# I think this charge controller will work



## Circus (Oct 6, 2020)

Just bought two 360w panels for my vehicle.  Definite overkill to baby my old batteries and compensate for the dark WI winter.   Want to keep the batteries @12volt.  How big of a charge controller do I need?

Two of these panels




Will this charge controller work?


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## ABMax24 (Oct 6, 2020)

That looks like what you'll need. The 40 amp would be too small for both panels.

But what is this for? 720watts is a lot of output.


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## Circus (Oct 6, 2020)

ABMax24 said:


> But what is this for? 720watts is a lot of output.


It is?  It'll be horizontal all the time.  I'm not a, fiddle with it, guy. I see advantages over doing the panels, see disadvantages  when converse.  Hoping it'll make the old flooded batteries last.  Battery prices are frightening by comparison.


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## ABMax24 (Oct 7, 2020)

Circus said:


> It is?  It'll be horizontal all the time.  I'm not a, fiddle with it, guy. I see advantages over doing the panels, see disadvantages  when converse.  Hoping it'll make the old flooded batteries last.  Battery prices are frightening by comparison.



What are the solar panels being installed on? How big of batteries are they charging and what are the batteries for?


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## Circus (Oct 7, 2020)

ABMax24 said:


> What are the solar panels being installed on? How big of batteries are they charging and what are the batteries for?


I know it's too big, now. Old batteries 240 Ah.. I plan to have both panels stacked on the roof of a minivan traveling, accessing one panel, then on site the lower panel is pulled out from the side using a quasi full extending drawer slide. Would like to avoid the wasteful upgrading suffered from 90% of the videos I've seen. Guess the question is, what's the harm? Is it possible idle PV panels do damage or something? It'll all be transferable to my next vehicle just like my 20 year old roof rack. Camping, avoiding motel bills, microwave, maybe a fridge, diesel heater, daytime AC, jumping bolts stranded on the side of the road . Who knows, maybe the end of civilization.


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## Circus (Oct 14, 2020)

Circus said:


> ... what's the harm? Is it possible idle PV panels do damage or something? ....



Well, a week has past and no one objected to my mppt choice. Just bought it. Hope it works as good as my, 12 year old, solar air and solar water.


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## Circus (Oct 26, 2020)

Holy Smokes, battery can takes about 45 minutes then the output is choked to a trickle . Yeaa!


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## sloeffle (Oct 26, 2020)

Circus said:


> I know it's too big, now. Old batteries 240 Ah.. I plan to have both panels stacked on the roof of a minivan traveling, accessing one panel, then on site the lower panel is pulled out from the side using a quasi full extending drawer slide. Would like to avoid the wasteful upgrading suffered from 90% of the videos I've seen. Guess the question is, what's the harm? Is it possible idle PV panels do damage or something? It'll all be transferable to my next vehicle just like my 20 year old roof rack. Camping, avoiding motel bills, microwave, maybe a fridge, diesel heater, daytime AC, jumping bolts stranded on the side of the road . Who knows, maybe the end of civilization.


Pictures please


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## Circus (Oct 26, 2020)

sloeffle said:


> Pictures please


Just got the mppt and drained one battery with a 50w bulb over night, so everything being bench tested in my back yard.


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## sloeffle (Oct 27, 2020)

Circus said:


> Just got the mppt and drained one battery with a 50w bulb over night, so everything being bench tested in my back yard.


The photo is definitely not as dramatic as I was expecting.  Based on your previous post I was hoping to see some solar panels attached to the top of your minivan.


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## Circus (Oct 27, 2020)

sloeffle said:


> The photo is definitely not as dramatic as I was expecting.  Based on your previous post I was hoping to see some solar panels attached to the top of your minivan.


Give me time.  Mount design is in flux.  It's easier when I knew what the pieces look like.  A fully extending drawer slide design is problematic. The present design has  both panels on quasi halfway extending drawer slides. Top panel go's half way to the left, bottom half way right.


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## Circus (Jul 15, 2021)

sloeffle said:


> The photo is definitely not as dramatic as I was expecting.  Based on your previous post I was hoping to see some solar panels attached to the top of your minivan.



I apologize for the wait.


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## peakbagger (Jul 15, 2021)

The key thing is not overdischarge the battery.  PV batteries rarely die of old age, they are murdered  by neglect or misuse. Dont just trust a factory Low Voltage Disconnect (LVD) setting, they usually pull down a lead acid battery far too low. A typical car battery is not well suited for PV its designed to crank out a lot of amps but not good for long charge and discharge cycles. Lithium batteries are far better suited for PV but they are still expensive and far less forgiving so they need a good BMS built into keep them from being overcharged. They also have narrower temp range.


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## Circus (Jul 17, 2021)

peakbagger said:


> Lithium batteries are far better suited for PV but they are still expensive and far less forgiving so they need a good BMS built into keep them from being overcharged. They also have narrower temp range.


Think I'll risk  old flooded Walmart marine batteries before risking thousands on LiFePo4s. The panels are so overkill the batteries should keep topped up no matter the season.  Just hold off on the big draws til daylight or run the engine ten minutes to brewing coffee. How much can idling a 3 liter engine cost anyway?


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## mellow (Aug 12, 2021)

Flooded batteries still have their place,  I just replaced mine in my camper and went with Rolls batteries this time, that way I do not have to upgrade my older MPPT solar controller and still gain some AH and not worry about a BMS system as well.


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