Confusion About Voltage.

[Ridge Runner]

What started out as a joke between me and RM has become an actual test, As I said to RM that I would do a test just for him I got a brainwave and decided to pick the oldest of my 3 X 115A/h batteries and just try and see how long it would run my ARB 47L Fridge, Anyways I had it fully charged and let it rest for 8 to 10 hours and fitted it in a battery box that I just bought that came with a pair of external terminals and a Cigar lighter socket and an LED meter on it,

So once fitted I clamped on my Fluke DMM and plugged in the fridge and set the Battery Cut Off to Hi which is about 11.80v under load and about 12.12 Open voltage which is some where up around the 40% state of Charge mark,, Well this has gone on for a few days now and it is still blazing away doing it's thing and every thing was fine until I phone the bloke at the solar shop, And I nearly gave him an ear bashing But I kept my cool, anyways he proceeded to tell me my battery was flat and then tried to tell me about my fridge, That did not sit well with me and when He said that my battery was flat and then half flat when it had over 12.5 volts in it that was it,

So I asked him to explain why it was half flat when all the charts and battery Guru's say otherwise "NO ANSWER", so I resigned to the fact that he was in Lala Land, so I got a load of Battery SOC Graphs and they all said the same as me, I checked the battery hourly with the Fluke DMM and used the battery tester on the Battery Box and me and the Fluke and the Battery box all came up with the same figures,

I know that temperature in different parts of the world can have an effect on a batteries state of charge and I have graphs that show this, I guess the guy at the solar shop only knows about batteries that are being charged 24/7 so he would not be use to seeing these sort of numbers, Lol.

Anyways here is a good chart that explains it all just about and here is my Fluke DMM as the battery hit the 90 Hour Mark. And this meter is extremely accurate and I bought it direct from Fluke UK and they even tested it in their Calibration House while I was there So I know this is right.

J.

 

[AngerManagement]

Not going here... masses of variables and then some.

And lets not start about open cct voltages and under load (what sort of load) etc.

Older style where you could measure each cell with a hydrometer was much more KISS. These days it is hit and miss...

I have 2 x 115 AGM's in my van approx 3.5 years old. Will sit quite happy at 13.1V at rest and little movement with low draw dow, fans and led lights, with a phone or two on charge - a drop is seen. Put my 60l 12v freezer/fridge on and they crap out within no time and it is suppose to average about 2.2A hr. The Voltage gets down well under 11v; under load no problem. Take the load off and voltage pops back up after a few min to 12.4 - 12.6.

Yet to put a current meter in series with the fridge, may do so this weekend... If I remember to do it LOL.

My guess is that while charging and open cct at rest measures OK, one or both batteries have an issue with one or more cells.

When doing critical batteries for MEDICAL stuff we often had to do load and charge and drains over a 12 and in some cases a 24 hr period - High end automated testing units and so many would pass basic testing and short term load and charging rates. But under a full testing process, maybe 30% would fail at new. Thus we always had plenty of 12V 6V and 2V batteries for camping etc. Man can a series of 2V deliver some current but need a truck to transport them.

Can not afford the time or $$$ to do heavy duty testing and not much you can do to repair some of the batteries these days. So keep em charges, try hard not to totally drain and once they start dropping more voltage than expected under load = replace them.

UPS for critical life support in some cases rated say 20min ( cover for time for generators to come on line ) So when purchasing them UPS had to rated to 60min. And tested every 3 months... BBattries replaced once the system could not last 30min, as it leaves a small margin of error. And all Batteries replaced every 12 months regardless. One would be surprised at how many batteries fail at 6 months... Some would ask why, but the thing is that when the systems are under test, they are under FULL MAX load AND many batteries will manage a partial load but under full load they loose their *****.

If you have a UPS for your PC and rated for say 15 or 20 min, pull the power cord and see how long it lasts while your working away and burning a critical CD and doing a backup to an external drive...

Long story short. Have 2 new Marine AGM's to go in to my van, but they are the wrong footprint lol but may then play and see if one or both the others are stuffed. And I will see how the new batteries perform - if I remember to take measurements and record times..

RM and RR - let us know your final outcome of your Joke / Actual tests

 

[Ridge Runner]

Not going here... masses of variables and then some.

And lets not start about open cct voltages and under load (what sort of load) etc.

Older style where you could measure each cell with a hydrometer was much more KISS. These days it is hit and miss...

I have 2 x 115 AGM's in my van approx 3.5 years old. Will sit quite happy at 13.1V at rest and little movement with low draw dow, fans and led lights, with a phone or two on charge - a drop is seen. Put my 60l 12v freezer/fridge on and they crap out within no time and it is suppose to average about 2.2A hr. The Voltage gets down well under 11v; under load no problem. Take the load off and voltage pops back up after a few min to 12.4 - 12.6.

Yet to put a current meter in series with the fridge, may do so this weekend... If I remember to do it LOL.

My guess is that while charging and open cct at rest measures OK, one or both batteries have an issue with one or more cells.

When doing critical batteries for MEDICAL stuff we often had to do load and charge and drains over a 12 and in some cases a 24 hr period - High end automated testing units and so many would pass basic testing and short term load and charging rates. But under a full testing process, maybe 30% would fail at new. Thus we always had plenty of 12V 6V and 2V batteries for camping etc. Man can a series of 2V deliver some current but need a truck to transport them.

Can not afford the time or $$$ to do heavy duty testing and not much you can do to repair some of the batteries these days. So keep em charges, try hard not to totally drain and once they start dropping more voltage than expected under load = replace them.

UPS for critical life support in some cases rated say 20min ( cover for time for generators to come on line ) So when purchasing them UPS had to rated to 60min. And tested every 3 months... BBattries replaced once the system could not last 30min, as it leaves a small margin of error. And all Batteries replaced every 12 months regardless. One would be surprised at how many batteries fail at 6 months... Some would ask why, but the thing is that when the systems are under test, they are under FULL MAX load AND many batteries will manage a partial load but under full load they loose their *****.

If you have a UPS for your PC and rated for say 15 or 20 min, pull the power cord and see how long it lasts while your working away and burning a critical CD and doing a backup to an external drive...

Long story short. Have 2 new Marine AGM's to go in to my van, but they are the wrong footprint lol but may then play and see if one or both the others are stuffed. And I will see how the new batteries perform - if I remember to take measurements and record times..

RM and RR - let us know your final outcome of your Joke / Actual tests

AM, I got a good tester that load tests them by sending a signal in to the battery, Not like the old type of drop tests where you short across the battery or the push button load meters and it also gives you a print out if you want it, Best thing I bought in a long while and has helped me save the batteries, marvellous thing it is. :Y:

 

[Redfin]

too much info, have a 100w solar panel on the roof of the Prado and the fridge keeps the beer cold 365 days a year.
All I need to know.

 

[Ridge Runner]

too much info, have a 100w solar panel on the roof of the Prado and the fridge keeps the beer cold 365 days a year.
All I need to know.

Yeah sometimes a simple setup is often the best. :Y:

 

[Ded Driver]

im using a simple 3 stage rule of thumb.
if the battery reads 13V or higher, all is great
12.5V, things are getting a bit down, get some charge happening soon.
12.0V, getting real low, get that charge happening asap

 

[PabloP]

Not going here... masses of variables and then some.

And lets not start about open cct voltages and under load (what sort of load) etc.

Older style where you could measure each cell with a hydrometer was much more KISS. These days it is hit and miss...

I have 2 x 115 AGM's in my van approx 3.5 years old. Will sit quite happy at 13.1V at rest and little movement with low draw dow, fans and led lights, with a phone or two on charge - a drop is seen. Put my 60l 12v freezer/fridge on and they crap out within no time and it is suppose to average about 2.2A hr. The Voltage gets down well under 11v; under load no problem. Take the load off and voltage pops back up after a few min to 12.4 - 12.6.

Yet to put a current meter in series with the fridge, may do so this weekend... If I remember to do it LOL.

My guess is that while charging and open cct at rest measures OK, one or both batteries have an issue with one or more cells.

When doing critical batteries for MEDICAL stuff we often had to do load and charge and drains over a 12 and in some cases a 24 hr period - High end automated testing units and so many would pass basic testing and short term load and charging rates. But under a full testing process, maybe 30% would fail at new. Thus we always had plenty of 12V 6V and 2V batteries for camping etc. Man can a series of 2V deliver some current but need a truck to transport them.

Can not afford the time or $$$ to do heavy duty testing and not much you can do to repair some of the batteries these days. So keep em charges, try hard not to totally drain and once they start dropping more voltage than expected under load = replace them.

UPS for critical life support in some cases rated say 20min ( cover for time for generators to come on line ) So when purchasing them UPS had to rated to 60min. And tested every 3 months... BBattries replaced once the system could not last 30min, as it leaves a small margin of error. And all Batteries replaced every 12 months regardless. One would be surprised at how many batteries fail at 6 months... Some would ask why, but the thing is that when the systems are under test, they are under FULL MAX load AND many batteries will manage a partial load but under full load they loose their *****.

If you have a UPS for your PC and rated for say 15 or 20 min, pull the power cord and see how long it lasts while your working away and burning a critical CD and doing a backup to an external drive...

Long story short. Have 2 new Marine AGM's to go in to my van, but they are the wrong footprint lol but may then play and see if one or both the others are stuffed. And I will see how the new batteries perform - if I remember to take measurements and record times..

RM and RR - let us know your final outcome of your Joke / Actual tests

AM, it is likely that your old AGMs are suffering from some sulphation on the plates. I have a battery charger that has a rejuvenation setting that will sometimes give these a bit of new life. I have used this to kick a couple of truck batteries in the guts and we now use them for long run low drain 12V applications.
The lower the voltage goes, the shorter will be the batteries life.

Rob P.

 

[ctxkid]

im using a simple 3 stage rule of thumb.
if the battery reads 13V or higher, all is great
12.5V, things are getting a bit down, get some charge happening soon.
12.0V, getting real low, get that charge happening asap

what DD said , spot on

 

[ctxkid]

Think about this
A battery has 6 cells (12volt battery) , each cell at full charge is 2.2volts , the battery will have an expected 1000+ duty cycles ower: erfect:
Is a battery in good health at 12.4 ?

my answer is no

 

[Ridge Runner]

Think about this
A battery has 6 cells (12volt battery) , each cell at full charge is 2.2volts , the battery will have an expected 1000+ duty cycles ower: erfect:
Is a battery in good health at 12.4 ?

my answer is no

At 12.40v a Battery is still 80% Charged or close to it, But by not going past that level is the best way to prolong the batteries life,

 

[Jaros]

Definitely no problems with that up here --don't want -30C either.

 

[Ridge Runner]

Well I am in the middle of testing the oldest XD-31 115A/h Deep Cycle Battery but only to the point of my Fridges highest Cut Out Setting because I am trying to find out it's run time without taking the battery down in to the danger zone, It comes rated down to 30% and comes with a long warranty so it should go the distance, The Medium Setting on the Fridge is equal to the Batteries Rating but I am not sure that I would ever need to take one of these batteries down that far,

I expected this to be over a couple of days ago not long after I started clowning around with RM, But I think this battery has shot me in the foot, The Voltage drop between each On and Off Cycle is a joke it is so small,

Because of how many folks have batteries go down in a couple of days I thought I would avoid that problem So I bought another 2 so Now I got 3 of them and to be honest I don't think I would ever need that much power, I am glad I did not stick to my original plan and that was to run 4 X 230A/h Monster batteries,

 

[AngerManagement]

Got to pull my finger out and swap the ones I have over. But the newer ones have a bigger footprint and that means modifications.

Need to go gold hunting this Easter and think on it.

Stay safe every one and swing low and slow.

 

[Ridge Runner]

Got to pull my finger out and swap the ones I have over. But the newer ones have a bigger footprint and that means modifications.

Need to go gold hunting this Easter and think on it.

Stay safe every one and swing low and slow.

What batteries did you buy AM, ??

 

[AngerManagement]

Will check as I got them second hand.... lol

About 16 months and limited use in a coffee cart.

 

[AngerManagement]

Hope this works

 

[Ridge Runner]

https://www.prospectingaustralia.com/forum/img/member-images/3760/1555509471_20190417_234538.jpg

Hope this works

Holy Smokes, If they are any good they will last a very long time, This one I am using is a 115 and it is still going so those 2X 125's could run your fridge for about 16 days or more. If you hooked them up with a solar panel and the weather got over cast they have enough to keep going until the weather clears up, :Y: erfect:

 

[AngerManagement]

But they are at home and the shity ones are in the van lol.

 

[Ridge Runner]

You are going to get some long run times out of those, because of their size, If they take a good charge then you will get over 8 days out of one of them in more mild weather So don't expect the normal 3 or 4 days out of one,

I have just fitted one of those kickass type meters to my Battery Box so I get the full info, then I am going to run the test again at 4*c this time like that Guy did on youtube and then I will run it as a freezer and test it again,

I just started charging the one I was testing, If I had a couple of them linked I would of used the bigger 26A Noco Charger but because it is just One I am using the 15A Noco.

J.

 

[ctxkid]

my victron tenders these
3 x 120's and 1 x 260 all second hands