Walmart Everstat 24DC 101AH for DIY Solar build (flooded lead acid)

[edo101]

Hey guys I am trying to do a DIY MPPT solar project for my senior design. I would need a battery for 5 months. I orginally was going to use this 35AH battery from amazon: http://www.amazon.com/UPG-D5722-Seal...s=35ah+battery But some people told me it wasn't going to be enough

So I started looking at http://www.walmart.com/ip/EverStart-...ttery/20531540 which is a 101AH Flooded lead acid battery.

However some have said it is not the right battery for an application like this so I wanted to ask you guys.

I don't think I need something as big as that battery. With some recaluations for worst case scenario, I estimate a need of 20AH over a span of 5 hours, so approximately 4AH. this would be for each day.

The load:
I plan on connecting a modified sine wave inverter (6W idle overestimated), microconytoller (14W max) that will be attached to the inverter, an actuator (motor 1), and rotisserie motor (motor 2).
motor1 draws 3.2A and motor2 draws 5.5A (both run 12V). For both motors they will only be on when they need to be turned.
Motor1 when on will run for 2 mins each time (1 min to slide up, 1 min to slide down) I would prbly do this at most 30 times a day for experiments
Motor2 is 5rpm so at absolute most I'm gonna have it on for 20 mins a day.

[inetdog]

Hey guys I am trying to do a DIY MPPT solar project for my senior design. I would need a battery for 5 months. I orginally was going to use this 35AH battery from amazon: http://www.amazon.com/UPG-D5722-Seal...s=35ah+battery But some people told me it wasn't going to be enough

So I started looking at http://www.walmart.com/ip/EverStart-...ttery/20531540 which is a 101AH Flooded lead acid battery.

However some have said it is not the right battery for an application like this so I wanted to ask you guys.

I don't think I need something as big as that battery. With some recaluations for worst case scenario, I estimate a need of 20AH over a span of 5 hours, so approximately 4AH. this would be for each day.

The load:
I plan on connecting a modified sine wave inverter (6W idle overestimated), microconytoller (14W max) that will be attached to the inverter, an actuator (motor 1), and rotisserie motor (motor 2).
motor1 draws 3.2A and motor2 draws 5.5A (both run 12V). For both motors they will only be on when they need to be turned.
Motor1 when on will run for 2 mins each time (1 min to slide up, 1 min to slide down) I would prbly do this at most 30 times a day for experiments
Motor2 is 5rpm so at absolute most I'm gonna have it on for 20 mins a day.

Start with the off-grid design calculator from one of the sticky threads. Although it is most often used for much larger systems, it should work just fine for you.

To ask questions and understand the answers, you need to get one thing about the terminology.

The measure of current is the Amp (A). If a 3A load runs for 2 hours, that is a total load of 6 Amp hours (AH).
If the voltage is a constant 12V, then the energy consumed is 72Watt-hours.
The capacity of a battery is measured in AH, so your statement about 20AH over 5 hours being 4AH does not compute. A load of 4A continuous over 5 hours would be 20AH. And to work well with that load, you should have about a 100AH battery.

[edo101]

Start with the off-grid design calculator from one of the sticky threads. Although it is most often used for much larger systems, it should work just fine for you.

To ask questions and understand the answers, you need to get one thing about the terminology.

The measure of current is the Amp (A). If a 3A load runs for 2 hours, that is a total load of 6 Amp hours (AH).
If the voltage is a constant 12V, then the energy consumed is 72Watt-hours.
The capacity of a battery is measured in AH, so your statement about 20AH over 5 hours being 4AH does not compute. A load of 4A continuous over 5 hours would be 20AH. And to work well with that load, you should have about a 100AH battery.

Yeah it essentially equates to 4AH. The motors are run very intermittently and their invidual ratings are (Imax=4.6amps, and 6amps) and are each 12V. The motors pretty much would not run for more than 2 minutes each time and like I said I don't see us running them for 60 mins each a day.

The actuator takes 51 secs to go from one extreme to another. so I bumped it to 1min back and 1 min forth.
The motor is 5rpm.
Actuator: http://www.amazon.com/Stroke-Linear-...inear+actuator

Isn't 100AH a bit excessive. How do you figure i need that much? I was gonna buy 35AH and call it a day especially since the most constant load on the battery would be put on for 5 hours straight a day at most and it would be a 14W controller plugged into a 200W (6W idle) inverter

[Amy@altE]

Yeah it essentially equates to 4AH. The motors are run very intermittently and their invidual ratings are (Imax=4.6amps, and 6amps) and are each 12V. The motors pretty much would not run for more than 2 minutes each time and like I said I don't see us running them for 60 mins each a day.

The actuator takes 51 secs to go from one extreme to another. so I bumped it to 1min back and 1 min forth.
The motor is 5rpm.
Actuator: http://www.amazon.com/Stroke-Linear-...inear+actuator

Isn't 100AH a bit excessive. How do you figure i need that much? I was gonna buy 35AH and call it a day especially since the most constant load on the battery would be put on for 5 hours straight a day at most and it would be a 14W controller plugged into a 200W (6W idle) inverter

OK, again, as inetdog said, make a loads list. You are all over the place.

Load Amps(A) x Hours = Amp hours (Ah)
Motor1 3.2A x 1 hour = 3.2Ah
Motor2 5.5A x .3 hour = 1.65Ah
Microcontroller 1.16A x 5 hour = 5.8Ah (14W / 12V = 1.16A)
Inverter 0.5A x 5 hour = 2.5Ah (6W / 12V = .5A)
__________________________________________________ ___________________
13.15Ah / 50% depth of discharge = 26.3Ah per day

That's assuming you are beating the heck out the battery, and don't care if it lasts longer than 5 months, and recharging it fully each day

[edo101]

OK, again, as inetdog said, make a loads list. You are all over the place.

Load Amps(A) x Hours = Amp hours (Ah)
Motor1 3.2A x 1 hour = 3.2Ah
Motor2 5.5A x .3 hour = 1.65Ah
Microcontroller 1.16A x 5 hour = 5.8Ah (14W / 12V = 1.16A)
Inverter 0.5A x 5 hour = 2.5Ah (6W / 12V = .5A)
__________________________________________________ ___________________
13.15Ah / 50% depth of discharge = 26.3Ah per day

That's assuming you are beating the heck out the battery, and don't care if it lasts longer than 5 months, and recharging it fully each day

So would 35AH battery be enough? And how long would it take recharge with a 50W panel? and a 12/24V 30A

http://www.ebay.com/itm/Time-LCD-10-20-30A-MPPT-Solar-Panel-Battery-Regulator-Charge-Controller-12V-24V-/301217898878?pt=LH_DefaultDomain_0&var=&hash=item4621fc617e

[Amy@altE]

A 50W panel is rated for about 2.7A. If you are using 26.3Ah per day, 26.3ah / 2.7A / .67 inefficiencies = 14.5 hours. Sorry, won't work.

Are you doing this in winter? Where are you? I'll assume pretty bad sun conditions for winter for 2.5 sun hours. Depending on where you are and when you are doing this, you may be better. 26.3Ah / 2.5 sun hours / .67 inefficiencies = 15.7A. x 12V = 188W panels.

[edo101]

A 50W panel is rated for about 2.7A. If you are using 26.3Ah per day, 26.3ah / 2.7A / .67 inefficiencies = 14.5 hours. Sorry, won't work.

Are you doing this in winter? Where are you? I'll assume pretty bad sun conditions for winter for 2.5 sun hours. Depending on where you are and when you are doing this, you may be better. 26.3Ah / 2.5 sun hours / .67 inefficiencies = 15.7A. x 12V = 188W panels.

Winter through Spring. School Spring Semester: Jan 20 to May.
I am in Texas. Hmm I have to only use 1 50W (we are under budget limits).
Panel I want to use: http://www.amazon.com/RENOGY%C2%AE-M...0W+solar+panel

So it looks like if I want to be able to use the setup multiple days a week, I can't use 10Ah a day?
How did you do that calculation and where did the efficiency calculation come from? I am new to all this and I do think I might be overcompensating for this cause I don't see us using the setup too much a week.

Since I can't go higher than 50W, you'd say go for the Walmart battery then? I found a 55Ah one on Amazon but its 110 dollars

[SunEagle]

Winter through Spring. School Spring Semester: Jan 20 to May.
I am in Texas. Hmm I have to only use 1 50W (we are under budget limits).
Panel I want to use: http://www.amazon.com/RENOGY%C2%AE-M...0W+solar+panel

So it looks like if I want to be able to use the setup multiple days a week, I can't use 10Ah a day?
How did you do that calculation and where did the efficiency calculation come from? I am new to all this and I do think I might be overcompensating for this cause I don't see us using the setup too much a week.

Since I can't go higher than 50W, you'd say go for the Walmart battery then? I found a 55Ah one on Amazon but its 110 dollars

The biggest mistake people make when it comes to a solar/battery system is the cost. To even run a couple of small motors in your experiment requires much more than 50watt panel and 35Ah battery.

If you set your "budget" you underestimated the cost for your test. If someone else set the "budget" and panel wattage then they either want you to fail or want you to discover the fact that running electrical loads from a battery which is charged with solar is an expensive project.

[edo101]

The biggest mistake people make when it comes to a solar/battery system is the cost. To even run a couple of small motors in your experiment requires much more than 50watt panel and 35Ah battery.

If you set your "budget" you underestimated the cost for your test. If someone else set the "budget" and panel wattage then they either want you to fail or want you to discover the fact that running electrical loads from a battery which is charged with solar is an expensive project.

Well Our budget is limit is 500 set by the school. Anything else would have to come from out of pocket. Right now and not including some circuits, our cost is at 457.11

Thats with 50W and 35AH.

I was convinced 35AH would be enough when you consider that most weeks we wont be using the motors on the battery. It just occured to me. We need to run everything off the battery just for presentation purposes. We would test everything on the battery but if planned properly it should occur in spaced out days.

As for when we are running expriments, it would be to test the motor programming which means running the motors maybe at most 40 mins (motor1) 20mins (motor 2). Show that our charging circuit works and that light sensors work to check position of sun.

When I calculated it, it seems 15 AH in a day at most is reasonable.

[Sunking]

Your first mistake was using Amp Hours. You should have been using watt hours. If you had done that you would have came up with 320 watt hours per day. Assuming 50% discharge daily on the battery would require a battery capacity of 640 watt hours. At 12 volts is a 620 wh / 12 volts = 51.6 Amp Hour battery. If you have one single cloudy day, you have to shut down until after you have one full day of sun.

To generate 320 watt hours in Dallas TX in January would require a [320 watt hours x 1.5] / 3.8 Sun Hours = 126 watts using a MPPT controller. If you use PWM will require [320 wh x 2] / 3.8 Sun Hours = 168 watts. Either way generates the same 320 watt hour per day of 25.8 Amp Hours per day at 12 volts.

[edo101]

Your first mistake was using Amp Hours. You should have been using watt hours. If you had done that you would have came up with 320 watt hours per day. Assuming 50% discharge daily on the battery would require a battery capacity of 640 watt hours. At 12 volts is a 620 wh / 12 volts = 51.6 Amp Hour battery. If you have one single cloudy day, you have to shut down until after you have one full day of sun.

To generate 320 watt hours in Dallas TX in January would require a [320 watt hours x 1.5] / 3.8 Sun Hours = 126 watts using a MPPT controller. If you use PWM will require [320 wh x 2] / 3.8 Sun Hours = 168 watts. Either way generates the same 320 watt hour per day of 25.8 Amp Hours per day at 12 volts.

what is 1.5 and 2 and why do you multiply them into 310 Whrs. And if I am understanding you, you mean I would need like a 150W panel to make up that daily usage the same day?

Let's say we decide to spend more, would that Walmart battery be fine for this situation? (Asking everybody really). The only SLA 55AH battery I can find is around 120 bucks.

[Mike90250]

You have not factored in any system losses, like a panel with a 50 watt sticker on it, will only produce 80% of it's nameplate power, except in an air-conditioned lab with a 1 Sun reference arc lamp.
Now you have 40 watts. Batteries only convert 80% of the recharge into storage, the rest bubbles away as lost gas (why then need vents, and distilled water added once in a while). Take 100 watt hours out, must recharge with 120Wh.

The losses just add up, and pretty soon, you have a dead battery.

[sensij]

As for when we are running expriments, it would be to test the motor programming which means running the motors maybe at most 40 mins (motor1) 20mins (motor 2). Show that our charging circuit works and that light sensors work to check position of sun.

Tell us more about the project. It sounds like you are building an MPPT circuit to get power from the panel... is it also a charge controller? That linear actuator is not cheap... is that to make the panel track? It is expensive to move a small panel to chase the sun, you might get more energy for your money by buying a bigger panel that is fixed.

[edo101]

You have not factored in any system losses, like a panel with a 50 watt sticker on it, will only produce 80% of it's nameplate power, except in an air-conditioned lab with a 1 Sun reference arc lamp.
Now you have 40 watts. Batteries only convert 80% of the recharge into storage, the rest bubbles away as lost gas (why then need vents, and distilled water added once in a while). Take 100 watt hours out, must recharge with 120Wh.

The losses just add up, and pretty soon, you have a dead battery.

But you'd take the 100AH walmart flooded battery?

[edo101]

Tell us more about the project. It sounds like you are building an MPPT circuit to get power from the panel... is it also a charge controller? That linear actuator is not cheap... is that to make the panel track? It is expensive to move a small panel to chase the sun, you might get more energy for your money by buying a bigger panel that is fixed.

Yeah its essentially a demo to track the sun and produce solar power at the same time.

So yes I am trying, emphasis on trying to build an MPPT circuit that will draw power from panel and charge the battery. That's why the project is adding up but its just a project we need to do to graduate.

Thats why I now feel like 35AH and 50W panel is good enogh because most of the testing should be done with a constant source of electricity. And then some done with none to show that the MPPT works and the tracking.

I don't know how to do C/C++ prorgramming well so I am using National INstruments for now and their myRio controller.