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Inverter/Charger for use with horrible park power? RV to run soley off Solar/Batteries.

ryankenn

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Aug 2, 2022
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61
Hello!

I posted in the welcome forum but I thought I would move this to the proper forum.

Our park (seasonal) has horrible voltage. Up until this weekend my plan was steering toward a Victron Multiplus II to limit shore current and supplement the power using solar and batteries. But this weekend exposed how bad the park can get, it was down to 87V when I was pulling 15A, so with my Hughes Autoformer I was seeing 95V inside. I now think I want to totally isolate myself from the shore.

So I am wondering what product I should be looking for. I was hoping it could still have a charger section where I could limit draw to maybe 8A (then park power would be 95V or higher) so that shore could supplement solar for charging the batteries. But I don't want it passing shore to my RV, only charge. When I talked to Victron PowerAssist will just supplement the current, if I am feeding it 95V it will pass 95V on to my trailer.

Should I just be looking at a couple of products instead of an all in one? Like a 95-120V input capable charger, then a separate inverter and MPPT?

We only go up for two nights at a time, 3 days max. I have a monitor on it and he usage for our longest time in trailer is 41.2kwh in a 44 hour period. That period contains about 20 hours of largely direct sunlight.

So for safety I want to say I need to supply 45 kwh in a 48 hour period with 20 hours of sunlight. I can fit (4) solar panels, looking at 220W panels. I feel safe in pulling 8A from shore as a charger.

Calculators for sizing the batteries aren't really clear for this kind of setup, nor do I know what kind of product I should look at. The trailer is 30A so I would want to size for that so we can use the trailer as intended.

Any ideas are appreciated.

Thanks
Ryan
 
Skip the all in one and just use the autoformer into a smallish RV converter. Maybe 45 amps at 12vdc rating.

Separate MPPT to match the solar.

Separate inverter maybe 2000 watts. If going 3000 watts I would step up to 24 volt battery. This will give the correct 120v to the appliances. The victron will do power support but not voltage support.

I would have 400+ Ah of battery with room for expansion.

My trailer is set up like this and works beautifully.
 
400 ah at what voltage? I was looking at the EG4 Racks, and a 48V 100ah is about $1500 but is 5.12kwh.

Is the RV Converter separate from the one built into the trailer?

I would like to see more info on your setup if you care to share. Especially what batteries you chose.
 
I did a DIY build with LFP cells and BMS for a battery.

Yes the existing converter might work fine depending on model.

the 400Ah at 12v would be the minimum I recommend to drive a 2000 watt inverter. Yes a 48v 100ah is fine to drive 2000 watts. Not sure what the total power expectations are. OK to go on the small side as long as the battery can supply the amps needed without stress.

The utility power would seem to supply 50 to 80% of the energy. The rest would need to be battery or solar. With 10kWh battery maybe no solar is needed. Just leave with a depleted battery to charge during the week. Can conserve power if needed or add solar if needed. How this is balanced will be your call.
 
Well on average we are using about 1800 watts when the AC is on, 450W when off. Its on pretty steady for about 4 hours of the day, but that is in large part to how poorly it runs off 100V. The fan is slow and we can't use High fan as it draws too much current. If it was fed 120V and I could put the fan on high for the hottest parts of the day it would most likely actually cycle on and off as it could get the temp down quicker.

In my scenario using Utility power is a last resort, I would prefer it only charge the batteries and I run solely off the batteries. Otherwise I am exposed to the low voltage again. And its hard on everything in the trailer.
 
Get a 3000w inverter for the a/c. You want/need a little more margin than a 2000w inverter can supply.

I like your idea of just connecting the shore power to a charger and using that charger to recharge the batteries. That way you get good clean 120v power in your rig. Look for chargers that can handle wider ranges of incoming power.

A 48v 100ah battery will run the A/C for about 2hrs (if I remember correctly). The solar will extend that slightly- having the charger plugged into the grid will help (but will depend on the size of the charger). You may need two batteries.

Good luck
 
Been a while. I picked up some used Canadian Solar panels (260W) cheap that are 7 years old. Doing a small test setup to run a baseboard heater in our garage with my old golf cart batteries. Still on plan to move parts of this setup to the trailer next spring. Battery prices keep coming down so hopefully it will be a good deal then.
 
We only go up for two nights at a time, 3 days max. I have a monitor on it and he usage for our longest time in trailer is 41.2kwh in a 44 hour period. That period contains about 20 hours of largely direct sunlight.
What has your build changed to now?

With good conditions my RV build with 2550 watts of panels could make 20 kWh a day, so with a 5kWh from a battery battery could make your power requirement.

I’d also check production off a solar calculator for your panels. With 20 hours of sun, that makes me think it’s low to the horizon and won’t make a lot of power.

I could get a 20 kWh day around March with the equinox with no clouds in the sky the whole day. Shorter winter days less, Summer more.
 
Just a couple of thoughts...

An EMS that cuts off power below X AC volts would work to prevent low AC voltage in the trailer.

A 120v AC charger from Victron has a low voltage cutoff of 100v. I don't have one of these, so I don't know what it does when AC voltage drops below the threshold. I would guess that it stops charging.
 
Thanks. I have seen a couple of chargers good down to 90VAC (advertised). That would be ideal as I could let the park charge the batteries non stop at about 8A (on the AC side) without dropping below 100.

As far as panels, I am only going to have 4. I bought three used ones to test at home. I am in Kingston, ON, so I think we are on the lower side of sun angle, but is there a site that you can put the number of panels, direction and your location to estimate it? I was aiming low so to be safe. For me I will likely only have about 1kw of panel production. But I can get 12-15A DC of charge current from the park to supplement that.
 
Check out the PVWatts site:

 
41.2kwh in a 44 hour period
this is a lot.
1800 watts when the AC is on, 450W when off.
I guess you are running the fridge of AC. - Put the fridge on Propane mode and test again your usage for a day or two.


I'm using a 3000W all in Hybrid Inverter as a UPS for my RV. I'm running of batteries / solar - plugged into the grid, but only use it occasionally to recharge the batteries.
The downside with many all in one systems - as soon as you charge - they are bypassing the power - so everything inside runs of the grid again. So you would need also a separate small trickle charger to keep it topped of.
 
Check out the PVWatts site:

This was my result with (4) 260W panels. We are at the park from May to September.

Untitled.jpg
 
this is a lot.

I guess you are running the fridge of AC. - Put the fridge on Propane mode and test again your usage for a day or two.


I'm using a 3000W all in Hybrid Inverter as a UPS for my RV. I'm running of batteries / solar - plugged into the grid, but only use it occasionally to recharge the batteries.
The downside with many all in one systems - as soon as you charge - they are bypassing the power - so everything inside runs of the grid again. So you would need also a separate small trickle charger to keep it topped of.
A portion of our problem is at 95-100VAC none of the applicances work properly. The AC doesn't blow as fast (fan speed) or as cold, and the fridge doesn't cool as well. We actually do switch to propane during the big weekends when the park power is at its worst, but there is a tradeoff as the fridge then impacts the trailer temp as the cabinets to the sides and above warm up. I also have a small bluetooth sensor in there and its far more precise in keeping a steady temp on AC. It sits at about 2-4 celsius on AC. On propane is goes almost to zero and as high as 7 Celsius on hot days.

I think with a true 120VAC we would use less power overall as neither the AC or fridge would run as long as they would be better able to cool at the right voltage.

I have been eyeing the EG4 3Kw as it has the Solar priority, battery to supplement or replace, and grid as last resort. It would also let me limit the charge current on the park to 10A. It also has a 2A setting, I only wish it was fully adjustable. Renogy's all in one does, but it has some troubling reviews.
 
I have been eyeing the EG4 3Kw as it has the Solar priority, battery to supplement or replace, and grid as last resort. It would also let me limit the charge current on the park to 10A. It also has a 2A setting, I only wish it was fully adjustable
this is what I'm doing. Solar First, Battery Second and Grid as backup.

The Charge current limit of 10A is on the DC side - so when you go with a 24V = 24V x 10A = 240w = 2A from the AC side. If you got with 48V = 24V x 10A = 480W = 4A from the grid.

I got my self another 24V 10A separate charger. That thing has a input range from 90-240V- since the 3KW Hybrid inverter can not charge and invert at the same time (they use the same circuit for that)
I think with a true 120VAC we would use less power overall as neither the AC or fridge would run as long as they would be better able to cool at the right voltage.
when you build it similar to what I did - you appliances always get perfect 120V from the inverter. All In One RV System  V4.png
you can ignore the right upper corner, that is the 12V system with a separate legacy solar system
 
Hello!

I posted in the welcome forum but I thought I would move this to the proper forum.

Our park (seasonal) has horrible voltage. Up until this weekend my plan was steering toward a Victron Multiplus II to limit shore current and supplement the power using solar and batteries. But this weekend exposed how bad the park can get, it was down to 87V when I was pulling 15A, so with my Hughes Autoformer I was seeing 95V inside. I now think I want to totally isolate myself from the shore.

So I am wondering what product I should be looking for. I was hoping it could still have a charger section where I could limit draw to maybe 8A (then park power would be 95V or higher) so that shore could supplement solar for charging the batteries. But I don't want it passing shore to my RV, only charge. When I talked to Victron PowerAssist will just supplement the current, if I am feeding it 95V it will pass 95V on to my trailer.

Should I just be looking at a couple of products instead of an all in one? Like a 95-120V input capable charger, then a separate inverter and MPPT?

We only go up for two nights at a time, 3 days max. I have a monitor on it and he usage for our longest time in trailer is 41.2kwh in a 44 hour period. That period contains about 20 hours of largely direct sunlight.

So for safety I want to say I need to supply 45 kwh in a 48 hour period with 20 hours of sunlight. I can fit (4) solar panels, looking at 220W panels. I feel safe in pulling 8A from shore as a charger.

Calculators for sizing the batteries aren't really clear for this kind of setup, nor do I know what kind of product I should look at. The trailer is 30A so I would want to size for that so we can use the trailer as intended.

Any ideas are appreciated.

Thanks
Ryan
Wow that park must have some long small wires for distribution for voltage drop like that.
 
We actually do switch to propane during the big weekends when the park power is at its worst, but there is a tradeoff as the fridge then impacts the trailer temp as the cabinets to the sides and above warm up. I also have a small bluetooth sensor in there and its far more precise in keeping a steady temp on AC. It sits at about 2-4 celsius on AC. On propane is goes almost to zero and as high as 7 Celsius on hot days.
on your RV roof you maybe get 5-6kWh of power out of solar every day.

You are comfortable pulling 8A @120v from the Grid = 920W * 24h = 23kWh

So your potential is roughly 28kWh. You use about 20kWh.
The math works.

I would almost go with a 48V system - since the 920w @ 48V are only 20A and 48V 20A charger are still somewhat affordable.

You wouldn't even need much battery 5kWh should be fine.
 
Shopping List:

3KW all in one Hybrid inverter
48V 18A battery charger Input Voltage AC 90-264V ∓ 20%
48V 5kWh battery

Bunch of cables and you should be able to run comfortable with that crappy grid and when you put the fridge on propane you could probably even be able to go boondocking for a while.
 
How many panels will this park let you put up?

A 100 watt panel is 1062 mm X 530 mm, or about .56 meter squared, so about 180 watt per meter squared. IME, as having run a 15kBTU AC in an RV will take a lot more than 4 X 260 watt panels; mine takes 2.55 kw of panels and the AC used 13 kw that day with a total of around 16 kw production.

About 1 kw of panels probably would not put a dent in your needs. I’m thinking around 3 kw of panels if your inverter can pull off park power to assist and will take the low park AC voltage. Keep in mind in a best case 2 kw will fit on a 35’ fifth wheel roof, the rest will be on the ground. That is if your high wattage needs are only the one AC, not a second AC, not hot water, and not a refrigerator.
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I have no idea on this part, but do you think your park power when it drops low keeps a good sine wave at 60 hz, or do you think it fluctuates? That portion I’d be concerned about as VAC input to the All in one or whatever you decide to go with.
 
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