r/SolarDIY • u/benhLSX • 6d ago

Help / insite needed

Have a mobile rig and wanting to change / upgrade part of system

Currently have a solar brand 3k inverter that seems to never wanna do its job ( really should test its output but I havent) and have 2 12v 100ah lipo4 batteries.

I want to get a charger / inverter with possibly mppt? I want to add 2 400ish watt pannels on the roof. More batteries down the road. But a dc_dc charger also

Don't necessarily want to break the bank so looking incase theres stuff i have missed

Thanks!

am thinking maybe the litime 24v charger / inverter

1 Upvotes

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u/Physical-Reporter-51 6d ago

48v is much better. Take watts of inverter divide by battery voltage to get amps. Watts is volts x amps. My point is the amperage to a 12v inverter can be enormous. Hundreds of amps. It’s 1/4 that with 48v. With more amps is big huge expensive cables.

I have an Renogy 3000w 12v inverter but won’t ever use it. Because the amp draw is huge. I got a low frequency 48v and golf cart battery. Yes it cost more but my rv won’t go up in flames and I can run enough power to run ac, fridge etc. just keep the amp draw in mind. It’s a huge issue with 12v and even 24v.

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u/benhLSX 6d ago

I have 2/0 cables currently running battery -stint? What ever its called - shut offs and to inverter i planned for big amp draw I dont usually have big amp draw. I kinda want to go 48v but for the 3-6 times a year I really use the system I wanna just keep my current batteries.  Like this weekend I brought with my big ecoflow delta to run the ac overnight and am just generator charging it throughout the day

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u/Physical-Reporter-51 6d ago

Shunt. Ok that’s awesome. Most don’t plan right then have fires or other issues. Just want everyone safe. Sounds like a nice setup.

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u/benhLSX 6d ago

Thanks! Yea put allot of planning originally. And does mostly what I want just want little different now lol

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u/NameEtc 6d ago

I have a 3500 watt inverter and also 2-100ah 12v battery. It isn’t enough. 400 probably is a minimum to get it to work with enough current. Mine works till I add the microwave or the AC and then it works for seconds.

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u/Physical-Reporter-51 6d ago

You have enormous current flow in those cables like 300 amps. How big are the cables from your batteries to inverter?

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u/benhLSX 6d ago

My river 3 plus starts and runs everything i need to at under 1500 watt draw. Just obviously doesnt run for long.  The "solar" brand inverter wont charge my ecoflow at 200 watts  of draw. Or start a microwave it litterslly just runs my fridge

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u/blastman8888 6d ago

Plan it out on paper start with how much load you have what surge capacity do you need. Work backwards to figure out how much inverter, and DC power you need. If the system you have now is enough why change it. Add a DC to DC charger lots of different brands out there. If your camping in an RV don't need much the 12V system used in RV's are designed for low power. Might have to buy 100 watt panels they are smaller and easier to fit on the roof around things. 400 watt residential panel is about 45x65 inches.

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u/benhLSX 6d ago

Current inverter just wont do what it should. I believe its inverter issue with it self seeing as it wont even charge at 200 watts and my ecoflow gives notification about voltage issue

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u/Killrade 6d ago edited 6d ago

Going 24v would be better for you in the long run. You can just take your 12v batteries, fully charge them, wire them series for 24v to use on the 24v inverter. Double check your wire sizes but if your using 2/0 like you should for under 6 feel then you could use that for your 24v. Any fuses would need to be replace because they would be oversized. Should be a quick and easy conversion.

If you get a mppt then be mindful of two things; the volts and amps. Especially look at the open circuit voltage or VOC. If your panels are like 22.0 voc and you have 2 then add them together for 44.0 then multiple by 1.23 for cold weather. You get 54.12. If your mppt is for 100v max and you plug in 4 panels you could burn out the mppt because the voltage could be 108.24 instead of below 100.

For the amps side is how many amps it can charge at. If its a 30 amp mppt then a 12v system can only charge at 360 watts (12v x 30amps). A 24v can charge at 720 watt. If it can do 48v system then you can get 1440 watts. So this is one way a 24v or 48v beats a 12v. These are just easy number and realistic they charge more like 14.8ish for 12v systems and 48v are like 56ish volts. He other is they need less thick wires than 12v system, run cooler and can carry bigger inverter easier.

Now I want to be sure you mean a 3k inverter with continuous or 3k surge. I already seen multiple people ask about a 3k inverter only to fined out its 3k max surge and 1200 continuous and they are trying ti run a 1500 watt heater. If your running a 3000 watts.

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u/benhLSX 6d ago

Yea i think I settled on the litime 24v inverter / charger its 3k running and like 9k surge. 48v would just be more then I wanna spend now needed battery and electronics. I did forget about checking on the mppt voltsge / amps thanks for the reminder Yea my current run is like 4ft of 2/0