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need help with 24v MPP setup in box van

Chris.D

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Joined
Dec 3, 2019
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hello, im new here.

i am planning to be going full time next spring in a retired 17ft uhaul truck and obviously ill need solar hah.

so far ive worked out the main components ill want.

* 24v MPP Solar inverter / charge controller AIO unit
* 2 Battle Born 12v 1200Wh lithiums in series.
* ebay 200w 12v panels that were linked on wills site. 4 of these panels in series.

my main power draw is my pc setup. under normal operation [no gaming] and using both monitors, all plugged into a kill-a-watt i average about 135 watt hours.
i will also be running a "iceco" fridge that has a danfoss compressor on it. i dont have the fridge yet, so i cant tell how much power that will draw. other than that i wont have any power draws that big. just small stuff. ie led lights.

i would like these batteries to last me as long as possible. especially because theyre the most expensive part of my solar set up.

at the moment, idk if ill be charging the batteries too fast, and then over charging them with 800 watts of panels. though my pc can pull around 375 watt hours when playing video games. but i dont want to have to run games on my pc just because im a full on the battery.

i use my computer for at least 10 hours a day. mostly for work but also a lot of media consumption. ex. youtube, netflix, hulu.

and if im doing that, its at lets say 140 watts per hour for 10 hours thats 1400 watt hours. plus the lights and fridge that i dont yet know will draw.

so should i got with more battery or cut down from 4 panels to 2? or will this setup work for me?
 
i forgot to add the specs for the panels.

each panel can output 24.335 VOC witch equates to 97.34 VOC when you series them. max operating current is 9.50 amps.

one more battery question. should i go with 2 of the 24v, 50Ah, 1200 watt hour batteries in parallel instead? not much of a power difference.
 
one more battery question. should i go with 2 of the 24v, 50Ah, 1200 watt hour batteries in parallel instead? not much of a power difference.
I'd go with the serial vs the parallel arrangement for the same reason I'd prefer 2p8s over 8s2p.
 
im new to these electrical terms and solar in general. so i dont quite follow.
 
2p8s means 2 cells in Parallel & 8 of those pairs in Series. That arrangement would yield a 24v 200ah battery from 16 100ah individual cells.
 

ive been watching this video. now with the MPP unit, and the software it comes with, could i just adjust the setting in such a way that it only charges up to 80% ? then at 80% it switches off the panels?
 
The BattleBorn batteries have a 10 year warranty. How long do you plan to be a van dweller? Other than straight abuse, I don't think I would be too worried about charging to 100% (just don't go over).
 
id say that ill be van dwelling for at least 10 years maybe 15. im currently located in the new england region. the plan is to move west for higher paying employment and after sometime of saving money from work, id like to purchase a small plot of land and build a permanent home. and at that point id like to be also close to retirement.

and the thing is, when i become retired. the goal is to own the land and my home outright so that there is minimal cost after im retired. not gonna be a lot of land anyways. half acre or so. just big enough to build a 3 bay garage and have the 3rd bay and maybe the 2nd closed off for living quarters. im big in to motorcycling so that might explain the emphasis on garage space.
 
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ive been watching this video. now with the MPP unit, and the software it comes with, could i just adjust the setting in such a way that it only charges up to 80% ? then at 80% it switches off the panels?
I have found that my MPP overcharges my Gel batteries on the default MPP "Gel" charge/float setting so I use the user defined MPP charge settings to keep them charged in line with what the manufacturer suggests (12.8V for gel) to maximize battery longevity. You do have to arbitrarily decide on a float voltage that is higher than your target then disconnect the battery from any load, wait say overnight then check the voltage with a disconnected, rested battery to see if you have it right. You can then adjust the user defined voltage up or down a couple to tenths to get it perfect. Some tips: If you use the Watchman software to make the adjustments you have to enter the password "administrator" the first time you change a user defined voltage setting but that does not change the setting. You need to go and click that voltage setting again and get a "change successful" pop-up to get it to stick. You must set the battery type to "User" defined first then adjust the user defined charge and float and cutoff settings. If you don't do it in that order you get a "False" error code on voltage changes you attempt. If you make these changes with the MPP inverter toggled to on you need to shut the MPP switch off and on after making these changes to get them to activate.
 
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id say that ill be van dwelling for at least 10 years maybe 15. im currently located in the new england region. the plan is to move west for higher paying employment and after sometime of saving money from work, id like to purchase a small plot of land and build a permanent home. and at that point id like to be also close to retirement.

and the thing is, when i become retired. the goal is to own the land and my home outright so that there is minimal cost after im retired. not gonna be a lot of land anyways. half acre or so. just big enough to build a 3 bay garage and have the 3rd bay and maybe the 2nd closed off for living quarters. im big in to motorcycling so that might explain the emphasis on garage space.
I understand the garage needs. I keep telling my wife when we move we need a (smaller) 1,500 sqft house and a 3,000 sqft garage. For some reason she does not agree...
 
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