Battery Over Charge voltages and Controller

[Bluwavguy]

Ok, so I've logged an hours worth of data from the Victron BVM and Solar Controller Monitor with the following results. Only when I got into the 45min time frame, that's after loading up the batteries with no solar, then connecting the solar, did I notice high voltages...SOC never changed and Charge Controller was in Charge Mode the entire time...

Been running my inverter the past 20 min while I am writing this and no high voltages but the SOC dropped down to 96.6 and current usage is -3.5A...so while the system is loaded I'm not receiving the high-voltages...it took 45 min for the high voltages to appear as I was running my inverter (since I can hear the fan rpms increase then I check the BVM) as I noticed high voltages in time periods 10-13....and again this is a brief voltage spike to as high as 16.4vdc is for a few seconds then voltages revert back down to 13.7 range....

At least the controller held a constant 13.96

well, I thought I had 15 measures noted vs the 13...

So my assumption the high voltages occur from the float state to the bulk state is moot....so I'm stumped unless the sulfation issue is appearing randomly....then goes away...

BVM	1	2	3	4	5	6	7	8	9	10	11	12	13
SOC	96.7	96.7	96.7	96.7	96.7	96.7	96.7	96.7	96.7	96.7	96.7	96.7	96.7
Batt VDC	13.6	13.66	13.5	13.66	13.53	13.69	13.8	13.8	13.86	15.4	13.6	13.9	13.96
Monitor
VDC	13.6	13.76	13.6	13.6	13.96	13.96	13.96	13.96	13.96	13.96	13.96	13.96	13.96
AH	0.1	1.2	1.9	2.6	3.2	3.9	4.5	5	5.7	6.1	6.6	7.1	7.5
Solar
Amps	10.2	9.84	10.5	4.1	6.1	6.8	5.81	4.8	10.6	4.8	6.9	3.8	2.67
AH	0.1	1.2	2	2.6	3.3	4	4.6	5.3	5.9	6.4	6.9	7.4	7.8

[Sunking]

It is impossible to take your batteries from 13 volts to 16 volts in minutes unless the batteries are bad, or you have hundreds of amps available from the charger. Ignore all voltages and read directly from the Battery Term Post.

[littleharbor]

Your DVM is only reliable when programed properly. As batteries age and lose capacity the accuracy fades unless updated with accurate battery capacity. BUT.... As Sunking says and I asked, can you take the voltage reading at the battery terminals with a known good meter?

[Bluwavguy]

Good morning Gents, my main source for information is a Victron 602S BVM (and was on the line with them yesterday, the guy has heard of random voltage spikes before), at my switchboard. At the controller monitor, mounted in my aft compartment, provides Solar (A and AH) and Battery (VDC,AH) stats. I used my DVM as a backup and also to conform solar VDC input to the controller.

When I have time I'll pull cables off the battery terminals one at a time. I need to keep my boat running so I won't pull all leads.

I did a lot of research and I'm still not convinced I have a sulfation issue. No where could I find info on sulfation causing voltage spikes during charge cycle.
Most all sulfation is related to lead acids (including AGMs) but when left in an uncharged state for prolonged periods of time and also when drained below 80% or more SOC. This is why some chargers have an equalization mode for flooded batteries. Not for AGMs. The Morningstar controller has two modes: Flooded and Sealed. Mine is set to Sealed and also to PWM mode.

The key for me is:

1) What is causing the high voltage run ups (since I am limited to having the same solar controller is the issue with it?) As mentioned yesterday, I was runnng wind generator all AM until about 2PM. It's controller auto brakes to prevent over charge and did so several time thoughout the day. (Unfortunately I cannot get specs from the Co besides the 14.2 charge setting). Not at any time did I observe high voltage spikes while this was my only charge source.

2) How much remaining capacity the 3 105ah batteries have left in them. They are not toasted but diminished and maybe at the end of their life cycle.

Shortly I'll receive from Victron and PC link to the BVM so I can data log the state of my house bank.

I also did research on 6VDC vs 12VDC batteries on the sailing forums....as we have space limits and no real means to lift heavy loads in and out of boats. So far I cannot find a single reason to switch to 6VDC to 12VDC given my load requirements. I can see the 6VDC use on larger vessels and those living off grid. In the early 80's I managed 24 6VDC battery bank on a naval warship as a backup source for our ship nav gyro. In my 4.5 years attached to this vessel I never had to replace a single one so I understand their utility and when well maintained.

For any remaining posts from those who may be interested. Please be specific with qualitative and quantitative responses vs impossible, toast, etc. As a naval engineer, two degrees in engineering, owner of multiple boats, multiple play toys, single engine pilot, captain of my boats I take a lot of pride in helping others solve problems. Never with one line answers unless I don't care or they are wasting my time....

[Sunking]

Good morning Gents, my main source for information is a Victron 602S BVM (and was on the line with them yesterday, the guy has heard of random voltage spikes before), at my switchboard. At the controller monitor, mounted in my aft compartment, provides Solar (A and AH) and Battery (VDC,AH) stats. I used my DVM as a backup and also to conform solar VDC input to the controller.

Quit using your victron for any useful information. It is completely bogus information. The only way to know what is going on is to use a known good DVM. Take voltage measurements right on the Battery Term Post. Additionally you can measure the voltage on the Controllers Output Terminals. If you see 16 volts at the Controller Output and 13 volts on the BatteryTerminals; guess what? You gotta a wiring problem.

I did a lot of research and I'm still not convinced I have a sulfation issue. No where could I find info on sulfation causing voltage spikes during charge cycle.
Most all sulfation is related to lead acids (including AGMs) but when left in an uncharged state for prolonged periods of time and also when drained below 80% or more SOC.

Then you did not do enough research or understand the information being presented to you. The voltage of a battery being charged is Voltage = Battery OCV + [Ri x Charge Current]

Battery OCV is battery open circuit voltage on a rested battery. example at 80% SOC is roughly 12.4 volts. Ri is the battery internal resistance. On a 12 volt AGM you would expect Ri to be around .006 Ohms. Charge current is straightforward, lets say 20 amps for a 280 watt panel. So 12.4 volts + [.006 Ohms x 20 amps] = 12.52 volts. Assuming the battery is healthy with Ri = .006 Ohms to take that same battery to 16 volts would require 16 volts - 12.4 volts / .006 Ohms = 600 AMPS of charge current. Impossible from a 280 watt 20 amp charger.

However sulfation significantly increases battery internal resistance. If the battery Ri were now say .18 Ohms with a OCV = 12.4 volts and 20 amps of charge current applied the voltage would be 12.4 volts x [.18 Ohms x 20 amps] = 16 volts. Your charge would be fooled into think the battery is charged up and reduce voltage to 13.8 volts indication Float Voltage on a fully charged battery. That is what sulfation does, it make th ebattery internal resistance high, thus the battery cannot take or give a charge.

Now having said all that, I do no tthink your batteries are completely shot because you say you can disconnect all charge sources, and the batteries can still provide power to your loads for a significant amount of time. That is how you test a battery. You put a heavy load on it and monitor the voltage. It is called a LOAD TEST. Put a 20 amp load on them and the voltage should hold. If it dips or crashes, the battery is bad dead.

Me thinks you have either a wiring problem, or you are relying on your Victron BVM which is worthless leading you on a ghost chase. Get a DVM out and see what is going on. Until you do that you are chasing ghost.

So please quit wasting your time and more importantly my time repeating myself, and get a DVM out and find the problem. You wil know exactly what is wrong in 5 minutes.

[LETitROLL]

The key clue i am seeing is the only time(s) you have high voltage, it only lasts a couple of seconds, that leads me to believe that current flow is decreasing from either a load, or the controller switching modes, and it is taking the controller a moment to stabilize and balance the voltage from the sudden change. I doubt you have any significant current flow at those times of high voltage, your meter is just reporting potential,

[Bluwavguy]

Solarking and LetitRoll, thank you both. I plan to isolate the batteries today and to see if I can determine if one of them is going bad and causing the ghost affect of the sporatic high voltages. Somewhere I read about capacitance affects in some batteries with age...If so, then, as I would assume all batteries should be replaced.

[Bluwavguy]

Gents,

I had to put off my battery issue reseach due to another boat problem thats been finally resolved. In the mean time I had Victron send me out a new unit and USB connect cable so I can log directly the actual events. Now that my Victron BVM has a working alarm I can audibly hear the high voltage alarm which only has been occurring (at least the past two days) with the Morningstar charge controller connected and while in float (the LED indicates its in float/boost/equalize status).

If I use only wind and it's built-in charge controller, which I have only it's nominal charge voltage of 14.2Vdc and no other info on the charge controller, the high voltage alarm does not sound (currently set at 15.5Vdc). I have since installed a in-line digital meter for the wind generator to monitor it's activities but sense my issues are either the Morningstar controller or Batteries or a combination of both.

Before I decide to invest in a new set of batteries think I'll look into fully integrated charge controller system that provides a direct interface to extract logging information. Ideally, it would be nice to see if there are means to monitor individual batteries while connected in series....have not looked into this but would assume a simple device (ie high-resistant shunt) tapped off of each battery to its own sender to a analog-digital-logger would be a ideal solution for a whole lot of people....

Will post once I get back into the details and isolation of batteries (need to travel so this will wait for at least a week).

Brian

[Sunking]

Brian I think you are making this more complicated than it need be. Batteries are super simple to test. The simplest test is the most revealing test, a simple Load Test every shade tree mechanic uses to test a battery.

All it takes is a Volt Meter and a Load. You take the battery and measure the voltage of the battery with heavy load on it. If voltage holds, the battery is good, if the voltage crashes, the battery goes to the trash.

The classic symptom of a bad battery is you put it on a Charger, and the battery quickly indicates it is full charged up because the voltage shoots up quickly and full the charger into think the battery is charged. You will see a good charge voltage on the battery. Now put a load on the battery, and the voltage crashes. From what I am ascertaining here is that is what you are seeing.

So take each battery, connect it to say a Inverter, and connect a good heft load on the Inverter and watch what the battery voltage does. You may very well have a bad MS Controller. But I suspect it is your battery. A bad battery has high resistance, and when connected to a charger will make the charger seem faulty. As soon as the charger pumps current into the battery, the voltage spikes. Only what that can happen is if the battery resistances is to high. A battery with high resistance cannot accept a charge, nor give off a charge.

Here is what a mechanic would use. A simple 100 amp load with a volt meter. You need to mimic that type of test using what you have. The meter you see here is just a volt meter on a chart with a 100 amp load resistor at 12 volts. You can make your own with car head lights, or regular light plugged into an inverter like a 100 watt light bulb.