diy solar

diy solar

Dual use RV/boat

Niskibum

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Joined
Apr 2, 2022
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21
Hi all, new to the forum and would like a little advice. I did a search, but didn't find this covered.

I have small boat with a Minnkota 80lb Ulterra trolling motor that needs new batteries. It is a 24v system, and I am considering going to Lithium. I also am in the process of doing a cargo trailer to toy hauler conversion, and will be setting up the power system this summer.

Since the toy hauler will be a 12 volt system, and the boat is 24, and in the interest of saving money, I was considering getting 2 12v 100ah batteries, and moving them between the two, changing from series to parallel as needed. I don't think a 24 volt battery would work, since the charge controller in the RV is 12v. It does have a lithium setting, hopefully one that will work well. This is the controller I have coming. I also have a solar setup on the RV to charge while boondocking, but the boat is for day trips only, and I will be charging after I return home.

My concern is how well the Lithium batteries will handle going from series to parallel, and what steps would be required to balance them when moving. I am considering the SOK brand. This would probably only be for a year, until I can purchase another battery/batteries as funding permits.

Thanks for any advice.
 
My concern is how well the Lithium batteries will handle going from series to parallel, and what steps would be required to balance them when moving.
I don't see any problem with this. Why do you suspect they would need to be balanced? They will always be charged and discharged together whether parallel or series right?
You will need to connect the parallel pair in a balanced manner of course: positive of battery 1 and negative of battery 2 (as opposed to both from the same battery which would create an imbalance).
 
Series to parallel is a good thing if they will be mostly charged in parallel.

The difficulty will be if both the toy hauler and boat need a battery at the same time.
 
since the charge controller in the RV is 12v. It does have a lithium setting, hopefully one that will work well. This is the controller I have coming
I wouldn’t use that myself. Those are best used for those not willing to think. They can work but you can do better.

For an easier solution that does require some thought but still simple to use, get one of these and 1000W of panels.
 
I wouldn’t use that myself. Those are best used for those not willing to think. They can work but you can do better.

For an easier solution that does require some thought but still simple to use, get one of these and 1000W of panels.
Thanks, that looks like a nice system, but it is considerably more than my budget right now, and I have no plans for an inverter in my build. I am only using 12v while boondocking, so no need for one. The only use for AC would be for recharging batteries when I get home, and I am considering just getting a Victron charger for that, and not using the PD controller.
 
more than my budget right now,
Well, the cost of the RV coinverter plus the victron… adds up roughly to the dollars of the MPP Solar $425 model.
The MS model is good for 600W of panels or maybe 800 depending on how you configure the panels.

You can turn the inverter off and it would just be there waiting if you wanted it; plus the built-in utility charger and transfer switch with almost no extra wiring to purchase are bonuses. These units eliminate many ancillary costs and have a lot of value built in to them.
does have a lithium setting, hopefully one that will work well. This is the controller I have coming. I also have a solar setup on the RV to charge while boondocking, but the boat is for day trips only,
Those are generally poor charging systems. But at $200, plus the victron charger range starts almost $200 you’re spending the money without the extra features. You’ll likely be buying a transfer switch but the MPP unit has that, solar charge controller, battery charger, and no wiring between devices.

Of course you’re free to do what you’d like to
am in the process of doing a cargo trailer to toy hauler conversion, and will be setting up the power system this summer.
…but you’re spending money anyways- why buy a RV converter system that can’t meet the other needs? You’ll be spending thousands camperizing a cargo trailer. Spend well or spend twice.
 
Not sure what converter charger you have on board right now but most of these charge rather slowly. If your rig is going to be plugged in for days before excursions that will be ok. If you are planning to go boating the morning after boondocking you may be disappointed. If you have the time I would suggest that you figure out the system you eventually need/ want so that you allocate space and present equipment to be usable for your dream system. Once you start camping and boating you may find that improving your power system becomes a much higher priority than you expected.
 
Once you start camping and boating you may find that improving your power system becomes a much higher priority than you expected.
Probably true. And I’m jaded. I’ve never seen an RV ‘converter’ I’ve liked. Anecdotal, sure, but comparing- I’ve torn my hair out over converters way more than issues I’ve seen with aio units. Plus even ‘Thor’ branded converters: I bought a small 15A (on purpose) that delivered 35+ amps and blew out all my fuses.
I just don’t trust these magical rv boxes.
 
Probably true. And I’m jaded. I’ve never seen an RV ‘converter’ I’ve liked. Anecdotal, sure, but comparing- I’ve torn my hair out over converters way more than issues I’ve seen with aio units. Plus even ‘Thor’ branded converters: I bought a small 15A (on purpose) that delivered 35+ amps and blew out all my fuses.
I just don’t trust these magical rv boxes.
For me the key seems to be oversizing the converter. I’ve never had a problem (other than underwhelming charging capabilities) with an rv charger/converter. Most of these converters are placed in an application where they are maxed out and under ventilated. I’m about to try mine on a lifepo4 battery. That will be interesting. Lifepo4 can take full amperage output for the full charge cycle. This will be much harder on the charger than fla that only takes max in for a short time.
 
Well, the cost of the RV coinverter plus the victron… adds up roughly to the dollars of the MPP Solar $425 model.
The MS model is good for 600W of panels or maybe 800 depending on how you configure the panels.

You can turn the inverter off and it would just be there waiting if you wanted it; plus the built-in utility charger and transfer switch with almost no extra wiring to purchase are bonuses. These units eliminate many ancillary costs and have a lot of value built in to them.

Those are generally poor charging systems. But at $200, plus the victron charger range starts almost $200 you’re spending the money without the extra features. You’ll likely be buying a transfer switch but the MPP unit has that, solar charge controller, battery charger, and no wiring between devices.

Of course you’re free to do what you’d like to

…but you’re spending money anyways- why buy a RV converter system that can’t meet the other needs? You’ll be spending thousands camperizing a cargo trailer. Spend well or spend twice.
I believe you misunderstood, I am considering only putting in the victron charger, not the PD controller, so that and a fuse box and I will be about half of that $425 model. I already have the solar controller and associated equpment from my last trailer, so I don't need to spend twice on that.

I will say though, even if it was in the budget, I wouldn't go with an all in one. If it goes bad while you are out camping you are screwed until you get it fixed/replaced. If my solar controller goes bad I can still charge with the generator. If the AC charger goes bad, I still have solar. If the inverter goes bad, you still have 12v. I don't want to drive a couple hundred miles and have to drive back home because I have no lights, or fridge, or running water.
 
will say though, even if it was in the budget, I wouldn't go with an all in one. If it goes bad while you are out camping you are screwed until you get it fixed/replaced. If my solar controller goes bad I can still charge with the generator. If the AC charger goes bad, I still have solar. If the inverter goes bad, you still have 12v. I don't want to drive a couple hundred miles and have to drive back home because I have no lights, or fridge, or running water.
I understand. I used to feel that way, too. I still think that way but a gazillion people have been making use of them for years now. Reliability doesn’t seem to be a problem. Plus, I’m going to run the thing for the summer and I’m confident in it
 
I understand. I used to feel that way, too. I still think that way but a gazillion people have been making use of them for years now. Reliability doesn’t seem to be a problem. Plus, I’m going to run the thing for the summer and I’m confident in it
It's my military background, triple redundancy isn't always enough but it's a start.

Reliability doesn't seem to be a problem, until it is.
 
Hi all, new to the forum and would like a little advice. I did a search, but didn't find this covered.

I have small boat with a Minnkota 80lb Ulterra trolling motor that needs new batteries. It is a 24v system, and I am considering going to Lithium. I also am in the process of doing a cargo trailer to toy hauler conversion, and will be setting up the power system this summer.

Since the toy hauler will be a 12 volt system, and the boat is 24, and in the interest of saving money, I was considering getting 2 12v 100ah batteries, and moving them between the two, changing from series to parallel as needed. I don't think a 24 volt battery would work, since the charge controller in the RV is 12v. It does have a lithium setting, hopefully one that will work well. This is the controller I have coming. I also have a solar setup on the RV to charge while boondocking, but the boat is for day trips only, and I will be charging after I return home.

My concern is how well the Lithium batteries will handle going from series to parallel, and what steps would be required to balance them when moving. I am considering the SOK brand. This would probably only be for a year, until I can purchase another battery/batteries as funding permits.

Thanks for any advice.
Have you considered going 24v with the toy hauler and a converter for 12v loads. This would allow you to transfer batteries easily wire and controller costs will easily pay for the converter.
 
triple redundancy isn't always enough
Reliability doesn't seem to be a problem, until it is.
I have several SCCs and inverters on hand. So yes, I’m probably comfortable partly because the risk is very, very low. I supplemented with guerrilla grid over the winter but I’m back depending on solar now. And I’m actually unconcerned for the reliability of the devices I’ve selected at this point.

But I hear you. Just been ‘watching’ stuff a few years now and these things do well by the looks of things.
 
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