VOLTS Whats AMPS, ....Did I do it right?

[Yawppy]

Ello!! Just got my 98 Dodge, bout three weeks ago. OK so did I do the math right so far? I made a list of stuff, collected the Volts Watts and Amps, calculated that I may use about 800watts to maybe 900watts daily....again, not sure I did the math right, I am not including a fridge/freezer nor a microwave just yet... still this set up I am hoping will run an LED 19" tv, laptop, and a few other small things such as electric razor, alarm clock, bluetooth radio, dvd player, if I did the calculations right.

Been researching, and think I have a decent set up... but to be sure I get it set up correctly and such, safety and efficiency come to mind so going to lay it out best a novice can, and am looking to hear what ya'll have to say, as this is my first go around with solar and electric stuff...here goes:

my solar panel/battery
W V AMPS IN/HR
SOLAR 100 12 8.3
V AH WATT HRS
BATTERY 12 122 1464 -55% for kill factor = 805.2 Watts

Charging = if everything is tracking the sun....(Doubtfull) I will receive 833 Watts per hour, I cut that in half for deficiencies.. so in an hour will get 416.6 watts charged back into the battery so in a day at about 9 hours : I will receive appx 312.5 Amps at 12V which is 3750W.

Ok so look forward to hearing what I may have missed, also how and could I power a microwave and fridge/freezer with this set up?

OK fun travels, see ya when our paths cross!

 

[Zil]

What kind of battery? AGM, wet acid, LiFePo?
So it sounds like you have one 100 watt solar panel.
Sounds like 122 amp hour battery. Depending on battery type, that is working amp hours of 60 amp hours.

 

[Yawppy]

Its a walmart quick start wet cell battery.

 

[akrvbob]

I'm sorry, I'm having a hard time following exactly what you have. Tell us:

1) the size of the solar panel in watts
2) Which model WalMart battery you have. When you say quick start, does that mean it's a starting battery or a marine battery? Do you have a CCA rating on it or a Group size on it?
3) Do you have a charge controller yet?

We're glad to help you but I want to make sure we are all on the same page.
Bob

 

[TucsonAZ]

Yeah, your post feels like a riddle, if I'm reading the same thing Bob was seeing, you have a 100w panel and 122ah battery, you're a little low on the solar wattage for sure and you will not be able to do all that you hope with that setup, you will have about 700 usable watts from the battery bank per day. The solar you're putting on, best possible day you'll have won't be able to put that much back into the bank, worst possible day, rain, whatever, it may struggle to put in 50-75 watts.

To keep things simple, plan on two panels and keeping your power consumption around 600w per day when you're getting good sun, make adjustments from there.

 

[Optimistic Paranoid]

Watts are not a particularly useful number for our purposes. You need to start thinking in terms of amp hours.

Simple example: say you have a 1000 watt microwave. 1000 watts divided by 12 volts = 84 amps (rounded off). If you ran it for 1 hour, you would use 84 amp hours. If you run it for only 5 minutes - say you're microwaving bacon for a BLT - then you would use 7 amp hours.

Similarly, if you want an electric refrigerator, you need to figure out how many minutes it will run in each hour to come up with an average amp hour figure for it. Which would then have to multiplied by 24 for a daily figure.

Of course, the microwave in the first example wouldn't be running off 12 volts, it would be running off an inverter, which is not 100% efficient, so there would be inverter losses also in the real world.

Regards
John

 

[akrvbob]

I agree totally with Optomistic Paranoid you are much better off teaching yourself to think in term of amps and not watts. That is the standardized language in the 12 volt world and just part of learning the language. It's no fun, but it's just the way it is. No manufacturer lists his battery in watt hours. WH does not exist. You need to think in terms of amp hours AH.

It's so normal to me that anyone who writes in using watts instead of amps, I generally won't even read it because you are making me do the translation so you don't have to. And if I do read it, I will answer in amps not watts. But if it seems like you don't understand, I will also generally try to explain it to you.

Bob

 

[Yawppy]

OK sorry bout the riddle.., a noob at this, I tried to cut paste from excell, it did not work so here is what I have

I bought a Walmart Battery Brand: Everstart, 29DC 845 Marine Cranking Amps 122 amp hours @ 1A.... just what is on the battery label.

I am waiting for a solar panel from ebay seller windy nations... a 100w 12v panel, with solar charger.

Now right now, I have no plans for a microwave , nor a fridge freezer...that may be in the works at a later date. Mostly I plan on a laptop, a 19" LED TV, and a portable dvd player, maybe ran appx 2 hours a day, guess that is where I get lost, but hoping I did the math correctly. K

---

Thats a wet cell..

 

[SternWake]

I would not expect a single battery to be able to power a microwave for very long.

Such devices present HUGE loads on a battery, and when huge loads are placed on a battery, the peukert effect says the battery has significantly less capacity to give.

Time at amps might equate to 12 amp hours for example, but with peukert factored in the actual amp'hours removed from the battery will be significantly higher.

And it will require that much more time to recharge. you can offset such huge loads by running the engine and letting the alternator partially power them, but you might have to hold the rpms at about 2000. Depends on the vehicle and the cabling between alternator and battery.

 

[highdesertranger]

is it a 12v tv and dvd player or do you have to run through an inverter? what is the power consumption of these? if run through an invertor what invertor? on the lap top do you need to run through an invertor? are you going to charge your cell phone off this? we need some more info to really help. highdesertranger

 

[TucsonAZ]

I would 86 the marine battery and go with two 6v golf cart batteries if you can afford to do so, in the long run it will save you money for sure and give you a lot more power, I saw them for under $90 each at Costco the other day. With those 100w will fall a little short of what you need to refill them, if you can add a panel, do so. 300w with two of those batteries would go a long way but two batteries and two panels will certainly take care of your needs.

Marine batteries are a poor compromise, better than a normal car battery but far from ideal. Also, check craigslist for "AGM", I have seen a lot of old UPS AGMs at really good prices, I'm running 5 of them myself.

 

[Optimistic Paranoid]

Also, be aware that while Walmart didn't TECHNICALLY lie to you, they sure went out of their way to mislead you.

122 amp hours at 1 amp means you could hook a 1 amp load up to the fully charged battery and it could power that load for 122 hours.

Battery manufacturers can also test for and publish the specs for 5amp loads, 10 amp loads, and 20 amp loads.

Amp hours at 20 amps has become the defacto standard that most honest manufacturers publish, and it's the most practical and useful for our purposes.

Needless to say, the 20 amp figure for your battery is gonna be a LOT less than 122 amp hours.

Regards
John

 

[akrvbob]

You have a good basic starter system there and it should serve you well. ya done good!!

Just bear in mind it is a very small system and it may or may not meet all your needs, especially in winter. The key is to monitor your battery and not take it below 12.2 volts any more than absolutely neccessary.

It should meet your needs very well but it may not meet your desires. If the battery gets low go into conservation mode and turn things off.

Bob

 

[Yawppy]

"You have a good basic starter system there and it should serve you well. ya done good!!"

Good to hear that, as this is just a start for me, I realize I can not run a micro or fridge on this alone, but money eliminates the option for a second panel and bat. So my plan is to use a laptop for maybe an hour or so, at night, nothing to heavy, the tv bout an hour or so to as well, during the day, will be busy doing other things, and sure eventually will learn more, and upgrade the overall setup.

"I would 86 the marine battery and go with two 6v golf cart batteries"

Money is of an issue for me right now, but for now hoping this will do as a "starter", and hoping the 100w solar panel can charge the battery sufficiently enough.

As for further info... I think my biggest consumption will be a laptop, and LED TV with portable DVD player, as the conversion van has a way to charge the phone. I am not planning this to run a micro, or fridge, till I can double the solar panel and another bat.

OK well will check back later, hope I have given enough info, I have a list of components if that helps, but mainly just wondering if a 100W solar panel is enough to charge a 12V bat, and if so at what rate.

Thanks again Yawppy

 

[Zil]

Two golf cart batteries at Sam's Club or such, may prove cheaper than one 12 volt battery, especially comparing Amp hours @ 20 minutes and also life time use.

 

[akrvbob]

You all are giving good advice, but when we respond to peoples posts, we need to tailor our advice to that person, not just give generalized advice.

He's on a tight budget and has already bought a group 29 battery. It's no longer an option to throw it away and go buy golf carts. That's bad advice for him.

The BEST is often the enemy of the GOOD. That's what's going on here. He's done the best he can, let's celebrate with him, not correct him.

Yawppy, my general advice for everybody is to buy all the solar and the highest quality components you can. It sounds like you have done a really good job of that, you should be pleased.

I understand your'e anxious to know that it is going to meet your needs but there are so many variables we can't promise you that. It depends on the weather, your location in the country and the time of the year.

What I can tell you is it is a very good starter system and hopefully it will meet your basic needs. The key with solar is to monitor the condition of your batteries and adjust your usage to the situation.

I have 570 watts, but I watch the weather and if I see a storm is coming that will last a week I go into emergency conservation mode and cut out all the electrical use I can so that my batteries will be full when the storm hits and then I use the minimum while it is going on. By doing that I usually can ride it out and my batteries are happy.

With only a 100 watt panel you are going to have to do that more often and use even less. There may be some times when you may not be able to watch TV or a DVD. But, that's okay because you did the best with the money you had.

Hopefully in the future you can upgrade the system so it will meet all your needs. That's exactly what I did. Five years ago I installed a 55 watt panel because that was all the money I had. Two years later I added a second 140 watt panel. today both those panels are still on my roof and serving me well. I don't regret buying it in the least.

Ya done good and it should work out just fine!!
Bob

 

[Zil]

i should not give my best advice because i may hurt someones feelings. they need the better advice for future purchases. the first post suggested the system was being planed, i read later the battery was there.

 

[Yawppy]

K thanks , I think this is just my starter, just trying to wrap my head on just how big I need to stride towards and just want to see If I am calculating correctly , been busy this week, it was her first visit to a mechanic, as she had a few stubborn bolts holding in the passenger seats... tried as I might she was in need of a torch... but they are out!!

OK back on topic here..K- so this 122 Amp hour battery, a 12v battery, from what I have googled is a 1,464 W battery, (Volts X Amps Equals Watts), however I can't drain the battery past a 55% life so that leaves me with 658w usable or 54amps..Watts/Volts=Amps, another googled formula) ....now I have a 100W solar panel ... how do I find out how much it delivers back to the battery?

Also not sure this helps but here are the numbers off the primary used items in the vehicle.... but remember, not always in use, maybe just an hour or so a day type deal,

Laptop V19 A2.37 W45.03
Led TV V12 A2.5 W30
DVD Player V12 A1 W12... USING THE FORMULAS I googled this means If I ran these all together for one hour I'd use 87 watts.... is this right?

K happy travels see ya'll later.

 

[SternWake]

Your are getting a better grasp.

Using wattage can be good in some instances as it accounts for changes in voltage where as amps do not,

However you are making it more difficult than it needs to be, for living on battery power.

Your 122 AH battery is likely 110 AH at the standard 20 hour measure of capacity.

So you have 55 amps hours to use. A little bit more if average discharge is less than ~5.2 amps and less if average discharge current is above that threshold.

This inexpensive device measures and counts and displays current passing through it. It counts amp hours, up to 64 before flipping over to zero.

it will only count current in one direction, so you would need one in between the solar controller and battery to count what the solar makes, and one between aux battery and the aux battery fuse block to see how much you are consuming.

Do a little math and you know fairly closely how much went into, and came out of your battery.

While this device will claim 130 amps, this is peak amps. You cannot pass microwave current through this device. Pretty much limit it to 40 amps or less and expect it to get warm/ hot passing that much current for an extended time.

http://www.amazon.com/High-Precisio..._sim_e_24?ie=UTF8&refRID=17TCCCEZN4XTHWV6K6CF

 

[Zil]

There is little information about that battery on wally web site. As posted above, deep cycle batteries are rated as amp hours @ 20 hours.
This battery is not 122 amp hours at that 20 hour standard. It can't be compared with other batteries as it is listed by wally.
The way I read that specification is you can use (50%) 54 amps for 1 minute. 26 amps for 2 min, 1 amp for less than 1 hour.
I am really sorry to seem negative but I want to help you to understand your battery and usage.
I found this web site to try to help. Get some information. http://www.solar-electric.com/deep-cycle-battery-faq.html