Author Topic: Best deal on solar storage batteries  (Read 1713 times)

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AD

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Best deal on solar storage batteries
« on: September 26, 2017, 10:42:46 AM »
I am picking up parts for a emergency solar backup power system.  This will not be connected and running until I need it.

I found a great deal on these 295W 39V Mono panels for $200 so I picked up 4 of them as the base of my system.

I need to get a good MPPT charge controler and a 3000+ watt inverter as well as batteries.

So I am looking for suggestions on components.

I will build the system and run it to get some data then break it down amd store untill I need it.

This is not ideal but living in a HOA I am restricted in what I can deploy.

I have massive shade on my roof that would not allow the panels to get optimal exposure.

If I need to set it up, it would go on my deck by the lake which gets the best solar exposure. 

I have plans innthe future to buy a place in the mountains in a few years where this system will be moved to when that happens. But for now it will be set up
, tested and stores.

 
The only dumb question is the one that did not get asked!!

ghrit

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Re: Best deal on solar storage batteries
« Reply #1 on: September 26, 2017, 04:06:28 PM »
Batteries don't necessarily do well in storage, there IS maintenance required or they won't be there when you need them.  Suggest having a look at SurvivalMonkey "off grid living" forum.  There be some powerful knowledge there that might give you a better starting point.  There are some other good reasons for building the system NOW but only if you have a current use for it, like say NPTOA or other stuff of that type.
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AD

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Re: Best deal on solar storage batteries
« Reply #2 on: September 26, 2017, 06:23:46 PM »
Ghrit

I want it to run 2 standard frig/freezers, some LED lights and a small window AC unit during the summer if we go grid down.

I really dont have a real world use for it now other than to pull some of the current units off grid amd run them.

The only dumb question is the one that did not get asked!!

AD

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Re: Best deal on solar storage batteries
« Reply #3 on: September 26, 2017, 06:29:26 PM »
This is the home   North at the top east to the right.

This sat image is probably 9 AM. You can see to open roof spaces but alos notice the shade from the big pine trees.

Early in the AM the top white roof is in sun but by early afternoon its in full shade from the tree at the top left side of the house.

The only dumb question is the one that did not get asked!!

ghrit

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Re: Best deal on solar storage batteries
« Reply #4 on: September 26, 2017, 10:25:23 PM »
Ghrit

I want it to run 2 standard frig/freezers, some LED lights and a small window AC unit during the summer if we go grid down.

I really dont have a real world use for it now other than to pull some of the current units off grid amd run them.
First step is to sum up all the loads.  Makes no difference for the moment if they are on or off, read the name plates.  Second consideration is what the starting loads on the fridge/freezers are, you can start assuming 6x full load running amps.  Your best bet to know exactly what the sum of normal loads over time adds up to, is to get yourself a Killawatt meter and measure things up.  You need that data for sizing of your battery bank and your collector panels.  That a/c unit is a horrible load to estimate, and starting load is WAY higher than you will like.  I take you as knowledgeable of electricity, so if you are REALLY interested in starting draws, find a clampon ammeter and go play.
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spacecase0

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Re: Best deal on solar storage batteries
« Reply #5 on: September 27, 2017, 09:36:39 AM »
just a thought
a clamp on adapter to your oscilloscope will really show you startup current,
I have seen 1/2 cycle spikes to 150A on a 15 amp breaker. not that it needed that much current to start, but it used it if it were there.
anyone know how loads like that are dealt with by most inverters ? I have never bothered to check

plugging in large toroid transformers can get you the highest start up current of anything, but most people don't have one if they don't have a fancy AC power conditioner.

ghrit

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Re: Best deal on solar storage batteries
« Reply #6 on: September 27, 2017, 10:54:48 AM »
Most, if not all, invertors will have overcurrent protection.  If the one under consideration doesn't, I'd be inclined to either not buy it OR put fast blow fuses in the circuit.
« Last Edit: September 28, 2017, 11:51:41 AM by ghrit »
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Tevin

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Re: Best deal on solar storage batteries
« Reply #7 on: September 27, 2017, 06:56:32 PM »
If I may be a self-serving shill for a moment, my blog www.offgridham.com addresses most of your questions.

I do agree with ghrit that storing batteries long term is going to be a problem. And you're going to need a lot of battery capacity to run your proposed load.

As for controllers, I use a Morningstar 45 amp MPPT and I'm very happy with it. You probably don't need a 3000 watt inverter.

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Re: Best deal on solar storage batteries
« Reply #8 on: September 27, 2017, 08:02:05 PM »
A thought hit me just now: Can we get large batteries dry  (like a new motorcycle battery)  and add acid when ready to use? I have a motorcycle battery on the shelf and the acid next to it because I got a deal on it. Be nice to get some big boys and activate them when needed. Hmmmm.
"Preparedness is a lot more than just buying stuff"

spacecase0

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Re: Best deal on solar storage batteries
« Reply #9 on: September 28, 2017, 07:23:06 AM »
I have read how dry lead acid batteries don't store well, but I bet they store very well before the acid is added.
if all else fails, fill the cells with nitrogen ?

I have also tried storing LiFePO4 batteries, ones with manual cell balancing or just single cells,
and they stored quite well over the years
I leave them at 3.33V a cell to start storing them

Tevin

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Re: Best deal on solar storage batteries
« Reply #10 on: September 28, 2017, 05:31:49 PM »
A thought hit me just now: Can we get large batteries dry  (like a new motorcycle battery)  and add acid when ready to use? I have a motorcycle battery on the shelf and the acid next to it because I got a deal on it. Be nice to get some big boys and activate them when needed. Hmmmm.

Yes, this trick will work if you can find an unfilled battery bigger than what is used in motorcycles.

Motorcycle batteries usually come dry for the very reasons you think...so they don't rot on the shelf before they can be used.

I'm not sure why they don't do this for larger car-sized batteries. I assume because it's a safety hazard to expect "civilians" to handle large amounts of dangerous sulfuric acid.

ghrit

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Re: Best deal on solar storage batteries
« Reply #11 on: September 28, 2017, 08:29:42 PM »
I'm not sure why they don't do this for larger car-sized batteries. I assume because it's a safety hazard to expect "civilians" to handle large amounts of dangerous sulfuric acid.
Car batteries are shipped dry, just as you say about bike batteries.  Most shops like NAPA wet down and charge very few for the shelves, and then only the high volume sales sizes.  If you have an odd one, they should tell you to wait a day or so so they can fill them and do a proper charge.  Lots of times they don't do a proper charging cycle, and the battery goes into the vehicle with not much more than enough to start a warm engine, and tell the buyer to drive for a while.  I don't know about any other sizes/types, but I have to think they are shipped from the distributor dry simply from a safety standpoint.
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olfart

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Re: Best deal on solar storage batteries
« Reply #12 on: October 01, 2017, 04:10:59 PM »
How about AGM batteries?  If stored with a small float charger attached, shouldn't they last a pretty good while?  I'm running a small solar setup using three 100 watt panels and three 80 amp-hour batteries to run my tankless gas water heater, LED lights for the bathroom, and eventually a 12v water pump.
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spacecase0

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Re: Best deal on solar storage batteries
« Reply #13 on: October 02, 2017, 01:20:05 AM »
How about AGM batteries?  If stored with a small float charger attached, shouldn't they last a pretty good while?  I'm running a small solar setup using three 100 watt panels and three 80 amp-hour batteries to run my tankless gas water heater, LED lights for the bathroom, and eventually a 12v water pump.
here is what I had happen with them
I bought 2 deep cycle AGM batteries about 10 years ago, kept them on a float charger,
for the first 5 years they ran my lighting when the power failed (when I use to live in the city)
after that I charged them every few months for 4 years (neither one had ever been stored below 12.5V ever)
one of them failed about 3 years ago with a shorted cell,
about 6 months ago I put the remaining one in my truck, and it starts it just fine.

2 years ago I got a set of 10 used AGM batteries, they were pulled from service from airplanes
not quite sure how long they waited before I got them, but I think it was a year or 2, so they are likely about 4 to 6 years old now
I used them for one 60mA lamp at night, in the day I would use it to run my HF radio to check into a radio net at 11am.
and they were connected to a 100W solar panel with a charge controller to keep from overcharging,
so they were always topped off by night time even on rainy days.
from when I started using them, 2 have failed at the terminals by leaking