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Old 01-10-2013, 11:04 AM   #21
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Mr. RT. good catch. I have given up my study to my son who is a writer for a couple of weeks, so holding the computer in my lap. Difficult to type, and difficult to read. Edits have been made. Probably alternator potential would be a better word.

Larry's suggestion is a good one, and very much worth looking into. I have checked out the link, and it is interesting.

I love spending time with my son, but it will be good to get my study with a desk back.
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Old 01-10-2013, 11:15 AM   #22
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Greetings,
Mr. Moonstruck. Ah, what parents won't do for their children.....Get one of these...
Amazon.com: Three Cheers Zebra Lap Desk: Home & Kitchen
Aw rats. Edited your post huh? NOW it's going to make ME look dense. I assure you I need NO help in THAT department!....Um, er...no wait.... Thanks....
(Folks, post #16 used to read, and I paraphrase...."starboard engine charges house......starboard engine charges start and bow thruster" Just so ya know.)
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Old 01-10-2013, 01:53 PM   #23
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Don: it is perfectly possible to direct the charge from both of your alternators to the House bank and then 'trickle charge' your Start/Thruster battery from the House bank. Many newer boats are set up this way and I changed my traditional like-yours set-up years ago to this model. This is the configuration recommended by PassageMaker's technical guy, among others. It makes a lot of sense: why have a perfectly good alternator sit there idle when it has completed its Start bank re-charge a few minutes after leaving the marina? And why upgrade one alternator to a large-case high-output 160A model (likely requiring new engine-mount brackets, cable upgrades, regulator upgrade, etc) when you have the capacity already installed?

Both Ample and Balmar make charging products to achieve what you are contemplating...& maybe others too that I don't know about. In the case of Balmar (the gear I am familiar with) you need their 'smart' regulators ( a good idea anyway to optimally charge your batteries and extend battery life); a CenterFielder to combine the charging output of both alternators and send the full charge to the House bank; and a DuoCharger to trickle-charge the Start bank from the House supply. Apart from rapidly re-charging your House bank and doing so optimally, the Balmar gear can be configured for different battery technologies. For example, you might like to use Trojan 6V golf cart batteries for your House bank (relatively inexpensive; easy to move around; truly deep-cycle and Optima spiral-wound AGM batteries for your Start bank (optimized for short high-discharge tasks like the bow thruster and starting; not as voltage-sensitive as many AGMs). The Balmar gear will apply specific charging profiles to the different battery types, allowing both to be re-charged optimally and freeing you up to chose the battery type to suit the application.

Take a look at this link to Balmar's diagram on how it is done: http://www.balmar.net/PDF/Centerfielder%20Manual.pdf
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Old 01-10-2013, 02:04 PM   #24
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Greetings,
Mr. Aquabelle. EXCELLENT reference! Thanks
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Old 01-10-2013, 02:40 PM   #25
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Don, if you desire to do something, you may find it more advantageous and easier to install a larger alternator for your house bank, for about the same $$ as installing "charging products." Plus you'll then have a spare alternator!
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Old 01-10-2013, 02:43 PM   #26
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To build a little on Aquabelle's excellent explanation, there is a Xantrex product called an Echo Charger which will accomplish the same thing as the Balmar Duocharge and you don't actually need to use the Centrefielder. Its about a year since I did the research but as I recall all the Centrefielder really does is protect the alternators from a field voltage in the event one of the engines is shut down. You can accomplish the same thing by using a NO oil pressure switch in series with each alternator field and control both fields in parallel off a Balmar 614. Which is in fact how I wired Gray Hawk last winter. The Centrefielder appeared to me to be a solution in search of a problem that didn't really exist for most applications BICBW.

For the engineers in the room its not a very professional drawing but its what I have. (on edit: apparently I can't attach a PDF so we'll try this again)

(further edit) - the Xantrex Echo charger is independant of the non-need for the Centrefielder. I don't think I made that clear - you could use a Duocharge to accomplish the "trickle" charge and still wouldn't need the Centrefielder.
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Old 01-10-2013, 03:09 PM   #27
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What a great resource this forum is. You guys are awesome. Thanks all.
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Old 01-11-2013, 08:34 AM   #28
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SCAN , Scan , Scan is the watchword .

The hassle is most folks dont .

The true chump change solution is a low voltage alarm.

IT will monitor the batt voltage and scream at you when the V reaches your preset.

What ME worry?


LowBat 12v Low Voltage Monitor and Alarm LOWBAT-XL Length: 2 7/8
Width: 1 1/2
Height: 1
Weight: .3
Shipping Weight (lb.): 1
Warranty: 1 Year

$39.00
Part # LOWBAT-XL

Samlex 12v/24v 6.6 Amp Low Voltage Start Solsum Controller Solsum6.6f Length: 5.7
Width: 3.9
Height: 1.2
Weight: .4
Shipping Weight (lb.): 1
Max Current, During Bulk Charge: 6.6
DC Output Voltage: 12/24

$34.00
Part # Solsum6.6f
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Old 01-11-2013, 03:53 PM   #29
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Bob's solution (at post #26) is very creative and certainly lower-cost, involving only one quality regulator and no Centerfielder (the Xantrex EchoCharge is around the same cost as Balmar's Digital DuoCharger, but only passes 15A (vs DDC 30A); and cannot be set up for different battery technologies, meaning whatever charge profile is applied to the House bank is imposed on the Start bank too. I think the DDC is the better kit for that purpose.)

The upside of the (higher cost) 2-regulator + CenterFielder solution is that you get two features not noted in my original post,viz: battery & alternator temperature monitoring.A battery's (or battery bank's) acceptance charge is highly temperature-sensitive and this also varies with the battery technology. So a regulator that can be set for a specific battery type (flooded, gel, etc) and which comes with a battery temperature sensing thermocouple, allows the charging rate to be automatically regulated and optimized over seasons and even during the course of a cruising day, as temps change. This is all about re-charging as quickly as possble consistent with long battery life, so this is a really valuable feature & makes a big difference to re-charge times in my experience.

Alternator temperature sensing is a real favourite of mine: the Balmar gear adjusts the output down of an alternator that is running a bit hot until it has cooled somewhat and then brings it back up to full output when its temperature has stabilized. The % of field adjusted and the temperature set-points are user-programmable. You might be surprised, when you contact an alternator manufacturer and ask them what maximum temperature they are happy for their alternators to operate at for extended periods, at the answers you will get: marine environments are very different to automotive and often with our installations, air flow & cooling of the alternator is nothing like it is on a truck.

The bottom line: different solutions with different costs and levels of sophistication are available, but the practice of directing all twin-engine alternator charge to the House bank in the first instance is a great idea if you want to minimize genset use. In my own case, 4-5 days out on the hook with lots of AC gear& a 3000W inverter (sat TV, dishwasher, electric oven, laptop charging, teenagers & other hi-demand consumers) involves no genset use or solar panel at all, just a move of a couple of hours/day between anchorages.
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Old 01-12-2013, 09:39 AM   #30
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Aquabelle and Bobofthenorth,

Thanks much, that is what I will look into. With the SOC meter, I have learned that I have been erring very much on the conservative side. I have found that I can run the fridge, all lighting, pumps, TV, DVD player, and the icemaker 12 hours without recharging. I had been shutting down the icemaker at anchor. It is a power hog, and we could probably go 24 hours without it.

I will probably change to a larger alternator or add a Balmar echo charger to the starting bank to save ginny time for recharging. This has been a learning experience. Thanks to all for the input. It is really appreciated.
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Old 01-12-2013, 11:59 AM   #31
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I don't have a dual alternator setup (only one engine), but I do have a Bluesea Automatic Charge Relay (ACR) which keeps the house and engine battery tied together for charing, and separate when not charging. I can override the relay setting using a switch at the helm, e.g. to use the house battery for starting.

I have the SOC meter for my Magnum inverter. Works great, but the boat went almost 30 years with a just a voltmeter so I can't argue that it's essential equipment.
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Old 01-12-2013, 12:45 PM   #32
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Originally Posted by Moonstruck View Post
Is there any way to add the starboard alternator to the house bank for charging only? With a total of 160 amps max on tap, it would be a shame to buy another alternator, unless they can't be tied together for charging only.

You can very easily utilize both engines alternators to charge yoyur batteries. Just get an ACR and install it between the house and start banks.

That way either engine or both will change the batteries.

Some are going th say "oh no the voltage regulators will fight each other!!!" In theory that argument has some merit, in practically the ACR setup works just fine.
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Old 01-12-2013, 03:49 PM   #33
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Don: Another way to reduce generator run time would be to up the size of your AC charger. I don't know if you can add another Charles to the one you have but Iota would be one brand to consider if you're looking for just a charger. I think Tom/Gonzo just installed one.
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Old 01-12-2013, 09:01 PM   #34
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Don: Another way to reduce generator run time would be to up the size of your AC charger. I don't know if you can add another Charles to the one you have but Iota would be one brand to consider if you're looking for just a charger. I think Tom/Gonzo just installed one.
Thanks, Larry. I am leaning toward just that-----adding another charger for quicker generator charging, and changing the port alternator to at least a 120 amp with smart regulator. As suggested before that will give a spare alternator. All suggestions to solve the problem have merit. After reading about the ACR, I am not certain how it works since it does not sense the battery with the lower voltage. I never realized that there would be so many choices. Is this a great country, or what?
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