SOC during Float charge (First Post Please be gentle and forgive my ignorance)

[RVLiFe]

My recommendation, Drop your Absorption to 14.1-14.2V. Float voltage to 13.6-13.8V. Drop your absorption time to 15min - 30min(or even none). Check your 500A SmartShunt and change the Charged current to .10V below your Absorption voltage of your MultiPlus and run that for a few days and report back. I'm not seeing any additional Amperage output benefit by leaving the settings where you have them now or any additional benefits that a higher voltage offers. In my opinion, it just overly stresses the battery unnecessarily. If you really feel the need to charge to 14.6V with a one hour absorption, just set up another profile in your MultiPlus and run it once a month, or better yet, once every three months.
If your SmartShunt and MultiPlus are both set to 14.6V, I'm wondering if your SmartShunt is even effectivly resetting and recalibrating to 100%. This is why it is recommended to change the charged current of the SmartShunt to .10V below your absorption voltage. It is stated many times on this forum in various locations.

 

[Sojourner1]

He may need 14.4v for balancing purposes but certainly wouldn't use 14.6v.

I was just reading some past Chins threads and didn't notice if individual cell voltage was able to be seen. Having the ability to see individual cell voltages helps if increasing charge voltage or abs time might be needed or required for some cell balancing. ?

 

[RVLiFe]

On a side note, I used to charge to 14.6V and hold them there until the tail current dropped to around 10 Amps. It used to take a good 30 minutes for this to happen. I could see the current drop rapidly as the battery was held at 14.6V. Now, even at 14.1V, the tail current drops to below 10 Amps within 10 minutes of hitting that voltage. When I do want to charge to 14.6V, the current going into the battery is well below 1Amp. So the point of the story is that the battery will change and it is normal. I feel that if I would have just kept the battery at a lower voltage and shorter absorption in the first place, it probably would have been more beneficial for the life of the battery but honestly, I haven't really lost any total Amp output even with the battery behaving differently or with the lower voltage settings that were recommended to me.

 

[RVLiFe]

He may need 14.4v for balancing purposes but certainly wouldn't use 14.6v.

I was just reading some past Chins threads and didn't notice if individual cell voltage was able to be seen. Having the ability to see individual cell voltages helps if increasing charge voltage or abs time might be needed or required for some cell balancing. ?

SOK recommends voltages between 14.2 and 14.6 for balancing purposes but honestly, is it really necessary to do it every single day and with every single full charge? Or is every few months going to get you there anyway. I haven't noticed any real or absolute difference in my batteries capacity by setting a lower voltage. SOK batteries states that they balance <14.4V. I would think that should state >14.4V but they still stand by their specs of <14.4V so maybe their proprietary BMS is different than everyone else's. Again, I don't think there is going to be any amperage gain by charging to 14.6V but I can see a benefit for balancing needs. Each battery is different and I still don't think its necessary every single charge cycle. Maybe someone has more experience and actual results about this. I just think it's natural to overthink all of this.

 

[pmartin696]

My recommendation, Drop your Absorption to 14.1-14.2V. Float voltage to 13.6-13.8V. Drop your absorption time to 15min - 30min(or even none). Check your 500A SmartShunt and change the Charged current to .10V below your Absorption voltage of your MultiPlus and run that for a few days and report back. I'm not seeing any additional Amperage output benefit by leaving the settings where you have them now or any additional benefits that a higher voltage offers. In my opinion, it just overly stresses the battery unnecessarily. If you really feel the need to charge to 14.6V with a one hour absorption, just set up another profile in your MultiPlus and run it once a month, or better yet, once every three months.
If your SmartShunt and MultiPlus are both set to 14.6V, I'm wondering if your SmartShunt is even effectivly resetting and recalibrating to 100%. This is why it is recommended to change the charged current of the SmartShunt to .10V below your absorption voltage. It is stated many times on this forum in various locations.

So last night I dropped my Absorption to 14.2V, Float to 13.6V and dropped the absorption times to the lowest allowed.. I also changed the smart Shunt to 14.1v. The system charged back up after restart, and then over the last 12 hours it slowly dropping. I'm assuming that when it gets to certain point it will then recharge again. Do I need to just wait for the system to recalibrate itself, or just see what it levels out at and then reset SOC to 100%

 

[Sojourner1]

It may take a few cycle for it to recalibrate the capacity, I'm not familiar with Victron equipment/ setting adjustments. Why in float are your batteries discharging. In float they should be at the voltage your settings are for float‽

 

[pmartin696]

It may take a few cycle for it to recalibrate the capacity, I'm not familiar with Victron equipment/ setting adjustments. Why in float are your batteries discharging. In float they should be at the voltage your settings are for float‽

Thats what I'm trying to figure out.. Is this normal? There is a 23W parasitic drain due to usage from the multiplus, Cerbo, Smart Shunt, and hotspot. But I thought at some point the Multi would kick back in to bring the SOC up... I guess I will just keep and eye out to see how low it drains...Right now there is no PV to charge... Just relying on the Multiplus till I can get it installed.

 

[Sojourner1]

If it's "floating" the batteries voltage will be what the float voltage is set for and the loads covered by the charger.

Example: my SCC float is 13.6v , so after solar charges the bank to 14.1v (my absorb) it switches over to float at that point batteries stay at 13.6v while the sun is out or the loads are less than what the scc can cover.

 

[Sojourner1]

I quickly glanced at the manual do you have it set to "storage mode".

From the manual....
Less maintenance and aging when the battery is not in use: the Storage mode The Storage mode kicks in whenever the battery has not been subjected to discharge during 24 hours. In the Storage mode float voltage is reduced to 2.2V/cell (13.2V for 12V battery) to minimise gassing and corrosion of the positive plates. Once a week the voltage is raised back to the absorption level to ‘equalize’ the battery. This feature prevents stratification of the electrolyte and sulphation, a major cause of early battery failure.

Also Section 5.1
On delivery, the MultiPlus-II is set to standard factory values. In general, these settings are suitable for single-unit operation. Float is 13.2v which is what you're showing.

 

[pmartin696]

I quickly glanced at the manual do you have it set to "storage mode".

From the manual....
Less maintenance and aging when the battery is not in use: the Storage mode The Storage mode kicks in whenever the battery has not been subjected to discharge during 24 hours. In the Storage mode float voltage is reduced to 2.2V/cell (13.2V for 12V battery) to minimise gassing and corrosion of the positive plates. Once a week the voltage is raised back to the absorption level to ‘equalize’ the battery. This feature prevents stratification of the electrolyte and sulphation, a major cause of early battery failure.

Wow thanks for going the extra mile and looking that up!! I wonder if that is really needed in LIPO battery situations as sulphation is not a issue?

 

[Sojourner1]

I added to that post. Look at section 5.1

 

[Sojourner1]

Is there a remote the system or how do you make adjustments?

 

[pmartin696]

This is RV mounted. I can get results remote using Cerbos GX... Most settings must be adjusted local with a USB dongle.

 

[pmartin696]

Wow thanks for going the extra mile and looking that up!! I wonder if that is really needed in LIPO battery situations as sulphation is not a issue?

I quickly glanced at the manual do you have it set to "storage mode".

From the manual....
Less maintenance and aging when the battery is not in use: the Storage mode The Storage mode kicks in whenever the battery has not been subjected to discharge during 24 hours. In the Storage mode float voltage is reduced to 2.2V/cell (13.2V for 12V battery) to minimise gassing and corrosion of the positive plates. Once a week the voltage is raised back to the absorption level to ‘equalize’ the battery. This feature prevents stratification of the electrolyte and sulphation, a major cause of early battery failure.

Also Section 5.1
On delivery, the MultiPlus-II is set to standard factory values. In general, these settings are suitable for single-unit operation. Float is 13.2v which is what you're showing.

I did look at this more and I don't think I am in storage mode as this is specific to lead acid batteries. My voltage is now down to 13.17v. I'm going to let it go and see when the charger kicks in.

 

[sunshine_eggo]

When lithium is selected, storage mode is disabled and temperature compensation is disabled, and depending on firmware, low temp charge protection is enabled.

Why is weak AC input selected?

 

[pmartin696]

When lithium is selected, storage mode is disabled and temperature compensation is disabled, and depending on firmware, low temp charge protection is enabled.

Why is weak AC input selected?

I selected it because I have a Inverter generator that I may need occasionally..Would it be better to uncheck and then just check when I need to use the Generator? What changes does it have when using just regular shore power?

 

[pmartin696]

Today its down to 13.07V & 77.8% state of charge.. I used a bit of DC last night to get it over 200W of DC usage thinking the charger would go back into bulk, but it didn't. Im sure its something I've set incorrectly, but not certain what it is yet..

 

[sunshine_eggo]

Review and change to the following:




You can leave battery monitor enabled if you're using it.

Do you actually have the external current sensor?








Do you have DVCC enabled in the GX?

Enable all VRM VE.Bus options and look for anomalies:

 

[pmartin696]

I figured it out and it’s entirely my fault! It was the VE. Bus Smart dongle. As soon as I unplugged the dongle it went into bulk charge. I think it’s because I took a shortcut and attached the positive and negative terminals of the dongle directly to the open bolts on the DC terminals on the multiplus instead of to the battery or bus bar and either it was reading the voltage that it was sending to maintain the coach DC system, or not taking into account resistance of path to the batteries. Anyway, it’s now floating at 100% correctly. I thought I had it set to read it’s settings from the smart shunt, but apparently it wasn’t or was overriding. Thanks for all the help!

 

[sunshine_eggo]

Glad to hear it.

Per my previous post, do you have DVCC enabled in the GX? That's where you identify shared voltage and temperature sources.