Reply
 
Thread Tools Search this Thread Display Modes
 
Old 01-08-2021, 05:23 PM   #1
Guru
 
Alaskan Sea-Duction's Avatar
 
City: Inside Passage Summer/Columbia River Winter
Vessel Name: Alaskan Sea-Duction
Vessel Model: 1988 M/Y Camargue YachtFisher
Join Date: Jul 2012
Posts: 7,543
Figuring Inverter Amperage

To my smarter than me mathematicians in TF World.

Scenario:

1. battery bank 12VDC

2. Inverter

3. A 120AC duel outlet

Battery bank connected to inverter, which is connected to the 120 outlet.

Question:

I have a 10 amp A/C load on the 120vAC outlet.

What would be the DC amp load on the house battery bank?
Alaskan Sea-Duction is online now   Reply With Quote
Old 01-08-2021, 05:24 PM   #2
Guru
 
City: Rochester, NY
Vessel Name: Hour Glass
Vessel Model: Chris Craft Catalina 381
Join Date: Aug 2019
Posts: 5,000
Figure somewhere around 110 amps DC. Basically, multiply by 10, then add some for inverter inefficiency.
rslifkin is online now   Reply With Quote
Old 01-08-2021, 05:34 PM   #3
Senior Member
 
City: Winthrop
Vessel Model: Pacific Trawler 40
Join Date: Mar 2020
Posts: 352
Quote:
Originally Posted by rslifkin View Post
Figure somewhere around 110 amps DC. Basically, multiply by 10, then add some for inverter inefficiency.
Sounds about right! Inverters use 5 to 10% more power than your pulling. As mentioned, inefficiency or loss in the conversion.
__________________
Iggy
Iggy is offline   Reply With Quote
Old 01-08-2021, 06:03 PM   #4
Guru
 
Ken E.'s Avatar
 
City: Bellingham WA
Vessel Name: Hatt Trick
Vessel Model: 45' Hatteras Convertible
Join Date: Nov 2016
Posts: 1,709
Quote:
Originally Posted by Alaskan Sea-Duction View Post
To my smarter than me mathematicians in TF World.

Scenario:

1. battery bank 12VDC

2. Inverter

3. A 120AC duel outlet

Battery bank connected to inverter, which is connected to the 120 outlet.

Question:

I have a 10 amp A/C load on the 120vAC outlet.

What would be the DC amp load on the house battery bank?

Rough numbers and ignoring losses, your load is:
10 amps * 120 volts AC = 1200 watts

Using your batteries through your inverter for this load, you need:
1200 watts / 12 volts = 100 amps from your batteries.

Apologies to engineers and electricians. I'm only an accountant.
__________________
Ken on Hatt Trick
Ken E. is offline   Reply With Quote
Old 01-08-2021, 06:04 PM   #5
Guru
 
oscar's Avatar
 
City: Bethlehem, PA
Vessel Name: Lady Kay V
Vessel Model: 1978 Hatteras 53MY
Join Date: Oct 2015
Posts: 1,094
Pulling 100A is going to require a LARGE battery bank.

A 200A battery is not going to provide 100A for 30 minutes.
__________________
https://ladykay.blog/
oscar is offline   Reply With Quote
Old 01-08-2021, 06:26 PM   #6
Guru
 
Cigatoo's Avatar
 
City: Narragansett Bay
Vessel Model: Grand Banks 36
Join Date: Sep 2016
Posts: 1,435
Keep in mind that most times this is not a continuous load. Take a 1,000 watt coffee maker (1000 watts / 12 volts = 83 amp hours) for example. They make the coffee (takes maybe 5 minutes) then cycle on and off to keep it warm. So over the course of an hour it is only drawing that 83 amp hours for 30 minutes. So actual draw over an hour would be 42 amp hours or so. A Victron monitor or the like will greatly help you calculate the amps used.
__________________
Charlie0
Cigatoo is offline   Reply With Quote
Old 01-08-2021, 06:32 PM   #7
Guru
 
O C Diver's Avatar
 
City: Fort Myers, FL... Summers in the Great Lakes
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 10,904
I would agree between 110 and 120 amps depending on inverter efficiency, whether pure or modified sine wave (and how the appliance handles the modified sine wave), and bank size. The larger the bank, generally, the higher the load voltage. As the bank load voltage drops, necessarily, the amp draw will increase to produce the same 120 VAC amperage. Duration of load will have a significant impact. Microwaving for 1 minute versus 10 minutes will generally show a significant increase in amperage draw by the end of 10 minutes.

Ted
__________________
Blog: mvslowhand.com
I'm tired of fast moves, I've got a slow groove, on my mind.....
I want to spend some time, Not come and go in a heated rush.....
"Slow Hand" by The Pointer Sisters
O C Diver is online now   Reply With Quote
Old 01-08-2021, 07:34 PM   #8
Member
 
City: Lacey WA
Vessel Name: Feisty Too
Vessel Model: Ranger 29 C
Join Date: Jun 2019
Posts: 8
Just order them from Greg's marine wire. Measure, specify the color you prefer, the fittings, and they come perfectly swaged with shrink wrapped terminals for about the price you'll pay for the wire. Never do my own again.
RichHurst is offline   Reply With Quote
Old 01-09-2021, 06:52 AM   #9
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 22,553
Inverters are most efficient at modest loads , it goes down with a tiny load .

Most inverter mfg. have a chart that shows efficiency at different loads.
FF is offline   Reply With Quote
Old 01-09-2021, 01:57 PM   #10
Guru
 
tiltrider1's Avatar
 
City: Seattle
Vessel Name: AZZURRA
Vessel Model: Ocean Alexander 54
Join Date: Aug 2017
Posts: 3,049
Quote:
Originally Posted by Alaskan Sea-Duction View Post
To my smarter than me mathematicians in TF World.

Scenario:

1. battery bank 12VDC

2. Inverter

3. A 120AC duel outlet

Battery bank connected to inverter, which is connected to the 120 outlet.

Question:

I have a 10 amp A/C load on the 120vAC outlet.

What would be the DC amp load on the house battery bank?
Confess, why did you ask this question?
tiltrider1 is offline   Reply With Quote
Old 01-09-2021, 04:43 PM   #11
Guru
 
Alaskan Sea-Duction's Avatar
 
City: Inside Passage Summer/Columbia River Winter
Vessel Name: Alaskan Sea-Duction
Vessel Model: 1988 M/Y Camargue YachtFisher
Join Date: Jul 2012
Posts: 7,543
Quote:
Originally Posted by tiltrider1 View Post
Confess, why did you ask this question?
Oh heck I don't know. I am replacing an old inverter and when you are retired you think of things like this.

I was curious......
Alaskan Sea-Duction is online now   Reply With Quote
Old 01-09-2021, 09:35 PM   #12
Senior Member
 
Barking Sands's Avatar
 
City: NEW PORT RICHEY
Vessel Name: M/V Intrigue
Vessel Model: 1985 Tung Hwa Senator
Join Date: Dec 2019
Posts: 323
Quote:
Originally Posted by Alaskan Sea-Duction View Post
Oh heck I don't know. I am replacing an old inverter and when you are retired you think of things like this.

I was curious......
And thinking about these things is educational on what types of set up might work well when wanting to use an inverter. Lithium- 24 volt bank of as many AH as you can afford really starts to shine.

In the example above:
Quote:
Using your batteries through your inverter for this load, you need:
1200 watts / 12 volts = 100 amps from your batteries.
Substitute the 12 for 24

Using your batteries through your inverter for this load, you need:
1200 watts / 24 volts = 50 amps from your batteries.

I have only recently been thinking about this myself. Especially since I got the Dakota Lithium batteries for my Golf Cart. They are all they are hyped to be IMO. And then going 24 volts helps keep amp loads down.
Barking Sands is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 04:02 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012