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Increase power on current portable generator

devojohn11

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Oct 14, 2020
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I built a 100watt Portable solar generator with 2-12 volt 18ah AGM batteries in parallel. It has been working for a couple years now and I want to increase its power using my and use my 12v, 79 AGM battery in parallel.
I also have 3 - 100watt panels, 24v controller, 24v inverter, and 3 - 8v 75a golf batteries.
I would like to be able to connect & disconnect the 100watt and 300watt systems so I still have use of the 100 watt as portable. Looking for ideas. What would you create with these components?
 
Welcome to the forums!
I would like to be able to connect & disconnect the 100watt and 300watt systems so I still have use of the 100 watt as portable.
If the 100W and 300W system each had their own MPPT they could be used separately or together to connect to the same battery array. Be aware though you can't just plug two 12V AGM battery banks together...if one is at a higher voltage than the other it will rapidly drain into the other...be sure both are at the same voltage before doing that.
 
You definitely should not couple the 18 and 79 Ah Batteries. The 18's will drain faster than the 79 and could get to a point where the 18's will be overdischarged and damaged. It would be OK if you were only taking a small amount of power but if you are doing that no need to couple them together in the first place.

You could get away the 79 and the 75's paralleled, they are close enough in capacity not to matter.


If you put all the panels together in a parallel array, then you could connect the charging side to both setups assuming you have a charge controller on each.
Won't matter how much power is there, the controllers will feed each system as they need

Yes I have a 24v (Series) Controller For 300watt system and and 12v controller (Parallel) for 100 watt system, If I understand you correctly, if I set up panels parallel (12v), I can connect these two systems even though they will have different wattage and amps because the controllers will handle the charging?
I get that I can’t connect the 12v AGM 79a to either system,, as the amps are too high for 12v system and watts not same as 24v system?
 
You definitely should not couple the 18 and 79 Ah Batteries. The 18's will drain faster than the 79 and could get to a point where the 18's will be overdischarged and damaged. It would be OK if you were only taking a small amount of power but if you are doing that no need to couple them together in the first place.

You could get away the 79 and the 75's paralleled, they are close enough in capacity not to matter.


If you put all the panels together in a parallel array, then you could connect the charging side to both setups assuming you have a charge controller on each.
Won't matter how much power is there, the controllers will feed each system as they need.
Yes I have a 24v (Series) Controller For 300watt system and and 12v controller (Parallel) for 100 watt system. Do the 3-12v panels ave to match wattage of batteries and controller?
 
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You definitely should not couple the 18 and 79 Ah Batteries. The 18's will drain faster than the 79 and could get to a point where the 18's will be overdischarged and damaged. It would be OK if you were only taking a small amount of power but if you are doing that no need to couple them together in the first place.

You could get away the 79 and the 75's paralleled, they are close enough in capacity not to matter.


If you put all the panels together in a parallel array, then you could connect the charging side to both setups assuming you have a charge controller on each.
Won't matter how much power is there, the controllers will feed each system as they need.
So I should keep 100watt system the same or change it to the one more powerful battery 79a AGM battery And create separate 300 watt/24v system with three 8V batteries in series?
 
I'm still not exactly sure what you want to do with them. All I can say is you need to keep the small 18 ah battery s separated.
I would tend to put the lowest capacity batteries with the lowest output inverter if you are using it as a portable because the less draw the longer the batteries will last. If you want to run it at home or a fixed setup, You could put the the large batteries together and run both inverters off them and leave the 18 Ah battery's aside. That too is doable.

There is another possibility I have done often as has a few people I know.
Put a shipload of panels with a big controller on small batteries and run a big inverter off them. During the day, the panels will provide the power more or less direct and the batteries will just act like " Ballast" for the inverter. If you get a passing cloud or small interuprion to the panels the batterys will take up the lesser output from the panels and then basicaly recharge once the sun is out again. Obviously it pays to have more panels than the output you require as with the controller. I have run Multiple controllers to get the Amp handling up and I have also run panels direct to the battery when I knew the draw was going to balance it all out. If you have an over/ under voltage alarm which I bought a little battery charger board off fleabay for, you get an audible warning when you are going too far either way. For what I was doing I could run a good many hours of the day with this basic but powerful setup.

A lot of offgridders I have spoken to are going the same way. Panels, particularly used ones are cheap as chips now. I picked up a load of 250W's the other day for $10 ea and I don't even buy anything under 225's now. I can pick up 190's from the scrap yard and the guy is happy to give them to me. Size does not matter, it's capacity that counts. The offgridders are going BIG on panels ( and controllers) and smaller on the still expensive batterys. Only have to get them through the night.

On your setup if you had plenty of panels replacing the power used, and even 300W isn't much, You can get aaway with using the small batteries easily whilever the sun is out. Night time you are reliant on battery capacity but not through the day when the panels can virtualy provide straight through power. I ran a 1000W inverter a while back just for fun from 2000W of panels and a single 7.2 AH battery. The load pulled the panel output down from 30V and the thing sat happily under 15 V for hours.

You can couple the bigger batteries into one bank and use both inverters with all your panels or you can seperate the systems. Just don't put the little 18Ah batteries with the big ones and you can do any config you want. :0)
Great advice and info. I hadn’t thought of more panels even though I know current ones are not going to give me much. Looks like it tome to find some used panels. Can you suggest best places to look?
Thanks!
 
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