Inverter Sizing

[bdosborn]

Just an FYI, I was *very* skeptical about using Bluetooth as a monitor for anything, much less an expensive battery. I've had rotten luck connecting reliably to anything over Bluetooth but the Victron app has been rock solid. I haven't had a single issue with getting the app to work.
Bruce

[Socal Tom]

Thanks for posting that worksheet, Bruce. I can see adding (or estimating) the hours the appliances will be used makes for more accuracy in planning the overall load and for battery sizing.

I have one other question, maybe I should make this a new topic...but my question is regarding monitoring both the solar system and its activity and also monitoring the battery state.

I've been looking at Victron's products and with 2/100 watt solar panels, I'm thinking the MPPT 100-30 will be my charger. I'm looking at the MPPT Control Monitor (the round one) to monitor the solar activity, running it through a shunt from the Battleborn 100Ah lithium battery.

I also want to monitor the state of the battery. So I was looking at Victron's BMV 712 Smart Battery Monitor. This also needs to run through the shunt...or a shunt......

My question is, is there a way of monitoring both the solar activity and the state of battery through a single monitor.... or what would be the best way to set up the two monitors I mentioned? I "think" having 2 shunt's, running each monitor through a separate shunt would be problematic and not the correct way to go about this. Looking for suggestions ... or more like... direction.

Thanks!John

I have two of these bayite monitors wired to one shunt. One measures power going out of the battery the other power going in. You can also wire them with a two way switch so that depending on the way you have the switch it measures power in or out. I used to flip the switch to measure the power out, once the solar stopped charging, then switch it back in the morning and reset the watts counter. It gave you a good measure of power in the battery.
https://www.amazon.com/bayite-6-5-100V- ... 198&sr=8-5

[saltydawg]

the 42 buck ali meter can tell which way power is going. So no need to change it for charge or discharge.

[Socal Tom]

The more I thought about it, the more I feel a large inverter is impractical in a TD. For iPad iPhone charging, a USB adapter makes much more sense, and will be more efficient. If you can’t locate a 12v cord for the laptop, then I would go for a small inverter or two. I had 350 watt inverter for a while. Never got used. The 200 watt portable one gets used now and then, but sometimes in the car, sometimes the trailer....

edit:
I feel like I should expand on this. A 100AH battery, what I consider typical for a TD, has about 1250 watt hours capacity, and with lead acid you want to keep it above 50%, so 625 watts is the real limit. So if you use that 1000W invertor, you will burn through most of that in 1/2 hour, leaving 125 to power lights etc. To recharge the battery you would need something around 200 watts of solar, and then it will take most of the daylight hours to recharge it, for another 30 minutes of power. If you want more than 30 minutes, then you need more battery and more solar. This is why it seems impractical to me. The light weight of a TD goes away when you start adding a big invertor. Honestly, I think you would be better off with a generator if you need that much power.
Tom

[Tom&Shelly]

Generally speaking, generalizing is ALWAYS wrong.

That said, if one looks at the electrical appliances in their home these days, many are inherently low voltage anyway (assuming the lights have all been converted to LEDs). LED lights, computer chargers, telephone chargers, clocks, televisions, DVD players, radios, etc. all step the 120 vac down to run on low voltage. All of these have 12 vdc equivalents on the market that folks take with them camping.

The major exceptions to the low voltage appliances in the home are large appliances with motors, and anything with heating elements.

Heating take a lot of energy, no way around that, and when camping there are usually more efficient solutions involving propane, diesel, white gas, a campfire, etc. (One exception is a hair dryer. My solution is a crew cut, but I have yet to convince Shelly to get one.)

Far as appliances with motors go, the ones in the home usually use 120 vac because that's available, and for small power draws (like small refrigerators) there are also low voltage equivalents. Other appliances take such large amounts of power for their motors (air conditioner, washing machine, dish washer, table saw, etc.) that it isn't practical to run them from a battery/inverter system. (Probably why I have yet to see a table saw while camping.)

So here's the point: There would seem to be little need for an inverter when camping, except to use an appliance created for the home that has a low voltage equivalent on the market. For some, that may be a more cost effective solution. For others, maybe not.

FWIW, I'm trying to size an inverter for an outbuilding, and running through a similar thought process. We'll keep the teardrop and a vehicle or two in there, so I'd like to use it as a light grade shop. But all the shop tools that are practical to run off of the inverter already seem to have versions with rechargeable batteries. Anything heavy duty wouldn't work well from a practical sized (for us) solar/battery/ inverter system anyway. (For those we'll go to gasoline.)

Tom

[tony.latham]

If you can’t locate a 12v cord for the laptop...

I'm prepping for our month-long trip to the Four Corners. My MacBook uses a USB-C cable for charging ––gotta have it for paying bills and stuff. It was a simple thing to find a 36-watt USB-C adapter for the 12-volt outlet. works great.



Tony

[featherliteCT1]

Tony,

Are you using some kind of charger like this one?
https://www.amazon.com/Charger-Delivery ... B07H2FTS3X

[tony.latham]

Are you using some kind of charger like this one?

It's this one:

https://www.amazon.com/gp/product/B08QZ7RTSW/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

I'll be using it to charge a new MacBook Air with the M1 chip. It uses very little power, so I'm sure that helps.

I did a one-hour test with the computer at 90%. When I checked it an hour later it was at 100%. No idea how long it took.

Tony