t have an MMSI.  After some investigation I found I need to get it from my country of registry, which will be Malaysia.  Turns out I need to apply for it along with a ship station radio license from the MCMC.  Surprisingly I can do that online.  Unsurprisingly, I need my registration information, including my assigned callsign, before I can proceed.  The registration is proceeding but is supposedly kind of a slow process.  So perhaps I won’t be installing AIS before I make the trip down to Singapore after all.

I also realized Garmin eTrex series GPSs don’t let me make use of an external antenna, which is kind of a shame.  Now I’m torn between getting a bigger 60CSx with external antenna support, or a smaller eTrex without.  In reality it’s 7.5 oz (60CSx) vs. 5.5 oz (eTrex).  But also in reality, it’s not going to be my primary GPS so I can probably get by fine without using an external antenna.  And the eTrex line is a lot cheaper.

Last but not least, I decided to poke around looking for some open source software with which I can make electrical diagrams, since I’d like to generate something useful when mapping my electrical system next week.  Options seem limited; I may end up using xfig.  On the bright side I’m pretty familiar with it having used it to make most of the figures in my thesis.

2 Comments

Filed under electrical, planning, shopping

2 Responses to Some electrical and electronics research

  1. Doug

    Over Christmas I did a lot of book browsing at Barnes & Noble to keep myself occupied at home. One of the books I came across was Sailboat Electronics Simplified. The book is written at a very simple level, but seems to have lots of good ideas for wiring as related to boats. It’s pretty cheap too, and can be browsed http://books.google.com/books?id=KzfnP_2ys2UC&printsec=frontcover . Might be handy for making an electrical plan.

  2. Kris

    In fact I have this book! It is part of http://www.amazon.com/Caseys-Complete-Illustrated-Sailboat-Maintenance/dp/0071462848 which also has a variety of other useful sub-books. I agree, it’s really useful.

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