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Author Topic: Yet another battery/solar question  (Read 348 times)

Notso

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Yet another battery/solar question
« on: July 14, 2019, 03:48:10 PM »
So just installed my 2 100W panels and a 100 amp hour battery.
The only constant drain is a little power meter (Voltage/amps etc) with a backlight so nothing major.
The battery when fully charged is at 13.7 volts both on the meter and on the cheap PWM controller. (installed for 2 weeks now actually so I know the level)
I added a small fridge (DC) and it draws 2.4 amps when first powered on. I can watch the power go from 13.7 to 12.8 in less than 3 minutes, and it goes down really fast. Within 5 minutes it was at 12.4.
Is this the normal rate?
I did a load test (with panels not connected) and it tests fine (high green, drops to low green during 5 seconds of load then stop load and it goes back to high green)
Even using JUST the vent fan I watch it drop about every 40-50 seconds, 12.8, 12.7, 12.6  etc...seems way too fast for just a fan too. (again, I am only testing 1 device at a time)

Also it seems the panels can't seem to keep it powered with that low of a draw, that is the only thing on the system drawing power.  I know the fridge is a large drain device, but that fast?
I know there is a lot of math involved. But in high sun times no obstruction 200W panels should be able to keep with this 1 device? Also should I switch to an MPPT? I know they are more efficient but both have their pros and cons (mine is a small system, just the fridge, 4 LED lights, 1 tiny in canister water pump)


BTW, when sun goes down it is at 13.7V, with only the meter on the morning (before sun up) it is at 12.7V

Panels:
https://www.amazon.com/gp/product/B07K233GT8/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1
Fan:
https://www.amazon.com/gp/product/B0050EEO94/ref=ppx_yo_dt_b_asin_title_o05_s01?ie=UTF8&psc=1
Fridge: https://www.amazon.com/gp/product/B073WYS3TR/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Pump:
https://www.amazon.com/gp/product/B01M3XOXQ0/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

Lights:
https://www.amazon.com/gp/product/B07GBTXN2T/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1


Camper_Dan

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Re: Yet another battery/solar question
« Reply #1 on: July 15, 2019, 12:52:51 AM »
Greetings!

Solar sucks...  Most full timers have scrapped it totally, myself included.

There seems to be a huge discrepancy between the shallow charge that you get with solar, and a normal charge while driving or with a battery charger.  I spent a lot of time without power when I was relying on solar alone.  When I added an isolator to also charge my house battery while driving, my problems soon disappeared.  When my solar panels got stolen, it literally made no difference, I still had plenty of power, just like I did in other rigs that never had solar.

Is your house battery a deep cycle one? And how old is it?  Part of the problem could be your battery.  For that fridge I'd do double your battery capacity, and triple your input power.  My cheaper solution was to replace powered fridges with a simple ice chest that require no power, don't break down, and don't add heat to my interior during the summer. 

Today, I have 2 deep cycle 100ah batteries, one for a house battery, and the other installed as a starting battery, and I can switch between them to power my house.  Each will last roughly a week before the battery protectors will cut them off to prevent over discharging them.  Even after shut off, my starting battery still has plenty of juice to start my rig.

As a backup plan, I have a small $99 gas generator, and combined with a $29 battery charger, so I can fully charge either battery from anywhere.  If I have shore power, that same battery charger can be used there as well.  Relying on the weather for power is a gamble I'm no longer willing to accept, especially since a better solution is also cheaper.  Normally, what little driving I do is totally sufficient for keeping my batteries charged.

Cheers!
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Notso

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Re: Yet another battery/solar question
« Reply #2 on: July 15, 2019, 02:25:02 AM »
Battery same as solar, bought together. Deep Cycle, I wouldn't use any other battery as a house battery.
I also have a battery isolater, a battery doctor version and it works well enough of course but it is nice to be in my driveway and not use the van for a week or 2 and still have power. I would never try to live off solar alone, plus having it to start the van is also a bonus if that battery dies (used it already for that....),
An ice chest is not something I really want though, the 2 stations up the street from me have had no ice for a week now so it seems powered fridge or ice chest have the same odds of working!
I was looking at another battery, or at least a 125 amphour would probably due me since I really almost never use this thing, and never for camping, only for trips across country to visit people. But I want to be able to have something cool to eat/drink any time. (and with 3.5yr old this is the better option).

Any way, it just seemed to be draining too fast even with just the fan only being on. Fridge I get might be heavy (but according to reviews they have said once down to temp it uses almost nothing).

Camper_Dan

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Re: Yet another battery/solar question
« Reply #3 on: July 15, 2019, 07:58:02 AM »
Greetings!

I'd check the age on the battery.  Many of those expensive batteries have sat on the shelf for years before they get sold. A battery shop should be able to give you a free load test on it too.

If the battery checks out, then it either has to be the load, or the charging.  If the loads check out okay, then it's the solar or the controller.

Both the panels and the controller should be checkable with a multi-meter, and should be checked close to solar noon ( sun at 12 oclock, regardless of time ) on a bright sunny, cloudless day.  Both the panel output and the controller output should be checked at the controller's in and out connections.

Cheers!
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Camper_Dan

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Re: Yet another battery/solar question
« Reply #4 on: July 19, 2019, 08:54:12 PM »
Bump to foil spammers
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