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Run power cables from minivan battery to inside the minivan


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Looking for someone who knows how to run power cables from a minivan's battery through a grommet in the van's firewall and into the cabin. The cables will power an inverter behind the front seats. Our portable Bluetti power station will be plugged into the inverter for fast charging while driving.  Our portable refrigerator will always be plugged into the Bluetti for camping. We have a convertible bed in the minivan and will be touring national and state parks this summer.

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Just about any mechanic can do this it's easy.  Going north on C Madero in Chapala. You pass a grain and cereals store on a corner on the right. The next east/west street goes back west the stereo shop  is located on that street on  the left just 70' or so before it gets back to C. Madero. It ia just across the street from the late Dr Herirdea's office if you knew him.

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A lot of people have drained their primary battery dead overnight by adding a fridge. I know of a few people who have done what you are talking about, but add a second battery with a battery isolator. The isolator allows the vehicle's alternator to charge both batteries but you don't drain the primary one.

 

https://en.m.wikipedia.org/wiki/Battery_isolator

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Agreed that this is not a rocket-science job, but.....  when powering an Inverter it is best to locate the Inverter as close to the battery as possible. The longer DC power cables are run, the more one looses amps and the larger the cables need to be. Best to put the inverter 'under the hood' and then run AC wiring back into the van.

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50 minutes ago, RickS said:

Agreed that this is not a rocket-science job, but.....  when powering an Inverter it is best to locate the Inverter as close to the battery as possible. The longer DC power cables are run, the more one looses amps and the larger the cables need to be. Best to put the inverter 'under the hood' and then run AC wiring back into the van.

Exactly,  In our RV the inverter is housed directly above the batteries in its own sealed housing.

 

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When calculation volt and watt drops for the length of gauge of wire remember all those turns running around the car add up to more than a direct line distance. Wiresizer is a phone app that could give you an idea when you know the combined power draws of devices.

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Thank you all for responding... within hours of my post! Very impressed again with this web board.

My thoughts from watching YouTube videos and reading the comments have been to run 6 gauge positive and negative wires from the battery through the grommet on the passenger side of the vehicle. I know 6 gauge wires are big and might be difficult to get through the grommet. Just getting access to the grommet will be a challenge.

Once through they would connect to a 300 watt pure sine wave inverter. It will mainly be used to charge our portable Bluetti battery while driving. The Bluetti has a maximum input limit of 200 watts. The inverter has an on/off switch, so we'll turn it off whenever the engine isn't running to avoid running down the van battery. There would be a 50 amp fuse or breaker near the van battery. I want the inverter in the cabin so we won't have to open the hood every time to turn the inverter on or off. 

Also I don't have the tools or experience to do this job myself and would be happy to pay someone to do it. Do you all know anyone I could hire to do this job, or maybe one of you guys? I'll try to find the stereo shop geeser mentioned and see about them.

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You are exactly right. It is possible to use a circuit that is only powered when the car is running and battery charging. In a boat i used to own I had a relay that was actuated by the output when the alternator was on. Might be advisable on an inverter as well.

I have had this Norcold electric chest in various cars for over 15 years.

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3 hours ago, MickeyO said:

I know 6 gauge wires are big

Seems way oversized for the inverter spec, check this link, 10 gauge may be more than sufficient for a 12 V feed to a 300 watt inverter, and the run length in a vehicle is of no real consequence, it is pretty short:

Part 1: Choosing the Correct Wire Size for a DC Circuit - Blue Sea Systems

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We don’t have room in our minivan for a second lead acid battery, so the one under the hood is really the only one to work with.

Thanks Go Solar for the chart about using correct wire size. I think the connecting wires on the BESTEK 300 Watt Pure Sine Wave Power Inverter Car Adapter DC 12V to AC 110V look to be about 12 gauge. That would be easier than 6 gauge all around.

Looking at the chart though, I get a little confused. Do you measure with the input to the device or the output? A round trip of 25 feet from the van battery to the device, and critical circuit type, would be either 300 watts / 12V = 25 amps or 300 watts / 110V = 2.72 amps. In the first case the chart says 6 gauge. In the second it says 12 gauge. Which is correct?

 

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Agreed that, if your inverter is only 300 watt, you don't need to have the inverter near the battery. Thought you might have a higher-wattage inverter as 300 watt is pretty small. Surely don't think that you need 6 guage DC wiring.....

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5 hours ago, MickeyO said:

Looking at the chart though, I get a little confused. Do you measure with the input to the device or the output? A round trip of 25 feet from the van battery to the device, and critical circuit type, would be either 300 watts / 12V = 25 amps or 300 watts / 110V = 2.72 amps. In the first case the chart says 6 gauge. In the second it says 12 gauge. Which is correct?

You just need to consider the DC run length, not the AC, and the 10 gauge should be fine, as you can see, it covers 30 A  (you need 25 max) to 10 feet as critical and 30 feet as non critical.       And I do agree with the other posters.....if the 12 V plug in the vehicle will handle a 300 watt inverter, just plug it in there and job done more easily that way, though I don't think most are rated to that amount of power.    

image.thumb.png.723c2bda61c6f266611e209d1b6fc465.png

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I can't agree with using the 'cigarette lighter' plug. At least if you actually want/need your 300 watt inverter.  Most vehicle plugs are fused with from a 10 to 20 amp fuse so 120 to 240 watts, AND continuous use at the higher wattage will probably blow the fuse. And those plug adapters never make very great contact anyway.  I'd stick to your plan of running 10 guage DC wiring from the battery through the firewall if'n it were me.

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Our vehicle has 10 amp cigarette lighters ... not enough to power a 300 watt inverter charging a portable battery at about 200 watts.

Thanks Go Solar for clarifying to use DC input for calculating wire gauge. It seems the calculation depends on whether the circuit is considered critical or non-critical.

The instructions for using the wire gauge chart say:

Critical circuits, with 3% allowable voltage drop, include

  • Panel main feeders
  • Bilge blowers
  • Electronics
  • Navigation lights

Non-critical circuits, with 10% allowable voltage drop, include

  • General lighting
  • Windlasses
  • Bait pumps
  • General appliances
  •  

Would a circuit to a pure sine wave inverter, which has a built-in 40 amp fuse, be critical or non-critical?

 

 

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If electric vehicle charging points were free and I were a little sneaky and knew how to install the proper batteries and charger for voltage and amps changes to charge the batteries, installing an electric car battery charging receptacle on the vehicle might be an additional option.

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