Need an electrician

[jackelope]

I have a fairly urgent situation where a customer of ours needs a power inverter or 2 hooked up in a Ford Transit van. They need to power 2 refrigerators that draw 15 amps a piece. I’m surrounded by very skilled automotive technicians who are not electricians. Will one 3000 watt inverter power 2 of these fridges or should I get 2 that are 2k watts a piece or will it just not work and the van will burst into flames or ...

Anybody?

[ctwiggs1]

Comes down to watts.  Volts x Amps = watts.  So if it’s 120v x 15a x 2 reefers you’re at 3600 watts.

Assuming the fridges are 120v

[jackelope]

Comes down to watts.  Volts x Amps = watts.  So if it’s 120v x 15a x 2 reefers you’re at 3600 watts.

Assuming the fridges are 120v

I’m not positive that it’s that simple. Really I don’t trust myself that it’s that simple.

[jackelope]

We can do multiple inverters if the van will power them through it’s normal charging system. Cost isn’t really a factor.

Time frame is the biggest factor. It has to happen tomorrow. I can get a couple 3k watt inverters and hook them up if the van will adequately power them.

[ctwiggs1]

Hold on using a lifeline and phoning a friend

@skillet

[NRA4LIFE]

Reversing what Curtis said, 3600W/12V=300 amps.  You need to have some pretty big wires going to those inverters.

[Magnum_Willys]

It is that simple.   Home breakers are typically 15 A which us why most space heaters, cooking appliances etc are rated at 1500 watts.   115V x 15 amps -1725 so theres your safety margin.

Likely the fridges normally could get by with 3000 watts but if both started under load at same time maybe you would need more power.  But you are gonna need a couple big  alternators!

I would just plug in or go propane like  RV

[CP]

I’m not an electrician, just an electrical engineer, but 15 amps is a hefty draw for a fridge.  I’m guessing that’s the surge and then it will drop to about a 3rd of that.  The high inductive load of a fridge surges for less than a second but then drops way down.  As others stated A*V = watts.  30amps for both fridges would be 3600 watts.  Make sure the inverter can take that surge and verify that we are talking surge here and not steady state.

For what its worth, I run a single fridge with a 1000-watt inverter, no problems.

[CP]

PS – It’s the batteries that will power the inverter, the charging system just has to keep the batteries charged.  There are going to be high currents but for a very short time.  Less than 1 second surge, then a few seconds to a couple minutes running steady state.  Most of the time a fridge draws zero amps unless you leave the door open.

[jackelope]

The rest of the story is that this is to transport a crap ton of covid vaccines.  And they sprung the need on me at about 5pm tonight. And it needs to be done tomorrow. I don’t know if it’s realistic. Stock van with factory charging system.

[highside74]

Dry Ice

[CP]

The rest of the story is that this is to transport a crap ton of covid vaccines.  And they sprung the need on me at about 5pm tonight. And it needs to be done tomorrow. I don’t know if it’s realistic. Stock van with factory charging system.

In that case use 2 3000w inverters.  Redundant circuits so if one fails the other isn't lost.  Plenty of battery, LiFePO4 batteries. 

[hogslayer]

I have a built in sub zero fridge at my house thats 48" wide and only draws 8 amps.  They will be listed as 15, but won't draw that much power.  Mini fridge is about 2-3 amps.  If they need to rent a refer truck let me know. 

[CP]

Seriously, this is doable.  Double up on the inverter, at least 2-100ah batteries in parallel for each, 3 would be better.  Lithium is best, but lead acid will work.  300ah of battery will run a freezer for days without a recharge.

[Magnum_Willys]

In that case go rent a genny on a trailer or stick a 4500 watt on your receiver hitch.

[Cougartail]

I’m not an electrician, just an electrical engineer,

That made me laugh!

[Stein]

CP's leading you right.  15A is a huge refrigeration load, you couldn't run that on any 15 A circuit in your house as it would trip every time it turns on.  Most modern refrigeration is actually pretty tiny, so you might be talking about some crazy quick freeze unit or maybe it's 15 A on the DC side?  I have a chest freezer that draws 3 A.

The one thing to consider is materials.  120 x 15 = 1800 Watts.  On the DC side, you have 1800 W / 12 V = 150 A, and that assumes no startup load.  Often the inverters are not right next to the battery, so you will need at least a #3 or larger (probably #2) for each unit, so 4 #2 conductors on the DC side.  In addition to some type of mechanical protection as well as a 200 a fuse or CB right off the battery unless you want to do some impromptu welding.  To rig the cables you need the right size eye terminals & shrink tube as well as a crimping tool or hammer type.

I don't work on vans, but the closer to the battery you can put them the better.  If you are running them off a battery bank, all the better, put them right next to each other and run a smaller cable back to the engine, most alternators are in the 90-120A max range and one set of slightly smaller conductors could feed the battery vs to sets of larger conductors.

Honestly, depending on what they have going on I would look at an alternate solution like a generator.  3600W is going to produce a ton of heat and that's just the inverters which will be added to the heat of the refrigeration units.  A residential space heater is usually about 1200 W max real power, so the inverters are like 3 heaters and the refrigeration units would be at least another 3 heaters, all in an enclosed space the size of a van.

Me thinks they don't really draw 1800 W each.  If so, be prepared for a bunch of heat and money in cables & batteries.

[HUNTINCOUPLE]

Dry Ice

 

[Angry Perch]

Hold on using a lifeline and phoning a friend

@skillet

A 'Rona Rig running around with a generator on the bumper and a chest freezer in the back.

[Stein]

Hold on using a lifeline and phoning a friend

@skillet

A 'Rona Rig running around with a generator on the bumper and a chest freezer in the back.

State inspected and approved to boot!   

[jackelope]

I have no clue which vaccine it is.

I also think this is over our head with 1 hour notice.  Going to probably call first thing in the morning and tell them we’re bowing out. Not sure anyone will be able to make this happen in 1 day with no notice.

[Stein]

Probably a good call, you don't want to be the guy on the news tomorrow night.

I would at least ask for some additional details, exact equipment they have, how long they need it to run, will the van always be running or how long will it be parked, etc.

It's actually a fairly straight forward project, but the stakes are high and the details and timeframe are low which always seems to make things interesting.

[jackelope]

Probably a good call, you don't want to be the guy on the news tomorrow night.

I would at least ask for some additional details, exact equipment they have, how long they need it to run, will the van always be running or how long will it be parked, etc.

It's actually a fairly straight forward project, but the stakes are high and the details and timeframe are low which always seems to make things interesting.

Straight forward for an electrician and an auto tech working together, parts and whatever else we need ordered in advance, some advanced notice it was happening, more specifics on the equipment being used, the list goes on.

[Stein]

Hey, we only knew this was coming for a year or so.   

[Westside88]

Not a short notice project to get right. If I were trying to run that type of load I'd be looking at a setup that could run off a generator while mobile and plug in while parked. I saw others had mentioned genset also.

[Magnum_Willys]

Throw the fridges in a uhaul with a generator - golden!

[Stein]

It's not the cheapest option, but you could buy a couple Yeti's.   

[Skillet]

Hold on using a lifeline and phoning a friend

@skillet

A 'Rona Rig running around with a generator on the bumper and a chest freezer in the back.

State inspected and approved to boot!   

Err'y body funny! 

It's true, I have a stamp of approval on my portable freezer game - but the stakes are much higher with the program the 'Lope is describing.

As mentioned, 15A freezer load on 110AC is an insane load, and not likely the actual scenario. What all systems like this need to be sized for is max start capacity and continuous run loads.  They are vastly different.

A normal modern consumer grade chest freezer pulls about 2.5 amps running (no matter the cubic feet), but can have a start-up load of 8-9 amps.  That is the initial load to get the motor turning and the compressor pumping.   Some higher end models have a "soft start", which slowly starts the electric motor and reduces the peak amperage draw on startup, but that is not something found on most consumer grade freezers.

If running multiple freezers, say three total, a 15amp 110AC circuit (ie., a 2000W genset) is plenty to run all three - but it can't start all three simultaneously.  Or even two at once.  You'd have to bring them online one at a time through some sort of switching, either manually or using a logic board, and prevent simultaneous startup during running.

To idiot proof a 3 freezer set up, you'd need a genny or inverter capable of handling the startup load of all three at once - a 4950 watt supply.  Since heat increases resistance, I'd go for a 5500 Watt genny or inverter. 

I used a 5500 watt genny to run two chest freezers and a commercial-grade freezer trailer during the winter fish sale, and never popped a breaker.  I don't think I would have had a problem with a 4000 watt genny, but why risk it?

If using an inverter, you'd probably need to get a 5KW peak supply inverter with a 100% duty cycle at 2000 watts.  It would handle the startup of all three compressors at once and easily run all three continuously.

That's my 2 amps worth, anyway.

[Fl0und3rz]

Hey, we only knew this was coming for a year or so.   

Still good info here.

[Fl0und3rz]

Hold on using a lifeline and phoning a friend

@skillet

A 'Rona Rig running around with a generator on the bumper and a chest freezer in the back.

State inspected and approved to boot!   

Err'y body funny! 

It's true, I have a stamp of approval on my portable freezer game - but the stakes are much higher with the program the 'Lope is describing.

As mentioned, 15A freezer load on 110AC is an insane load, and not likely the actual scenario. What all systems like this need to be sized for is max start capacity and continuous run loads.  They are vastly different.

A normal modern consumer grade chest freezer pulls about 2.5 amps running (no matter the cubic feet), but can have a start-up load of 8-9 amps.  That is the initial load to get the motor turning and the compressor pumping.   Some higher end models have a "soft start", which slowly starts the electric motor and reduces the peak amperage draw on startup, but that is not something found on most consumer grade freezers.

If running multiple freezers, say three total, a 15amp 110AC circuit (ie., a 2000W genset) is plenty to run all three - but it can't start all three simultaneously.  Or even two at once.  You'd have to bring them online one at a time through some sort of switching, either manually or using a logic board, and prevent simultaneous startup during running.

To idiot proof a 3 freezer set up, you'd need a genny or inverter capable of handling the startup load of all three at once - a 4950 watt supply.  Since heat increases resistance, I'd go for a 5500 Watt genny or inverter. 

I used a 5500 watt genny to run two chest freezers and a commercial-grade freezer trailer during the winter fish sale, and never popped a breaker.  I don't think I would have had a problem with a 4000 watt genny, but why risk it?

If using an inverter, you'd probably need to get a 5KW peak supply inverter with a 100% duty cycle at 2000 watts.  It would handle the startup of all three compressors at once and easily run all three continuously.

That's my 2 amps worth, anyway.

I did your setup.  What do you charge to move bodies?

[Skillet]

I think I'll stick to fish 

[jackelope]

Follow up. I got some more accurate specs on the refrigerators this morning. Called an auto electronics shop we use from time to time. Sent the vaccine-mobile over there this morning and they got it dialed in. I don't know what they did but my guys are picking it up now. I know the original amp draw they told me was higher than it actually is and I know there are 2 1500 watt inverters installed in the van. Beyond that, I'm not sure what all they did. My guys are taking it directly to Overlake. Fridges are getting delivered and installed tomorrow.

I want to thank everyone for the time they took to help out. We can handle some pretty significant stuff here but this one was out of the realm of normal for us, especially on such short notice.

[wadu1]

Follow up. I got some more accurate specs on the refrigerators this morning. Called an auto electronics shop we use from time to time. Sent the vaccine-mobile over there this morning and they got it dialed in. I don't know what they did but my guys are picking it up now. I know the original amp draw they told me was higher than it actually is and I know there are 2 1500 watt inverters installed in the van. Beyond that, I'm not sure what all they did. My guys are taking it directly to Overlake. Fridges are getting delivered and installed tomorrow.

I want to thank everyone for the time they took to help out. We can handle some pretty significant stuff here but this one was out of the realm of normal for us, especially on such short notice.

[Angry Perch]

Glad you got it worked out. Getting it done for the cause.

[Ridgeratt]

Glad you got your information.