2000 or 3000 watt inverter?

[oldtool2]

I am considering putting in an inverter on my 8280ss 5th wheel. It is something that probably will not get a lot of use. Not planning on running the AC with it, just a fan, computer, TV. Maybe the coffee pot or microwave though. The ones I am considering are:

3000 Watt Continuous/6000 Watt Peak Power Inverter

2000 Watt Continuous/4000 Watt Peak Power Inverter

Would like the thoughts from some of you boondockers out there. Which one would you go with and why? There is $130.00 difference between them which is a fair amount and don't want to spend any more than I have to. I did look at the 1000 and 1500 watt units but not sure if they would be big enough.

Another question. When you tie this into your 110volt ac do you still run your converter? If not how do you shut it off?

Jim

[Herk7769]

Battery bank size will determine inverter size.

How big is your battery bank in Amp Hours?

I will try to show complete calculations on battery life and recommended inverter size once you have that number.

[oldtool2]

Originally Posted by Herk7769

Battery bank size will determine inverter size.

How big is your battery bank in Amp Hours?

I will try to show complete calculations on battery life and recommended inverter size once you have that number.

Thanks, will check for you. Just looked, it was bought last year for an electric motor for a boat. When I got this trailer battery didn't look too good so put this one in. It is a:

Autocraft starting marine battery M24-3
cold cranking 800 amps
reserve 135 amps
marine cranking amps @ 32 degrees 1000 amps

Only one right now but plan on installing two 6 volt. Also thinking about a portable solar panel to charge them. Guess I will have to install switches because been told not to hook different ah batteries together. Don't understand why that would be a problem though?

Jim

NOTE: Put a 2 amp trickle charge in the battery I removed 4 days ago. This am makes 3 days sense I removed the charger. Just checked it and it is holding 12.3 volts. I have no idea how old this is or what it is rated at. Can't read the tag on it. It is a:

Alpha cell premium gel battery
195 GXL
Typical Runtime (minutes)**: 196
Max. Discharge Current 900 amp

Here is the only info I can find out about this battery. At:

AlphaCell GXL GelCell Batteries Gel Top Terminal Batteries - Alpha Technologies Ltd

Would this be a good battery for the trailer? I like the idea that it is sealed, no gas collecting or venting required.

Jim

[Jim Schings]

Originally Posted by Herk7769

Battery bank size will determine inverter size.
.

Not quite sure why you say that? Inverter size will be determined by what his maximum and continuous loads will be. The battery size will only determine how long he can pull that load before the battery will be depleted. There is no direct relationship.

That being said and all other things being equal, I would go with the largest inverter that you can afford based upon your planned budget. A larger inverter will typically run cooler at a given load. (and of course, you have the extra power should you need it.


Based upon your PLANNED demand the smaller of the two will work fine for you.. (2000/4000W unit)


The only drawback to the larger unit is that it may take another 500ma of current (not much to be concerned about) when idling and on with no load.

[ScottBrownstein]

I just added a second inverter to my rig. Since it has a residential reefer I already have a Xantrex Prowatt 2000 installed. I know that you can buy cheaper units (like the one you are showing) but a true sine wave unit means that you can power virtually anything without concern. Interesting that you also asked the 64,000 question about wiring it to your existing 110V distribution system. Xantrex has a cool automatic transfer switch that allows me to power up the inverter for an entire circuit and forget about it when you plug in as the switch will automatically switch the load to shore power, or generator whenever present. I think I paid less than $50 for the switch and maybe $300 for a 1000 watt unit.

[Herk7769]

Originally Posted by oldtool2

Autocraft starting marine battery M24-3
cold cranking 800 amps
reserve 135 amps
marine cranking amps @ 32 degrees 1000 amps

Jim,

To determine the AH rating of a Marine battery that gives capacity in RC (Reserve Capacity in minutes - NOT amps as you stated) you multiply the RC in minutes by 0.417.

So your single M24-3 battery has an AH rating of 135*0.417 or 56 AH at a 25 amp discharge rate.

25 amps at 12 volts = 300 watts Continuous

The attached chart shows a 100 AH battery as it gets destroyed as the current demand goes up. You can use it "as a percentage" for any storage battery (yours is not as it is a starting battery) so assume it will do MUCH worse than this example.

Enter the graph at 25 amps and you will see that it just about correlates with the 100 AH battery capacity line at 20 hours.

At a 5 amp continuous draw (60 watts), the battery will deliver 100 percent of its rated capacity for 20 hours.

At 25 amps (300 watts) it will deliver 56% of that 20 hours or 11 hours and 15 minutes.

Now for a typical electric coffee pot (1500 watts) @ 12 volts you would need to draw 1500/12 or 125 AMPS from the battery. As you can see it is "off the charts" and the battery won't last more than a few minutes before it is dead.

This is why you will need MANY batteries to feed a 3000 watt inverter. You will need to SHARE the draw across several 12 volt "stacks" to use that much power without destroying your batteries.

The ideal is to configure your battery stack such that no individual battery is loaded up with more than 25 amps EVER.

If you need 100 amps total (1200 watts) you will need FOUR 12 volt batteries so no battery sees more than 1/4 of the amp load (25 amps each).

Also remember that discharging a battery below 50% of its rated capacity before recharging will cause permanent plate damage and permanent loss of capacity.

Until you are ready to put in some heavy duty battery upgrades, I suggest a good quality pure sine 300 Watt inverter for you and make your coffee on the stove.

http://www.invertersrus.com/gp-sw300...TTHhoCQDzw_wcB

[Herk7769]

Originally Posted by Jim Schings

Not quite sure why you say that? Inverter size will be determined by what his maximum and continuous loads will be. The battery size will only determine how long he can pull that load before the battery will be depleted. There is no direct relationship.

That being said and all other things being equal, I would go with the largest inverter that you can afford based upon your planned budget. A larger inverter will typically run cooler at a given load. (and of course, you have the extra power should you need it.


Based upon your PLANNED demand the smaller of the two will work fine for you.. (2000/4000W unit)


The only drawback to the larger unit is that it may take another 500ma of current (not much to be concerned about) when idling and on with no load.

All things are never equal.

Most of this assumes near unlimited battery amperage available.

My camper does not have enough payload to carry enough batteries to continuously drive a 4000 watt inverter for more than a few minutes at full rated output. 333 amps off the batteries.

333 amps divided by 25 = 14 12 volt batteries at 75 pounds each = 1050 pounds of batteries

If using 6 volt batteries, you would still need 14 batteries to do this as each battery would have more AH available BUT you would need TWO to get the required 12 volts. AH does not double in series; voltage does.

An idling inverter should draw even less ma than that, unless it was previously overheated and the cooling fans are running. The monitoring electronics and display draw almost nothing.

[Herk7769]

thinking about solar?

As I explain here, the maximum watt hours in a 80 AH battery is 80 AH times 12 volts or 960 watts available for 1 hour.

It does not matter what you WANT to power, you can't get blood out of a stone.

[oldtool2]

Originally Posted by Herk7769

Jim,

To determine the AH rating of a Marine battery that gives capacity in RC (Reserve Capacity in minutes - NOT amps as you stated) you multiply the RC in minutes by 0.417.

So your single M24-3 battery has an AH rating of 135*0.417 or 56 AH at a 25 amp discharge rate.

25 amps at 12 volts = 300 watts Continuous

The attached chart shows a 100 AH battery as it gets destroyed as the current demand goes up. You can use it "as a percentage" for any storage battery (yours is not as it is a starting battery) so assume it will do MUCH worse than this example.

Enter the graph at 25 amps and you will see that it just about correlates with the 100 AH battery capacity line at 20 hours.

At a 5 amp continuous draw (60 watts), the battery will deliver 100 percent of its rated capacity for 20 hours.

At 25 amps (300 watts) it will deliver 56% of that 20 hours or 11 hours and 15 minutes.

Now for a typical electric coffee pot (1500 watts) @ 12 volts you would need to draw 1500/12 or 125 AMPS from the battery. As you can see it is "off the charts" and the battery won't last more than a few minutes before it is dead.

This is why you will need MANY batteries to feed a 3000 watt inverter. You will need to SHARE the draw across several 12 volt "stacks" to use that much power without destroying your batteries.

The ideal is to configure your battery stack such that no individual battery is loaded up with more than 25 amps EVER.

If you need 100 amps total (1200 watts) you will need FOUR 12 volt batteries so no battery sees more than 1/4 of the amp load (25 amps each).

Also remember that discharging a battery below 50% of its rated capacity before recharging will cause permanent plate damage and permanent loss of capacity.

Until you are ready to put in some heavy duty battery upgrades, I suggest a good quality pure sine 300 Watt inverter for you and make your coffee on the stove.

Go Power! 300 Watt 12 Volt Pure Sine Wave Inverter

A lot of info, thank you! I won't be dealing with Advance auto parts any more! Was told that Marine and dp cycle were the same. I now know that is not true. Did some research on their web site and got the following info:

The battery does have a reserve capacity of 135 minutes, so it will put out 25 amps for that time until it drops below 10.5 volts, and the battery will need charging.

The Amp Hour rating of this battery is 56.25 amp hours at 25 hour rate.

M24-3 offers 75 Amp hours at 20 Hour Rate

Do you know what the ah rating would be for this battery?

Alpha cell premium gel battery
195 GXL
Typical Runtime (minutes)**: 196
Max. Discharge Current 900 amp

196 X .417 = 81.7 ah ? I do believe that thus battery is a deep cycle but can't be sure from the info I have found on it.

Guess I will be making a trip to Pep Boys to see what golf cart batteries they have.

As for the coffee I have a good old fashion one. Just got to play with it, can't remember how much coffee to use and how long to let it perc.

Jim

[Jim Schings]

Originally Posted by Herk7769

......
333 amps divided by 25 = 14 12 volt batteries at 75 pounds each = 1050 pounds of batteries

If using 6 volt batteries, you would still need 14 batteries to do this as each battery would have more AH available BUT you would need TWO to get the required 12 volts. AH does not double in series; voltage does........

As an EE, I understand all of that, but still stand by my statement: Inverter size will be determined by what his maximum and continuous loads will be. The battery size will only determine how long he can pull that load before the battery will be depleted. There is no direct relationship.

An idling inverter should draw even less ma than that, unless it was previously overheated and the cooling fans are running. The monitoring electronics and display draw almost nothing.

Just checked on a couple (2000 - 3000 W ratings). (Per manufacturer). In in the OFF position with the remote control it will use ~300mah. In the ON position with no load, it could double that. I know mine (2000w) uses that much. I suspect some of that is input cap leakage, the other electronics involved and probably some other resistances used for noise reduction. In any case, a small amount of load.