Batteries continually die

[Vintageblues]

I purchased a Skoolie a couple months back that was already converted into an RV. It only had a single gel battery and a 2,000w inverter and we noticed things were dying quickly. I upgraded to 3-12v 100AH battle born batteries (so 300AH altogether). They still die very easily with very little apparent drain on them. I then replaced the inverter with a 3000w Renogy inverter. Again. They die quickly despite reading 100% at the beginning of the day and die while the sun is still up. I do have 300w of solar panels on the roof which I intend to upgrade but it seems like there’s still a mystery parasitic drain happening somewhere. The only things that are running are my RCA side by side mini fridge which consumes 100kwh annually. And my Dyson vacuum that’s plugged in. There’s also a propane hot water heater. I leave my water pump turned off. I understand this is like searching for a needle in a haystack of possible issues but any ideas are appreciated. It’s crossed my mind that my charge controller might also need to be upgraded. It’s just a 20A Renogy Rover. When responding please keep in mind that I’m a complete novice so layman’s terms are AWESOME! Thanks for your help in advance.

 

[chrisski]

Need more panels now and a way to charge your batteries. This is an example of a Converter that can plug into a generator to charge your battery.

Get a battery Monitor or Shunt to measure your loads. THere’s other ways to get loads, but these are easiest.

Once this is inline, you can turn loads off one by one to find truth data.

My guess is, the 3000 watt inverter draws 24 watts per hour (500+ watt hours a day) just to be powered up, and the RCA fridge draws the rest. The park likely only pushes 300 watt hours to 1500 watt hours a day. This time of year approaching the shortest day of the year, I get 2 X panel rating for flat panels on the roof.

So in my area, to turn on. 300 watt inverter costs me a 300 watt panel, with very little, 100 watt hours to power loads, of which the fridge consumes much more.

The Battery is only 2400 watt hours.

 

[sunshine_eggo]

The 100% reading on the Renogy is a completely worthless number that should be ignored. If you have an actual battery monitor that's reporting 100%, then it's not configured properly.

Short version: You are using more energy than you are collecting every day.

Long version:

First, confirm all connections are properly torqued and of high quality. Poor connections between the charger and battery can dramatically impede charging.

Assuming you have the MPPT, 20A renogy will never output more than 20A * 14.4V = 288W.

Additionally, if your panels are flat on the roof, this time of year, you're lucky to get about 70% of that as an absolute maximum.

So, your fridge uses about 0.27kWh/day.

Your inverter likely consumes about 0.36kWh/day because it takes energy to turn AC into DC.

If you use ANY additional power beyond the above two items, your 300W of panels may not be able to keep up this time of year.

You will know your battery is fully charged when you measure 14.4V at the battery terminals. Below that, it's not fully charged.

 

[BentleyJ]

Its not really like a needle in a haystack, its more like the process of elimination. There are only 2 places for the current to go.
1) DC: Are there any other DC loads or appliances connected to the new batteries other than the Inverter and Charge Controller.
2) AC: Are there any other AC loads or appliances connected to the inverter.

 

[BryceFreeman]

Hi, the daily power generation of 300w solar panels is not enough for 3*100ah batteries. Also you can get a multimeter to read the batteries' volts one by one when they show fully charged and when they die.

 

[sunshine_eggo]

Hi, the daily power generation of 300w solar panels is not enough for 3*100ah batteries. Also you can get a multimeter to read the batteries' volts one by one when they show fully charged and when they die.

@Vintageblues

Please disregard this advice. It is nonsensical. This person is a rep for Eco-worthy and provides dubious advice of low quality.

With LFP batteries, charge current is very flexible. You pretty much just need to avoid charging at higher than the maximum rate.

Your PV charging ability and solar conditions determine how much energy you can use on a daily basis.
Your battery capacity determines how long you can go between charges.

 

[Rednecktek]

I do have 300w of solar panels on the roof

Sorry Sunshine, I gotta agree with Bryce on this one. We all know that having panels flat on the roof is a big hit on performance and 300w of panels in good conditions might hit 1500Wh on a good day which is only about 1/3 of the capacity of his system.

But, back to the OP:
Your inverter is eating a good chunk of power each day, your vacuum is sucking down a little for its control voltage, and your fridge needs to eat as well. All these added up are very likely WAY more than your flat panels on the roof can generate. Start with shutting off the inverter and unplugging the Dyson for a day and see how much difference that makes.

Another thing you should look into is getting some more panels on the roof and/or deployable panels to their own controller that you can point at the sun for a day.

Definitely try to get the readings of "Full" and "Dead" with a multi meter so we can see just how far off everything is.

The "Full" reading on the SCC is based on the voltage of your batteries. For lead acid (which everyone and their uncle defaults to) it's a pretty linear voltage-to-capacity line, but LFP is very much waitwaitwaitwaitwaitDEAD very flat curve. If your SCC thinks the batteries are full at 12.8v or so then your batteries are only about 30% or so full, so you're only seeing 1/3 of your capacity to begin with.

 

[Checkthisout]

Have the batteries ever been charged up with standard charger, converter etc off shore or generator power?

 

[Supervstech]

I’d like to clarify things…

You have a total of 300W of solar, mounted flat on the roof.

You have 3840Wh of lithium batteries.

You operate an inverter, a refrigerator, and a Dyson vacuum.

You need a dc volt meter or a shunt or another style of energy usage meter on the battery.

Simple math says the fridge uses average 273Wh per day, but that is ac Watts, the inverter is not 100% efficient, and there will be conversion losses… let’s say 85% efficient, or 322Wh per day average… ACTUAL measured daily consumption may be much better or worse.

The inverter will consume energy any time it is powered up. Could be from 10 to 50W… constantly… let’s say 10, that is 240Wh a day gone.

Now… your solar can output a max of 300W, in winter, with flat mounted panels, let’s say 180W… average full sun hours in winter is 3… so, maybe 600Wh… a day…

Your batteries are capable of 3844Wh… but in winter with only 300W of solar… mounted flat. Well… math is pretty simple.

 

[sunshine_eggo]

Sorry Sunshine, I gotta agree with Bryce on this one.

You should know better.

We all know that having panels flat on the roof is a big hit on performance and 300w of panels in good conditions

Didn't I pretty much say the same here?

Assuming you have the MPPT, 20A renogy will never output more than 20A * 14.4V = 288W.

Additionally, if your panels are flat on the roof, this time of year, you're lucky to get about 70% of that as an absolute maximum.

might hit 1500Wh on a good day which is only about 1/3 of the capacity of his system.

Not relevant. What if someone wants a week's worth of backup for a small load. Should they really have enough PV to charge 7X their daily need as your claim suggests?

Let's be specific:

Hi, the daily power generation of 300w solar panels is not enough for 3*100ah batteries. Also you can get a multimeter to read the batteries' volts one by one when they show fully charged and when they die.

This is a completely false statement. 300W of solar panels has nothing to do with battery capacity. It certainly may be insufficient for the OP's demand, but buddy Bryce said nothing of the sort.

This:

Short version: You are using more energy than you are collecting every day.

is the fundamental issue, and it had nothing to do with the size or type of battery. Bryce said nothing of the sort.

These are the important concepts here:

Your PV charging ability and solar conditions determine how much energy you can use on a daily basis.
Your battery capacity determines how long you can go between charges.

Which circles back to:

Short version: You are using more energy than you are collecting every day.

 

[400bird]

Sorry Sunshine

At first I thought this was a dig at Vintageblues that I just wasn't cool enough to understand ?
But, now I see you were responding to sunshine_eggo

I agree with Sunshine, 300w could be plenty of your load is a constant 5 watts, regardless of how large the bank. But, that's probably not the situation here.

The solar on the van is probably inadequate to recover used energy and support loads, plus using the SOC on the charge controller is just none sense. Might as well ask a waffle, the info would be just as accurate.

 

[Rednecktek]

Not relevant. What if someone wants a week's worth of backup for a small load. Should they really have enough PV to charge 7X their daily need as your claim suggests?

That would be my plan, but I'm a fan of 3 days backup and enough panel to recharge the whole bank in a day because where I live that sunny day is probably months away yet. ?

I agree with Sunshine, 300w could be plenty of your load is a constant 5 watts, regardless of how large the bank. But, that's probably not the situation here.

I can tell you from personal experience that 300w of panel can't always keep up with 120Wh of load. Weather and location are MAJOR factors.

 

[Checkthisout]

I had some sun today and got 1.2 kwh out of my 2400 watt array.

Translate to the op would be about 150 watt hours.

Neeeeeeeeeeddddddd more panels stat!

 

[sunshine_eggo]

I had some sun today and got 1.2 kwh out of my 2400 watt array.

Translate to the op would be about 150 watt hours.

Neeeeeeeeeeddddddd more panels stat!

Yikes!

Had storms/clouds for most of the day. My usual "charged by 11am" didn't happen. Never got to peak SoC.

Cloud edging and cold temps showed intermittent 3325W out of a 2970W array.. in November...

Managed 8.8kWh when I can usually get 18+

 

[Checkthisout]

Yikes!

Had storms/clouds for most of the day. My usual "charged by 11am" didn't happen. Never got to peak SoC.

Cloud edging and cold temps showed intermittent 3325W out of a 2970W array.. in November...

Managed 8.8kWh when I can usually get 18+

I'm in the blue zone in WA State.

 

[Rednecktek]

Me too, which is why I tell people I "Play" with solar rather than "Work" with solar. Because solar doesn't work out here.

 

[Checkthisout]

Me too, which is why I tell people I "Play" with solar rather than "Work" with solar. Because solar doesn't work out here.

Works good in summer but even then, we got trees trees and more trees!

Generator is a necessity for my miniscule constant 50 watt draw from about now through the end February

Albeit, I changed over to lithium a couple weeks ago and yikes...just yikes what a diff.

 

[50ShadesOfDirt]

OP inherited a solar gear setup from someone else, with the skoolie purchase. In these cases, it would be a great idea to start documenting/tracing the entire wiring system & solar gear (house wiring, not automotive side, other than grounding), and see how things were done.

There could be all kinds of suspect choices and such, and until you map it out, you're not really sure what's going on. Some of these things could easily be draining, interfering, shorting, etc.

Hope this helps ...

 

[Q-Dog]

You can't use more watts than you collect. What more is there to say?

OP needs more solar or another way to charge batteries; like a generator, or plug into the grid, or use the alternator to charge while driving.

 

[KITROBASKIN]

Like said, connections need to be examined and tightened if necessary.