100 Watt Solar

[Raspy]

Originally Posted by jwcolby123

I am losing count of folks claiming "keeps it at full charge".



What I know is that unless you are monitoring current flowing into the battery, knowing that the battery is at full charge is problematic. What I also observe is that few if any of the "full charge" folks are sharing how they know this.


And folks wonder why I dismiss such tripe. I have a distaste for tripe.

So, are you assuming none of know when our batteries are charged? I either read it on my battery monitor, which is calibrated to my batteries, or go old school and read rested voltage. Either way, it is close enough to know what full charge means.

Are you the official arbitor of tripe?

[Evirk]

Here's a little more info. Ran some tests using a clamp on amp meter.
I have a Group 27DC battery. Rated 80 amp hours @ 20Hr (anybody know what the 20 Hr means? Pulling 20 amps/hour?)

Anyhoo . . .

With the CO Detector, Fridge Console (on gas), (4) Led lights
Max Fan off 0.5 amps
Max fan 50% 0.9 amps
Max Fan 80% 1.3 amps
Max fan 100% 1.9 amps

With the CO Detector, & Fridge Console
Max Fan off 0.1 amps
Max fan 50% 0.5 amps
Max Fan 80% 1.0 amps
Max Fan 100% 1.8 amps

CO Detector & Fridge Console
Hood fan on 0.5 amps
Hood Fan therefore concluded to be 0.4 amps

Put together a little table of usage

Time Time CO, Fridge Always On
Start End Amps Max Fan LED Lights Hood Fan
5:00 6:00 1.0 80% 0 Off
6:00 7:00 1.0 80% 0 Off
7:00 8:00 1.3 80% 4 Off
8:00 9:00 2.2 80% 4 On
9:00 10:00 1.3 80% 4 Off
10:00 11:00 1.3 80% 4 Off
11:00 12:00 1.3 80% 4 Off
12:00 13:00 1.8 100% 0 Off
13:00 14:00 1.8 100% 0 Off
14:00 15:00 1.8 100% 0 Off
15:00 16:00 1.8 100% 0 Off
16:00 17:00 2.2 100% 0 On
17:00 18:00 1.8 100% 0 Off
18:00 19:00 1.9 100% 4 Off
19:00 20:00 1.9 100% 4 Off
20:00 21:00 1.9 100% 4 Off
21:00 22:00 1.9 100% 4 Off
22:00 23:00 1.9 100% 4 Off
23:00 0:00 1.9 100% 4 Off
0:00 1:00 1.0 80% 0 Off
1:00 2:00 1.0 80% 0 Off
2:00 3:00 1.0 80% 0 Off
3:00 4:00 1.0 80% 0 Off
4:00 5:00 1.0 80% 0 Off


Total 37.0 Amp Hours
Charging Time 6.0 Hours
Charge Rate Req'd 6.3 Amps

Panel 100 Watts
Volts 12 Volts
Max Charge Rate 8.3 Amps

In the end it looked a little too close for comfort. If I'm even close I'm going to use up something approaching 1/2 the capacity of the battery which as I understand it is actually 100% if I want to keep using it over and over. So, I chickened out and got the 200 Watt unit. (It IS a big sucker and not light at 39#) Will be trying it out tomorrow in the driveway to see how it holds up against similar loads. Real life test this weekend. Not much time for learning so wish us luck.

Again, thanks for all the input. Hopefully some of my data will be of use to someone. BTW, can anyone recommend a hydrometer for testing the S.G. of the liquid in the battery?

Cheers

Evirk

[Raspy]

Ervik,

Do you actually have a flooded cell battery that has removable caps and requires water periodically? My last one of those was on my Oliver and I was very happy to get away from that mess. Constant corrosion and constant water maintenance. Not an AGM or a maintenance free battery? You probably know this, but the hydrometer is for flooded batteries where you must suck some water out to check its specific gravity

It was probably a good choice to go with the 200 watt solar system. My maxim is that usage will always rise to meet supply. Now you have some headroom.

[Glenn Baglo]

Originally Posted by Raspy

Ervik,

Do you actually have a flooded cell battery that has removable caps and requires water periodically?

Do you wipe after a bowel movement? It's not that difficult. Just needs to be done.

[jwcolby123]

Originally Posted by gordon2

When I say it, it means that my Trimetric is reporting full charge... but I also know how to use a hydrometer. Just don't feel the need to explain it every time.

Now about that anal tripe... (and political bashing)...

Lol it was soooooooo difficult to say "My trimetric reports a full charge."

I do understand. Does that qualify as some sort of disability?

Unless one tells me how they know, they don't know. Simple as that. Lots of folks say "full charge" and who knows. Maybe.

My wife gets well over 100mpg in her car. Really. Believe me. She does.

She has a plug-in hybrid and mostly drives under 20 miles around town.

The only way I am believing that is if explained. Simple as that.

As for Anal tripe, insisting on a full page explanation of how a Scamp is a ball and a fifth wheel is...

Really? And has it ever even one time changed someone from calling the Scamp a fifth wheel?

I drive an 18 wheeler. I connect a fifth wheel many times every day. And it isn't even a fifth wheel. Think about that. My tractor actually has 6 wheels, though most have 10. And a "dually" has 6 wheels already. So what is it called on them? A 7th wheel?

Just damned idiotic I think. But if it makes you feel better, well, you just tilt at those windmills. And it makes me feel better to call it Anal Tripe.

[jwcolby123]

Originally Posted by Evirk

Here's a little more info. Ran some tests using a clamp on amp meter.
I have a Group 27DC battery. Rated 80 amp hours @ 20Hr (anybody know what the 20 Hr means? Pulling 20 amps/hour?)

Anyhoo . . .

With the CO Detector, Fridge Console (on gas), (4) Led lights
Max Fan off 0.5 amps
Max fan 50% 0.9 amps
Max Fan 80% 1.3 amps
Max fan 100% 1.9 amps

With the CO Detector, & Fridge Console
Max Fan off 0.1 amps
Max fan 50% 0.5 amps
Max Fan 80% 1.0 amps
Max Fan 100% 1.8 amps

CO Detector & Fridge Console
Hood fan on 0.5 amps
Hood Fan therefore concluded to be 0.4 amps

Put together a little table of usage

Time Time CO, Fridge Always On
Start End Amps Max Fan LED Lights Hood Fan
5:00 6:00 1.0 80% 0 Off
6:00 7:00 1.0 80% 0 Off
7:00 8:00 1.3 80% 4 Off
8:00 9:00 2.2 80% 4 On
9:00 10:00 1.3 80% 4 Off
10:00 11:00 1.3 80% 4 Off
11:00 12:00 1.3 80% 4 Off
12:00 13:00 1.8 100% 0 Off
13:00 14:00 1.8 100% 0 Off
14:00 15:00 1.8 100% 0 Off
15:00 16:00 1.8 100% 0 Off
16:00 17:00 2.2 100% 0 On
17:00 18:00 1.8 100% 0 Off
18:00 19:00 1.9 100% 4 Off
19:00 20:00 1.9 100% 4 Off
20:00 21:00 1.9 100% 4 Off
21:00 22:00 1.9 100% 4 Off
22:00 23:00 1.9 100% 4 Off
23:00 0:00 1.9 100% 4 Off
0:00 1:00 1.0 80% 0 Off
1:00 2:00 1.0 80% 0 Off
2:00 3:00 1.0 80% 0 Off
3:00 4:00 1.0 80% 0 Off
4:00 5:00 1.0 80% 0 Off


Total 37.0 Amp Hours
Charging Time 6.0 Hours
Charge Rate Req'd 6.3 Amps

Panel 100 Watts
Volts 12 Volts
Max Charge Rate 8.3 Amps

In the end it looked a little too close for comfort. If I'm even close I'm going to use up something approaching 1/2 the capacity of the battery which as I understand it is actually 100% if I want to keep using it over and over. So, I chickened out and got the 200 Watt unit. (It IS a big sucker and not light at 39#) Will be trying it out tomorrow in the driveway to see how it holds up against similar loads. Real life test this weekend. Not much time for learning so wish us luck.

Again, thanks for all the input. Hopefully some of my data will be of use to someone. BTW, can anyone recommend a hydrometer for testing the S.G. of the liquid in the battery?

Cheers

Evirk

Good data. Just be aware that the numbers you think you are getting for the charge side are rarely if ever true. Put the clamp meter on and log the amps.

The first problem is that you are actually using current at the same time that the panels are providing current. Subtract that first because that is not charging the battery.

The second problem is that the rated panel current is under ideal lab conditions, at a very chilly temperature, and with a ginormous light shining a calibrated amount of light onto the panel.

Truth!

Another issue is that the rated current is with the panel absolutely perpendicular to the light source (sun) which will almost never occur and can be pretty far off. Which is why you are adjusting the panels three times a day. And are you going to remember to do that?

And then there is the season (more atmosphere between you and the sun during winter)

And the charge curve of the battery. And the chemical losses as current goes in and out of the battery. And battery sulfation every time you don't charge it all the way back up. All real things.

Etc Etc ad nausium.

And yes, I am going to get grief from lots of folks for bringing this to your attention, but as you have seen, that matters not to me. What I want is for you to understand the challenges standing between you and yet another trip to the local Wally World to replace your battery, way too soon.

If you understand these things and you deal with them, then your battery can last a long time. Which is why I recommended "over-paneling" the system.

Of course as someone pointed out, more info than you asked for and one panel will work just fine! Seems unlikely.

[gordon2]

Originally Posted by jwcolby123

Lol it was soooooooo difficult to say "My trimetric reports a full charge."
...
Unless one tells me how they know, they don't know. Simple as that. ...

What good does it do to say "My trimetric reports a full charge" without also specifying the programed values used for the Trimetirc, the battery type, capacity, age, temperature at the time, etc. ???

For example, if one programs the Trimetric for a 100 Ah battery but uses a 200 Ah battery then the report of full charge is meaningless.

So lets just say I dont know.. don't have a clue even. Because I am not going to go into that great detail. I can live with your doubts.
...

[Lynn Eberhardt]

I'm the one who gave the short answer "yes" based on the original question. Should have added "probably."

[Jon Vermilye]

Originally Posted by Evirk

...Here's a little more info. Ran some tests using a clamp on amp meter.
I have a Group 27DC battery. Rated 80 amp hours @ 20Hr (anybody know what the 20 Hr means? Pulling 20 amps/hour?)...

Cheers

Evirk

The term 20 hour rate is used to compare battery amp hours. Unless you draw down batteries at the same rate, amp hour capacity is meaningless. So, some common rate needs to be established.

The 20 hour rate means draw down the battery with a load that will completely deplete the battery in 20 hours. In your example, an 80 amp hour battery would be discharged at 4 amps, which would put it at 0V in 20 hours.

If you draw down the battery at less than 4 amps, it will provide more than 80 amp hours; draw down at more than 4 amps & it will provide less. Peukert's Law is used to determine the actual amp hours available with different loads. Also remember the 20 hour rate is depleting the battery to 0V, something that should never be done. You actually have around 1/2 the rated amp hours if you wish to be kind to your battery...

[RogerDat]

I will say that was one of the more detailed battery draw analysis I have seen. Should do a good job to ball park ones solar needs.

I was told a good rule of thumb is 6 x full amp output. You get 4 hours of peak panel output, morning and evening output will be about 1/2 peak. The 4 hours of half is same amps as 2 hours of full. Add the 4 hours mid-day full output and the 2 hours worth of full from morning and late afternoon for 6 hours of full amperage.

As with all rules of thumb it is only a guide. Northern or southern latitudes, partial shade, cloudy day, seasonal differences can all impact that. It will however give you a rough idea of amps hours going in as a starting point.

I think the poster did an excellent job of establishing some real world numbers that while not suitable for lab work are certainly better than just making a SWAG at what usage might be. Like some folks who shall remain nameless. :-)

Considered the propane fridge draws power as well as the different draw associated with fantastic fan speed. Those are both good to have. I plan on borrowing those numbers for my own SWAG at solar but I don't approach it to provide 100% replacement with plenty of head room.

My goal would be more along the lines of on most days I end up fully charged despite usage during the day. The night deficit is fully replaced OR the deficit in amp hours can be tolerated for a few days. I can lose 5 - 10 amp hours a day from battery and still go for a week to 4 days before battery is at 50% charge. I charge from tow vehicle so unless I need to spend several days stationary the solar can have a small deficit. Too many cloudy days might present a conserve power situation. I'm looking for > 50 watt and not over 100 watt. If I need more I will look into expanding with a second panel. Or second battery. If I can stand a 7 to 4 day deficit on one battery two would up that a good amount.

Would rather have an 80% solution that is easy to store and handle than a 160% solution that is a PITA to deal with but that is me. Having boondocked for a week or more in my younger days I can certainly see where other scenarios might be more valid for other campers.

[jwcolby123]

Originally Posted by gordon2

What good does it do to say "My trimetric reports a full charge" without also specifying the programed values used for the Trimetirc, the battery type, capacity, age, temperature at the time, etc. ???

For example, if one programs the Trimetric for a 100 Ah battery but uses a 200 Ah battery then the report of full charge is meaningless.

So lets just say I dont know.. don't have a clue even. Because I am not going to go into that great detail. I can live with your doubts.
...

The point Gordon is quite simply that when you appear on this thread and give an answer, you present yourself as an authority. You have been on the forum for long time, answered a lot of questions, etc. The OP is obviously asking for information from an authority, and thus when you say "I use x and it fully charges my battery" you present an "authority voice" that one panel is enough. In this case it would be very helpful to discuss how you know your battery is fully charged. You claim it is fully charged, how do we know that you even 'have a clue' how to determine whether that is true? TBH from your response above, it doesn't look to me like you do.

I am not an authority. But all I am presenting is "here is what you should think about", not "Yes I think one panel is enough because it fully charges my battery under these circumstances", or at most I am saying "I have doubts that one panel is enough for the following reasons...", which I have been very specific about.

I think a lot of people, yourself included are trying to be helpful, and I do appreciate that.

[jwcolby123]

Originally Posted by Raspy

So, are you assuming none of know when our batteries are charged? I either read it on my battery monitor, which is calibrated to my batteries, or go old school and read rested voltage. Either way, it is close enough to know what full charge means.

Are you the official arbitor of tripe?

Pretty much... Tripe is such a fun word.

Even more so with Lead Acid, unless it is using a shunt, your battery monitor is useless. Is this one of those little "4 bars" POS thingies? You didn't say what the monitor does or how it determines the battery state, so I'm going with useless. As for reading rested voltage... yea right, I believe that. You turn off the panels, all current draws, then wait x hours to take the voltage. And this is part of the routine (implies usual, regularly) you go through to "Be your battery's BMS" as someone put it.
LOL, "Official arbiter of Tripe". I have a new title!

[jwcolby123]

Originally Posted by Glenn Baglo

Do you wipe after a bowel movement? It's not that difficult. Just needs to be done.

ROTFL!!!


My nomination of 'Best response ever'

[Raspy]

jw, AKA the tripester

I'm sorry you are having trouble understanding what most of us are talking about here, and how our systems work. You may have missed the fact that many of us have been using solar and batteries for a long time and have a pretty good idea of how it all works.

Stick around, and join the conversation. We'll get you up to speed. That is, unless you don't want to be nice.

[jwcolby123]

Originally Posted by Raspy

jw, AKA the tripester

I'm sorry you are having trouble understanding what most of us are talking about here, and how our systems work. You may have missed the fact that many of us have been using solar and batteries for a long time and have a pretty good idea of how it all works.

Stick around, and join the conversation. We'll get you up to speed. That is, unless you don't want to be nice.

ROTFLMAOBTC. Buddy, I almost certainly know more about electronics, chargers and batteries than you ever will.

I learned electronics at the age of 13 by reading the 1955 ARRL handbook 3 times cover to cover. The complete (albeit tube in that book) theory that every amateur radio licensee had to learn.

I taught electronics for my freshman high school electronics shop class. The USN trained me for 105 weeks to fix mainframes, tape drives, rotary printers and more stuff than I can even remember. I spent the next 6 years fixing systems in the Intelligence center on the Aircraft Carrier USS Kennedy CV67. I then spent 15 more years working on graphics systems, back when you needed to actually read schematics and use o'scopes. I spent hundreds of hours wire wrapping boards and running OrCad to design and print schematics for medical device prototypes for Puritan Bennett ventilators.

I have studied battery chemistry for dozens of hours, both Lead Acid and Lithium. I have a still somewhat basic understanding of how the devices are actually made, films with deposition layers applied to them in the case of Lithium.

I actually understand how a individual solar cell works, how they are put into systems, serial and parallel, and how the panels are put into systems. I actually understand what PWM is, I have built PWM systems for a variety of uses, even other than battery chargers. I understand buck and boost converters, the circuits (which BTW use PWM) used to perform their charging 'magic'. These converters are what are used for MPPT controllers. I study this stuff because it fascinates me.

So Raspy, you got nothing on me. As for you knowing how solar systems work, why don't you demonstrate it instead of meaningless bluster. TBCH I think you think you know, but from your answers I don't believe you know what you think you know.

I on the other hand do! Down to the circuit level for chargers. Down to the chemistry for batteries.

So yea, you can 'get me up to speed'. You have my complete attention.

[Mike_L]

I like your approach, summing the estimated consumption to get an idea of total demand and sizing power production/battery capacity accordingly. It worked for me quite well.
My panels are flat on the roof of my unit. I see maximum output for about 6 hours per day, on either side of noon, however I see some output from sunrise to sundown.
When the sun isn't shining, all consumption is from the battery. When there is sunlight, consumption is supported by the solar panels AND the battery. So, demand on your battery is total consumption minus input from your solar panels. The battery acts as a cushion, supplying power when demand exceeds panel output.
As sunlight and power generation diminishes, the battery makes up the difference but only carries the full load during darkness. As soon as the sun rises, the panels begin sharing the load so battery demand decreases.
I have observed that my units battery monitor shows a full charge by 11:00am and the charge controller for my panels goes from "charging" to "charged". The panels keep the battery full until evening when the battery starts contributing.
It's not a situation where total consumption comes from the battery which is replaced by the panels.

[Evirk]

First of all, thanks Jon for explaining 20 HR. Makes sense, you need to compare apples to apples after all.

And thanks to everyone else for pitching in to help the Solar Newbie.

In answer to Raspy, yes it's flooded cell. Bought the cheap battery when we got the camper (it's used) and battery was toast. Didn't know if the converter worked so figured if it didn't I would ruin a cheap battery instead of an expensive one.

jwcolby, thanks for your input. On your advice I did compare the Renogy panel amp rating with my handheld. They were smack on which frankly surprised me. I expected a little disagreement. After a while I quit comparing and trusted the Renogy panel. As for the in minus out equals accumulation, I follow. What I was doing with my table was estimating what goes out in 24 hours, figuring regardless of what else happens, I have to put it back in during the same 24 hours or I lose ground.


Update:
Hooked up my new 200 Watt Renogy panel around 8:30 this morning. By the way, the instructions tell you to NEVER connect the controller to the panel before connecting to the battery. So when I opened the panel, guess what? It was already connected and of course it was already collecting photons or whatever. Unplugged it, connected battery, then reconnected panel. No apparent damage.

Sun was out but thin hazy clouds so not actually DIRECT sun. Started charging at 7.3 amps but climbed steady to 8.3. Highest I saw all day was 9.5, and lowest was 2.8 (sun behind cloud, no panel shadow).

So, from 8:30 am to 2:30 pm I put in 30 amp hours per the Renogy panel accounting.

Think I'm glad I went with the 200 watt although the 100 might well have worked but I'd have spent much more time having amp anxiety.

Now, if you folks can offer some suggestions on where to put a second battery ....

[CarlD]

A second battery??? Just spend your kids retirement and replace it with a 1 LFP.

[David Tilston]

Originally Posted by jwcolby123

ROTFLMAOBTC. Buddy, I almost certainly know more about electronics, chargers and batteries than you ever will.

Typically, when I say tripe like that, it is when I am dead wrong. Just say'n.

Do please tell me about how everything works. I read recently that all solid state effects are related to quantum tunneling. This has me a bit confused. Could you please explain?

[Raspy]

Originally Posted by jwcolby123

ROTFLMAOBTC. Buddy, I almost certainly know more about electronics, chargers and batteries than you ever will.

I learned electronics at the age of 13 by reading the 1955 ARRL handbook 3 times cover to cover. The complete (albeit tube in that book) theory that every amateur radio licensee had to learn.

I taught electronics for my freshman high school electronics shop class. The USN trained me for 105 weeks to fix mainframes, tape drives, rotary printers and more stuff than I can even remember. I spent the next 6 years fixing systems in the Intelligence center on the Aircraft Carrier USS Kennedy CV67. I then spent 15 more years working on graphics systems, back when you needed to actually read schematics and use o'scopes. I spent hundreds of hours wire wrapping boards and running OrCad to design and print schematics for medical device prototypes for Puritan Bennett ventilators.

I have studied battery chemistry for dozens of hours, both Lead Acid and Lithium. I have a still somewhat basic understanding of how the devices are actually made, films with deposition layers applied to them in the case of Lithium.

I actually understand how a individual solar cell works, how they are put into systems, serial and parallel, and how the panels are put into systems. I actually understand what PWM is, I have built PWM systems for a variety of uses, even other than battery chargers. I understand buck and boost converters, the circuits (which BTW use PWM) used to perform their charging 'magic'. These converters are what are used for MPPT controllers. I study this stuff because it fascinates me.

So Raspy, you got nothing on me. As for you knowing how solar systems work, why don't you demonstrate it instead of meaningless bluster. TBCH I think you think you know, but from your answers I don't believe you know what you think you know.

I on the other hand do! Down to the circuit level for chargers. Down to the chemistry for batteries.

So yea, you can 'get me up to speed'. You have my complete attention.

Yep. As I said, stick around, we'll get you up to speed. There are a lot of folks here that have a lot of experience and know this stuff very well. They are willing to help when and where they can. We'll give you some practical advice and help with things as they come up.

Batteries can be tricky, but don't get frustrated.

Once you get a little real experience, you can venture out on your own and try a few simple projects on your trailer.

Stick around, be nice, and I'm sure you'll pick up some practical knowledge.