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Controller for 175W panel to 200Ah LiFePo4 battery

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Hey all, I'm putting together my first PV system and am uncertain what amperage I should look for in my charge controller. I will also charge the battery with the vehicle's alternator, aware that the 175W panel will take forever to fully charge the battery (I have limited roof space). If I understand correctly, I would need a minimum of ~15A for the 12V system but should leave some breathing room. How many additional amps would be sufficient? Would a 20A charge controller do the trick and would anything greater even make a difference powering a 200Ah battery off a 175W panel?
 
Is that the highest wattage panel you could find for the size?

What are the specs on your panel (Voc and Isc)?
 
Is that the highest wattage panel you could find for the size?

What are the specs on your panel (Voc and Isc)?
Voc(V): 20.23V
Isc(A): 10.89A

The panel is by Newpowa and is 26.57"Wx58.35"L. That's about the maximum length that I can fit on my roof with the vent fan positioned where it is. I didn't find any other panels at that size with comparable wattage. They make 210W panel but its extra 6" push it past the back of my roof and would likely hit the hatch when open. I have a Mitsubishi Delica, too narrow to rotate the panel 90 degrees and double up. I'm also complicating things by keeping the rear AC vent just behind the driver's seat because I'll be traveling with my dogs in the back. That's where the length constraints come from.
 
Voc(V): 20.23V
Isc(A): 10.89A

The panel is by Newpowa and is 26.57"Wx58.35"L. That's about the maximum length that I can fit on my roof with the vent fan positioned where it is. I didn't find any other panels at that size with comparable wattage. They make 210W panel but its extra 6" push it past the back of my roof and would likely hit the hatch when open. I have a Mitsubishi Delica, too narrow to rotate the panel 90 degrees and double up. I'm also complicating things by keeping the rear AC vent just behind the driver's seat because I'll be traveling with my dogs in the back. That's where the length constraints come from.

Perhaps you should look into that DC-DC (with MPPT) charger that Renogy offers, since it can do both charge from alternator and from solar:


It is safer to charge lithium (via alternator) using a DC-DC charger anyways, since lithium can put too much load on an alternator and potentially burn it out (due to low resistance)...
 
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Thank you. Will Prowse was impressed by it a year ago:
. I think I will give it a go. Funny how I haven't come across it in other research. Thanks again.
 
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Cool, yeah it looks like you can also get the BT-2 bluetooth module for it and get some advanced app management functions as well...
 
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