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jacc asked

12V 30A Victron DC-DC Non-isolated Charger Draws 55A!??

I have a 12V 30A Victron DC-DC non-isolated charger that may not be working correctly (or I've really missed something). It draws 55A!. A relay selects 1 of 2 sources. The DC-DC draws 55A at about 9.7V from a 12V 30A Iota inverter. From a Ford Ranger alternator, voltage drops to about 9.7V and current spikes (at least to 27A) but a 50A thermal breaker quickly opens so I do not have an accurate reading. A VA meter is installed on the input to the DC-DC and the App shows similar V values. I have verified the wiring.

Orion DC-DC Converters not smart
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Justin Cook answered ·

@Jacc, since this is clearly a highly atypical installation for this unit, please post a diagram and photos of the installation and wiring used, as something is clearly amiss somewhere in the system.

For basic reference, lower voltage = higher current, so while the Orion will normally draw ~34A from the start battery when properly connected, that's assuming a ~13.6v power source. Attempting to feed it 9.7v will of course cause its current draw to spike - when v goes down, A goes up - but the fact that your alternator could possibly drop to 9.7v under any circumstances indicates that something is either terribly awry with your alternator, the voltage regulator, and/or the wiring, thus why I ask that you post photos and a diagram.

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jacc answered ·

Load is connected to the battery and the battery monitor shunt with 20A breaker, but is disconnected for this test. The V-A meter has a hall effect sensor on the positive into the DC-DC (not shown).

When the Iota is on shore power, I get 55A and about 9.7V into the DC-DC and no current out of the DC-DC as the battery monitor still shows about 2.5A from the MPPT (wildfire smoke is greatly attenuating solar). I have not left shore power on for more than about 15 seconds but the 55A is constant. The DC-DC gets a little warmer for those 15 seconds.

To me, this looks like a DC-DC fault.


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Justin Cook avatar image Justin Cook ♦♦ commented ·

Well your alternator at 9.7v is clearly not a fault in the DC-DC. More to the point, however, where is your start battery?? The DC-DC charger is designed to be connected to a start battery as the source and a secondary battery as the target... this is a battery-to-battery charger, NOT an alternator-to-battery charger.

Connection of any device, from any manufacturer, in a manner other than as stated in the user manual will obviously run a very high risk of aberrant behavior from that device.

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