Well it appears another lesson learned. My dash voltmeter was wavering today between 12.9 or so and somewhere around 11.2. My digital add on showed 12.6 to 14.2. With drops to 12.3 when brakes and or signals were used. For sometime I thought it, the dash, just read low but today I saw it moving back and forth and the digital move up to 14 when it moved.
So now I am thinking this will not end well. Having read the Forum about alternators, sensing wires, batteries and isolators in the past I developed my preferred explanation. The solar panel was keeping the battery charged and the sensing wire was telling the alternator to stop charging when it read 12.6. Couldn't be the isolator as it is now a switch. The batteries were load tested before departure.
As fate would have it I decided I might need to have it checked so I wasn't left on the side of the road. So I looked down the road and saw a sign for Tennessee RV. Got off on the ramp parked on the side street and went into the service desk. I thought this might be the same Tennessee RV I have heard about on the Forum. Yup same one. They validated what was probably happening and the only breakdown was in my confidence. Great to find such a welcoming shop within a days drive of home.
I'll follow this thread to see why an alternator would let a battery go to 12.6 I thought float was around 13.2 and alternators always pumped out 14.2.
I think it would go to 14.2 and receive and quickly back off leaving the battery at 12.6 and continuing down with the solar maintaing the charge. 13.2 did appear but I could not watch it close enough in heavy traffic to tell you how long.
Not sure I understand. I have solar and my alternator charging rate is ALWAYS 14.2 at the gauge.
Interesting. Not sure why both the solar controller and the alternator would show 12.6. It is currently at 12.8. We have been camped since 4 and it is a little over an hour since sundown.
At home we always had 13.2 or 14.2 on them during the solar day. But there was no higher running draw.
Where it me I would dig a bit deeper. Like Twig I have solar and running down the road my gauge showes 14.1 as does the VMSPEC.
X3 on what Twig and Bruce said. When you are driving, the charging source putting out the highest voltage "wins" and the other sources (like your solar panels) become secondary. The alternator is usually going to be dominate and will normally be putting over 14 volts into the batteries. My digital volt meters always show over 14 volts in both battery banks while we are driving. The batteries don't care where the charging voltage originates - they will accept the charge until they are "full" and at that time it doesn't matter how many charging sources are active, because all they are doing is "maintaining" the fully charged batteries.
I'm guessing your dash volt meter is giving erroneous readings.
Could this be a voltage regulator issue?
George,
I would recommend a systematic investigation of your charging system. Start at the alternator - see what it is putting out at idle. Then check the voltage at the "switch" that replaced your isolator. Then check voltage at the POS posts on your batteries - see what you've got there. After that, you will have a good idea what the volt meters on your dash should be reading.
Note: You will have a small loss in voltage reading from your batteries to your dash meters, due to the long wire runs.
Thanks Chuck...good morning project.
Don't forget. This is a dual charge system. DUVAC. So even though the start battery will show full charge to the alternator, it will still juice up the house batteries. I hate to ask it.....but have you had alternator work done?
Nevermind. You said the isolator was removed.
I went to a switch because of the dual system. Wanted to isolate the lithium from the older system. The alternator is three years old.
I'm thinking one of your 12v batteries could be bad.
As you can see, there are a lot of "could bees". You need to grab your digital voltmeter and troubleshoot it.
If you need the "how to", let us know.
Thanks Brett et al. Set out to check and the coach almost failed to start. Very slow turnover that I have not experienced before. When it did start dash voltmeter went to 14 and digital to 14.1 and stayed there as we moved to another site. Solar was not a player as we were in the shade.
Had slower than normal starts as we left home but block heater was used after that.. We must have done the load tests wrong three weeks ago. The Optimas are three years old but have never been run flat. Not experienced enough to figure out other reason for failure but will take them in for testing. If one is bad, intend to replace with 8d AGM.
Fascinated with this and will run all the system as Chuck suggested and make sure I am not throwing parts this time. Thanks and will update my discoveries.
Make sure all of your battery connections are clean and tight. First thing to check are sense and excite wires. It is common for the crimp on connections at this age to fatigue and make poor connections and then fail. Start with the easy stuff. 14.1 volts is good. If your start batteries are discharged it can take many hours to fully recharge them.
George,
What means do you have to charge your chassis battery from shore power?
Or only solar? And if solar, is solar to house and/or chassis bank?
George,
Man Oh Man! If the Optimas tested well recently, that points to a more difficult to find poor connection or cable (internal) compromise somewhere. And that compromise could be in many different places within your AM Solar System as well as within your Alternator/Battery charging circuits. Because your starting is lethargic and your voltages aren't unreasonable, it appears that heavy duty charging current and heavy duty load current paths should have your troubleshooting priority. By the way, in my experience, a single 8D AGM gives less starting "oomph" than two Optima Red Tops in actual practice.
Before your post this morning, I felt that the electrical and electronic explanations for what you were seeing were simple and straightforward - and found all of the other "Expert" Advice priceless! Now (??)
I can't pretend to understand what the integration of your present system electrical configuration is, but your dash, digital, and Victron indications are pretty clear:
From what you have described (of course, I don't even know for sure if you have two or three battery banks with your new lithiums, nor do I know how your isolator replacement switches are configured, or their positions during the readings/behavior that you have noted)
BUT, during the daytime, "running down the road condition," your solar system and Victron controller are providing an output voltage higher than what the alternator output voltage regulator wants to achieve. The Victron controller output voltage is felt on the chassis battery bank (+) terminals, right where the alternator sensing line senses it's voltage.
Steady state, the chassis battery bank, being nearly fully charged, appears to have a current draw that is low enough that the solar panels can provide the needed current. Thus, the alternator stops charging. Now, when you add on loads through flashers, brakes or turn signals, the chassis battery bank current draw increases to more demand than what the solar panels can provide and (I assume) the Victron voltage to droop, which causes the Alternator, through its sensing wire, to see a bank voltage that is lower than its setpoint and the alternator starts charging again. The "flopping around" of dash and digital indications all come from the differences in the various indicator's sensing points and the changing of loads that are causing two sources of battery bank charging current to fight one another.
The "proof in the pudding" is that your chassis battery bank, at the end of the day, reads the same 12.6 volts on the solar controller and the alternator (is "alternator" your dash or digital readout, maybe, or is it something else?). You say that it is now 12.8 after dark and several hours after shutdown for the day. 12.8 Vdc IS a fully charged chassis battery bank after a road trip. It will come up into the 13.2 float range (essentially Open Circuit Voltage (OCV), under "Parked, Plugged-In" conditions) if left on float for a longer period, but it is being charged going down the road, so you are good.
I have a whole host of questions regarding how and why AM Solar is trying to charge with solar plus alternator going down the road (why not one or the other, if you have a switch?) and how your battery bank's wiring is integrated to prevent this charging source contest. Staying on either solar or the alternator exclusively would eliminate all of the toggling/flip/flopping (changes in heavy loads not withstanding). But it would take an AM Solar Engineer to answer those questions. From my experience, it is usually only the design engineer(s) who fully understand the true inner workings of the controllers and the trade secret integration features of the various components in a system as complex as yours. So, AM Solar, maybe Allan maybe, Roger (on a long shot) can lead you to the AM Solar/Victron component that now isn't working reliably (I assume that it hasn't been working this way since day one, two (+) years ago when you first installed the system).
I encourage FT owners to strongly consider the elegance and simplicity of the original FT design before they change out to "glitzy tech", complex components that are much more prone to issues and once they partially or completely fail, are impossible for the layman to operate, troubleshoot, diagnose and repair. It's OK to move off of the original KISS design if you have a solid electrical/electronic understanding of what you are doing and accurately document it, but if not, it becomes very confusing and disorienting to the novice (actually to most people, including many if not most techs). Once again from my experience, most of the staff at Tennessee RV or anywhere (FT) elsewhere, even FT Nacogdoches, barely understand DUVAC and remote sensing, much less anything as unique and highly integrated as your AM Solar/Lithium/Alternator system.
Call me if you would like, but if I'm right, you don't have a problem with basic components other than maybe cables, so, most likely not batteries, alternator, voltage regulator, dash voltmeter and all of the other various options previously proposed by other FoFums. Instead, you have an AM Solar component that is supposed to prevent the contest between two charging sources, that is no longer doing its job, or a cable/wire somewhere that is poorly connected/internally compromised.
HTH,
Neal
60Threesevensevenzero 7459
Had to leave site until later this afternoon and will be back on it. Sooo greatfull for everyone's help.
George- I hope your Red Tops are not bad, but if you do need new start batteries I would suggest looking at Group 31 maintenance free truck batteries. I have 2 in my U270 with the Cummins ISC and they are 950 CCA each- plenty of starting power. You could even put in a 3rd if you want to. By the way, the Group 31 batteries were just over $100 each at a truck stop and I have seen them for $25 less on sale.
Good luck with your battery issue. Hope it turns out to be a loose connection or something simple............. ^.^d
Red tops are spiral wound AGM's and can dissipate the engine compartment the motors heat better due to the spiral wound design and are more resistant to the engines vibrations adjacent to where they are installed in a U270. Yes they are more money.
Because of the batteries temperature the hot compartment should have the batteries charged at lower volts.
I set my alternator and solar to be at 13.6 volts at the batteries just like Foretravel did new as a compromise to not having a BTMS on the engine batteries only.
Hot weather 14.2 at the battery is maybe 1 volt overcharging all the batteries in the coach. Shorter life?
House maybe less as they are not in the engine bay. Engine fior sure.
Regular flooded cell VRLA flat side construction probsbly does not dissapate the heat as well from the engine and from the overcharging. That maybe why Foretravel used the red tops on every unicoach made and set the alternator to 13.6.
Lots of 10 year or longer life reports here to show that they were pretty correct in both the batteries and the charging circuit set voltage.
My small solar is also 13.6 at the batteries as it's controller is not currently temp compensating.
Inverter Charger is temp compensating and as the house batteries temp changes you can see on its panel the different voltages during charging based on the temps.
Let me address a couple of things quickly.
First Neal
I owe you an apology. My byline says I have an all Victron system but that is only the house system. The installation of that system was done by my friend and myself following the guidance of AM Solar who we purchased the kit from. They neither produced the product nor completed the installation. That system has worked flawlessly since it was installed and from my perspective was worth everything I spent on it.
As to the modification of the isolator function. I decided on a marine switch instead of an isolator because I wanted to keep the two systems entirely separate. For the same reason I wanted to use all Victron, I did not want to generate my own conflicts if I could avoid it. There are a number of discussion of this modification on the forum. It doesn't complicate the original it simplifies it.
Brett
I have the Black and Decker Smart charger with me for use tomorrow on the Optimas and it should let me know quickly where I am with those. I do not have a trickle charger currently in the system although I do have one. I had not installed as the solar made it unnecessary. My chassis solar is a 100w panel to a Morning Star controller. It was not switched previously but willl be tomorrow. There is no connection to the house solar. I did run a 2/0 cable from the house bus bar to the chassis bus bar and that is connected through a marine switch. I have not used it and no longer use the power boost on the driver panel.
Bob
Thank you for your insight on the Optimas.
My first step tomorrow will be to check the connections in areas I did not before departure. I had used Corrosion protection on the starter and examined the others for corrosion. I did not check the back of the alternator before but did today and it could use a cleaning. I will then go through the steps Chuck outlined and see what I have. As I mentioned I will add a switch to the solar. I will also be able to make an easier start with the block heater tonight since we moved from Boondocking to a post site.
I think we are finished.
Cleaned connections on alternator and tested. Removed batteries after measuring 14.1 on both POS and they coasted down in unison. Had them load tested no issue. Cleaned all connections, treated and tightened. Start up was normal quick fire with no drag or delay. I had turned off the block heater yesterday so I could test a cold engine
Dash digital alternator 14.1
Dash voltmeter 14 or so
Dash digital is now 13.2
I had cleaned the terminals and connections before we left BUT the fuel filter was changed a week or so later. The tech did not allow for the angle of the driveway and the fuel line emptied into his container and overflowed onto the batteries. I thought it had been cleaned up but should have removed the cables and cleaned the terminals again. I believe the vibration worked small amounts of the fuel further down the posts. I did not realize that diesel can act as an insulator. Makes sense but didn't know it.
So we will see when we hit the road again but the alternator is clean, terminals are clean and the solar is switched.
Thanks for all the suggestions. As well as the PMs from Chuck and Roger.