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Old 22-01-2014, 04:50   #31
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Re: 24v Batteries.. Series or Parallel First?

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Originally Posted by Pelagic View Post

I of course fully charge on passages by motor sailing for a while (230amp 24v alternators) when the autopilot loads are heavy.

I am now installing 4 x 327W Sunpower Panels and switching the many original halogen and incandescent reading and engine room lights to LED, so it will be interesting to see what my new consumption levels are.

Thanks all for your advice on sorting this out.
Sounds good.
4 X 327w is alot of solar and will probably make your generator obsolete.

I have 400w of solar and a propshaft alternator which makes my generator obsolete. I only run it for maintenance and backup even though I have no gas onboard.
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Old 22-01-2014, 17:55   #32
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Re: 24v Batteries.. Series or Parallel First?

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Originally Posted by Fuss View Post
Sounds good.
4 X 327w is alot of solar and will probably make your generator obsolete.

I have 400w of solar and a propshaft alternator which makes my generator obsolete. I only run it for maintenance and backup even though I have no gas onboard.
I am trying to make my Northern Lights Gen (10kw) non critical by switching to a DC water maker and LEDís, so that if the gen is down, I only loose the air cons which is no big deal.

Fuss I am interested in your shaft generator as Stargazer is fitted with one but the previous owner said they could never get enough RPM from free-wheeling under sail to justify keeping it connected.

I have thought of switching to a low RPM Permanent Magnet Alternator, but focused on the Solar first which is a passive solution

How do you do your prop shaft generator?
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Old 24-01-2014, 08:41   #33
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Re: 24v Batteries.. Series or Parallel First?

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Originally Posted by Pelagic View Post
I am trying to make my Northern Lights Gen (10kw) non critical by switching to a DC water maker and LED’s, so that if the gen is down, I only loose the air cons which is no big deal.

Fuss I am interested in your shaft generator as Stargazer is fitted with one but the previous owner said they could never get enough RPM from free-wheeling under sail to justify keeping it connected.

I have thought of switching to a low RPM Permanent Magnet Alternator, but focused on the Solar first which is a passive solution

How do you do your prop shaft generator?
Sorry for the late reply.
I would keep the existing watermaker and run it off the inverter.

There can be alot of reasons why propshaft alternators don't work, boat too small (needs 45+ feet), wrong ratio, wrong alternator, small prop, wrong gearbox.

The propshaft alternator install looks good and very promising, the ratio looks around 6:1 is that right?

Do you have a 3 bladed fixed prop?
Is your cutlass bearing in good condition?
Does the gearbox accept a side load and is it hydraulic so that the prop always spins or does it stop spinning when put into astern.?

Advantages of an alternator over a pmm is that you can switch it off, easily regulate it and that it makes amps while motoring as well over the full rev range, effectively acting as an extra alternator.
Disadvantage is that it takes amps to run (about 2 for this one I think as it looks small)

At what alternator revs does this alternator start producing amps? it needs to be around 1000. Also what are the specs... amps at 24v?

At what speed do you stop sailing and start motoring?

Can you "normally" do 5.5kts+ ?
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Old 17-01-2015, 05:37   #34
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Re: 24v Batteries.. Series or Parallel First?

Wow!! my turn to apologize as I had to put my boat refit on hold to do an overseas project. Back to work on my boat again.

my answers below

Quote:
Originally Posted by Fuss View Post
Sorry for the late reply.
I would keep the existing watermaker and run it off the inverter.

There can be alot of reasons why propshaft alternators don't work, boat too small (needs 45+ feet), wrong ratio, wrong alternator, small prop, wrong gearbox.

The propshaft alternator install looks good and very promising, the ratio looks around 6:1 is that right? Yes

Do you have a 3 bladed fixed prop? Yes
Is your cutlass bearing in good condition? Yes...turns easy by hand
Does the gearbox accept a side load and is it hydraulic so that the prop always spins or does it stop spinning when put into astern.? Intermediate Bearings prevent side load...Always spins

Advantages of an alternator over a pmm is that you can switch it off, easily regulate it and that it makes amps while motoring as well over the full rev range, effectively acting as an extra alternator.
Disadvantage is that it takes amps to run (about 2 for this one I think as it looks small)

At what alternator revs does this alternator start producing amps? it needs to be around 1000. Also what are the specs... amps at 24v?

At what speed do you stop sailing and start motoring? >5knts

Can you "normally" do 5.5kts+ Yes ?
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Old 17-01-2015, 06:52   #35
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Re: 24v Batteries.. Series or Parallel First?

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In real life, as opposed to theoretical hypothesizing, and in contrast to many published authorities, it matters very little what path the connections take. It is more important to use an adequate wire gauge.......
I agree. The second drawing of the two is simpler and less likely to get screwed up at some future date. Take the power off wherever it is convenient. Use the largest cable you can find/afford. Use proper connection techniques. Many vendors will attach the lugs for you if you buy the cable and lugs from them.
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Old 17-01-2015, 06:57   #36
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Re: 24v Batteries.. Series or Parallel First?

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If you search these forums you will find that Maine Sail has done just this and proved that the cable connection position does matter. I guess he hasn't responded because he has got bored arguing with you and goboatingnow.

As he and others repeatedly post ALL manufacturers recommend connecting the cables in such a way as to balance the loads on each battery.
It's easy to rig a test to get the results you want. Or set it up incorrectly in the first place. We are talking very short runs of very large cable here. The resistance (if constructed correctly) is negligible. If you were to scatter the batteries all over the boat, the wiring sequence would make a bigger difference.
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Old 19-01-2015, 11:51   #37
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Re: 24v Batteries.. Series or Parallel First?

Remember that the 12 volt (nominal) "battery" is really 6 x 2 volt (nominal) cells in series.
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