I could use some advice about a 12VDC to 120 VAC inverter project:

[meep]

the marine (hybrid) was a good move. Functionally, you could have also parallel’d a starter battery in to handle the current, but it would be susceptible to discharge stress as the pack as a whole dropped into deeper discharge - the deep cycle(s) would be fine with it but the starter battery would groan.

the marine batteries are a hybrid, which also can be compromise. they give up some depth of discharge for additional burst current. IIRC the typical rule of thumb for a marine battery is down to 50%, whereas a good deep cycle can dig as low as 20%. Starter batteries are happiest, generally, when not brought below 80%.

 

[JHZR2]

I can’t help you with brands of inverters, but I’d echo the idea of using a robust UPS with external batteries.

Since this is a mission critical situation set up two sets of big Ah batteries, and swap over to the second when necessary. Have a rate capable charger for the banks that can be switched between them.

The car thing in a pinch sounds interesting, but if I was really serious about that and the mission critical nature I’d probably buy a hybrid and tap into the hv battery. Otherwise I’d probably look at the two battery bank setup and use the car to charge the other bank as needed.

 

[JHZR2]

I occasionally get HF emails, and got one that had new items. For whatever reason this caught my eye:

3000 Watt Continuous/6000 Watt Peak Pure Sine Wave Power Inverter

Amazing deals on this 3000W/6000W Pure Sine Wave Inverter at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

What is interesting and caught my eye on the email was the automatic transfer switch. So it looks to me like you could use this almost like an UPS and have some peace of mind…. And have it be connectable to your car when the situation demands it.

It’s HF and brand new so who knows if you really want to push it with a mission critical application like yours. I suspect most all of this sort of thing is made in China. What you need to identify is what variant is most reliable. Still can’t help you there, but the built in transfer on this is interesting. Who knows if it is “no break”…

 

[meep]

I occasionally get HF emails, and got one that had new items. For whatever reason this caught my eye:

3000 Watt Continuous/6000 Watt Peak Pure Sine Wave Power Inverter

Amazing deals on this 3000W/6000W Pure Sine Wave Inverter at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

What is interesting and caught my eye on the email was the automatic transfer switch. So it looks to me like you could use this almost like an UPS and have some peace of mind…. And have it be connectable to your car when the situation demands it.

It’s HF and brand new so who knows if you really want to push it with a mission critical application like yours. I suspect most all of this sort of thing is made in China. What you need to identify is what variant is most reliable. Still can’t help you there, but the built in transfer on this is interesting. Who knows if it is “no break”…

I want this to be a good product so badly.

 

[DuckRyder]

+1 on Samlex. Don Rowe is a good supplier.

You'll need to provide adequate power cables for the load of course.

 

[sky jumper]

I occasionally get HF emails, and got one that had new items. For whatever reason this caught my eye:

3000 Watt Continuous/6000 Watt Peak Pure Sine Wave Power Inverter

Amazing deals on this 3000W/6000W Pure Sine Wave Inverter at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

What is interesting and caught my eye on the email was the automatic transfer switch. So it looks to me like you could use this almost like an UPS and have some peace of mind…. And have it be connectable to your car when the situation demands it.

It’s HF and brand new so who knows if you really want to push it with a mission critical application like yours. I suspect most all of this sort of thing is made in China. What you need to identify is what variant is most reliable. Still can’t help you there, but the built in transfer on this is interesting. Who knows if it is “no break”…

I have several "all in one" inverter/charger/auto transfer switch units --- Tripplite APS2012, the "utility" version of it, and a cheap offshore model. I no longer use them because:
1) they require a good battery to be connected or you get no power out, not even pass-through house power. if the unit thinks there's an issue with the battery it will shut down completely and will require manual intervention to restart it, even if house power is on. I argued with the tech guys at Tripplite about this and they insisted it was a deliberate design decision -- I called it a design flaw.
2) There's multiple "safety shut down" features that will cause the unit to completely shut down even if a good battery is connected and house AC power is on --- and again it requires manual intervention to restart it. I would randomly find it shut down for no reason at all -- battery 100%, house AC on - no power out. Tripplite said "you probably had a power surge on your AC mains".... so you shut the whole dang thing off??
3) the built in battery charger was mediocre (not applicable to the HF unit).

After several years of unpredictable service I switched to regular inverters and built my own auto transfer switches with 40A DPDT relays (load across the common, house AC across the coil and NO, inverter across the NC) and those have been bullet proof for 8yrs in continuous duty service. Not matter what's going on with the inverter or batteries there's always AC power to the load so long as house power is live.

 

[meep]

I have several "all in one" inverter/charger/auto transfer switch units --- Tripplite APS2012, the "utility" version of it, and a cheap offshore model. I no longer use them because:
1) they require a good battery to be connected or you get no power out, not even pass-through house power. if the unit thinks there's an issue with the battery it will shut down completely and will require manual intervention to restart it, even if house power is on. I argued with the tech guys at Tripplite about this and they insisted it was a deliberate design decision -- I called it a design flaw.
2) There's multiple "safety shut down" features that will cause the unit to completely shut down even if a good battery is connected and house AC power is on --- and again it requires manual intervention to restart it. I would randomly find it shut down for no reason at all -- battery 100%, house AC on - no power out. Tripplite said "you probably had a power surge on your AC mains".... so you shut the whole dang thing off??
3) the built in battery charger was mediocre (not applicable to the HF unit).

After several years of unpredictable service I switched to regular inverters and built my own auto transfer switches with 40A DPDT relays (load across the common, house AC across the coil and NO, inverter across the NC) and those have been bullet proof for 8yrs in continuous duty service. Not matter what's going on with the inverter or batteries there's always AC power to the load so long as house power is live.

Beautiful. What are you powering with this home brew UPS? I assume theres a modest float charger propping the batteries and idling inverters up? What inverter brand have you settled on?

 

[sky jumper]

Beautiful. What are you powering with this home brew UPS? I assume theres a modest float charger propping the batteries and idling inverters up? What inverter brand have you settled on?

the battery charger is a bit tricky. it has to float 13.6v while providing enough charge current to power the inverters. I've only found 2 that will do it --- a Stanley BC25BS and a cheap 8A "7 stage" charger on aliexpress-- 8A charger . It's noteworthy that I have 3 of the Stanley chargers and only 1 will hold the 13.6V. I have 6 of those 8A Foxsur chargers from aliexpress and they all work very well, keep them on all my vehicles/lawn tractors/etc.
I like the EDECOA pure sine inverters on Amazon. they are dirt cheap and work well.

 

[Quantico]

In my opinion I would buy a blue optima large battery. Or similar deep discharge type. Put it in a large boat battery box and get 12 volt cables from inverter clamped w large clamps like they use for mid size jumper cables. The inverter just needs the clamps bolted on its leads. You get a noka 1.5 amp battery maintainer and leave that battery on the tender...
You need power just unplug the battery tender and plug your ox generator into the inverter.

I have had good luck with the 500 or 750 watt harbor freight inverters. And bet the power out will be just fine.
I used this setup with my pontoon boat.. with a 1.5 amp charger.. the boat had ac power 750 watts.. and that 12 volt battery ran a stereo and lights. Ran for days with a huge optima battery. Very reliable..

Optima bat. 250.00
Inverter about 70.00
Boat bat box. 20.00
Clamps. 20.00
If you need an extention cord use a 12 guage.. short as you can get away with.

 

[JimPghPA]

Here's a update to what I ended up doing. I upgraded the battery from the 51R to a 24F Walmart Maxx, including a new Honda battery tray and cover from a 2013 Odyssey for the 24F battery, installed an apex 200 amp at idle and 350 Amp Max alternator that was tested at Apex to put out 188 amps at idle. This alternator has a smaller pulley so I had to put a smaller serpentine belt on to make up for the slack caused by the smaller pulley. I've got the ground from the battery going to the motor mount on the engine with 0 gauge wire. I have 0 gauge wire going from the alternator output to a 350 amp fuse that's under the hood. The same side of that 350 amp fuse that is connected to the alternator is also connected to the plus of the battery. Those wires are all zero gauge. Then I have 0 gauge ground coming from the same engine mount by the alternator for the ground and zero gauge coming from the other side of the 350 amp fuse for the Plus and those go through the firewall behind the glove compartment and route beside the passenger front door coming out behind the passenger front seat with about 14 in of Slack and an Anderson 350 amp connector. Also I have an Anderson 350 amp mating connector connected to 0 gauge wire that is connected to a meanwell 2200 w pure sine wave inverter that has a peak output rating of 4,400 w. The meanwell inverter has two fans that automatically adjust the speed according to the heat load of the inverter. I have Velcro on the bottom of the inverter so that it sticks to the carpet behind the front passenger seat which is the floor of the back passenger seat. I have a whole cut near where the inverter sits for a male end of a 100 ft 12 gauge outdoor rated extension cord to feed in from under the car. I have a cap on that hole, and a cover that matches the black floor. And underneath the car I have changed the plastic quick release tabs that hold the plastic trim below the hole by extending pieces on those quick releases so that they are even quicker to release without having to use a tool or screwdriver.

 

[JimPghPA]

The inverter alone cost $830. I had a shop that specializes in hi output stereo systems do the wiring because I didn't have a crimper for zero gauge and I didn't know how much of it to buy and I was too busy taking care of a family member at the time. That ran me about $860. The battery I lucked out on and caught that on a Walmart rollback online special for $88 and that's the maxx version of the 24F.
I bought the Anderson connectors on Amazon. And the 350 amp fuse and a couple of spares. And of course the battery tray and cover I picked that up at a pretty decent price from OEM Parts Source. By the way they're out of business now. And I picked up a 100 ft 12 gauge outdoor rated extension cord off of Amazon. I've got about $2,000 tied up in this upgrade. What's really nice about it is that I figure I will get about 3 hours to the gallon running the inverter if I ever need to the power of the house furnace in the winter time and the refrigerator and anything else that has to get powered. Unfortunately the family member that I was really concerned about maintaining power to supply their oxygen machine passed away last October.

 

[JimPghPA]

The inverter alone cost $830. I had a shop that specializes in hi output stereo systems do the wiring because I didn't have a crimper for zero gauge and I didn't know how much of it to buy and I was too busy taking care of a family member at the time. That ran me about $860. The battery I lucked out on, and caught that on a Walmart rollback online special for $88 + tax and that's the maxx version of the 24F.
I bought the Anderson connectors on Amazon. And the 350 amp fuse and a couple of spares. And of course the battery tray and cover I picked that up at a pretty decent price from OEM Parts Source. By the way they're out of business now. And a 100 ft. 12 ga. outdoor rated extension cord that I also bought from Amazon. I've got about $2,000 tied up in this upgrade. What's really nice about it is that I figure I will get about 3 hours to the gallon running the inverter if I ever need to the power of the house furnace in the winter time and the refrigerator and anything else that has to get powered. Unfortunately the family member that I was really concerned about maintaining power to supply their oxygen machine passed away last October.