Power Feed that automatically senses when vehicle is running?

[sandalscout]

Hi all,

I saw something this morning while I was looking around for something completely not related, I came across a simple device that connected directly to the battery of a vehicle. It somehow (presumably voltage increase) was able to determine when the vehicle was running, and would provide a switched voltage output. I didn't think much about it at the time, but now, I realize that this might be a solution for some of my in-cab electrical feed needs, since apparently my truck does not have many/any switch power sources in the cab. I have absolutely no idea what the things was called, and I cannot find it in my history now. Any ideas?

I'll likely go with a more traditional setup of pulling switched power out from under the hood to a fusebox in the cab, but I use a wheelchair and cannot physically reach anything under the hood, so I generally am paying local shops for work like this..... easy is better for them, unfortunately.

Thanks,
Matthew

 

[john61ct]

Do you mean an ign solenoid?

https://www.expeditionportal.com/fo...eap-isolated-dual-battery-setup-for-50.77503/

 

[DaveInDenver]

Voltage sensing is how the Blue Sea 7622 ML-ACR works but there are other voltage sensing relays.

This one is used by hams to prevent running a field station battery into excessively deep discharge. It disconnects the load when it hits an adjustable set point, which allows as low as 10.6 V to be chosen. In 2018 this isn't as much of a problem but 10+ years ago before solar got really affordable we'd run our stations straight off a battery and didn't want the generators running all day. The VSR will reconnect when it senses greater than 12.8 V.

https://powerwerx.com/low-voltage-disconnect-battery-guard

There's also variations that add timers in, so they will disconnect either after some period of time or if voltage goes too low. In fact many mobile radios have time off timers for the same reason, where they'll turn themselves off. Commercial radios will do it with an ignition sense while the ham radios usually just do it strictly on time.

 

[sandalscout]

It was quite a bit more simple than these. The one I saw was a small red plastic coated component/box of some sort. It had 2 or three wires. I believe it connected to both sides of the battery, and then had a single power out on it.

I've never seen anything quite like that in the past. Using a more traditional relay setup will likely be what I end up going for, but I thought this was interesting.

 

[DaveInDenver]

There are all sorts of low voltage disconnects and voltage sensing relays. I just happen to have used those Powerwerx ones.

This one is $12 on Amazon:
https://www.amazon.com/Electronics-...1-spons&keywords=low+voltage+disconnect&psc=1

This one is $48:
https://www.amazon.com/Voltage-Batt...648391&sr=8-4&keywords=low+voltage+disconnect

Eaton makes all kinds of variations of them.
http://www.cooperindustries.com/con...power_management/low_voltage_disconnects.html

 

[sandalscout]

Ah, okay, that makes sense. I thought they were all going to be big and bulky like that. I don't think it was pitched as such, rather an accessory power port of some sort, but that gives me a path to look down. Thanks!!

 

[sandalscout]

Dave, thanks for the links, some more poking around got me back to what I originally saw. Of course, it's not red, but this was it.

https://camera-source.com/universal-intelligent-12volt-power-source.html

 

[DaveInDenver]

Size is dependent really on how much current you wish to switch through them. The Powerwerx is about the size of a deck of playing cards and is rated for 35 amps continuous.

 

[DaveInDenver]

Dave, thanks for the links, some more poking around got me back to what I originally saw. Of course, it's not red, but this was it.

https://camera-source.com/universal-intelligent-12volt-power-source.html

That's doing a similar function but is limited to 7.5 A continuous and isn't adjustable. They all do approximately the same thing, create a pseudo ignition hot that switches off when the battery charge begins to go too low.

 

[john61ct]

Many combiners / VSR / ACR are two-way.

IOW voltage going high closes the connection for any charge source on either side to flow to the other side, concurrent loads carried as well.

Not just the engine running causing House bank to charge, but also solar can charge your Starter batt.

There are one-way diodes, Echo charger, many ways to skin a cat.

And yes big currents require paying more.

Best is Blue Seal ML unit at 500A, bulletproof will outlast all of us.