Problems with Charge controller (?)

[RACarvalho]

Hello!

I'm trying to figure out if I have a problem with my charge controller.

The battery voltage on the control panel is never the same as the Victron battery monitor shows while charging and the charge controller (55A) never delivers anything above ~15A and ~13.1 V.....

I know the battery monitor is working properly because when the batteries are being charged by the engine alternator or the solar panel I see voltages above 14V and higher charging currents.....

Below you have screenshots of the battery monitor and control panel that where taken at the same time showing different battery voltages (and low charging current) and a screen shot showing that , at a different day, the engine alternator was delivering really good charging current /voltage to the batteries...

Questions are:
1 - Why the charge controller doesn't increase the voltage and delivers more current?
2 - Why there is a divergency in voltage reading between the control panel and the battery monitor?
3 - Is the charge controller faulty?
4 - Will this low voltage charging damage my AGMs?

Thank you for any info!!!

[Chateau_Nomad]

Use a current clamp (clamping ammeter) to read actual current in amps being delivered by the solar panels to the charge controller. Then use a voltmeter to read the voltage.

[RACarvalho]

Originally Posted by Chateau_Nomad

Use a current clamp (clamping ammeter) to read actual current in amps being delivered by the solar panels to the charge controller. Then use a voltmeter to read the voltage.

The installed Victron 712 battery monitor have a shunt in the negative battery cable and measure exactly what is getting in/out of the battery and since it is connected directly to the battery, it also measures the voltage there.

The solar in fact is irrelevant for battery charging because it is only a 100W solar panel but it's charge controller always gets the voltage above 14V when charging which, I understand, is the right voltage for AGMs ...

My main concern is the converter/charger not charging at the right voltage and damaging the batteries

[16ACE27]

Originally Posted by RACarvalho

Hello!

I'm trying to figure out if I have a problem with my charge controller.

The battery voltage on the control panel is never the same as the Victron battery monitor shows while charging and the charge controller (55A) never delivers anything above ~15A and ~13.1 V.....

I know the battery monitor is working properly because when the batteries are being charged by the engine alternator or the solar panel I see voltages above 14V and higher charging currents.....

Below you have screenshots of the battery monitor and control panel that where taken at the same time showing different battery voltages (and low charging current) and a screen shot showing that , at a different day, the engine alternator was delivering really good charging current /voltage to the batteries...

Questions are:
1 - Why the charge controller doesn't increase the voltage and delivers more current?
2 - Why there is a divergency in voltage reading between the control panel and the battery monitor?
3 - Is the charge controller faulty?
4 - Will this low voltage charging damage my AGMs?

Thank you for any info!!!

I assume when you say "charge controller" you are referring to your converter/charger?

You have multiple "issues":

Resolve you different voltage readings with a good voltmeter directly on the battery terminals to determine which is right and which direction to troubleshoot.

Your converter is a "smart" multistage charger. It will charge your batteries at:
14..3 - 14.6 VDC when the batteries are low and need to be BULK CHARGED.
as the current draw diminishes the charger will go into ABSORBTION mode at 13.5 - 13.7 VDC. As the battery "fills up" and current draw approaches 0 amps the charger will shift to:
FLOAT MODE at 13.0 - 13.2 VDC to keep it fully charged.

Your alternator has more on its plate than just the house batteries. It wants to put out 14.4 - 14.6 VDC as soon as it comes on line to replenish the chassis battery draw-down when starting. Due to other chassis loads you have to run the engine a long time before it shifts into "float" voltage at 14.1 - 14.2 VDC. Since the house batteries are in parallel with the chassis battery they will always read the same voltage unless the BIRD/BIM disconnects them.

Your solar charger is an "opportunistic" charger so unless your house batteries are 100% charged it will keep the charge voltage high to put as much into the house batteries as it can if the sun is available for charging.

So is your converter working correctly?

Test it by disconnecting the solar controller, unplug from SP and don't run the engine. Drain the house batteries to 50% - 60% by the static voltage chart.
Then plug into SP and let the charger do its thing. You should see all 3 stages as it charges the house batteries back to 100%.

Realize the converter's analysis of the state of charge of the house batteries can be warped by the presence of other chargers. Not a big deal as long as the batteries are getting charged. I can't see any reason your AGM batteries would become damaged if charged at a lower voltage/rate than their optimal voltage/rate.

[RACarvalho]

Originally Posted by 16ACE27

I assume when you say "charge controller" you are referring to your converter/charger?

You have multiple "issues":

Resolve you different voltage readings with a good voltmeter ...

Your converter is a "smart" multistage charger. It will charge your batteries at:
14..3 - 14.6 VDC ....

Your alternator has more on its plate than just the house batteries. It wants to put out 14.4 - 14.6 VDC as soon as it comes on line to replenish the chassis battery draw-down when starting. Due to other chassis loads you have to run the engine a long time before it shifts into "float" voltage at 14.1 - 14.2 VDC. Since the house batteries are in parallel with the chassis battery they will always read the same voltage unless the BIRD/BIM disconnects them.

Your solar charger is an "opportunistic" charger ....

So is your converter working correctly?

Test it ....

Thank you ACE,
Yes, I'm talking about the converter/charger.

I know all the above and have tested in the past with a voltimeter directely on the battery and it validated the Victron, not the Firefly display voltage...

The two first pictures I posted show the state of charge of the battery bank and that is the test - I discharged the batteries to that point and then plugged into shore power to see how the charger would react, the picture below is the 13h charging profile since I plugged into shore power...
Nothing smart about those curves other than the three deeps that, I assume, is the BIM connecting to allow current to go to chassis battery.
The battery bank is 330AH total, and at that discharged state and being AGMs, I was expecting the "smart" converter/charger to bump voltage to 14.4V and way higher current that is shown on the battery monitor...
The solar is "disconnected" because the MH is under its cover...

[RACarvalho]

Ok, I just finally read the WFCO 9800 series converter manual and I think it is completely inadequate to charge AGMs....
I'm looking at another converter/charger, what you guys think of Progressive Dynamics PD9200 series?
Is there anything from Victron that I could use in the prace of my WFCO 9855?

Thank you!

[Geterdun]

Originally Posted by RACarvalho

Ok, I just finally read the WFCO 9800 series converter manual and I think it is completely inadequate to charge AGMs....
I'm looking at another converter/charger, what you guys think of Progressive Dynamics PD9200 series?
Is there anything from Victron that I could use in the prace of my WFCO 9855?

Thank you!

How did you come to that conclusion? The WFCO 9800 specificall lists battery types as LA/AGM in their specifications and the charging profile for AGM is almost exactly what the charging profile is for FLA batteries as they use the SAME CHEMISTRY.

But it's your money to throw away......

[Scubawise]

Originally Posted by Geterdun

How did you come to that conclusion? The WFCO 9800 specificall lists battery types as LA/AGM in their specifications and the charging profile for AGM is almost exactly what the charging profile is for FLA batteries as they use the SAME CHEMISTRY.

But it's your money to throw away......

Agree no original converter change and AGM Fine

[RACarvalho]

Originally Posted by Geterdun

How did you come to that conclusion? The WFCO 9800 specificall lists battery types as LA/AGM in their specifications and the charging profile for AGM is almost exactly what the charging profile is for FLA batteries as they use the SAME CHEMISTRY.

But it's your money to throw away......

According to WFCO it will only bump the voltage to 14.4V if the battery is completely depleted, which seems to validate my observations:
Since I never let my battery bank goes below 50% SOC, the converter/charger never goes to 14.4V, never goes to bulk charge.

It happens to be that VMAx tank clearly warns charging below the specified 15A will reduce the life of the batteries.
I have 3 batteries so I should be seeing 45A charging....


I'm also suspecting that charging at lower than 14.4V leads to these batteries never getting fully charged, what would explain why I was never able to get the Ah I was expecting before voltage drops too low.

[Geterdun]

Originally Posted by RACarvalho

According to WFCO it will only bump the voltage to 14.4V if the battery is completely depleted, which seems to validate my observations:
Since I never let my battery bank goes below 50% SOC, the converter/charger never goes to 14.4V, never goes to bulk charge.

It happens to be that VMAx tank clearly warns charging below the specified 15A will reduce the life of the batteries.
I have 3 batteries so I should be seeing 45A charging....


I'm also suspecting that charging at lower than 14.4V leads to these batteries never getting fully charged, what would explain why I was never able to get the Ah I was expecting before voltage drops too low.

Batteries don't require Bulk Charging unless they are depleted, and no, the battery does not have to be "completely deleted" for the converter to shift into Bulk Charging mode:

The converter normally provides a constant target output voltage of 13.6 volts (nominal) to power all the branch circuits. However, it is current limited, and if the output (load) current reaches its maximum, the output voltage will drop as necessary to hold the converter’s maximum output current level (the amperage rating) without exceeding it.
If the output current reaches its maximum (normally caused by a discharged battery), this will cause the converter to go into Bulk Mode, which means the target output voltage will change
to 14.4 volts and a timer will start. Although the converter is outputting 14.4 volts, you will not be able to read that on a voltmeter due to the voltage-current relationship. From the paragraph above, as load current increases, output voltage decreases. The actual output voltage will not rise
until the load is reduced, which happens naturally as the battery charges or if 12-volt appliances are turned off.
Bulk Mode will be maintained until the current draw drops to approximately five amps, or until the timer reaches four hours (whichever happens first). Then the target output voltage is changed back to 13.6 volts for Absorption Mode. Lights that are powered from the output may change brightness slightly at that time.
After the output has been maintained at 13.6 volts (Absorption Mode) for 44 hours, the converter will change to Float Mode with an output of 13.2 volts. This output may then reset to Absorption Mode (13.6 volts) if power is interrupted, or to Bulk Mode (14.4 volts) if the output current limit is reached.

You will find the same or similar algorithm in all RV Converters. The only way you will be able to charge your house batteries the way you want is to buy a stand-alone charger and charge the batteries when they are isolated from the DC buss.

[RACarvalho]

Originally Posted by Geterdun

Batteries don't require Bulk Charging unless they are depleted, and no, the battery does not have to be "completely deleted" for the converter to shift into Bulk Charging mode:



You will find the same or similar algorithm in all RV Converters. The only way you will be able to charge your house batteries the way you want is to buy a stand-alone charger and charge the batteries when they are isolated from the DC buss.

Yes, I know the text above from WFCO but what happens when the BATTERY MANUFACTURER specifies that the charging voltage should be between 14.4V and 14.9V ????
https://www.vmaxtanks.com/XTR27-110-...ery_p_175.html
The only thing I have seeing so far from the converter is float voltage....
The converter is using float voltage/amperage to charge 50% of the battery bank....
Not only takes forever to charge but if i'm reading that webpage right, it is probably damaging the batteries in doing so....

[Scubawise]

Is your converter bad?

https://www.doityourselfrv.com/how-t...m_medium=email

[Geterdun]

Originally Posted by RACarvalho

Yes, I know the text above from WFCO but what happens when the BATTERY MANUFACTURER specifies that the charging voltage should be between 14.4V and 14.9V ????
https://www.vmaxtanks.com/XTR27-110-...ery_p_175.html
The only thing I have seeing so far from the converter is float voltage....
The converter is using float voltage/amperage to charge 50% of the battery bank....
Not only takes forever to charge but if i'm reading that webpage right, it is probably damaging the batteries in doing so....

Read the whole page instead of selective reading

[RACarvalho]

Ok, another trip and more data...

The 1 year / 4 months old 330ah battery bank failed again during last two weeks overnights. It failed in every overnight. I can't get more than 17Ah from them.

The BIM is doing its job linking the batteries during travel for 1h and disconnecting for ~25min. then connecting again, etc.
The solar panel is charging whatever it can put out (never more than 40W tough)
But the converter never puts more than 10A of charging and never above 13.66V so I think the batteries never get fully charged and that is the reason the battery bank goes to 11V only 1h into the overnight under a 13a load....

During overnight, we almost never see above 150W of power draw so 330Ah (or half of it) should be enough to get us through the night w/o problems but batteries are dead within 1h to the point I cant start the generator and so I have to start the engine, then the generator...

Even in that situation (dead battery) the converter doesn't charge more than 10 amps.... on a 3 battery bank that is less than 4 amps per battery and since VMax says the charging current needs to be 10amps or above (30 amps for 3 batteries in parallel (?)) and never goes above 13.66V when VMax says it should be above 14.4V I'm thinking the converter damaged my batteries... is it possible?

Arriving at home I disconnected the batteries from the MH and put it on a 20A charger and the batteries accepted the full 20a and it took 4 hours to fully charge the batteries with voltages reaching 14.69V....
This bank of batteries is failing with 1 1/2 years, the same amount of time the original bank failed , even tough it costs 3x more and is 50% bigger....

When these batteries where new, I would not see voltage below 12.8V even when loads where above 500W, almost 40ah of load....

What do you guys think?

Do I have a bad converter?
Why a 55A converter doesn't charge above 10A even on dead batteries?
Why none of the 3 charging sources (converter, alternator and solar controller) are bumping the voltage above 13.66V, only the external charger?
Can these different sources be interfering with each other?
Should I buy another converter?
Should I add a dedicated battery charger that will charge the house batteries at the right voltage and amps?

Any input is highly appreciated .

Tks

[javelin]

Well I am not a battery expert, but I think AGM batteries do not like fast charging, especially on the bulk phase of the re-charge. I “think” your WFCO charger is probably just limiting the bulk charge current level on purpose so as not to overheat your AGM batteries (damaging them potentially). Low and slow bulk cycle on AGM vs fast and high current bulk cycle on wet cell. If you had wet cell batteries and your charger was set for that type of battery, then you should see a much higher bulk charge current (for discharged batteries). If in doubt call the manufacturer and verify what the charger should be putting out for AGM at specific states of charge.

[RACarvalho]

Originally Posted by javelin

... I think AGM batteries do not like fast charging...

I understand that but this is a bank of 3 batteries with stated capacity (20h) of 110ah each so even my 20A charging "test" is still a rate of charge of only ~6.3ah (6% of capacity) on each individual battery while the manufacturer states that minimum charging current should be 10a.... (30a for the three batteries)....
I suspect that by charging at a too low of a current the converter may have damaged the batteries...
I'm running another test right now to confirm that....

[RACarvalho]

Ok, just finished another test and I think my batteries are toast...

The test:
Background:
MH is disconnected from shore power.
Batteries where fully charged and (external) charger showing "float"mode at 14.33V
Assuming 12.05V is 50% SOC

Test:
I added ~23a of load and monitored the voltage.

Results:
The picture below confirms what we felt on the road:
The batteries can only provide 17ah before voltage falls below 12V.
Before that, the voltage stayed at 12.8V for most of the time but as the batteries reached 16.5ah the voltage started to drop really fast.

Conclusion:
Despite the fact that the batteries are rated at 110ah (330ah total) at 5ah (15ah total) rate of discharge and I'm running at 23ah rate of discharge, 17ah is only 5% of the stated 330ah original so the batteries are probably toast.

Questions:
1 - Is it possible AMGs develop memory effect? If yes, is there a way to "erase" this?
2 - Second set that failed, probably for the same reason, before I buy another set of batteries, what should I do/check/change in order this $$$ problem doesn't happen again?

[Chateau_Nomad]

Well if cash isn't an issue, stick in a Victron MultiPlus... then adjust the charge amperage to what yo see fit.

My Sungoldpower 3k inverter/charger works exactly the same way... I "could" crank it up to 90 amps... hint: a 100watt solar panel is not going to give you much more than an effective trickle charge. So I'm assuming you're plugged in when not driving?

[Beau388]

Originally Posted by RACarvalho

I understand that but this is a bank of 3 batteries with stated capacity (20h) of 110ah each so even my 20A charging "test" is still a rate of charge of only ~6.3ah (6% of capacity) on each individual battery while the manufacturer states that minimum charging current should be 10a.... (30a for the three batteries)....
I suspect that by charging at a too low of a current the converter may have damaged the batteries...
I'm running another test right now to confirm that....

Your are correct. The max charging current for AGMs is 8% to 13% of the Amp-h capacity of the battery bank; i.e. 4 100 amp-h batteries should only be charged at 32 to 52 amps maximum for battery longevity. Check the Optima, Lifeline or Trojan sites for statement accuracy.
In AGM cells lead paste on the grid has to receive hydrogen ions from the sulfate through the acid paste and glass insulate. This is a slow process. In a liquid cell the movement is much faster and the hydrogen Ions only have to move through a porous glass separator. The absorption stage is where the hydrogen ions reunite with the oxygen atoms in the lead oxide paste forming water. If you rush the process, you out-gas hydrogen gas through the pressure relief valve on the AGM battery gradually reducing the batteries discharging ability.

[RACarvalho]

Originally Posted by Chateau_Nomad

Well if cash isn't an issue, stick in a Victron MultiPlus... then adjust the charge amperage to what yo see fit.

My Sungoldpower 3k inverter/charger works exactly the same way... I "could" crank it up to 90 amps... hint: a 100watt solar panel is not going to give you much more than an effective trickle charge. So I'm assuming you're plugged in when not driving?

Cash is almost always in short supply so I would say it is a problem but so is to pay $900 for a battery bank that only lasts 18 months...

I know Victron and their inverter/charger products from my previous boating life but I don't see how I would add that to the system w/o a major change in the MH system.
I was thinking on adding a Victron Phoenix Smart Charger getting power from the Converter entrance and delivering it strait to the batteries, so it would be in parallel, but I'm not sure this is the correct/safe way to do it.

Before I buy new batteries I want to fix what caused these batteries to go bad.
We are always in shore power except when in transit and the walmart overnights ( 3 overnights during last two weeks) so these batteries where not supposed to go bad as fast as they did...