clummzie avatar image

Confirmation that h-pin switch is live and working

Orion Smart DC to DC 12/30 Non isolated in 2016 Sprinter with smart alternator.

All wired up and seems to be working OK with the h-pin (right side) wired to a fuse that's only live when the engine is switched on and the black loop removed.

It takes a few seconds after starting the engine to start charging the leisure battery and seems to behave exactly the same as when the black loop was initially in with no h-pin wiring.

Is the switch definitely working?


Orion DC-DC Converters not smart
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2 Answers
Stefanie avatar image
Stefanie answered ·

Hi @Clummzie,

the bridge still must be installed (together with the wire to the H-pin) for engine detection override, so that once engine is switched on, the L-pin get >7V. That's how I understand the manual.

Section 4.5 and Figure 4 image on the left side.

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Single L pin and H pin wiring is shown.

a is remote on off bridging the pins.

b is H pin only

c is L pin only.

Both b and c have switched shown.

Leaving the bridge in is probably putting it into voltage switching from the alternator, but that's a guess.

clummzie avatar image
clummzie answered ·

That's what I though to start with but then the shop (I bought it from) tech support told me to take the bridge/black cable loop out as per

It does seem to work but I'm frazzled after hours messing about and I just wanted to make sure I'd done it correctly!

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If you have it wired with the H-Pin without the bridge, then it's simply a remote on/off switch.

If the bridge is out and nothing connected to L or H it won't turn on. Despite power on input connections.

With the bridge in, it is permanently switched on. But will not charge until the input voltage is high enough.

So what they're saying is that it needs to see a positive voltage on H or low on L or bridge to turn on. I'd guess this is for two reasons, safety and turning off the very small drain from the device when it's on, but not charging.

That's a really clear explanation, thanks @kevgermany.

The 'switch' does work as I started the engine and pulled out the live fuse that triggers it and the charger didn't kick in at all until I replaced it.

I guess the Sprinter needs a switch as the smartalternator drops the voltage to save power?

Wondered that myself. However I think the settings are enough to cope with the alternator. But...

One thing I didn't mention is that there's a configurable time delay between charge kick in voltage and charge starting. Gives the alternator time to put something back into the starter battery.