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wandering-parakeet avatar image
wandering-parakeet asked

Do I need fuse on Orion-Tr Smart Input and Output?

1) I have a travel travel that I pull with a tow vehicle. I plan to put the Orion-Tr Smart in the trailer, and have it powered with the 12V from the 7-pin connector on the trailer hitch. Do I need a fuse on the input side of the Orion? Or would this be redundant with the fuse for the 7-pin connector in the tow vehicle (presumably 30A)?

2) My batteries are already protected by a circuit breaker (placed near the batteries) that is appropriately sized for the gauge/length of the cable. Would it hurt to have an additional breaker on the output of the Orion? Should this second breaker be sized to the device (18A) or to the cable (which is already protected at 80A at the battery)?

orion-tr smartfuses
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Alexandra avatar image
Alexandra answered ·

@Wandering Parakeet

I would fuse near the source as well. An short whether before or after the charger and batteries as well as vehicle electrical system needs to have some protection.see the manual.

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wandering-parakeet avatar image
wandering-parakeet answered ·

The vehicle electrical system is already protected, so when you say "I would fuse near the source as well", do you when between the 7-pin connector (on the truck) and the Orion? The picture in the manual is not entirely helpful, unless I think of the 7-pin connector on the hitch as replacing the "input/starter battery" in the diagram.

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kevgermany avatar image kevgermany ♦♦ commented ·
As you have a fuse on the feed to the trailer, it covers Alexandra's suggestion. There's no backend from the Orion input side. Fuse is to protect the wiring, so if the trailer feed fuse blows, it will cover the feed to the input side of the Orion.


A fuse in the positive output from the Orion would not be bad. It should be sized for the max output of the Orion plus a bit of margin, not the continuous output. Your cables should already be adequately sized.


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wandering-parakeet avatar image
wandering-parakeet answered ·

Okay... got it. I don't need an extra fuse on the input to the Orion.

If I put protection on the output, it seems that you would recommend a fuse and not a breaker? In a previous post, someone had recommended MEGA fuses, but they don't seem to come in a size smaller than 40A... which seems excessive for an 18A Orion. Any recommendations?

Do you recommend disconnecting the Orion output when other DC sources are active (e.g.,. an AC/DC converter operating at 14.6V)?

Thanks!

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kevgermany avatar image kevgermany ♦♦ commented ·

Midi fuses are good if mega too big. I have one on the output at the Orion as well as at the battery end. So the output connection is fused at both ends. It's a 5M run, heavy cable in conduit but I don't want a failure downstream of the Orion causing an undetected constant full current load. Like @Kevin Windrem said, not strictly necessary, hence my wouldn't be bad earlier comment.

To expand on the charge side. Each charger generates voltage. The outputs all join at the battery positive. The voltage their limits output current, and more sophisticated chargers such as the Orion will sense this and switch modes, eventually down to float. Important thing is to charge within battery specifications of current and voltage. Also consider what chargers will operate at the same time. You wouldn't normally charge from AC and your engine alternator at the same time. But solar will be active when the engine is running in daytime.

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Kevin Windrem avatar image
Kevin Windrem answered ·

Fuses and circuit breakers are generally to protect WIRING not a device. So think about where fault currents could ORIGINATE. The battery is considered the primary source of unlimited fault currents so wire protection should be as close to the battery as possible. Other devices such as your Orion's output probably don't need additional protection of they are current limited. That is, a short would not create currents that could burn the wiring if the wire is sized to handle the short circuit current of the Orion's output.

That said, having a breaker near the Orion's output would allow you to disconnect it from the battery for diagnostics, etc.

Chargers are generally content to coexist with other charging sources. The only reason I can think of to disconnect one or the other is if the combined charging current exceeds the battery's maximum charging current.

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