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Old 01-20-2018, 09:13 PM   #41
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Bow Thruster Battery

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Originally Posted by psneeld View Post
iI believe the relay is to power a 24 volt load with otherwise 12V charging.

People have reportedly used it for 24V thrusters, lets see if FF chimes in with his experoence and 12/24V relays.

I have that setup, but I was curious how one could partition a house bank and recombine it in series to 24 volt. It’s “easy enough” with a dedicated 12 volt in series bank for a 24 volt thruster that is charged at 12 volts. After all, John has been championing the use of a house bank for everything for all tasks but I can’t see how that would work for a 24 volt thruster.
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Old 01-20-2018, 09:55 PM   #42
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If I really **needed** 24V for my high-amp consumers, I'd go 24V everywhere and use 24-12V converters for low-amp consumer circuits.

And I completely acknowledge, for very high currents and very long wiring runs, a single consolidated House bank may not be practical.

Just saying a separate split bank design should only be used when that truly is the case, not just because heavy wire feels too expensive.
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Old 01-20-2018, 10:23 PM   #43
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If I really **needed** 24V for my high-amp consumers, I'd go 24V everywhere and use 24-12V converters for low-amp consumer circuits.

Just not practical. Way too expensive to retro.
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Old 01-23-2018, 09:14 AM   #44
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A look at the "hot rod" car suppliers will find relay setups created to provide 24V for 12v cars.

As the electric thrusters have severe on time limits , these relays work fine.

Our boat uses hyd , since the white smoke never comes out.
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Old 01-23-2018, 10:01 AM   #45
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One option is to put two 12v batts in series for the 24v and use two separate 12v chargers, one on the "bottom" batt, one on the "top" batt. Then run 12v loads on the bottom batt. This is not an optimum solution as the bottom batt will cycle more and will die before the top batt. But this is not the end of the world, just replace both when bottom gets weak, or you could even swap the two after a couple of years.

Since each is individually charged, they should top up equally once the charge process is complete.

You want to make sure that the chargers have isolated output, but I think that is pretty universal.

Just throwing out ideas...
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Old 01-23-2018, 10:58 AM   #46
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Sidepower sells a 12v-24v box specifically for powering a 24v thruster from a 12v system by adding an additional 12v battery. PN 10112-a, but pricey.
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Old 01-23-2018, 01:02 PM   #47
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Just not practical. Way too expensive to retro.
Absolutely...another test bench excercise/theory versus real world.

there are many ways to skin this cat, some expensive, some less so.

ultimately the existing components determine which new components are necessary...and thus the cost and complication.
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Old 01-23-2018, 02:01 PM   #48
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Absolutely...another test bench excercise/theory versus real world.

there are many ways to skin this cat, some expensive, some less so.

ultimately the existing components determine which new components are necessary...and thus the cost and complication.
This thread is topical for me as the thruster bank may be nearing the end of its useful life (about 9 years of age). The PO replaced the FLA batteries with 2 12VDC AGMs, that are combined in series with a relay when the 24 VDC thruster is engaged. The batteries are charged on shore and genny power with a Victron 60 amp charger and with a Balmar Digital Duo Charge (BDDC) while travelling.

Last summer the inline 30 amp fuse on the BDDC popped when I tested the thruster for 1 minute trials. After fuse replacement, the system operated as per specs, but I am concerned with the remaining longevity of the AGMs. These are expensive to replace and I am considering replacement with a couple of Group 31 starter batteries. The batteries are located under the master berth, and the PO went with AGMs because of the gassing issue. So I guess the question is would gassing be less of an issue with "no maintenance" batteries?

It's not intuitive to me how one could "partition" a subset of batteries from a combined house bank so they could be combined in some fashion with a relay to power a 24 VDC thruster...and then return them back to their house bank duties. I would seem to me that would be more difficult to achieve than staying with the current setup.

Jim
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Old 01-23-2018, 03:55 PM   #49
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would gassing be less of an issue with "no maintenance" batteries?
Absolutely. AGM are far less robust and shorter lived than top-notch FLA, but some people are bothered by the smell of routine offgassing. AGM do gas but lots less, should not be noticeable as long as they're not sealed up in a box.
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Old 01-23-2018, 04:04 PM   #50
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Absolutely. AGM are far less robust and shorter lived than top-notch FLA, but some people are bothered by the smell of routine offgassing. AGM do gas but lots less, should not be noticeable as long as they're not sealed up in a box.
I think he was referring to the cheap sealed non-AGM batteries sold for cars.

My advice is that given 9 years of service, put AGMs back in there. Total cost of ownership is highly likely to be much less than cheap automotive units. You can get decent AGMs at the warehouse clubs and mass merchants.
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Old 01-23-2018, 04:17 PM   #51
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It's not intuitive to me how one could "partition" a subset of batteries from a combined house bank so they could be combined in some fashion with a relay to power a 24 VDC thruster...and then return them back to their house bank duties. I would seem to me that would be more difficult to achieve than staying with the current setup.
If you're actually interested in investigating further, I'd get in touch with Ann-Marie about the Trollbridge.

My understanding is that it does not need the House bank to be split in half, an unbalanced setup is fine with most of House on A side continuing to be used and charged at 12V, B can be a single 12V member.

To the extent B gets very depleted (it's not getting any charge while in use) there is some inrush when it goes back to being paralleled, but her design takes that into account, she says even using LFP.

And the less balanced the two sides, there would be uneven wear.

So personally I think splitting House in half might be the better way to go.

Or B can just be a Starter batt if you like.

Note the Duo would not be needed between the two banks anymore.
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Old 01-23-2018, 04:23 PM   #52
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Total cost of ownership is highly likely to be much less than cheap automotive units. You can get decent AGMs at the warehouse clubs and mass merchants.
A big Yes to the first, but IMO No to the second.

But I'd love to be proven wrong.

Only AGM worth buying for that use would be Odyssey, Lifeline or Northstar.

Firefly if persistent PSOC issues, but with 9 years seems not relevant here.

If previous was a different AGM, next round might be 12?
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Old 01-23-2018, 04:45 PM   #53
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Only AGM worth buying for that use would be Odyssey, Lifeline or Northstar.
Based on what? I might tend to agree with you for house/inverter bank use, but for starting type purposes guys are getting great service from the Duracells of the world.
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Old 01-23-2018, 04:56 PM   #54
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I gave my arguments above for true deep cycling batts for this use.

Deka (Duracell actual maker) does not make AGMs that meet that criteria.

Besides those three makers, the only others are far more expensive.

Trojan's haven't been out there long enough, and their over-reaching marketing materials are not a great sign.
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Old 01-23-2018, 07:25 PM   #55
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My boat thruster (3Kw Vetus) is powered off the 6 GC deep cycle house bank along with everything else. Uses a total of maybe 30 ft of 2/0 cable. Only one bank to worry about. KISS.
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Old 01-23-2018, 08:34 PM   #56
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Exactly.

Extra banks need replacing more often and dilute total power available.

Wiring's a one-time deal.

But yes, this is not *always* practical.
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