Electrical Mod -- Feedback Requested

[gengiant]

BL: Pleased with my setup. As a reminder, my system has 400aH (four 100aH Battle Born batteries). Here are my notes from two days of towing:

12 May
5:45 - Unhooked shore power @ 5:45 am. Upon departure battery capacity was 97%. Refrigerator was pre-cooled and stocked.....


Conclusion
Four batteries ended up being perfect to ensure there is some reserve capacity should there be unforeseen delays, etc. The truck supplements the batteries while underway with ~6 to 9A of 12vDC through the 7 pin cable, but an additional supplemental charge source (either from the truck, generator, or solar) would be needed if I wanted to "boondock".

Howard,

Were you running the fridge off the inverter (120 VAC) or off propane? Seems like an awfully big power draw if running off propane. We have yet to tow for longer than 3.5 hours (2 trips to the coast), but even on the crappy single 12 V OEM battery, our meter hadn't even dropped to 75% by the time we got to the campground. That was running the fridge off propane while towing.

[howson]

Howard,

Were you running the fridge off the inverter (120 VAC) or off propane? Seems like an awfully big power draw if running off propane. We have yet to tow for longer than 3.5 hours (2 trips to the coast), but even on the crappy single 12 V OEM battery, our meter hadn't even dropped to 75% by the time we got to the campground. That was running the fridge off propane while towing.

No propane while towing (personal choice). That was one of the primary reasons for the project in the first place.

Read this thread if you want more info: https://www.mygrandrv.com/fo...-With-Inverter

[gengiant]

No propane while towing (personal choice). That was one of the primary reasons for the project in the first place.

Read this thread if you want more info: https://www.mygrandrv.com/fo...-With-Inverter

Got it! I just read that entire thread. Good info to know!

[Jerry P]

Great info! Hopefully I can go 6-8 hrs with the single battery being charged from the tow vehicle through the 7 pin cable. Thanks!

[howson]

Great info! Hopefully I can go 6-8 hrs with the single battery being charged from the tow vehicle through the 7 pin cable. Thanks!

Powering a Dometic refrigerator through an inverter? Not if your power consumption (and charging rate from the truck) matches my experience. The pic below is from a trip I just concluded today, 1 Jul. Row 2 has the averages--important number is I averaged consuming ~32 amps per hour. With a 100aH lead-acid battery it would be just about dead after two hours.

[Jerry P]

So, with only the Dometic 610 watt fridge drawing 3-4 amps from 1000 watt inverter....the tow trucks 100 amp alternator charging a single 100ah battery in the 5th wheel wouldn't keep up with the demand?

[howson]

So, with only the Dometic 610 watt fridge drawing 3-4 amps from 1000 watt inverter....the tow trucks 100 amp alternator charging a single 100ah battery in the 5th wheel wouldn't keep up with the demand?

If your refrigerator requires 4 amps of 120V AC that means your inverter is pulling 40 amps of 12vDC from your battery. With one 12V battery rated at 100ah (which means 100 amps for one hour, or 50 amps for two hours with no accounting for loss) you'd quickly kill a lead acid as you can only tap into about 50% of it's rated aH before needing to recharge it. A Battle Born lithium can provide nearly 100% of it's rated capacity, but either way one battery will quickly be depleted.

Regarding your truck's alternator, my '17 Ford SuperDuty provides a measly 9 amps of 12V through the 7-pin connector. That's a mere .9 amps of 120V AC if passed through the inverter. That's why companies like AMSolar sell kits to bypass the 7-pin connector with components that will pass more 12V amperage to your battery(ies). Something I will do eventually.

Don't forget there's a 12V circuit in your refrigerator that requires power, too, to make it "go" (whether on propane or 120V AC).

One more note--please use "Reply with Quote" in lieu of just "Reply" so I get notified you've posted to me. (Thanks!)

[Jerry P]

If your refrigerator requires 4 amps of 120V AC that means your inverter is pulling 40 amps of 12vDC from your battery. With one 12V battery rated at 100ah (which means 100 amps for one hour, or 50 amps for two hours with no accounting for loss) you'd quickly kill a lead acid as you can only tap into about 50% of it's rated aH before needing to recharge it. A Battle Born lithium can provide nearly 100% of it's rated capacity, but either way one battery will quickly be depleted.

Regarding your truck's alternator, my '17 Ford SuperDuty provides a measly 9 amps of 12V through the 7-pin connector. That's a mere .9 amps of 120V AC if passed through the inverter. That's why companies like AMSolar sell kits to bypass the 7-pin connector with components that will pass more 12V amperage to your battery(ies). Something I will do eventually.

Don't forget there's a 12V circuit in your refrigerator that requires power, too, to make it "go" (whether on propane or 120V AC).

One more note--please use "Reply with Quote" in lieu of just "Reply" so I get notified you've posted to me. (Thanks!)

Howson you're just bursting my bubble....lol! Such good info. So amperage conversion from dc to ac current is 10 to 1? Back to the drawing (thinking) board. Thanks!

[howson]

So amperage conversion from dc to ac current is 10 to 1?

Yes. And it's important to know how much of a battery's aH rating you can "tap" before it needs to be recharged. If you haven't read this thread yet, it might be very informative: https://www.mygrandrv.com/forum/show...your-Batteries

[jh.xsnrg]

Another point of information. Our smaller main fridge (6.1cf are they?) in the Imagine draws about 330w, and runs with about an 80-90% duty cycle (now that I can measure such things easily) on a warm day. I have 400w of solar, so during a sunny day, it will just keep up. The AC fridge in the outdoor kitchen draws 60w when running and cycles much less, so now we just leave that on going down the road, and still switch the big one to gas for long trips.