Battery bank : lead acid

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
Hello; i was planning on adding 2@ 300 watt solor panels ($1400 +-). Is there a recommended brand that is good? Also, will 900 watts be able to charge a 1400 ah battery bank?
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
Hello; i was planning on adding 2@ 300 watt solor panels ($1400 +-). Is there a recommended brand that is good? Also, will 900 watts be able to charge a 1400 ah battery bank?
I realize there are many variables to consider and my understanding of electrons, coulomes and , joules is basic ; so, calculations are complicated to say the least.
However, my level of understanding is basically based on the heat and energy of a 100 watt light bulb and I was trying to get a feel for the equivalent charging potential.
 

wholybee

Solar Addict
Joined
Feb 11, 2021
Messages
465
50W of solar will charge a 1400ah battery. It will just take a very long time. To answer a question of sizing solar panels and a battery, you first need to establish what electronics will be used and for how long each day, and how many cloudy days of no sun you want to be able to go before a sunny day to recharge.
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
Right now I am totally DC. I have a little Coleman DC cooler and it seems to run well using 4 to 7 volts. I do not know how to use a tester to measure amps.
I have the emergency DC lights available.
I guess my ambition to run a 12 anp deep freezer that runs on and off ( compressor doesn't seem to a lot)
So, is it possible that when I move to AC will be able to get a general idea of weather or not this configuration will run fluently?
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
12 amps ×120 v = 1,400 watts
I have a 1,400 ah vmax 6 v parallel/ series 12 v bank that I understand this translates to a roughly 700 ah.
Also, I understand this means I can run 1 amp for 700 h.
Does this mean I can run 10 amps fo 70 hours?
Furthermore, how is it calculated for a 12 amp intermittent current of a new little deep freeze that dosent seem to run a lot.?
 

wholybee

Solar Addict
Joined
Feb 11, 2021
Messages
465
I am not completely following you.

12 amps ×120 v = 1,400 watts
True
I have a 1,400 ah vmax 6 v parallel/ series 12 v bank that I understand this translates to a roughly 700 ah.
Also, I understand this means I can run 1 amp for 700 h.
Not quite sure what you mean. Do you have four 6V batteries connected in series/parallel for 12V? What is the AH of each individual 6V battery?
Does this mean I can run 10 amps fo 70 hours?
In theory, yes. However the Ah you can get out of a lead acid battery goes down at higher loads. Not an issue at 10A on a 700Ah battery. But at 100A, the battery will be dead long before 7 hours.
Furthermore, how is it calculated for a 12 amp intermittent current of a new little deep freeze that dosent seem to run a lot.?
You need to know what percentage of time the freezer is running. Multiply 12A by that %.
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
Thanks, is there a formula to figure out how long 12 amps can be sustained with a 1,400 AH battery bank? I have 12@ 6v 225 AH in parrall series configuration.
 

JeepDaddy

Solar Addict
Joined
Feb 1, 2021
Messages
245
Location
Kent, WA
how long 12 amps can be sustained with a 1,400 AH battery bank?
1400AH/12A = 116.7 Hours at 12 volts, somewhere less than 11.67 hours at 120 volts with inverter losses.

I have 12@ 6v 225 AH in parrall series configuration
However, Assuming a 12 Volt system, 12 225AH 6 volt batteries would be 1350AH of which 50% is generally considered usable.
So you are looking at 675AH usable Amp-Hours at 12 volts.
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
thanks, good info .
11 hrs passes the over night survival a d 2 to 3 cloudy days will drag it Down yet still 11 hours is decent because frozen food will be fairly safe considering I can shut it off to conserve if need be.
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
I plan to invest in another 600 watts of a decent solor panals to augment the ( harber frieght) 300 panel array.
And I plan to add more and more when the $$$ ( lol) permits.
Yet, my present DC emergency led ( periodically as needed ) lights and colman DC refrigerator ( that runs continuously) and is just barely capable of keeping food sanitary for long after defrost)
Anyway, the point I am making is this simple DC emergency system I mentioned and with 300 watts of ( harbor freight) panels just barely allows the potential difference of the said Battery bank to utilize the 2 volts available before the controller 10.5 volt battery safety shuts it down.
So; basically , my understanding is that a 12 volt potential difference in the battery bank allows only 2 ( at most) volts of potential difference to be utilized before the 10.5 shutdown occurs.
Finally, what am I missing here if I am expecting to achieve 6,7 or 8 or the calculation ov 11.67 hours out of a mere 2 volts of available potential difference of my battery bank.
And, do you think that ( under ideal conditions) that 900 watts of solor panel charge would maintain with any consistency.
Thanks so much for your time.
Reply at your convenience and have a great weekend and holiday.
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
I guess more complex formulas and concepts concerning the coulomb and joules would describe how my battery bank would allow roughly 2 volts to translate into 11.67 AH
Trial and error with an inverter and a periodic 12amp at 120 volts current might offer more insight; because, it seems like that available 2 volt surface charge on a 1400/2 AH battery bank would be quickly be destroyed by a much weaker current.
 

Alphacarina

Solar Enthusiast
Joined
Feb 22, 2021
Messages
214
A few thoughts to consider
1.) Harbor Freight is a terrible place to buy solar panels - You should be paying $1 per watt or less
2.) How many panels you need to recharge any battery bank is dependent on how much load the batteries are powering
3.) Lead acid batteries should never be pulled down to less than 50% SOC
4.) If your main load is a refrigerator, it won't be pulling the rated wattage 24/7 - It will cycle on and off and use much less
5.) A small 12 volt refrigerator will draw much less than a 120 unit running on an inverter - Don't buy a larger refrigerator than you actually need
6.) Peukerts Law has a lot to do with how much power you can draw from lead acid batteries - Not so much for lithiums
7.) No amount of calculation will give you accurate measurements of what you'll need in real world usage

Don
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
Realogy? I was thinking of purchasing 2@ 300 watt arrays. I fo need to find a good panel; however, the harbor freight deal is ot terrible because 300 watts,( 3@ boxes) ($ 600)with wires, controller, lights are actually maintaining ( extremely insufficiently) 1400 AH battery bank that has a continuous 4 or 5 volt DC Coleman ( ( junk) cooler running.
So, I don't argue that you get what you pay for; however, it is definitely a good way to get you feet wet in the emergency lighting scenario.
Thanks for the info, have a great EASTER.
Peace
 

JeepDaddy

Solar Addict
Joined
Feb 1, 2021
Messages
245
Location
Kent, WA
As mentioned, Harbor Freight panels and controllers are not good other than as a toy. You can do much better for the money.

Thermoelectric coolers are horribly inefficient. I'm assuming that your Coleman cooler is thermoelectric. You would be money ahead by investing in a more efficient type of cooler like a compressor or propane (ammonia absorption). Perhaps something like this: Propane Fridge

I would also recommend using some of the resources available online to learn about 12 Volt DC electrical basics. It's important to know the difference between volts, amps, amp-hours, etc. Here are some videos that Will Prowse has put together: Beginners solar and Electrical videos from Will Prowse
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
Thanks; I appreciate the your response and the additional resources you have provided. I really need to invest $1500 to add at least 600 watts to my 300 watt.
Furthermore, I have 3@ controllers to monitor 3@ 100 watt harbor freight solor panel arrays. Is there a good 300 watt panel array available; because, I need two of them; and , do I need additional controllers, most 300 watt panel arrays have the cost of the controller factored into the cost.
Thanks again,
Steve
 

AE4KR

Ham Radio Tinkerer
Joined
Jun 2, 2020
Messages
62
Location
Near Salt Lake City, UT
If you're going to consider monocrystaline panels, which require more square footage for a given output than newer polycrystaline designs, at least look at buying them used and save 50 - 70% per-watt over the Walmart kit. A source some here have had good luck with is here. Shipping may cost additional money, but you're still way ahead.

A little self-education will allow you to buy individual components which outperform (and outlast) the Walmart kit for a much lower cost.

The Harbor Freight panels are amorphous silicon, not even monocrystaline, and their user guide says they lose 25% of their capacity in the first six months. Toy indeed.
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
thanks, I will have to figure how to research the technology.
actually, I was down hearted thinking about giving Walmart Corp. More money.
. But, the only information I have been finding is harbor freight is bad.
. Well, mono and polycrystaln are good key words.
. I also understand that the less light reflected is important. The last I heard was the science behind how the eyes of insects such as moths reflected very little light. Is this technology out?
 

cisumma

New Member
Joined
Apr 2, 2021
Messages
112
I am going to end this post with a couple dumb questions and then dive in to how a real photovoltaic cell is made.
Anyway, I have 3@ 100 watt harbor freight kits that will be moved to the back yard.
Now, I have those 3@ charge controllers that seem to protect the battery bank. Would it be possible to load the existing 300 watts to one of these controllers and utilize one or 2 of these controllers with new panels? ( it seems to be common knowledge that these harbor freight panels will never produce 300 watts).
First, Why is it that my controllers show that charging is happening; yet, when I put a DC multi meter on the panel output It won't read any Volts?
Secondly, the manufacturing connectors and connections will most likely be incompatible; so , before o start cutting and splicing wires is it safe to say that as long as I keep the polarity right it is possible to tie different systems together?
Finally, right now I have a few SSW locations for panels ;also, I understand DC likes big braided copper ; however, is it not good to just run 3 home runs of Romax out to these locations and keep the wiring simple?
Thanks everyone for you time and information.
 

Jeeper1941

New Member
Joined
Apr 5, 2021
Messages
9
I am going to end this post with a couple dumb questions and then dive in to how a real photovoltaic cell is made.
Anyway, I have 3@ 100 watt harbor freight kits that will be moved to the back yard.
Now, I have those 3@ charge controllers that seem to protect the battery bank. Would it be possible to load the existing 300 watts to one of these controllers and utilize one or 2 of these controllers with new panels? ( it seems to be common knowledge that these harbor freight panels will never produce 300 watts).
First, Why is it that my controllers show that charging is happening; yet, when I put a DC multi meter on the panel output It won't read any Volts?
Secondly, the manufacturing connectors and connections will most likely be incompatible; so , before o start cutting and splicing wires is it safe to say that as long as I keep the polarity right it is possible to tie different systems together?
Finally, right now I have a few SSW locations for panels ;also, I understand DC likes big braided copper ; however, is it not good to just run 3 home runs of Romax out to these locations and keep the wiring simple?
Thanks everyone for you time and information.
I bought the 45kits years ago. Alot of disappointed owers had problems with their charge controller if you can call it that. Get yourself another charge controller. I still have mine. Both are used for voltage display mostly and the different voltage outputs at time.
 
Top