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Old 29-01-2010, 12:17   #1
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Dedicated Genset Start Battery Questions

My Electric Lagoon 410 has 3 "house" batteries along with its massive 144v bank.
The Genset (16kw)start and windlass are also attached to this house bank. Both the Genset and the windlass are in the bow compartments and the house bank is in the stern, about 20' away. When starting the Genset I momentarily loose power to the NAV equipment which I now isn't good for the equipment. I may have an issue with the house batteries, I'm not sure how old they are and haven't had time this winter to test them. My thinking here is to add a Genset/windlass battery at the genset to run off the Alternator which I also am not sure what it's charging since the house bank has a 144v/12/ converter/charger to them and I don't see anyway the alternator is connected to the bank (still working on the wiring diagrams). My other problem is I don't have a good flat mounting point at the Genset to mount a battery. So the questions are:
Is one 12v 90AH (group 24) battery enough for the 2 devices?
Can the genset Alternator handle the load (75a) of a typical windlass?
Can I just wire the Windlass to the battery through its relay?
I guess I'm going to have to build a shelf for the battery, mount it in a box
and strap it down?
Since it's a genset can the block be used as a ground for the battery?
I'm figuring on a quick charger if the battery goes dead but may also go for a 2 position switch so I can charge through the inverter. For the life of me I haven't figured out how the Alternator and inverter/charger interact at this point, my guess is that the alternator is just providing power for the Genset but haven't gotten to that part of the wiring diagrams I'm producing. There isn't any smart switch that I've seen so I can't imagine their connected.

Thanks for any input!

Steve in Solomons MD
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Old 29-01-2010, 13:01   #2
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If this is one of the Solomon Lagoons, then you might want to get ahold of David Tether, who designed the system. He's now at Electric Marine Propulsion - Mission

Quick feedback: You've got to be getting some significant voltage drop from the house bank to the genset/windlass with that long a run. I'd think having a dedicated start battery for the genset, at least, would be a good idea. If you go with AGM, then you have much more mounting freedom than with lead acid.

Check on the specs for the genset to see what size start battery you would need. I would think that the same battery could also handle the windlass, though you might want to have the genset running when using the windlass. Those things can put a lot of demand on a battery.

As for the rest of your questions, I'm hesitant to comment due to the complexity of the system. I'd think that Mr. Tether (or Lagoon, maybe) would be the place to ask.

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Old 30-01-2010, 04:36   #3
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Thanks ID,
I have talked with Tether a number of times, He and Calder were on board last summer as well to see what has been changed and evaluate the system. But there are issues with Tether and Solomons that kind of distance him from helping at this point. To add to the confusion the genset wasn't installed by Solomons and the original company that did do the work doesn't have any info, the installer on a custom job isn't working for them any more. I was hoping for more "in theory" response since I know there aren't enough of these systems out there to get an exact answer. Maybe a direction to look at.

Steve in Solomons VA
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Old 30-01-2010, 04:50   #4
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Most Gen sets have a low output alt. (10 - 30 amp) as they ususlly only charge the starting battery. if you use the gen battery for the windless you would likely need a larger one than a group 24 to have enough reserve for the windless.
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Old 30-01-2010, 06:06   #5
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Will, Muffin and Lucy,
Hola from chilly Annapolis.

Steve in Solomons,
Our L440 has a dedicated genset start battery although the windlass is not on it. I'm not an electrical engineer and I definitely don't play one on tv but, were it me I would consider the Sears Platinum P-2 for your proposed application. They are AGMs, deep cycle and I believe they are made by Odyssey for Sears and I believe run about $200. We swapped out our house band with Odyssey 2250's and replaced our engine start batteries with the P-2s under the premise that we were essentially getting Odyssey technology for a better price. The reason we went with Odysseys for the house instead of Sears was Sears didn't carry a Platinum the size of the Odyssey 2250's.
I would think the P-2 would handle the draw of the windlass and as TPPLs they should recharge at a faster rate; or at least that's my theory.
And no, I haven't stayed at a Holiday Inn Express lately either, so do your own research. Hope this helps a little.

PS. be careful researching the Odyssey's the price may make your heart jump!

PSS. Will and Muffin, send us some sun!
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Old 30-01-2010, 06:19   #6
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I think I'd try a "perfect is the enemy of good" plan. Since it "almost" works now, you may not need much more to keep the nav system from crashing.

Solution #1 - Since you clearly have good size cables running forward, install an AGM battery very close to the windlass wired in parallel with the house bank (e.g. making a 4th battery in the house bank that's connected by long cables to the other 3). I'm assuming your house bank are not gel batteries with very different charge parameters. I agree that the Odyssey is a good option for the new battery.

This solution breaks a lot of battery rules (like mixing different battery chemistry and long cables) but it would be an inexpensive and easy experiment in your current configuration that might do the trick. I've never actually tried this - someone else on the board might see a major flaw in this plan.

Solution #2 - Install another battery back by the nav gear that is connected to the house bank only with an echo charger. Power the nav gear from this battery.



Carl
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Old 30-01-2010, 07:34   #7
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If you look at the catalog supply for high performance boats like eddie marine or rex marine you will find aluminum battery boxes that can mount to the bulkhead, maybe that will solve your mounting problem
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Old 30-01-2010, 08:51   #8
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My understanding of the Solomon 410's is that the genset was a DC model that first charged the propulsion bank which then used the converter to charge the house bank. If your house bank is not in great shape, with the long run, and that is being used to run over the genset, then I could certainly see where the big drain and voltage drop is causing the problem you're seeing.

The suggestion for going with the Sears/Odyssey PM-2 is a good one, since it would give you the benefits of a start battery as well as deep cycle. I'm wondering if the genset's built in alternator isn't being used for anything. Given the concept of the system, I bet it isn't. I wouldn't worry about it being on the small side for the start battery, since you probably use the genset quite a bit, anyway, it will have plenty of run time to charge the start battery. Also the Sears/Odyssey will tolerate deep draw downs quite well, plus you can mount it on the side, if need be.

I think you'd be fine grounding it to the block. I wouldn't mix the batteries with a parallel system, the Sears/Odyssey has very different charging characteristics.

Figure out what's going on with your house bank, obviously.

Hope this helps.

ID
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Old 31-01-2010, 06:26   #9
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Guys,
Thanks!
ID I also am getting the feeling the Alternator isn't being used for anything but the genset run power. It's a 15kw AC inverted to DC and then going to the main bank. From there power is fed through the 144v to 12v converter to the house bank. The 3 house bank batteries are Lifelines. The Alternator is stated at 12v, 360w which I assume is a 30A capacity. Recommended battery just states 12v 70AH. I'm not on the boat but I think the windlass is 12v at 1000w or 80A draw. Not sure about the startup draw yet. I'm figuring on a fiberglassed shelf with a tie-down strap in a case mounted to the bulkhead in the front compartment. I just don't like the long run to the stern. The procedure prior to anchoring will be to start the genset and have it ready for emergencies. Good to here about the grounding though I will look at the grounding as is and see what was done. I'll have to move the Windlass relay and control wires but that's a piece of cake. And of course verify the condition of the existing house batteries. I'll check out the Sears batteries and other options.

Thanks for the input,
Steve in Solomons MD
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Old 31-01-2010, 06:40   #10
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A fast Hey! "The procedure prior to anchoring will be to start the genset and have it ready for emergencies."
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Old 31-01-2010, 06:45   #11
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A fast Hey! to Kirk and Donna. Get down here n the sun!

Steve:
"The procedure prior to anchoring will be to start the genset and have it ready for emergencies."
The down is easy...it is the UP that hurts! (Just pullng your leg!... hmmm...L1 or L2?)

Good luck!
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Old 31-01-2010, 06:46   #12
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Will,
How much snow you guys get up there? Centreville got 6" and I'm sure Solomons got the same. I was just on line looking at the Sears Platnums and all I see is praise at a cheaper price than the Odysseys'. No one can find a difference.

Steve in Solomons MD
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Old 31-01-2010, 07:59   #13
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Steve,

Kirk and Donna are in Annapolis and mentioned the Sears Batteries We are in the Bahamas for the winter and no snow!

What is the Windless model? 80 - 100 amps is normal for most
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Old 01-02-2010, 03:25   #14
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Damn Will, rub it in!
I'm pretty sure the windlass is 80A, Lewmar, but I need to check the model # this week and shovel the 8" to 10" off the boat. The stock Alternator is a 30A and the Genset stock battery requirement is a 12v/80Ah battery. Since the windlass should only run for about 15 mins around a 200Ah battery would do the trick (when hauling up). I'll scope out the space and measure up for a fiberglassed in shelf also.

Thanks and enjoy that weather down there!

Steve in cold Solomons MD
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