Wanting to add solar to my RV, which 400 watt kit?

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stillRV

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Hi, I just bought my first RV, it's a 2006 Winnebago. I am an RV and solar newbie. I would like to be able to dry camp for several days.

It has a generator, but it does not have an inverter nor any solar. I have one 85ah lead acid, and I plan to add another (I have room for up to 2 batteries under the step). It has a 45 amp converter.

My daily load will be low I think: Some LED lights, the propane fridge, perhaps the propane furnace, and a laptop all day. Maybe a 12v monitor with the laptop. I think I can get by using only 12v for most of the day - so if I were to purchase an inverter, I might only use it for microwaving meals.

At night I'd use the laptop for a bit, and maybe a 12v heated blanket while sleeping.

I'm considering one of these 400 watt kits:
400 Watt 12 Volt Solar Starter Kit
400 Watt 12 Volt Solar RV Kit
New 400 Watt 12 Volt Solar Premium Kit

I'm a little confused about all the options! I think I want the MPPT controller. So I'm looking at the Premium kit linked above. Would this let me connect the solar panels in series so I can use thinner wires down into the controller?

In addition to solar, I'd like to be able to recharge my batteries quickly by running the generator for an hour or two. So I'm considering replacing the on board 45A converter with an inverter/charger cabable of charging at higher current. I believe even a 50 or 60A smart inverter/charger would charge much more quickly than my single-stage 45A converter.

Do you think this is a good setup for my needs?

Eventually I'd like to upgrade to Lithium batteries. But I think there is some complexity involved because the coach electrical system uses a 12v lead acid, and the systems are connected by an isloator that isn't "smart" about lithium batteries.

Thanks!
 
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TonyL

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Admittedly, i have only taken a quick look at the kit you are thinking of, but it seems that all the panel connections will have been predetermined as the kit includes wiring connections. I apologize if that is incorrect. Do you have room for larger batteries than the 85Ah which I think equates to size 24 or 27, could you fit 2 of size 31, which would give more capacity. We bought two marine style batteries from Walmart at around $100 each back in 2019, which were used extensively in 2020 and we had no issues. I will update that in November when we can get back to our unit and see how they have faired for a year disconnected but without attention.
We have a permanent 200 watt panel on the roof and a portable 160 watt, but have high draw due to the residential fridge, hence we run 4 batteries in parallel (includes the two that came with the unit). Last year we managed for several weeks using solar and the generator for around 2 hours at night and never dropped below 12.4-5 volts by morning, hope this gives you some idea of what is achievable.
 

TonyL

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Just reread your post, why buy a large inverter just to microwave a few meals when you have a generator? If it's the noise, consider a portable small inverter generator when you have little loading.
 

stillRV

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Just reread your post, why buy a large inverter just to microwave a few meals when you have a generator? If it's the noise, consider a portable small inverter generator when you have little loading.

That was my initial plan - to just use a small inverter and the generator when I need more power. But I believe I need a larger multi-stage charger anyway to be able to recharge the batteries quickly. For a little bit more money I can get the inverter/charger in one device and it's large enough for times when I want to use an induction cooktop or other things I'm not thinking about at the moment.

I like the 1000w inverter at Renogy, it's cheaper and would meet my needs most of the time. But it only does 30A charging. The 2000W Renogy inverter charges up to 65A. So should be adequate for when I upgrade to a 200+ah Lithium in a few years.
 

TonyL

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A 1000 watt inverter is not going to run a microwave and I doubt it will run an induction cooktop.
A 2000 watt might, but don't expect it to last for long before two batteries give up! What I meant was to forget the inverter and use a portable inverter type generator when you need mains voltage.
 

Lou Schneider

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I'd just drop in a pair of lithium batteries - they're called plug and play for a reason. You'll get them about 90% or more full from a stock converter and their charging rate doesn't taper off as they fill up. When you use power, lithiums respond the same at 20% SOC as they do at 80% SOC so they can power a microwave throughout the charge cycle. Lead acid batteries taper off as they discharge so you can only microwave when they're fully charged.

Amazon is selling the Chins 12 volt, 100 amp-hour lithium battery for $360, making them cost competitive with lead acid batteries.

As far as replacing your converter, etc. do that later if at all.

https://www.amazon.com/CHINS-LiFePO4-Battery-2000-5000-Off-Grid/dp/B08FMTRYPT?th=1
 

stillRV

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Lithium batteries aren't that complicated - you can install up to two 100 ah lithium batteries into an existing system designed for lead acid batteries and they'll work just fine. A regular converter/charger will fill them up to 90-95% of their rated capacity.

Instead of upgrading the converter/charger, I suggest getting a pair of "inexpensive" lithium batteries and use your existing converter with them.

Amazon is selling the Chins 12 volt, 100 amp-hour lithium battery for $360, making it cost competitive with lead acid batteries. The Chin batteries have received good reviews and unlike lead acid, lithium batteries don't fade as they discharge. You can run a high draw device like a microwave on an inverter regardless if the batteries are at 80% or 20% capacity. Lead acid batteries fade as they discharge so you would only be able to microwave when the batteries are close to full charge.

I thought mixing the two battery chemistries was not good? Won't the battery isolator will connect the coach lead acid battery to the house lithium battery?


As a result of the previously mentioned differences, our team strongly suggests you do not tie your lithium battery bank directly to your lead-acid batteries.

When you are looking to interconnect your lithium-ion batteries with your lead acid batteries, the only method we recommend is with a battery isolator or DC to DC charger in line between the two


That is starting to make my project too big, I need to upgrade in steps. I'm thinking these steps:
1) Solar panels & controller - so I can recharge all day when it's sunny
2) Inverter/charger - so I can recharge the batteries quickly
3) Lithium batteries & DC-DC charger & smart isolator - to have more battery capacity
 

donn

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With a 400 watt solar setup your going to need aboit 4 to 6 batteries to utilize the panels to their full potiential. With your puny, yes puny battery it would be nearly impossible ro run any more than a couple of lights and the water pump sparingly.
 

Lou Schneider

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I thought mixing the two battery chemistries was not good? Won't the battery isolator will connect the coach lead acid battery to the house lithium battery?


As a result of the previously mentioned differences, our team strongly suggests you do not tie your lithium battery bank directly to your lead-acid batteries.

When you are looking to interconnect your lithium-ion batteries with your lead acid batteries, the only method we recommend is with a battery isolator or DC to DC charger in line between the two


That is starting to make my project too big, I need to upgrade in steps. I'm thinking these steps:
1) Solar panels & controller - so I can recharge all day when it's sunny
2) Inverter/charger - so I can recharge the batteries quickly
3) Lithium batteries & DC-DC charger & smart isolator - to have more battery capacity
I'd put the lithium batteries at the top of the list and forget about the DC-DC charter and smart isolator for now. You don't want to intermix lead acid and lithium in a single battery bank so you'll have to get rid of your existing lead acid house battery. The engine charging line already goes through a relay or isolator, so it's only providing charging voltage, not letting the lithium batteries interact with the lead acid chassis battery.

Solar, the house converter and the inverter only connect to the house batteries. So there's no intermixture with the lead acid starting battery.

If you install more than about 200 ah of lithium you'll have to worry about having a DC-DC charger, smart isolator, etc. But up to about 200 ah lithium is plug and play into an existing system.
 

stillRV

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I'd put the lithium batteries at the top of the list and forget about the DC-DC charter and smart isolator for now. You don't want to intermix lead acid and lithium in a single battery bank so you'll have to get rid of your existing lead acid house battery. The engine charging line already goes through a relay or isolator, so it's only providing charging voltage, not letting the lithium batteries interact with the lead acid chassis battery.

Solar, the house converter and the inverter only connect to the house batteries. So there's no intermixture with the lead acid starting battery.

If you install more than about 200 ah of lithium you'll have to worry about having a DC-DC charger, smart isolator, etc. But up to about 200 ah lithium is plug and play into an existing system.

I think it would 8-12 hours or even longer to recharge the 200ah lithium on my converter. I don't want to run my generator that long when dry camping.

This is based on the research I've been doing this week about recharging batteries via on-board generator & the converter. I've read it's mainly for slow recharging when connected to shore power. A "smart" multi-stage one can charge quicker, but mine is not.
 

Isaac-1

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Ok first off all batteries, particularly lead acid batteries have a maximum charge acceptance rate, meaning having a bigger charger or more solar after a certain point does not speed up charging, at least it does not speed up charging without also killing the batteries, for a pair of 12V flooded lead acid batteries that peak charge rate is going to be near the output of 400 watts worth of solar panels, providing they are not powering any other load at the same time (fans, lights, etc). To put it another way it takes about 8 hours to fully charge a set of lead acid batteries, or about 5 hours to bring them to 80% charge from a deep discharge state. Lithium batteries can charge MUCH faster, though still have a practical limit of around 2-3 hours to fully charge.

Having said that I vote for none of the above, as all of those kits take a very dated approach to RV solar, though they do use what the vendor sells.

A better approach is to use a single 350-400 watt residential solar panel mated to a good MPPT controller like those offered by Victron most likely their 30 amp model. https://www.amazon.com/SmartSolar-MPPT-100-Charge-Controller/dp/B073ZJ3L13/ which is a good mate for around 400 watts worth of flat mounted solar panels. You can probably buy a single 380-430 watt solar panel from a local solar installer, they are big and bulky so not typically sold on Amazon, total cost will likely be $300 for the panel. Just add wires and mounting brackets and you will be good to go as long as you have room for one large panel vs 4 smaller ones.
 

stillRV

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Thank you for the suggestions. I am having trouble seeing how a simple lithium battery upgrade would help me dry camp for several days. Yes the lithiums would give me more power initially, but I do need to recharge them.

As a test, I drained the battery to 12v (resting voltage), then plugged in the RV to test how quickly the converter charges it. With my interior lights on, I was measuring 10 amps into the battery using my digital multimeter.

I was surprised how quickly the voltage dropped to 12v, I had only the interior lights on for a little more than an hour. I haven't switched them out for LEDs yet.

I'm willing to buy one of the cheaper lithium batteries (probably one of the many 200ah on Amazon for around $600-700), but I am still pretty sure I need solar and a new converter to make it all work (to be able to dry camp for several days). Tell me I'm wrong if I am.
 

stillRV

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Also, when I have my solar controller set to charge the lithiums, and I'm driving, won't the solar controller over charge my lead acid chassis battery? Both battery systems are tied together when driving, right?
 

DonTom

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Just reread your post, why buy a large inverter just to microwave a few meals when you have a generator?
1. It not good for the genny to start it cold and shut it off in a minute or so, as is often done to just heat up a meal.

2. An inverter makes no noise, quiet hours and such.

3. No exhaust to bother others.

4. For when the genny craps out (as happened to me on the 2nd day of a 3 week stay at Organ Pipe Cactus Nat'l Mon., AZ last year). With no genny, I still made my morning coffee and warmed up a meal in the MW oven--and BTW, they have quiet hours there. I got by with using my RV engine to keep the batteries charged up, which I would do during the allowed generator run times.

It's a requirement for my RVs to have several thousand watts of 120 VAC available without a genny running. My new RV inverter didn't have the capacity for such, so see message number 59 here.

I would not be able to stand any RV that didn't have enough inverter to run the MW oven and make coffee, but perhaps that is only my hang-up.

-Don- Reno, NV
 

TonyL

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Don, your point one doesn't make sense to me. All generators start from cold don't they? And as to only running for a minute, when we use ours if we want toast (sorry we're heathens, we drink instant coffee) we just let the generator run for twenty minutes. Have done this for the two years we have been able to spend in the US and our generator is fine. The point I was trying to make, was not to buy a huge inverter, without having a primary source of power. I don't know what batteries or capacity you have, but I would guess it's a lot more than either I have, or the OP. At the end of the day, all any of us are doing is saying what works for us.
 

Mark_K5LXP

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Without having any hard usage numbers this is all just a debate in imponderables. Curious and interesting but no hard answers. My input would be don't let perfection be the enemy of good enough. One can architect a system that would be "ideal" and work under every circumstance. If time and budget allow, you can do whatever you can afford. Unless this is powering a heart-lung machine I might approach it with the idea that gaps in operation are an option especially if there's a backup path. So maybe try a given solar installation and see how it plays. See if the existing batteries operate an inverter "long enough" to make toast, or coffee, or whatever. One may discover that even if there are some circumstances you have to revert to plan B, or plan C that might be OK, or from there decide what system revision to incorporate to resolve it. One can rationalize installing whatever hardware they want for any given purpose and that's fine, but I find adding electronics and batteries to anything adds cost and reduces reliability, so that capability needs to be weighed against the benefit.

Mark B.
Albuquerque, NM
 
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JayArr

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Just reread your post, why buy a large inverter just to microwave a few meals when you have a generator? If it's the noise, consider a portable small inverter generator when you have little loading.

The way inverter chargers work they use the same bank of power transistors to both charge or invert. So to get a large charger you will also get a large inverter. Nothing wrong with this. Nobody ever complains that their inverter has too much capacity.

I'm charging two deep cycle lead acid batteries and my choice is a Xantrex inverter/charger that has 100Amps of charge capacity and 2500W of inverter capacity. I could run the microwave off the inverter but other than very short bursts I won't, I'll start the genny.

The huge charge rate is important, it can charge both my batteries to 80% in a couple of hours. Yes, it can take far longer to "fully" charge the batteries but for a boondocking trip I consider it sufficient to just top up the batteries to 80% every couple of days. When the trip is over and I get back to shore power I plug in and charge them completely. I agree with Mark completely - don't let perfection be the enemy of good enough.

The other option is to run a small generator for longer periods of time. You'll have to decide which you would rather do before you determine what kind of inverter/charger you buy.

Lithium batteries have a whole bunch of advantages and one big disadvantage - they empty your wallet up front and pay you back pennies at a time. The cost analysis depends a lot on how much boondocking you'll do. It's far easier to see the savings if you live in it full time or spend months at a time travelling. We use our trailer for one long vacation in the summer and a bunch of weekend camping trips in the spring and fall and with this limited use the numbers didn't pay off for me. I'm sticking with lead acid.
 

Alontheway

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Check eBay for prices as you may can buy panels, controller and get the wire at hardware store for less money. The pre fab kits are nice as you dont need to think, but you pay extra for that.

Yes, your one battery will not suffice for what you are describing to need.
Laptop will suck juice.
Electric blanket will suck juice.
The propane furnace fan will suck a lot of juice.
Microwave for camping... Maybe consider changing lifestyle for camping as you are camping. Use the stove. For food and cooking it is most efficient to use the propane for everything you can, no electric anything for cooking as those use a lot of electricity... unless you have a lot of battery. If you have 3-4 batteries then an induction cooktop might even make more sense.

Two options I would consider for batteries:
1: toss your old battery (trade it in for the $10 credit), and get two golf cart batteries. Dont keep spending money on a Marine battery that will never be the right battery.
2: Get something like the Jackery lithium system which is all self-contained, and has a small inverter and DC charging ports and will work with solar.
You can take the Jackery inside in winter, or use it wherever you need it when shtf unlike a premaritally mounted RV battery.

300 watts might be enough for you, but 400 will be plenty. Consider that when camping you will not always get full and direct sun, so the extra panels are needed to generate the watts needed.
I have 200 and as soon as daylight happens they are providing all the power I need and recharge the batteries well before nightfall.
Some of the power consumption you describe would suggest you just go ahead and get 400 watts; you're talking about microwaves and electric blankets so are not there yet for conserving electricity in the best way possible.
If you have room on the roof and the budget for 400 I would strongly suggest to do that up front rather than wish you had, or to try to upgrade later and find out your MPPT is not big enough to handle double...
Run the panels in series so you do not need huge gauge wire. two 12 volt in series will give you 24 volts, but its really 36 as the 12 volt panels put out 18 volts. Double that and its 72 volts. So shop for an MPPT controller that can take 72 volts. They will all change it to the 12 volts needed for your camper.
Or run 36 volts (for 4 panels this is two in series and two parallel).
Or get bigger panels that are 200 watts each and run that in series...
So many options. Some depend on your roof too and how you need to lay out the panels.

I have two 6 volt golf cart batteries that are 7 years old and it will run my DC fridge, LED lights, fans, charge phone- all just fine, but if I add in the furnace then the battery will be low come sun-up. These are old batteries though.
Since you do not have a DC fridge, then that is different. If I took out the fridge then I would be fine running the furnace. It still runs the batts low, but not devastatingly low.

Well, good luck, hope I raised more questions than answers...
 

Lou Schneider

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I think it would 8-12 hours or even longer to recharge the 200ah lithium on my converter. I don't want to run my generator that long when dry camping.

This is based on the research I've been doing this week about recharging batteries via on-board generator & the converter. I've read it's mainly for slow recharging when connected to shore power. A "smart" multi-stage one can charge quicker, but mine is not.
Lithium batteries charge much faster than lead acid, which is one reasoncI suggested upgrading the batteries first. You can use your stock converter and it will charge a lithium battery to 90% 3-4 times faster than lead acid. You may only be able to charge a lead acid battery at 10 amps from a non-boosted converter while lithium will absorb up to 30 amps per 100 ah capacity from the same source. Boost the voltage and they'll charge even faster. Lithium batteries don't "brown out" as they discharge, the performance at 20% SOC is almost identical to 80% SOC so unlike lead acid batteries you can use the full capacity of a lithium battery before you have to recharge.

I have two 105 ah lithium batteries in my motorhome. The stock 13.6 volt converter charges them at it's full 50 amp capacity, minus any other power I'm using, throughout the entire charging cycle. Thus it takes about 4 hours to recharge them from empty, 2 hours from 50% SOC, etc.
 

stillRV

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I ended up buying a 200ah lithium battery, a 90A lithium compatible converter, and two 240w solar panels. I found a used Victron 150/45 mppt controller. Also found a used Victron DC-to-DC charger for the alternator connection. Now I just need warmer weather to put it all together.
 
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