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

[ryankenn]

Our site is seasonal so the trailer never moves. Took 3 hours to get it in where it is. The plan is to put the four across the top of our covered porch, angled slightly so the overall angle facing south would be 20 degrees or so. The panels I have, are old Canadian Solar 260W units. Farms here are swapping them out for more power dense models, so I only paid $90CAD each for them. Once I get the three I have up and running and verify the output I will buy one more as that's what would fit easily on that roof. There is a chance I could run two horizontal and 4 vertical for a total of about 1.5kw. But my hope was each part would just supplement. I would always be charging the battery from the shore at 8A, and during the day the panels would also share the trailer load. I just need to be able to get through two night with AC running. So around 15A when on at night, but the charge from the park would be slightly off setting that.

The system you put above is pretty much where I was going to start, although I had dabbled in the idea of making my own powerwall from cells, either way I would start with 5.1kw to see if it would work. But would I need the standalone charger if I have the hybrid inverter that has the built in one? Using that I would take advantage of its ability to share loads and prioritize them. Money being no object I like the Victron Multiplus II as it has true power sharing, so I could pull from all three sources depending on my load.

We have a 13.5 A/C, and we keep the fan on low, looking at it the draw is about 13A (we have the soft start so there is no spike). Our HW tank is propane only. Inside loads are just TV idle/on with a Roku stick, plus my daughters 100 plug in adapters. All those loads even when one are only 1-2A total. Even fixing the voltage we have been in the habit of turning on the A/C to use the microwave, and would continue to do that so we could get away with the smaller inverter and battery bank.

 

[eXodus]

But would I need the standalone charger if I have the hybrid inverter that has the built in one? Using that I would take advantage of its ability to share loads and prioritize them. Money being no object I like the Victron Multiplus II as it has true power sharing, so I could pull from all three sources depending on my load.

the cheaper All in One Hybrid Inverters can not charge and invert at the same time. They are designed for primary off-grid use.
As soon as you are connected to the grid and charge - it's going into bypass - and you are back on the bad grid power you want to avoid.

The Multiplus is a great device, must stuff from Victron is. Just pricey and Victron rates their inverters in VA vs everyone else in Watt. So a Victron 3000 VA = 2400W - so depending what you run - you might need to get the Multiplus 5000 VA.

Be aware - it has no Solar Charge Controller. So you need to factor that in as well, it's getting pricey really fast with Victron. It's great amazing quality and great tech - something I would recommend on a Full Time Cabin or RV every day - but for occasional use like you do? You decide.

I don't know how far you can turn the charger of the Multiplus down.

 

[ryankenn]

Thanks for the advice. I would do Victron if money was no object for sure. I never thought to ask about the ability to charge and invert. I will do that now, or go the route you put above.

 

[Vigo]

So theres a whole lot of 120v equipment that will go down to 85 or 90v. Probably most of it.

I think the main thing is that if the 120v device in question is a battery charger, you probably are not going to get good clear info from the manufacturer about what it does under those circumstances. But we can still make an educated guess. The chargers in a lot of all-in-one inverters have charts in the manuals that give some idea as to the ‘de-rate’ when input voltage drops. Even if no info is given, it’s easy to take a safe approach: Assume it’s horrible! Overcompensate! Battery chargers are a lot cheaper than batteries in the big picture.

What i mean is, if you want to do 55a charging at 120v and expect input voltage drop to 85-90v, buy a 100a charger for the task. Just buy a much larger charger than you ‘need’, and run it at maybe 60% of its capacity, so that you won’t suffer a ton of variability when input voltage drops. 60a may be close to 100% of what it can do with an 85v input.

But i see no big issue living that way. Even if you can only consistently pull like 600-800 watts from shore power, it wouldnt take all that much battery to cover the daytime-only shortfall from AC use. This scenario is WAY easier than making it all the way from sundown to sunup with no input to the system (aka offgrid).

 

[ryankenn]

Are chargers (48V is the way I am going) rated in charge amps? So a 10A charger delivers 10A to the batteries, and I need to back calculate to find what the draw would be on the park.

 

[Vigo]

Yes, chargers are rated in charging amps at the OUTPUT voltage, not the input voltage. Converting between them though, is very simple.

Volts x Amps = Watts.

48x10=480.

Fudge it upwards a bit for inefficiency, maybe now its 550.

Then, Watts / Volts = Amps.

550 / 120 = 4.5a from shore power.

 

[ryankenn]

So really I could get a 15A charger and stay around 8A on the shore side OK. Every bit of charge I can squeeze out is better for me in terms of battery and/or panel sizing.

 

[Vigo]

Yes. My 600-800w balpark estimate was based on being able to get 8amps at 80-100v from your shore power. 600w being sort of worst case. But 600w for 24 hrs (14kwh) sounds like more than you actually use anyway, so i think you’ll be golden.

Lets say you run a 1500w ac for 4 hours and most other times your loads are less than 600w other than short periods (microwave, kettle etc). 1500w minus 600 from shore is 900w ‘gap’, times 4 hours is 3.6kwh.

Basically if you had a 5kwh lifepo4 battery, such as one server rack batt, youd be fine! If shore power ever was lost, youd just have to give up ac use to make that 5kwh last, but if shore was ‘reliable’ at 600w youd be fine and dandy with just 5kwh. 10kwh and youve got some pretty good backup power too.

Also consider instaling a smaller ac unit. Theyre cheaper than batteries.. I have a 5000btu wondow unit in my rv (in addition to 13kbtu rooftop) and i can run that thing all night with my 5kwh of lifepo4. Rooftop units are hungry bastards.

 

[ryankenn]

The more I look at the numbers you guys are helping me with, the more it seems like I could do this without solar. If I get a decent size battery I may be able to just use that to isolate myself. The park would be pulling 8A non stop, where inside the trailer I draw 15A for a time, then only 3-4A, which would recover the battery until the 15A came back. I only used 42kwh in 44 hours, so roughly 20kwh a day, and the shore can provide it, I am just asking it to do it at high and low current draw. Hmm. I could always add panels if needed.

 

[Vigo]

Whoops. I thought 14kwh was more than you used in a day, that was incorrect. But i still think its doable.

 

[time2roll]

Yes I would try to make it work on the miserable utility power provided. Put that solar money and effort into a monster battery. Possibly two chargers to throttle the power drawn. Possibly a second booster to run in series. My Frank's booster does 16% and has worked well into the low 90s. Dedicated inverter is fine as there is no real need to pass through the low voltage or manage it.

 

[Skypower]

Yes I would try to make it work on the miserable utility power provided. Put that solar money and effort into a monster battery. Possibly two chargers to throttle the power drawn. Possibly a second booster to run in series. My Frank's booster does 16% and has worked well into the low 90s. Dedicated inverter is fine as there is no real need to pass through the low voltage or manage it.

It looks like the Frank’s electronics autoformer (boost) is out of business. Some of those got stuck on boost and when the line voltage came back to normal then the output was way high. Looks like Hughs autotransformer is the only turn key (wired up). Frank’s “Super” model actually has a two stage boost for a total of 16% boost and that’s apparently what you have, congratulations! The Hughs is a 10% boost. The other alternative is to use a “Buck boost” transformer. Example; Acme T-1-12683 (41 amps @ 20% boost) Amazon $256.26. (Two for split phase) Those have two boost wiring diagrams pertaining to this conversation, 10% or 20% boost. With a 20% boost; 87/104.4 95/114 100/120 106/127 110/132!!! As you can see it needs to be bypassed or re tapped after 106 line volts! 30 years ago I wired one up much like a Hughs for my dad. He liked this one RV park but the power was so bad the none of the AC units could run. I gave it to my folks and they thought I was a genus. The only problem was the park “Karen“ manager and claimed the thing was hurting the power system. I think she was upset that someone was able to run the power bill up and get around the designed in wiring deficiency. The next time my folks went there, it was installed inside the motorhome and out of sight. My mom and dad just smiled and waved at Karen.

 

[ryankenn]

Signature Solar came back and said the EG4 3000 can invert and charge at the same time.

 

[Skypower]

Keep in mind that the great majority of inverter/chargers or hybrids still need good power to charge from the grid. If you are planning on running solar for the majority of your needs, please calculate how much solar areas you really need and is that much southern sky actually available to you in the park. Then figure real word battery $$ needs. Perhaps Tim2roll’s idea of two boosters in series may be the least expensive and feasible means to maintain power. But figure you will only be able to use 2/3rds of the original rated watts from that service when there’s low voltage.

 

[Skypower]

Dup.

 

[zulu]

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.

You remind of the guy on the Titanic who suggested lowering the ocean to prevent sinking.

Instead of trying to cope, leave this campground. That voltage is way way too low and autoformers only boost about 10%.

 

[Johneb]

I'm in the 48v inverter/charger with the biggest battery bank you can afford group. Then you dont have to depend on The park power. Love the picks. I wouldn't want to leave there either.

 

[ryankenn]

We aren't leaving. We have tons of friends and the big benefit is its 20 mins from our home. So working on it is easy, and if we have issues in park or at home, we can go quickly. We use it much more because its close. I am going to go 48V for sure, just trying to see what the best price I can get for a big battery is.

 

[Johneb]

Pre built? Or build your own battery?

 

[ryankenn]

Hard to say. AliExpress is a wasteland of not knowing what you are getting. From reputable stores you get about 3.3kwh for $1100CAD delivered. If I paid about $1700 for cells, minus costs to build and BMS I would get 5.2kwh. Just depends on how much effort I want to put in.