? Interpreting an ammeter... ?

[TimC]

I recently installed Bayite ammeters to measure the solar generation and my power usage from the battery bank. I understand that if I maintain a good SOC on the voltage that I can just compare Wh on the generation side and Wh on the demand side and see that I am recovering well each day. What else am I looking at? Will SOC tell me anything about my battery capacity and whether it is diminishing? It's AGM batteries so I can't really do a hydrometer test.

This was taken while there was no demand and a full charge on the bank. Production on the bottom, demand on the top. Will a photo of my charge controller screen at the same time help interpret real SOC?

[Socal Tom]

Top Left is voltage, gives you a general idea on state of charge of the battery anything over about 12.6 volts with no significant amp draw is pretty close to full charge

Top Right is instantaneous amps moving through the system. On the demand side, its how much is being pulled out of the battery at that moment, on the supply side its what is going in the battery at that moment. ( generally this means that if solar is making 7 amps, and the fridge is using 3 amps you will show 0 demand and 4 supply)

Bottom left is instantaneous watts essentially the same as the top right, but watts instead of amps ( watts =amps x volts)

Bottom right is the cumulative watt hours used. This totals up the watts that moved to or from the battery since the last time it was reset.




If the watt hours supplied are greater or equal to the watt hours used, then your solar panel made up for more than you used ( due to efficiency losses you expect a full charge to be about 10% more watt hours supplied vs used)

If the watt hours supplied are less than the watt hours used, then your battery has been depleted somewhat.

My batter is an 85amp hour battery, to estimate total watt hours I multipled 85 amp hours x12.5volts ( I'm not going to explain why I used this number, it will add confusion here) so I ESTIMATE that I have about 1062 watt hours in the battery. Since I want to stay above 50%, I want (watt hours used - watt hours supplied) to be less than 531 watt hours.

I generally reset my baylite meters once I unplug for a trip. The lowest numbers are usually in the morning when power has been used all night, I use between 200 and 400 watt-hours over night. By sunset ( when solar stops charging), I've usually put back slightly more than I used so I consider the battery fully charged.


-Note- This thread is about to get spammed by some people that will tell you my estimates are wrong and argue about the exact voltage and a bunch of other stuff. I shared how I interpret these things, and I believe most of us weekend warriors will find my method to be good enough for our intended use.
Tom

note I should add, once the battery is near full charge, your charge controller limits the power sent to the battery, so don't be concerned if you are in full sun, with a full battery and its not reporting very many amps or watts being sent to the battery.

[TimC]

-Note- This thread is about to get spammed by some people that will tell you my estimates are wrong and argue about the exact voltage and a bunch of other stuff. I shared how I interpret these things, and I believe most of us weekend warriors will find my method to be good enough for our intended use.
Tom

No! Never on tnttt!

Thanks Tom. Seriously though, I find the banter back and forth about such differences a bit amusing at times. I just skim through most of it. I too am looking for approximations.

So, I have/had 144 aHr in my battery bank when new. Who knows what reality was; I just choose to believe and not worry about it. They are going on six years old so I suspect some deterioration. I'm gonna guess that the 72 aHr useable is likely down about 25%. Guesstimating again... Gonna do some research next off season and possibly upgrade to a new bank. While I'd like to go LiFePo4 I doubt I'll have the funds to sink that kind of money into it. I'm not considering the long term costs. Just what I'll be able to spend at the time. What little research I have done on those I have come to the conclusion that when compared to AGM the AGM's performance (life) is almost always under stated and the LiFePo4s will have perfect performance. How about that statement for drumming up some disagreement? Hee hee.

Thanks again.

Tim

[Socal Tom]

After you use a few times and monitor it you can get a feel for what its got left. There are charts like this one in the morning before the solar starts charging see what the voltage is and compare to the chart. For example if it says you used about 30% because voltage is 12.3 ish, then the watts you used would be about 30% of capacity. In my case, my 85AH battery is acting more like 100AH.
Tom

[Socal Tom]

. While I'd like to go LiFePo4 I doubt I'll have the funds to sink that kind of money into it. I'm not considering the long term costs. Just what I'll be able to spend at the time. What little research I have done on those I have come to the conclusion that when compared to AGM the AGM's performance (life) is almost always under stated and the LiFePo4s will have perfect performance. How about that statement for drumming up some disagreement? Hee hee.

Thanks again.

Tim

I look at it like this. My current battery has a target capacity of about 45AH ( 1/2 of 85AH). So I could save some weight by dropping to a 45 AH lifepo, but then I don't have reserve for when the sun doesn't come up. You can run a lead acid battery below 50%, it shortens the life, but at 100$ every 5 or 6 years Its not a big deal.
Tom

[Socal Tom]

. While I'd like to go LiFePo4 I doubt I'll have the funds to sink that kind of money into it. I'm not considering the long term costs. Just what I'll be able to spend at the time. What little research I have done on those I have come to the conclusion that when compared to AGM the AGM's performance (life) is almost always under stated and the LiFePo4s will have perfect performance. How about that statement for drumming up some disagreement? Hee hee.

Thanks again.

Tim

I look at it like this. My current battery has a target capacity of about 45AH ( 1/2 of 85AH). So I could save some weight by dropping to a 45 AH lifepo, but then I don't have reserve for when the sun doesn't come up. You can run a lead acid battery below 50%, it shortens the life, but at 100$ every 5 or 6 years Its not a big deal.
Tom

[TimC]

After you use a few times and monitor it you can get a feel for what its got left. There are charts like this one in the morning before the solar starts charging see what the voltage is and compare to the chart. For example if it says you used about 30% because voltage is 12.3 ish, then the watts you used would be about 30% of capacity. In my case, my 85AH battery is acting more like 100AH.
Tom

I have a chart like this on my utility cabinet door. I just didn't know that part you mentioned above for calculating capacity. It'll get me in the ballpark for sure. Very cool. After a night of use (fridge, fans, lights) I'll take a reading and do some gozintas. Should the battery be at rest for a period before reading volts? Or is a morning after reading good enough?

Thanks again

Tim

[Socal Tom]

After you use a few times and monitor it you can get a feel for what its got left. There are charts like this one in the morning before the solar starts charging see what the voltage is and compare to the chart. For example if it says you used about 30% because voltage is 12.3 ish, then the watts you used would be about 30% of capacity. In my case, my 85AH battery is acting more like 100AH.
Tom

I have a chart like this on my utility cabinet door. I just didn't know that part you mentioned above for calculating capacity. It'll get me in the ballpark for sure. Very cool. After a night of use (fridge, fans, lights) I'll take a reading and do some gozintas. Should the battery be at rest for a period before reading volts? Or is a morning after reading good enough?

Thanks again

Tim

I think looking at it several mornings should get you in the ball park. If its really cold you might wait a bit before you take the reading ( warming up can raise the voltage a bit). I think it will be obvious after a few days if its 72AH or 144ish

[saltydawg]

-Note- This thread is about to get spammed by some people that will tell you my estimates are wrong and argue about the exact voltage and a bunch of other stuff. I shared how I interpret these things, and I believe most of us weekend warriors will find my method to be good enough for our intended use.
Tom

Well your wrong, there I said it. Now in real life I dont know that meter, and sounds like you do so your probably right.

but your still wrong

[Tom&Shelly]

-Note- This thread is about to get spammed by some people that will tell you my estimates are wrong and argue about the exact voltage and a bunch of other stuff. I shared how I interpret these things, and I believe most of us weekend warriors will find my method to be good enough for our intended use.
Tom

Well your wrong, there I said it. Now in real life I dont know that meter, and sounds like you do so your probably right.

but your still wrong

I was going to tell him he was wrong, but then I thought, "why not talk about how to manufacture plate aluminum..."

Seriously, good explanation Tom.

Tom

[Socal Tom]

-Note- This thread is about to get spammed by some people that will tell you my estimates are wrong and argue about the exact voltage and a bunch of other stuff. I shared how I interpret these things, and I believe most of us weekend warriors will find my method to be good enough for our intended use.
Tom

Well your wrong, there I said it. Now in real life I dont know that meter, and sounds like you do so your probably right.

but your still wrong

My wife agrees with you. Doesn’t matter the topic, I’m wrong.

[RJ Howell]

I recently installed Bayite ammeters to measure the solar generation and my power usage from the battery bank. I understand that if I maintain a good SOC on the voltage that I can just compare Wh on the generation side and Wh on the demand side and see that I am recovering well each day. What else am I looking at? Will SOC tell me anything about my battery capacity and whether it is diminishing? It's AGM batteries so I can't really do a hydrometer test.

This was taken while there was no demand and a full charge on the bank. Production on the bottom, demand on the top. Will a photo of my charge controller screen at the same time help interpret real SOC?

I've run these for years and ran them like you have. One for solar input and the other for house draw. Starting full like you have, it's now just watching the cumulative wH's. I reset mine each time we head out to start it all again. As we try running different appliances it gives a great way to see just what is happening.

I do agree 'mostly' with the description given. Your voltage reading tells me there is supply (panel is working). A good voltage SOC reading is a battery at rest which should be +12hrs or so. Current and Power are both what is happening in real time and finally Energy is the cumulative (resettable) feature. I bought these specifically for that feature.

I do like the ones with the external shunt, yet in reality I haven't found much difference in accuracy with the internal shunt units (tested both). I guess I just like seeing the shunt.. LOL

In the Overlander I only run 1 meter. I've become so used to how we used our battery and I'm re-charging in that by DC/DC.

Safe Travels!

[TimC]

Thanks everyone. All good answers, except those that were not

As I tour this season I will build a little confidence about my battery capacity and performance. I hope to get many more years out of my battery bank, but, I realize it may be sooner than later that I upgrade.

The nice thing is I'm camping and if I run out of power it isn't the end of the world. I'll still keep warm with blankets, I'll still be able to cook with wood or propane, I'll still be able to function without the phone.

[Tom&Shelly]

The nice thing is I'm camping and if I run out of power it isn't the end of the world. ...I'll still be able to function without the phone.

MADNESS!!!

Tom

[RJ Howell]

You seem to be on a good path for figuring out your power needs/requirements. I do suggest you do a Power Audit. I built a spreadsheet as I did mine so I could add/subtract appliances according to the the battery bank/charging system I wished to employ. It's a great way to play with systems and see what you can do. It also helps to figure out a good recharge system to maintain power level.

I am a big fan of DC/DC and was very surprised how well on such small wires it still worked. This is not for everyone, but met our touring/camping style.

So may options for so many folks!

Safe Travels!