Batteries really depleted overnight or is it a BMS problem?

[Mcstiggens]

400w solar to 400ah of battery isn't like a hard rule, but more minimum common sense starting point. Reality is a 3x w to AH ratio is approaching reality for full timing
So even 400w ain't gonna get it but its going to be way better that 165w panel.

Yea, it's just what I have hooked for for the moment. It's all been done in haste, totally in an emergency, so no time for planning properly. I do have 1600w worth of 185W panels but I have not had the time to set that up. It all came at me at once. So I am just trying to piece together something that will work in a pinch, which is why I am not relying on the single 165'er to do the job.

 

[sunshine_eggo]

"Is there a reason you're not using this?"

Only because I'd have to run the genny for 8 hrs.

but you're okay with running 40 hours for the 10A charger you're using?

Unfortunately I could not find a 40+ amp charger locally that is not for starting a vehicle, thus, the 40 amp is only for 5 second bursts, not for continuous charging. The most I could find was 10amp continuous. I ordered a Li Time 40amp charger.

Why are you looking for a charger when you have a 55A on board?

You have two options:

Get 10Ah/hr (2.5% of total capacity) of generator running
Get 55Ah/hr (13.8% of total capacity) of generator running

You've chosen the second one. Non-inverter generators are actually most efficient at max power with 70-80% rated being the sweet spot between efficiency and longevity.

You're burning more gas per Ah with the small charger than you would be with the converter.

What am I missing?

 

[Mcstiggens]

@Rocketman has the best answer for you!
You can't beat Victron for mobile applications.

I do agree but my issue is that I am totally unprepared for this and that includes my budget. Therefore, I have to do all of this at the lowest cost possible, as quickly as possible. That is why I am so woefully unprepared and uninformed. I do have sights on the Victron hardware in the future when I intend to/can afford to build a 48V shed system that I will run the shop and RV off of. For now though, its Mcgyver time.

 

[sunshine_eggo]

I do agree but my issue is that I am totally unprepared for this and that includes my budget. Therefore, I have to do all of this at the lowest cost possible, as quickly as possible. That is why I am so woefully unprepared and uninformed. I do have sights on the Victron hardware in the future when I intend to/can afford to build a 48V shed system that I will run the shop and RV off of. For now though, its Mcgyver time.

Alrighty Angus... Figure out how wire that converter to charge the battery, and you can run whatcha brung and get a dramatic improvement over what you have and save money on fuel by getting more storage per hour of run time.

 

[Mcstiggens]

but you're okay with running 40 hours for the 10A charger you're using?

Because the charger is silent, doesn't draw attention and uses no propane. It's more of a necessity than preference.

Get 10Ah/hr (2.5% of total capacity) of generator running

No using gas generator for that. Was using solar generator with inverter from my shop. I also have use of a 110 outlet way over in a barn that I can charge with. Long story but, I am setup too far away from A/C to run cords and plug in the trailer AND the goal is to not rely on it. I have setup the batteries on the A/C using 10amp charger because it is an emergency until I can set up my system properly. Otherwise, I'm not paying the bill on the A/C so I'm trying not to rely on it.

 

[Mcstiggens]

Alrighty Angus... Figure out how wire that converter to charge the battery, and you can run whatcha brung and get a dramatic improvement over what you have and save money on fuel by getting more storage per hour of run time.

Well, If I'm running the genny, then the converter is already wired into the 50amp system on the trailer, so yes, that does work effectively, as long as I'm running genny. I am trying to be low key though. So If I ran it for 8-12 hrs, I would likely draw attention and some neighbor would report me to the county or some dumb shit

 

[sunshine_eggo]

Because the charger is silent, doesn't draw attention and uses no propane. It's more of a necessity than preference.

No using gas generator for that. Was using solar generator with inverter from my shop. I also have use of a 110 outlet way over in a barn that I can charge with. Long story but, I am setup too far away from A/C to run cords and plug in the trailer AND the goal is to not rely on it. I have setup the batteries on the A/C using 10amp charger because it is an emergency until I can set up my system properly. Otherwise, I'm not paying the bill on the A/C so I'm trying not to rely on it.

So you charge the solar generator at your shop, take it to the trailer and use it to power the charger?

The only valid argument is if the solar generator can't handle 900W output.

At only 10A output, if you're charging with it, you need to leave it charging all night and deplete the solar generator maximizing your onboard charge rather than only run the "generator" for an hour.

You've routinely used more from your batteries than you've replaced. This is how it's going to be until you get a means of replenishing more than you use.

 

[sunshine_eggo]

Well, If I'm running the genny, then the converter is already wired into the 50amp system on the trailer, so yes, that does work effectively, as long as I'm running genny. I am trying to be low key though. So If I ran it for 8-12 hrs, I would likely draw attention and some neighbor would report me to the county or some dumb shit

You clearly understand your proximity restrictions, but you need to understand your power restrictions.

If you only put 10A into a battery for 1 hour, guess what? You only have 10Ah into the battery at most. That's 120Wh. That will run your furnace blower for about 30-60 minutes at a guess.

I'm finally remembering our original dialogue... that damn PowerMr 24V/3000W unit is still in the box...

it goes back to that conversation...

1) you get X per day from sources.
2) you can only use X per day before you start eating into your battery.

If #2, you will eventually deplete your reserves and run your battery flat every day while not meeting your needs.

You may have a goal of not relying on your barn outlet, but you only have one panel that doesn't meet your needs. You can't meet a goal just by stating it.

IMHO, part of your daily routine needs to be shuttling the solar generator back and forth between the barn and trailer either charging it up or discharging it into your trailer, and the only time it can be idle is when you're sleeping or physically unable to move it. If there's power in the generator, it needs to be charging the trailer.

 

[Mcstiggens]

IMHO, part of your daily routine needs to be shuttling the solar generator back and forth between the barn and trailer either charging it up or discharging it into your trailer, and the only time it can be idle is when you're sleeping or physically unable to move it. If there's power in the generator, it needs to be charging the trailer.

Well the solar generator has a two 100ah led acid batts with a 1500w inverter. It is hooked up to 250W solar array. It was intended to take the light loads such as shop lights and recharging batteries for shop tools. Generally throughout the day when the sun is out, it has no probs doing all that and now has been trickling the 10 amp charger during the day as well for the trailer.

Since it has come to light that the LifePO4 batts on the trailer were never properly charged, I plan to take them to the barn with a proper 40amp charger and charge them for a day. Then I will put them back on the trailer, calibrate the shunt/monitor and use the combination of the 165w tender panel on the trailer + occasional propane genny + trickle charge from the solar genny using the 10amp charger. That's the best I can do for the near future. I'll work out the long term solutions as time allows.

 

[Mcstiggens]

Why are you looking for a charger when you have a 55A on board?

BTW, the converter is 55amp under optimal conditions but the little ultra quite genny I am currently running only has 20/30amp capability, so that puts a damper on optimal charge capability.

 

[Rocketman]

BTW, the converter is 55amp under optimal conditions but the little ultra quite genny I am currently running only has 20/30amp capability, so that puts a damper on optimal charge capability.

You are mixing up your 120v amps with your 12v amps.

That little generator can generate 20amps at 120v.

20amps *120v = 2400 watts
converted back to 12v…
2400w/ 12v = 200amps.

Your little generator (mathematical) could completely charge your 400ah battery in 2hrs (which is too fast for those batteries).

So with the proper charger it will have no issues charging your batteries.

 

[Rocketman]

Also, above you said you have 1600w of panels that you have not installed.

Get a couple of 2x4’s and McGuiver a ground array…
Use 1/3rd of them pointing south
Then take 2 panels and make a triangle and point those East and west for the rest of the panels. The East/west array will be overpanelled.

Post your panel specs and we can help figure out how to wire them up and how many on each array. (And post the installed SCC that is already in your rv).

You only need to buy a couple of mppt Solar charge controllers and maybe some wire and you can stop using the generator so much. In the winter you may still need it… we will see.

 

[TacomaJoe]

Your shunt is your best friend and the best tool to see what is up with your system. There is no current calibration needed for it. When you are charging it will show how many amps are running into the battery. Same thing when discharging. Don't look at %, you want to just see the amps in or out.

The shunt will need the capacity set to 400A, then get your batteries fully charged and set the meter for 100%. From there you can watch your capacity using either Ah or %. You should be seeing close to 400Ah of usage before they are discharged.

 

[Mcstiggens]

You are mixing up your 120v amps with your 12v amps.

That little generator can generate 20amps at 120v.

20amps *120v = 2400 watts
converted back to 12v…
2400w/ 12v = 200amps.

Your little generator (mathematical) could completely charge your 400ah battery in 2hrs (which is too fast for those batteries).

So with the proper charger it will have no issues charging your batteries.

Yea, delicately not the first time I got things cornfused in this realm.

 

[Mcstiggens]

The East/west array will be overpanelled.

I am definitely planning a quick and simple Mcguiver array with the panels. I like your idea but could you elaborate a bit on the concept of

"overpanelled" please.

 

[sunshine_eggo]

I am definitely planning a quick and simple Mcguiver array with the panels. I like your idea but could you elaborate a bit on the concept of

"overpanelled" please.

Over-panel means you put more power on the controller than it can use. Most MPPT tolerate this just fine and pull only what they can. PWM must NOT be over-paneled.

By connecting arrays of different orientations in parallel you lower the peak power, but you spread your harvest more evenly over the day.

This means that the MPPT is less likely to waste available power at any given time because the arrays that aren't optimally oriented at the moment will produce less power/current than the more optimal arrays.

When this is done, each of the separate array voltages needs to be the same, but the number of parallel series strings may be different

You could orient your 8 185W panels thusly:

2S East
2S2P South
2S West

And have each of those groups wired in parallel to each other. You could get away with a cheaper controller and spread out your harvest over a longer portion of the day.

A 2S4P South array would harvest more than the above, but it would require a MPPT capable of handling the maximum output of the array, i.e., a 100A controller, to ensure you don't lose any available power.

However, a 60A MPPT would probably be a little over-paneled, but since the E and W arrays will be at max when the other is at min, you don't need as much MPPT current to capture what the panels give you at any given moment.

 

[Mcstiggens]

Post your panel specs and we can help figure out how to wire them up and how many on each array. (And post the installed SCC that is already in your rv).

So here we have the specs from the 7 185watt panels. So actually we're only dealing with 1, 295W for this array.
I was initially thinking about all my solar power combined. The 250watt array that I have set up for my portable solar generator are 22v and the 7-185W are 45V. So obviously they can't be tied together. The single 165W on the trailer is also 20-ishV.

So if I understand you correctly Rocketman,
These 7 could be configured in 3 separate arrays tied together in parallel right?

Are the individual arrays also linked in parallel?

So the Renogy is what I have in place already in the 250w (2x100+1X50W)
The Sharp is from the 7 185W

 

[Skypower]

For lithium batteries, there are only two times a voltmeter is accurate, full and empty with no load. Anything in between is a guess and not worth considering. Only a good shunt type monitor can count remaining capacity and measure what’s going in or out of the battery.
The battery charger listed imho is totally insufficient for 400ah of battery. It would take forever to charge and probably be a loosing battle with any load while it’s charging. A skimpy charger wire or bad connection might display an Incorrect state of charge/voltage.
Consider getting a bigger, lithium capable inverter/charger. Some of these are actually less expensive than a charger alone. If you have a “three way” refrigerator, that could be the reason for a fast battery drain. That type on 12 volts actually uses more energy than four full sized refrigerators. When boondocking, use propane only on those, or replace it for a more efficient one. Lithium batteries don’t like freezing. They either shutdown or they are damaged if charged under freezing conditions.
Pictured below are shunts that work well and branded under various names. Victron shunts are more expensive, better and offer more connectivity options.

 

[sunshine_eggo]

So here we have the specs from the 7 185watt panels. So actually we're only dealing with 1, 295W for this array.
I was initially thinking about all my solar power combined. The 250watt array that I have set up for my portable solar generator are 22v and the 7-185W are 45V. So obviously they can't be tied together. The single 165W on the trailer is also 20-ishV.

So if I understand you correctly Rocketman,
These 7 could be configured in 3 separate arrays tied together in parallel right?

Yes, provided they are all in parallel and none are in series.

2E
3S
2W

A 40A controller would handle the 3 South and harvest a little from the others @ high noon. You're still over-paneled a little, but you'd not miss out on as much if you just configured it 7P South.

Note that all blatherings assume no shading from sunrise to sunset. If shading or partial shading is a factor, things must be oriented in whatever way completely minimizes shading/partial shading.

Are you certain the existing 250W array is configured correctly?

 

[Mcstiggens]

Are you certain the existing 250W array is configured correctly?

As far as I am aware, yes. They are wired in parallel, facing true south at around 38 degrees (i believe).
As you can see, the sun is just hitting them straight-on at 11:50am