Orion XS at Argofet - my tests

[sailing_jo]

I wrote an earlier post about this subject. However, I re-post my setup, for your convenience, see attached pdf.
simplified_scheme.pdf (1014,5 KB)

I find it desirable to separate the Orion XS from the Pb batteries, because an Orion XS directly connected to a Pb-battery would unintentionally activate once a dedicated Pb-charger is active. I have heard/read critical comments about placing an Orion XS after a FET (like Argofet). Provided there are also lead acid (Pb) batteries attached to the FET, that serve as voltage buffers, I saw no reason why this setup shouldn’t work. I installed it and now observe it does work like a charm.

The lead acid batteries serve as a buffer to the Orion despite both being separated by a FET provided the difference between “shutdown voltage” and “start voltage” is properly chosen. I repeat my earlier rational: when the alternator is running, there is a voltage at the battery of about 1.0 to 1.5 V above the voltage the battery would/will acquire without an alternator. For all voltages within that window-of-voltage, the FET is “open” towards the Pb batteries. That gives a window of, say, 0.7 V (between “start voltage” and “shutdown voltage”) for the Orion XS to safely operate. The Orion XS, once it starts to draw current (during charging), will lead to a drop in voltage on all FET outputs. If the voltage drop, however, is kept within the window of (say) 0.7V, there will always be a counter voltage on the conventional Pb batteries (i.e. the FET is open form alternator (power input) towards the Ph batteries). This is what I referred to as ‘buffer’, because the current/voltage control of the Orion can operate with sound voltage/current stability due to the presence of other Pb batteries.

Here 2 screeshots of a rather challenging TEST CASE, where I gave a narrow window of operation
(starting voltage 13.9V, shutdown voltage 13.5V, lock-out: 13.2V. Yes, I know what the manual reads.)

picture 1: motor slightly above idle, where the (non-regulated) alternator charges the Pb batteries. The alternator slowly crawls towards the starting voltage (13.9V in my test case). Once the starting voltage is exceeded, the Orion XS activates and starts to charge the house bank leading to voltage drop to the shutdown voltage 13.5V. The internal controls of the Orion XS limit the current draw to only about 20 A in this case, to ensure a voltage of 13.5V, as desired.

picture 2: turn off motor. The Orion XS disengages, as it should. I am quite certain, that the same picture will emerge, if the bow thruster is activated. The Orion will disengage (because of low input voltage), as it should, to prevent additional power draw in this situation.

[Loki]

I understand what you say and my reasoning was the same as yours. But I tell you that I clearly saw voltage spikes with a setup like this, but only after 30 minutes to an hour of the alternator running without a load besides the Orion chargers (bow thruster not in use).

What I think is the explanation still stands as discussed here. A voltage drop of even 0.1V is sufficient to momentarily disconnect the battery from the alternator when the battery is fully charged, regardless of the voltage lock setting.

However, your setup has 2 separate batteries, including the engine battery, while mine has only 1 (bow thruster battery), so it may be why you don’t see the issue.

Anyways, if you decide to keep it, make sure to check the voltage regularly over a long period (several hours) to make sure that there is no spike. If you do see a problem, make sure to post it on this forum so other users are aware. Hopefully my issue was for a different reason that doesn’t apply to your setup.

[sailing_jo]

I ran my system for hours with smooth profiles. For the biggest part of this time, of cause, the Pb-batteries were full and the alternator was simply feeding the Orion XS to charge the house bank. More critical are the cases explained above. Low alternator output (because of low engine-rpm), and all batteries still hungry, as well as shut-down events or bow-thruster activity (where the entire voltage suddenly drops). That is where the Orion XS setup parameters matter.

I suspect your observations has a different cause. If I understand your setup, you have a daisy-chain of two charger (where one of the two chargers is actually a parallel pair of Orions). I can easily imagine that the dynamics of this chain of elements (both having an internal control, unaware of the other) is causing difficulties. But really, I can only report on my setup, which does work smoothly. If I come across strange observations, I will report here.