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14-01-2025, 21:44
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#1
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Registered User
Join Date: Sep 2017
Location: Langley, WA
Boat: Nordic 44
Posts: 2,677
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12 DC power transient protection.
I have always used an inverter to drive my on board computer. I disliked the wasted power stepping up to AC power and then back down again to run the computer. By doing this I think the power going to the computer would be isolated from battery bank voltage spikes and sags.
I just ordered a PC designed to run on 12 volts. I would like to run this directly from the house battery bank but I am still concerned about voltage transients that could damage the computer. So I am looking for recommendations for 12 volt DC-DV isolators. I don't need much current. Six amps should cover both the computer and a monitor.
I see the Victron Orion-tr-12-12-9 which looks good for this purpose. What other products would fit my needs? Any other insights on running a PC directly from batteries would be appreciated.
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14-01-2025, 23:29
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#2
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registered user
Join Date: Dec 2012
Location: back in West Australia
Boat: plastic production boat, suitable for deep blue water ;)
Posts: 1,194
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Re: 12 DC power transient protection.
Maybe the first step is to check what kind of protection is built into your PC, often reverse polarity protection is included, or the voltage might be regulated and protected already. Note I would think most people connect GPS, radar, plotter, MDF etc. directly to the plus of battery and these electronics are similar to PCs or are in fact PCs.
You can easily make a reverse polarity protection with 4 (Schottky) diodes. A spike protector can be made with a MOV (metal oxide varistor), plus a few other components, or one can use a simple power supply (without the transformer). As really, the voltage on the plus of battery is not a constant, as various chargers switch on and off frequently. The worst thing that can happen are faulty regulators/chargers, solar whatever the open circuit is, ie about 21 Volt for a 12 volt panel, wind generator up to 60 Volt (ouch).
Or maybe the simplest solution is the use a buck converter, that is good for 8 amps or bigger, set the output to 12 Volt, and you're fine. I used this approach on my boat, for the last 8 years. My buck converter is good for 30 amps, and gets barely warm, never hot. And the spare buck-converter is still sitting in the draw.
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15-01-2025, 05:08
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#3
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Registered User
Join Date: May 2013
Location: Portland, ME
Boat: McCurdy & Rhodes 56
Posts: 260
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Re: 12 DC power transient protection.
You might think about protecting your other electronics from voltage drops and spikes by getting a larger one to cover everything - VHF, AIS, autopilot, etc.
I'm using a Victron Orion XS 12/12-50 in power supply mode. New design, very efficient. The higher amperage is to cover higher autopilot loads in rough conditions.
Separate converter for Starlink Mini to push up the voltage through the long skinny power cable.
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16-01-2025, 23:13
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#4
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registered user
Join Date: Dec 2012
Location: back in West Australia
Boat: plastic production boat, suitable for deep blue water ;)
Posts: 1,194
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Re: 12 DC power transient protection.
Like Mal R. above, I have those Orion DC-DC chargers, both on the boat and RV, but..... I used them between the starter AGM batteries and the LFP batteries.
Yes, you can use them as a power supply but they are in OZ about $500. A buck-converter for 20 Amps cost $10 to $30 each. Here is one example, but Amazon, Digikey or Alie-express all sell similar units.
\ https://www.ebay.com.au/itm/22404663...ETCKH988Y8TVH8
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17-01-2025, 02:41
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#5
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Registered User
Join Date: Jul 2012
Location: Switzerland
Boat: So many boats to choose from. Would prefer something that is not an AWB, and that is beachable...
Posts: 1,367
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Re: 12 DC power transient protection.
DC-DC converters also do a DC-AC-DC conversion somewhere inside. So if your problem is "stepping up and then down" the DC-DC converter will not fix that.
Look at the powersupply of your PC. Most can actually accept a rather wide range of voltages, or they wouldn't even work on a typical 12V system, which after all rarely sits on 12V. These systems are typically build with use in vehicles in mind, and so they ought to be able to cope with the typical boat DC environment as well.
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17-01-2025, 07:00
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#6
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Moderator

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,297
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Re: 12 DC power transient protection.
Quote:
Originally Posted by K_V_B
DC-DC converters also do a DC-AC-DC conversion somewhere inside. So if your problem is "stepping up and then down" the DC-DC converter will not fix that..
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Somewhat pedantic point, but there is no AC current involved in DC-DC buck or boost converters. See: https://en.wikipedia.org/wiki/Buck_converter; https://en.wikipedia.org/wiki/Boost_converter. Buck and boost converters are forms of switching power supplies.
So these DC-DC converters WILL solve the OP's problem, providing stabilized voltage.
I run all my electronics off DC-DC converters for the sake of voltage stability.
I even run my SSB radio off a large DC-DC converter, which is great for the performance of the radio since it prevents voltage sag, delivering constant 13.6v.
For the OP: I run my on board computer from a USB PD power supply. Many modern mini-computers are supplied like that. This neatly solves the problem. But if your computer uses 12v (or 13.6 -- you should check) through a coax plug, then using a Victron Orion is a good idea. That's how I power my monitor.
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17-01-2025, 18:16
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#7
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Registered User
Join Date: Sep 2017
Location: Langley, WA
Boat: Nordic 44
Posts: 2,677
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Re: 12 DC power transient protection.
Quote:
Originally Posted by Mal Reynolds
You might think about protecting your other electronics from voltage drops and spikes by getting a larger one to cover everything - VHF, AIS, autopilot, etc.
I'm using a Victron Orion XS 12/12-50 in power supply mode. New design, very efficient. The higher amperage is to cover higher autopilot loads in rough conditions.
Separate converter for Starlink Mini to push up the voltage through the long skinny power cable.
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Thank you for your comments.
I have never had any of my marine electronics affected by power issues, even when activating a 1500 lb windlass from the same battery bank. I do have a buck booster on my Ham radio that is specifically made to not cause RFI to the radio. Ham radios are very sensitive to voltage sag during transmit. My concern is limited to the sensitivity of the computer.
The Victron Orion XS 12/12-50 costs over double what the computer costs.
So, I will be reading reviewing all the comments before deciding what to do.
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17-01-2025, 18:19
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#8
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Registered User
Join Date: Sep 2017
Location: Langley, WA
Boat: Nordic 44
Posts: 2,677
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Re: 12 DC power transient protection.
Thanks to everyone that replied. Haven't decided what to do at this point. New computers are coming tomorrow.
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