Switch for Renogy Solar Charge/ DC to DC Controller

[monks-cat]

Apologize if this should have been posted in the "beginner section".

I noticed that the algorithm on the 50 amp Renogy DC to DC charger with built in MPPT is rather strange. It limits alternator output to 25 amps when there is any solar coming in. Since my solar is unlikely to provide anywhere near 25 amps, I'd like to turn off my panels while driving to get the full 50 amps from the alternator.

Is the best way to do this is to simply install an inline switch on the power side of the solar cables ? This is what I do on standard 12v equipment in the van, but not sure of proper solar protocol since I'm dealing with a power source.

Is there a switch that you'd recommend?

 

[sunshine_eggo]

I'd put a 24VDC breaker on the incoming PV + wire.

Will has links to some breakers here:

Solar Power System Fuses and Circuit Breaker

Building a vehicle mounted solar power system? Let me help.

www.mobile-solarpower.com

 

[monks-cat]

I'd put a 24VDC breaker on the incoming PV + wire.

Will has links to some breakers here:

Solar Power System Fuses and Circuit Breaker

Building a vehicle mounted solar power system? Let me help.

www.mobile-solarpower.com

I'm guessing ideally this would be close to the panel to protect the wiring... I should do that regardless. Or would it be kosher to place it near the solar charger so its more accessible?

 

[sunshine_eggo]

I'm guessing ideally this would be close to the panel to protect the wiring... I should do that regardless. Or would it be kosher to place it near the solar charger so its more accessible?

Doesn't matter where you place it. It will protect the wire.

 

[monks-cat]

Doesn't matter where you place it. It will protect the wire.

If the wire shorts prior to the breaker than aren't you in trouble? I've been told to treat solar panels like batteries, placing fuses close to them as possible.

 

[Browneye]

Unless your panel wiring configuration requires fusing, it's unnecessary and adds confusion. Inline connectors with fuses are rather more convenient as well, if you do need/want them:


For your panel cut off a dual mini-breaker for both legs in a waterproof housing makes for a really handy switch - you can use a high-capacity breaker since its sole purpose is switching. Both are cheap on amazon:

Here's now I set mine up so I can shut down the panels without having to go up on the roof and pull MC4 connectors:

 

[sunshine_eggo]

If the wire shorts prior to the breaker than aren't you in trouble? I've been told to treat solar panels like batteries, placing fuses close to them as possible.

Technically, code doesn't even require fusing panels until you have 3 or more parallel strings because the panels are self-fusing, and they are current limited. You actually test solar panels by shorting the leads and measuring current.

The only reason for this "breaker" is it doubles as a switch.

 

[Browneye]

Yup. I used 60a breakers for the PV cut off. Links if you need them, but lots of selection of these on amazon. PV wire is 10awg, battery leads 8awg. Now the switching breaker on the battery side IS a breaker for the controller - 50A for a 30A SCC, and it also switches so you can disconnect the controller. You want your fuse/breaker to be 1.5 to 2 times the load amperage. I'm going to put some labeling on there warning to not turn off the controller if the panels are on - don't want some layman to get confused there (wife).

In my case, the other (smaller) controller is for my portable 'suitcase' panels - a pair of 80w. Both controllers connect to a common positive side bus bar - play very nice together. This is a new installation, testing last week saw 8.1A from the 160w pair, and 14.5A on the 430w pair on the roof. I was pretty happy with that kind of output at 10am on a winter day.

 

[Browneye]

BTW, let us know how the Renogy DC-to DC charger works out of you. I'm going to need something when I get my lithium pack built, and loathe to spend $260 for a 30A Victron Orion.

If I can't adjust the voltage output on my IOTA converter/charger I'm going to have to replace that too. My setup uses a 45A, so I'm looking at the PowerMax PM3-45. They're like $120.

Here's the YT vid that clued me in on this setup:

 

[sunshine_eggo]

Yup. I used 60a breakers for the PV cut off. Links if you need them, but lots of selection of these on amazon. PV wire is 10awg, battery leads 8awg. Now the switching breaker on the battery side IS a breaker for the controller - 50A for a 30A SCC, and it also switches so you can disconnect the controller. You want your fuse/breaker to be 1.5 to 2 times the load amperage. I'm going to put some labeling on there warning to not turn off the controller if the panels are on - don't want some layman to get confused there (wife).

Where do you come up with that? You want 1.25X the max rating of the wire.

BTW, let us know how the Renogy DC-to DC charger works out of you. I'm going to need something when I get my lithium pack built, and loathe to spend $260 for a 30A Victron Orion.

Have you priced the Renogy? On sale for $255, regularly $300 for a 50A charger and a garbage MPPT limited to 25Voc.

I'll take Victron any day over Renogy.

If I can't adjust the voltage output on my IOTA converter/charger I'm going to have to replace that too. My setup uses a 45A, so I'm looking at the PowerMax PM3-45. They're like $120.

I'm a big fan of PM line. I have 3 of the LK units (50, 100, 100A) for RVs and other "uses." However, @smoothJoey has had a very negative experience with them.

Progressive Dynamics is a favorite and they can be "programmed" with the little dongle thingies.

 

[Browneye]

I was probably looking at 20 or 30A of charging on the dc to dc. With 600w of solar and a 45a converter/charger I figured I wd be good otherwise. What did OP install? 50A?
I thought I saw Renogy for about half the cost, but if it fails it’s worthless.

Trying to keep costs in check. Replacing all the charge sources gets expensive. Wifey is asking WTF are you doing? Lol

 

[Browneye]

Where do you come up with that? You want 1.25X the max rating of the wire.




Have you priced the Renogy? On sale for $255, regularly $300 for a 50A charger and a garbage MPPT limited to 25Voc.

I'll take Victron any day over Renogy.



I'm a big fan of PM line. I have 3 of the LK units (50, 100, 100A) for RVs and other "uses." However, @smoothJoey has had a very negative experience with them.

Progressive Dynamics is a favorite and they can be "programmed" with the little dongle thingies.

Progressive Dynamics is $200
Powermax is $130.
IOTA is about $160 with a Lipo dongle, and even then I’m not sure they hit the mark.
I put a dsl45iq4 in about 15 years ago for GC2’s.

The simple fact is that I don't want to spend $400-plus on dc to dc and converter/charger replacements. Looking for a cheaper option. Ya got any suggestions?

 

[sunshine_eggo]

I was probably looking at 20 or 30A of charging on the dc to dc. With 600w of solar and a 45a converter/charger I figured I wd be good otherwise. What did OP install? 50A?

Yep.

I thought I saw Renogy for about half the cost, but if it fails it’s worthless.

Reliability is hit and miss, but their customer service/tech support is consistently horrific.

Trying to keep costs in check. Replacing all the charge sources gets expensive. Wifey is asking WTF are you doing? Lol

Whooo lawdy. I feel your pain there.

Progressive Dynamics is $200
Powermax is $130.
IOTA is about $160 with a Lipo dongle, and even then I’m not sure they hit the mark.
I put a dsl45iq4 in about 15 years ago for GC2’s.

Ah.. I got it backwards. IOTA has the IQ4 boards... If you can get them to cough up the voltages and charge profiles, I'm sure you can find something that works. The PM3 charge to 14.6 with a 30 minute hold, absorb at 13.8V and "float" at 13.2V. These tend to work okay, but many RVs have junk wiring between converter and battery, so the voltage drop really interferes with the unit's ability to stay at peak voltage/current. If you're on shore power, the 13.8V will get you fully charged for sure, but running on a generator may take a long time if you're trying to get fully or nearly fully charged.

@smoothJoey experience:

Bad experience with Powermax

I don't like to do this, but I feel obliged to warn the community. I ordered a Powermax PM3-30-24LK. Unfortunately it lasted

diysolarforum.com

 

[monks-cat]

BTW, let us know how the Renogy DC-to DC charger works out of you. I'm going to need something when I get my lithium pack built, and loathe to spend $260 for a 30A Victron Orion.

If I can't adjust the voltage output on my IOTA converter/charger I'm going to have to replace that too. My setup uses a 45A, so I'm looking at the PowerMax PM3-45. They're like $120.

Here's the YT vid that clued me in on this setup:

I like the 50 amp DC to DC with MPPT . But I have plenty of juice in my alternator to support 50 amp. Been using it about a year no complaints. Will seemed to like it as well in his review. Better design than Renogy's dedicated DC to DC's unless they updated those. Note that the MPPT only likes 12v panels in parallel I believe, so quite limited. Also note the algorithm I mentioned in my first post, so turn off panels if you want alternator on full blast. But if you are hooking up your 12v panels in parallel already than this is about as cheap as it gets for a dc to dc and mppt charge controller. I believe a victron 20 amp DC to DC alone is about as expensive.

 

[Browneye]

Supposedly the IOTA has adjustable pots for voltage - you have to open it up and hack it. I was going to pull it out and see if I could get the cover off without drilling rivets, and see if I could identfy the 'IQ4' plug in board. For all we know it's just plugged into a rj11 jack on the board. The IQ4 is great for FLA, just way not so much for lifepo. Figured to have to replace it with something more compatible with lifepo.

InvertersRus has the PM3-45 for $105. Free ship.
Amazon has the Orion 12-12/30 for $220 right now - why is non-isolated more expensive? I just want to ground it to the frame bus.
I think that's about as good as I can get cost wise for these.

I have 230A cells coming from China-Amy for $450, and a overkill bms for $150.
The panels and controllers and ancillary bits and pieces ran about $700, and a Xantrex PSW inverter at $150 was a steal.
Then the starter battery was caputz, so that was $130.

It's getting ridiculous. LOL
Wifey asked today, "So are you pulling these dollars out of your ass?"

The problem we have is most campgrounds already have hookups in the price - so you just plug in. And most trips are at least three or four hours of driving, so 30A driving is plenty. It's mostly sunny, so free power there. Unless we intentionally camp off grid, the batteries stay mostly always fully charged. Which is great for FLA, not so much for lithiums. And when it's way hot out then the genny runs for AC while you're driving, so would have both 'shorepower' and dc to dc at the same time. I can see I will need to be able to shut one or the other off to gain control. OTOH, if you're off grid, your house pack is down, and it's cloudy and/or raining, it would be nice to get a decent charge out of your alternator while driving. I wonder if I could be by with 18A Orion. They're not much cheaper than the 30 though.

And why I clicked on this thread cuz it clicked with me.

I almost just bought a couple of more new GC2's and called it good.

EDIT: I can use a isolated or a non-isolated Victron, and can more than likely get by with the 12/12-18. They're $116. If I really need juice I can fire the genset and run the 45A converter/charger.
Solves some issues for me at least.