RV usage enough batteries amp/hour ?

[jvbutter01]

Trying to replace my current FLA batteries with LifePo. I have already 8 cells of 280ah. Trying to figure out if I series them to make 24v @280ah, will this be enough? Its winter time, and the RV has been put to bed for few months. I cannot use my Victron 712 to check the usage. I also don't want to wait until next year to finish the battery bank. I will NOT have any solar for recharge at this point. Only small generator. The idea is to run off batteries for 2-3 days before recharge.

Considering I will need (from estimates below) a 3k/watt inverter to change 24v to 110v for RV panel usage. Inverter will have a 150a draw at max load. Max usage is 7042watts per day estimated.
24v @ 150a = 3600watt. this is 1 hour and then the battery is dead. Obviously it wont run full amps for 1 hour as shown below. Bottom is 7042 usage for a day. Does this mean I will need parallel string of 280a to supply 1 days worth of 7042Watt? This doesn't seem right, but its the math I have tried to figure out.

Looking at the Battery FAQ
How do I convert my Watt Power needs into a number of battery Ah?
You need 6 kWh/day and you want 3 days autonomy: 6000 x 3 = 18,000 Wh

My math but be off somewhere. At this point, i need 3 strings of 24v 280ah.

120v
Item watts usage watt/usage
coffee pot 1500w 30min/d 750
microwave 1600w 5min/d 500

12v
vent fan 200w 24hr/d 4800
radio 25w 8hr/d 200
heater fan 132w 6hr/d ` 792
int lights ???w
12v H2O pump ???w
fridge - propane
total 7042

 

[Sojourner1]

Your #s are off. Here are some recordings from this month. I boondock fulltime in a 5th wheel, charge 99% of the time with solar. Using 12v 500ah. Just to give you an idea.


This an average day from earlier this year.


Production from that period of time.

 

[Sojourner1]

I forgot to add that my 3000w inverter/ charger (see sig) which I don't turn off has a 2ah idle draw or roughly 48a daily consumption, roughly 630Wh +/- (Wh= v x ah)

 

[Rocketman]

Batteries are only part of the equation, you need to generate the power, is your solar enough to power the rig?
Eight 280ah batteries I would think should be ok. My MotorHome 36’ class A, has 440 Ah of lead batteries @12v (so only about 200 usable). This is enough to power my rig - use my microwave (everything except run the a/c. To charge the batteries I have added four 200watt solar panels.

eight 280ah cells would be equivalent to 560ah of batteries @ 12 v. This is twice the usable power that is in my rig. I assume you will be powering the 12v side of your RV off this big battery through some converters.
Good luck with your project

 

[jvbutter01]

@Sojourner1 Thanks for the data.. wow, your pretty detailed. I will assume you didn't have AC running on those days since it was November, and rainy you showed. I dont plan to run the AC, would be nice, but I live in Oregon, we dont get that hot here.

@Rocketman yes batteries are only part. I really really didn't want to add solar to the trailer yet. I have yet to really work on the trailer, so I don't know where to run the cables from roof to battery bank. This started out to be a "lets replace the FLA with something that lasts longer when boondocking." Now i started thinking about how nice to have coffee in the AM and microwave if needed at nights for popcorn. I do have 2k watt generator for recharge. I was hopping a 24v 280ah or / 560 parallel bank would be enough for 2 days.

I was going to use standard 12v battery setup to keep simple. However from my estimate of 150a max current draw on the inverter for the 110 side of the trailer, i would need to swap out the cables. Currently the batteries are in the A frame of the trailer. I will move them inside, to the Front where the bedroom is and in the under bed storage area. I would still have about 20ft to run cables to the power center about 3/4 way to back of trailer. the stock 6awg cables wont quite cut the mustard from the wire charts I have looked at. So cost of new 2/0 cables, running them, and pushed me to keep stock awg and switch to 24v. yes I will have a 24v to 12v converter for the 12v side of the trailer for jacks awnings motors and such.

 

[Sojourner1]

I could and have run the 15k air conditioner off the batteries but I have solar to help offset some of the load if doing that besides added a microair soft start to the ac unit. I just hookup my Honda eu2200i if ac is needed.

I try to be where ac is not needed.

 

[jvbutter01]

When looking at inverters and idle amp draw, what is the item looking for? in the fig below, is it the ZERO LOAD POWER item? for this, it looks like 9watts for the 12v model and 11watts for the 24v model. Am i reading this correctly?

 

[Sojourner1]

It appears that way.

Mine is 25w +/-.

 

[jvbutter01]

ok, thanks. I will be looking into my converter/inverter here soon. battery packs are coming along. Will do some bench testing and I dont want to buy duplicate test equipment.

 

[jvbutter01]

I forgot to add that my 3000w inverter/ charger (see sig) which I don't turn off has a 2ah idle draw or roughly 48a daily consumption, roughly 630Wh +/- (Wh= v x ah)

So how many of us turn off your inverters when not immediately in use? My thought is to have inverter on 100% of the time. I don't really want to have to turn off and on the box just to flip a switch, or run the microwave. If its my power source, i think it should be on 100% of the time.

 

[Sojourner1]

There are some folks that use these inverters like a light bulb, on & off as needed. Some turn it off when the go to bed. If you need to worry about a small amount of power add another battery or panel but that's just me.

As far as turning on and off depending on the inverter it can be controlled from inside the trailer from the remote control beside so many other features.

 

[jvbutter01]

There are some folks that use these inverters like a light bulb, on & off as needed. Some turn it off when the go to bed. If you need to worry about a small amount of power add another battery or panel but that's just me.

As far as turning on and off depending on the inverter it can be controlled from inside the trailer from the remote control beside so many other features.

thanks... agreed... if you are worried about it, get a battery. we get cold in early / late season, no option of shutting it off.

 

[chrisski]

Our 9 w or 11 w consumption on the multi-plus seems reasonable. I have a Samlex 2000 watt inverter that says 1 amp current at 12 volts in idles (12 watts), and that’s exactly what I measure it at. That comes out to 280 watts, or a little over 10% of the 2700 wh of daily usable power off my batteries.

If I’m alone I’ll shut it off, but if I’m with my family, I leave it on for them.

 

[jvbutter01]

@chrisski yes another reason I'm looking at the Multi-plus. considering the AIMS are just as expensive ($1100 3kw) and Go Power ( $1500) I don't see any reason to not get the Multi-plus.

 

[chrisski]

I have the Bluetooth line of Victron, and I like the ability to monitor my VIcron devices. My SAMLEX inverter does not do that. My Victron Battery Monitor and two charge controllers are all networked together, and I do wish I could see the inverter. If there’s a SMART version of the multi-plus, I bet it does it.

 

[jvbutter01]

what do you mean by "smart" version?

 

[chrisski]

Smart version is the BlueTooth enabled. At least that’s what I think Victron calls Blue tooth.