Strange battery behavior

[Scalf77]

Originally Posted by boywonder

My house batteries are inside....near the controller, and I've got the controller temp compensation probe on the batteries........can't think of what else I could do here....

Does your battery monitor have the optional temp probe, if the charge voltage is being compensated by temperature, the expected voltage for float would also need to be compensated for temp. Over 77 your float voltage could be compensated lower, and not meet the float voltage threshold. in F1.0

-greg

[ShuttlePilot]

Greetings Boywonder, just to confirm what your question is, because solar/battery discussions have a way of going wildly off course, not accusing anyone it just happens, your concern is that you believe your seeing the LinkPro drift and become inaccurate as the battery bank cycles up and down each day at times when the Auto Sync requirements are not necessarily met?

"Not necessarily met" as in, parked in the driveway with no loads, very shallow discharge cycles and lots of float charge mode?

Or am I way off and your LinkPro just isn't ever Auto Syncing?

-Eric

[boywonder]

Originally Posted by ShuttlePilot

Greetings Boywonder, just to confirm what your question is, because solar/battery discussions have a way of going wildly off course, not accusing anyone it just happens, your concern is that you believe your seeing the LinkPro drift and become inaccurate as the battery bank cycles up and down each day at times when the Auto Sync requirements are not necessarily met?

"Not necessarily met" as in, parked in the driveway with no loads, very shallow discharge cycles and lots of float charge mode?

Or am I way off and your LinkPro just isn't ever Auto Syncing?

-Eric

Hi Eric: Yes, you've got it.....either the Linkpro is drifting or my batteries are dying a not-so-slow death....

[boywonder]

Originally Posted by Scalf77

I am kind of inline with ShuttlePilot. I believe the key parameters that target the linkpro to think it is fully charged are:

• F1.0 Charger's float voltage (Auto-sync parameter). This value must be equal to your battery charger’s float voltage. which is the last stage of the charging process. In this stage the battery is considered full.
  Default: 13.2V Range: 8.0 – 33.0V Step size: 0.1V
• F1.1 Charger's float current (Auto-sync parameter). When the charge current is below this percentage of the battery capacity (see Function F5.0), the battery will be considered as fully charged. Make sure this Function value is always greater than the minimum current at which the charger maintains the battery or stops charging.
  Default: 2.0% Range: 0.5 – 10.0% Step size: 0.1%
• F1.2 Auto-sync time (Auto-sync parameter). This is the time the Auto-sync parameters F1.0 and F1.1 must be met in order to consider the battery as fully charged.
  Default: 240sec Range: 5 – 300sec Step size: variable

Make sure the float voltage the monitor expect to see is the same thing being provided by the charger, Do you have any high always on loads that might be outside of the minimum current at float.

The obvious, which you probably already checked, make sure there are no loads that do not go through the shunt.

See if your charger let's you change the absorption parameters, some chargers let you adjust the minimum time and other parameters.

Happy Hunting
-greg

Thanks Gregg! The above is some stuff that I can take action on!

[ShuttlePilot]

Ok, got it. I'm thinking in my head three questions or goals to answer.

1) Is your battery bank achieving full charge at some point regardless of the monitor reading? This would be the first question I would want answered because batteries are expensive and it's a waste of time to calibrate a monitoring instrument to unreliable/failing equipment. I'm assuming you have this part handled unless you have questions about it.

2) Is the LinkPro Auto Syncing as it's supposed to when the full charge (the conditions mentioned above) perimeters are met? On my system this will happen every sunny day sitting in the driveway like your describe. I think Greg is covering this part.

3) Where is the drift coming from when State of Charge (SOC) goes up and down a few times but doesn't bring the batteries up to 100% for a few days. And with each cycle the Meter is measuring "short" so the percent displayed is drifting a little lower each time. I think this is what your witnessing.

Where I'm thinking this issue is in the Assumed Efficiency Factor in the Monitors equation. Xantrex calls it the Charge Efficientcy Factor (CEF) Bogart calls it the AEF. As I mentioned this is a constant that assumes the amps nessissary to charge a battery is greater than what is removed. Here is the kicker. Each battery manufacture and type is a little different depending on the internal resistance. Xantrex defaults this setting to 90 or 90%. so for each 9 AH removed from battery 10AH must be replaced to read the same percentage. 90 is pretty conservative Bogart defaults to 94 which is still conservative. However what this dose is keep a user from over discharging a battery because the drift is toward a less discharged battery. Meaning the user will think the battery is lower and will conserve until a full charge and Auto Sync (fully charged battery) is achieved.

Now this CEF constant can be changed. By increasing to say 97 the monitor will be more accurate to the actual loss or resistance or your particular battery. Here it's where it is for a link Pro

F5.6 Charge Efficiency Factor (CEF). CEF is the ratio between the energy
removed from a battery during discharge and the energy used during
charging to restore the original capacity. It is recommended to keep this
value at “AU” (automatic calculation). The setting “100” disables charge
efficiency compensation.
Default: AU Range: 50 – 100% / AU Step size: 1%

Here is the caution in this. Battery resistance is related to temperature. You mentioned that your batteries are inside and a fairly constant temperature. Also, you mentioned that your using the Temp Sensor on your LinkPro which if calibrated correctly will apply the Temp correction in the calculation. Because of this your battery resistance probably dosen't change much. BUT for those with batteries outside, not using a Temp Sensor on the LinkPro, have a Bogart Trimetric which dose not correct for temp. INCREASING the Charge Efficiency Factor can cause your monitor to display a higher SOC than the battery actually is and cause you to drain your battery deeper than you may like to. That is the disclaimer.

Anyway I had some time to kill and my mind was turned on so sorry for the long post. I really hope this might help. Honestly, the drift you describe is pretty good. I've seen much worse on systems that was deemed acceptable.

Again I would be concerned about #1 above first then tighten up the data monitoring after.

-Eric

[boywonder]

Originally Posted by ShuttlePilot

1) Is your battery bank achieving full charge at some point regardless of the monitor reading? This would be the first question I would want answered because batteries are expensive and it's a waste of time to calibrate a monitoring instrument to unreliable/failing equipment. I'm assuming you have this part handled unless you have questions about it.

It seems so based on the solar controller.....
When the batteries are at 12.8V the controller is putting out little-to-zero current in direct sunlight. When I put a large load on the batteries, the charge current goes way up as expected.

Originally Posted by ShuttlePilot

2) Is the LinkPro Auto Syncing as it's supposed to when the full charge (the conditions mentioned above) perimeters are met? On my system this will happen every sunny day sitting in the driveway like your describe. I think Greg is covering this part.

I think this is my basic issue......seems like it used to.....

Originally Posted by ShuttlePilot

3) Where is the drift coming from when State of Charge (SOC) goes up and down a few times but doesn't bring the batteries up to 100% for a few days. And with each cycle the Meter is measuring "short" so the percent displayed is drifting a little lower each time. I think this is what your witnessing.

yes.....pretty much.......although there is plenty enough sun and solar panels to get the house batteries to 100% but they never get there, at least on the monitor.....the solar controller thinks they are charged.

Originally Posted by ShuttlePilot

Where I'm thinking this issue is in the Assumed Efficiency Factor in the Monitors equation. Xantrex calls it the Charge Efficientcy Factor (CEF) Bogart calls it the AEF. As I mentioned this is a constant that assumes the amps nessissary to charge a battery is greater than what is removed. Here is the kicker. Each battery manufacture and type is a little different depending on the internal resistance. Xantrex defaults this setting to 90 or 90%. so for each 9 AH removed from battery 10AH must be replaced to read the same percentage. 90 is pretty conservative Bogart defaults to 94 which is still conservative. However what this dose is keep a user from over discharging a battery because the drift is toward a less discharged battery. Meaning the user will think the battery is lower and will conserve until a full charge and Auto Sync (fully charged battery) is achieved.

Now this CEF constant can be changed. By increasing to say 97 the monitor will be more accurate to the actual loss or resistance or your particular battery. Here it's where it is for a link Pro

F5.6 Charge Efficiency Factor (CEF). CEF is the ratio between the energy
removed from a battery during discharge and the energy used during
charging to restore the original capacity. It is recommended to keep this
value at “AU” (automatic calculation). The setting “100” disables charge
efficiency compensation.
Default: AU Range: 50 – 100% / AU Step size: 1%

Here is the caution in this. Battery resistance is related to temperature. You mentioned that your batteries are inside and a fairly constant temperature. Also, you mentioned that your using the Temp Sensor on your LinkPro which if calibrated correctly will apply the Temp correction in the calculation. Because of this your battery resistance probably dosen't change much. BUT for those with batteries outside, not using a Temp Sensor on the LinkPro, have a Bogart Trimetric which dose not correct for temp. INCREASING the Charge Efficiency Factor can cause your monitor to display a higher SOC than the battery actually is and cause you to drain your battery deeper than you may like to. That is the disclaimer.

...got it......BTW the temp monitor on the batteries is for the solar controller.....

[ShuttlePilot]

Originally Posted by boywonder

When the batteries are at 12.8V the controller is putting out little-to-zero current in direct sunlight.

This statement concerns me. I wouldn't change anything in the LinkPro just yet. Which Samlex Solar controller are you using? I think we should confirm item #1 Is your battery bank achieving full charge before moving to far ahead. Be right Back.

-Eric

[rallypanam]

Originally Posted by ShuttlePilot

This statement concerns me. I wouldn't change anything in the LinkPro just yet. Which Samlex Solar controller are you using? I think we should confirm item #1 Is your battery bank achieving full charge before moving to far ahead. Be right Back.

-Eric

Good catch.. it should be above 13 before it goes to float, no?

[ShuttlePilot]

I'm currently being held captive waiting for a delivery that I must sign for. So lets talk about fully charged lead acid batteries. Bear with me as this may be obvious for most members.

Fully charged (very loose definition) is that point where a high enough voltage has been applied for long enough time where all chemical reaction within the battery has stopped. To continue to apply a higher voltage or for more time from that moment the electrical energy will only be converted into heat. The proverbial "boiling a battery". This point in the chemical reaction is accurately determined with a hydrometer but how do you determine in a sealed battery or a battery that is inaccessible. You make an educated guess.

Here is my method.

1) Find out what the manufacture of the battery states the Absorb or Cycle Use voltage should be. Not what any charger/controller manufacture says.
Here is the data sheet for a UPGI battery, since a lot of us have these.
http://files.upgi.com:8086/UPGFileSe...pecSheet/45972
You will find Cycle Use is recomended to be between 14.6 and 14.8 volts at 77 degrees F. Call it 14.7

Here is for LifeLine as a lot of us have these.
http://lifelinebatteries.com/wp-cont...cal-Manual.pdf
Absorb voltage is 14.3 volts at 77 degrees F. found on page 19.

2)Apply the charge to the battery bank until that absorb voltage is reached. I like to use a plugged in manual charger or power supply as it won't turn off or lower the voltage on me. If that is not available use what you got that will go high enough for long enough. If all you have is a Progressive Dynamics with a charge wizard it will only get to 14.4 volts in manual mode then that what you use.

3)Once the voltage reaches the absorbe voltage(14.7, 14.4, 14.3) I start a stopwatch. when this stops, this time will be the absorb time at 77 degrees F.

4) Determine the stop time for Absorb. Here is where the money is. Using the assumption that when the flow of Amps drops to 2% of the Amp Capacity of the battery or bank charge is complete. So in boywonders case he has 250 amp Hours of capacity, 2% of that is 5 amps of charge current. So holding his battery bank at his charge voltage for enough time to see the Amps flow drop to 5 I would stop the watch and call it fully charged. This is the time to zero out your monitor so it reads 100%.

This regime is ideally what you want your solar charger to repeat on it's own or as close to it as possible. If I can get these results during a battery assessment I would then assume the battery bank is healthy and move on to other equipment like solar controller and monitors.

- Eric

CORRECTION : boywonder has 350 amp hours of capacity. So his 100% fully charged point would be 7 amps at the Cycle Use voltage. 350Ah x .02 = 7Amps.

[Scalf77]

Originally Posted by ShuttlePilot

Fully charged (very loose definition) is that point where a high enough voltage has been applied for long enough time where all chemical reaction within the battery has stopped. To continue to apply a higher voltage or for more time from that moment the electrical energy will only be converted into heat. The proverbial "boiling a battery". This point in the chemical reaction is accurately determined with a hydrometer but how do you determine in a sealed battery or a battery that is inaccessible. You make an educated guess.

Here is my method.

1) Find out what the manufacture of the battery states the Absorb or Cycle Use voltage should be. Not what any charger/controller manufacture says.
Here is the data sheet for a UPGI battery, since a lot of us have these.
http://files.upgi.com:8086/UPGFileSe...pecSheet/45972
You will find Cycle Use is recomended to be between 14.6 and 14.8 volts at 77 degrees F. Call it 14.7

Here is for LifeLine as a lot of us have these.
http://lifelinebatteries.com/wp-cont...cal-Manual.pdf
Absorb voltage is 14.3 volts at 77 degrees F. found on page 19.

2)Apply the charge to the battery bank until that absorb voltage is reached. I like to use a plugged in manual charger or power supply as it won't turn off or lower the voltage on me. If that is not available use what you got that will go high enough for long enough. If all you have is a Progressive Dynamics with a charge wizard it will only get to 14.4 volts in manual mode then that what you use.

3)Once the voltage reaches the absorbe voltage(14.7, 14.4, 14.3) I start a stopwatch. when this stops, this time will be the absorb time at 77 degrees F.

4) Determine the stop time for Absorb. Here is where the money is. Using the assumption that when the flow of Amps drops to 2% of the Amp Capacity of the battery or bank charge is complete. So in boywonders case he has 250 amp Hours of capacity, 2% of that is 5 amps of charge current. So holding his battery bank at his charge voltage for enough time to see the Amps flow drop to 5 I would stop the watch and call it fully charged. This is the time to zero out your monitor so it reads 100%.

This regime is ideally what you want your solar charger to repeat on it's own or as close to it as possible. If I can get these results during a battery assessment I would then assume the battery bank is healthy and move on to other equipment like solar controller and monitors.

- Eric

CORRECTION : boywonder has 350 amp hours of capacity. So his 100% fully charged point would be 7 amps at the Cycle Use voltage. 350Ah x .02 = 7Amps.

Eric,
Nice write up (procedure).

boywonder,
I thought I would post this link to keeping your battery monitor more accurate.
It kind of makes you wonder the positives of using one of these things, but it is better than not having one.

-greg