question

Edouard Lafargue avatar image
Edouard Lafargue asked

Orion Tr-Smart behind Argofet

I am trying to get a definitive answer to this: is it possible to connect an Orion-Tr Smart behind one of the outputs of an Argofet, in a situation where the lead-acid battery is the starter battery only ? Like in the schematic below (do not pay attention to the "48" for the Orion, that's the only icon I had with me...):


img-0084.jpeg


I have seen posts in this forum that seem seem to indicate this works fine, and others that it leads to issues, so no definitive answer, unfortunately!

Does anyone have concrete evidence of this setup working correctly? As far as I can tell, on a setup like this the voltage on the alternator should be stable and follow the voltage of the lead acid battery (plus the small drop of the argofet), so the Orion should also be happy as long as the alternator can deliver enough power. Or am I missing something?


orion-tr smartalternatorArgo FET Diode
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2 Answers
Sarah avatar image
Sarah answered ·

Hi @Edouard Lafargue yes this configuration works well. I have a very similar setup on my catamaran with two engines/alternators/Orions. In addition to isolating the starter battery from the Orion the system is protected from any BMS disconnects which have the potential to do considerable damage to the alternator.

With regard to load I have 60 amp ‘dumb’ alternators that have internal thermal regulation. Using one 30 amp orion (per alternator) works well with the current dropping to around 25 amps after half an hour as the alternator heats up.

I also use a third smaller Orion to give the engine (and generator batteries) a weekly one hour maintenance charge from the house batteries. The Argofet isolator works to stop the charge from being visible to the main Orions and creating a feedback loop. For what it’s worth I use the Cerbo Relay 1 and the scheduled generator timer to trigger the maintenance charge.

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Edouard Lafargue avatar image Edouard Lafargue commented ·
Thank you, that’s great feedback!
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Edouard Lafargue avatar image Edouard Lafargue commented ·
@Sarah about your comment on the third smaller Orion: that's exactly what I intend to do as well - i.e. an Orion used for maintenance charge that is connected to house batteries/solar, so I'm glad to see it works fine for you - I followed the same reasoning of having the Argofet prevent a feedback loop, avoiding any risky manual switching.


On that last point: do you think that connecting an Orion to a battery isolator to charge two (isolated) lead acid batteries would work at all? Since the Orion would not 'see' the voltage from the batteries by default because of the argofet, my impression is that it might work as long as the energize output is connected to one of the two batteries, but I'd be curious to have your opinion.

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Sarah avatar image Sarah Edouard Lafargue commented ·
Hi @Edouard Lafargue the output of my ‘maintence’ charger is connected to the input of a three output Argofet (2 engine batteries and a generator battery). It works well and keeps the three starter batteries isolated from each other. Some alternators would have issues in this environment and would need to make use of the energise input.
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Edouard Lafargue avatar image Edouard Lafargue Sarah commented ·

Nice, so it looks very much like what I had in mind, doesn't it? See schematics below.

As far as I can tell, this is the best of both worlds: charge all batteries over alternator or solar, keep them isolated, and minimize any manual switching that's always error-prone.


screenshot-2023-07-24-at-52129-pm.png


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screenshot-2023-07-24-at-52129-pm.png (364.6 KiB)
Sarah avatar image Sarah Edouard Lafargue commented ·
Looks like a nice setup - good luck!


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mvas avatar image
mvas answered ·

Why don't you connect the Orion DC-DC directly to the alternator? What's the purpose connecting the Orion DC-DC through the Argo FET?

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Edouard Lafargue avatar image Edouard Lafargue commented ·
The idea would be to ensure the starter battery doesn't start charging the service battery if the service battery starts being depleted, unless there is a better way of achieving this?
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mvas avatar image mvas Edouard Lafargue commented ·
The Orion DC-DC already prevents that from happening.
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Sarah avatar image Sarah commented ·
Hi @mvas you are correct you could hook the Orion directly up to the alternator output. In this case putting it behind the Argofet allows for a second periodic maintenance charge of the engine battery from the house battery.
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Matteo Mannini avatar image Matteo Mannini Sarah commented ·

How do you start the engine with the starting battery connected to one output of the diode? Is it necessary to separate the starter motor from the alternator (they normally are in parallel) and wire the starting battery directly to the starter motor?

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