Historical Battery min/max captured while battery disconnect in “off” position – relevant?

marleecamps

I have a 2019 400 Boondock with AGM batteries, factory-installed solar, Victron 75/15 solar controller, 3-way frig, and inverter switch.  I am nearing 10,000 miles of towing/camping over the past two years, mostly using shorepower. 

Odd question – Are the min/max battery level readings captured during time periods when the battery disconnect is turned off and visible in the history tab of the Victron controller relevant?  I was looking at this recently and noticed during the past two non-camping weeks, the min has ranged from 9.51 to 12.57 (well below the desired threshold of 12.05), and the max has ranged from 11.34 to 12.78.  (During the past two days, however, readings have been in the normal range with battery disconnect in off position.)  Readings are normal whenever the camper is hooked up to house power, shorepower, towing or boondocking – or in other words, whenever the battery disconnect switch is in “on” position.  I cannot tell if this has always been the case or something new, given the 30-day limit on history.

I am very confident that the battery disconnect was in the off position during the time periods in question, as this is part of my home arrival checklist that I validate religiously, and I would have noticed if not when firing up the camper pre-trip.  I am also confident that all appliances were turned off – with the exception of my accidentally leaving the frig in the “on/auto” mode during one of these two weeks; I made sure it was turned off during the second week in question.  I am also very confident that the inverter was turned off in both cases, and the breakaway pin is securely in place.

Can I ignore these readings as irrelevant, or do I have a potential battery problem?

rh5555

One thing you should be aware of:  Even with the battery disconnect turned "off", your solar panels are still hooked up to your battery.  You will therefore see battery fluctuations with ambient sunshine. 

It is unclear (to me, at least) if your low battery reading of 9.51 volts was measured when the battery disconnect was turned "off".  If so, that needs investigating.

marleecamps

Yes, the ranges noted above are all when I am fairly certain that the battery disconnect was in the off position.  And I should have noted that the Victron history shows a consistent zero consumption for each of those days.  (Yes, I did know the solar panels connect to the battery directly and are not impacted by the battery disconnect switch.)

Any ideas why my battery levels are showing such low charge levels?  Truly at a loss.

rh5555

I'm assuming that your history is from the Victron Solar controller.  The currents recorded by this controller are the charge currents from solar to battery.  It knows nothing about other drains on your battery.  You'll need to install a shunt like this to fully diagnose any unexpected battery drain.  These shunts are very useful if you plan to spend any significant time away from shore power, and well worth the investment.

marleecamps

Thank you for your insight.  Yes, my source is the Victron controller app. 

My original question remains as to whether or not I have a potential problem with my 2-year-old AGM batteries, given the min /max stats recorded via the app on days when the battery disconnect is in the off position.  If they are not relevant, this would be good news. And frankly, would make sense, given the mapping of stats against activity for the past 30 days.

I rarely boondock for more than four or five days at a time, and checking the Victron app while doing so has, to my limited knowledge and experience, shown the battery levels to remain within acceptable threshholds while doing so.  I am judicious with the use of lights, electronics, etc and flip the Alde and frig over to propane until returning to shorepower.  I highly doubt I will ever boondock for any extended length of time, but it is helpful to learn what I will need to add if I choose that path in the future.

This battery/solar/controller area is very new to me, so I do have much to learn.

pthomas745

I've been looking at that History screen for a while, trying to figure it out.  There is a wealth of info, but trying to discern exactly what the "max" and "min" voltage actually means is a bit difficult.  If this is a simple voltage readout, it seems to me it would suffer from the "rested" battery issue, especially for the "min" voltage.

 If the battery actually dropped to 9.5 volts, there would be repercussions inside the trailer: the gas monitor would alarm, for example.  Or the Alde would show an error, too.  They both require 10.5V (or about that). 

So: is the "min" voltage only showing the sudden drop in voltage as the fridge is turned on?  Or the fan turned on to high?  Is this "min" voltage averaged over a certain period of time?  Or is it the "instantaneous" measurement of a device that is activated?  I'm leaning toward an "instant" reading that doesn't have much value.  I think I will go nose around in the Victron Forums again!

@marleecamps if you could show us a screen shot of your history page, that would be great.

Here is a screen shot I found a few weeks ago that annotates the views on the history page.

marleecamps

The ranges that cause me angst only occur on days where the camper is in my driveway with the battery disconnect off.  Nothing running (that I know of).  I am looking at the captured min and max battery charge level on each day.

 All readings on days where I am prepping (hooked to house power), towing with inverter on, or hooked to electricity at campsite are normal.  This is what causes me to suspect they are not valid.  Or I have something really wrong with my batteries - which I would want to know.

I can attach a couple of screen prints tomorrow.

pthomas745

Ok, thanks.  If a battery was going wonky like that...it would be wonky all the time, I would suppose.

Sharon_is_SAM

I found this thread very helpful:  https://tab-rv.vanillacommunity.com/discussion/comment/164301#Comment_164301

If you do not have a shunted battery monitor then the controller voltage is a combination of battery voltage plus solar panel and/or inverter voltage.  I am curious what the voltage drops to when you turn off the battery switch.  Per @rh5555 in the linked thread, to get a more accurate battery voltage, you should disable the controller.  

rh5555

Given the information to date, I would hazard a guess that you have a bad connection somewhere between you solar controller and the battery.  That would make the solar controller intermittently think you have a low battery.  I'd look at the connections at the solar controller and at the battery, there may also be an in-line fuse to check.

Easiest way to verify this is to use the Victron app.  First disable the controller in the "Settings" (cog icon), and Battery menu.  Then return to the main screen and select "Trends", select Battery Voltage to view:

Now jiggle the wires (technical term), and look to see a sudden plunge in the reported battery voltage.  That will be your bad connection.  Fix it and finally go back to the settings menu to re-enable the charger.

Hope this helps...

Denny16

That is a clever trick, thanks for sharing @rh5555.
 Cheers 

marleecamps

@Sharon_is_SAM - Thank you so much for the helpful link.  While my head spun in circles around the mathematical discussion (so much for that college calculus class), the shortcut provided by @rh5555 was easy to understand and follow.

This morning, I temporarily turned off the MPPT controller (battery disconnect already in off position), waited 30 minutes, and took a reading.  Current battery level 12.45, which is just below 80% charge.  Four days ago, I hooked up the camper to house power to ensure the battery was fully charged (battery disconnect in on position).  Then I unplugged the cord and turned battery disconnect to "off".  The camper resides in my driveway during camping season and receives a few hours of partial sunlight on sunny days - such as this week.  So it seems odd that my battery reading would currently be close to 80%, since there should be nothing drawing power.

Victron controller has historical max battery level from the past four days range from 13.33 to 14.39, and lows range from 11.78 to 12.89.  If I can trust the numbers.   Oh, and here is a screen capture showing a few days with readings in the questionable range (battery disconnect off, nothing drawing power).



Based on @pthomas745's comment, I did spend some time on the Victron forum site this morning but didn't find anything that seemed relevant to my question regarding those low historical readings.

My primary concern continues to be whether or not I have faulty or failing batteries, despite the fact that they are only 2 years old and have rarely been used for actual boondocking and allowed to run down below the desired 50% level to my knowledge.  

I think my next step will be to closely monitor and document battery levels as compared to status of battery disconnect, shore/housepower or battery usage, etc. each day in order to more accurately troubleshoot any potential issues.  I did purchase a multimeter, which was delivered yesterday, so I will be perusing YouTube for "how to use multimeter" as well.  I have three remaining week-long camping trips planned starting next week into early October, so I will have plenty of opportunity to capture readings at each scenario.

Any additional guidance or suggestions welcome.

marleecamps

@rh5555 - Just saw your note.  Heading out to camper shortly to investigate.

pthomas745

It looks as if you are getting plenty of solar input, but it seems like the battery is not charging. Constantly in "bulk mode", with no consumption.

I'm wondering if...a simple reset of the controller would help.  There is a fuse at the bottom of the controller you could pull to reset.  While you are looking at the battery and doing the "Wiggling Test" a quick look at the solar controller wiring might be useful, too.

What meter did you buy?  They are deceptively simple.

 PS: you mentioned "inverter".  While doing all the other tests, make sure the inverter is off.

marleecamps

@rh5555 - all cables and wiring between the batteries and controller tight and tidy.  No drop in voltage as I jiggled them several times.  As long as I have the compartment open, I am going to learn how to use my new multimeter next... 

marleecamps

@pthomas745 - yes, inverter off.

I will check the controller fuse shortly.  Opening my Vici multimeter box at the moment.  A good thing to own and learn how to use.

rh5555

Well, darn.  I had hoped you'd find something easy.  My next place to look is the inverter.  It's the only other thing that is still connected to your battery when battery disconnect is turned "off".  There is a big fuse for the inverter that sits inside a clear plastic box.  If you pop off the cover and remove that fuse, then you can remove the inverter as a suspect.  If your battery no longer sags, you have found your culprit.

marleecamps

Multimeter, piece of cake.  12.61.  Which matches the current reading on the Victron app.

Here are photos of my inverter.  I do not see a plastic box or anything that looks like it's holding a fuse.  Is it the black metal box on the right?

Also, I toggled the on/off switch on the inverter just for kicks and giggles.  Old habit from my IT days...  sometimes that actually works...

marleecamps

Well I think I have located the fuse but have no clue how to access it.  Doesn't seem to be a removable panel without tearing the whole back apart.

pthomas745

Stinger fuse looks like this. Inside the plastic holder on the right.

marleecamps

It is located inside a separate compartment between the center bunk and passenger side exterior storage area on the 2021 400.  Removec four screws on the exterior compartment wall to expose.  Now to see if I have the right screwdriver to remove fuse.  Smaller than usual screws.

rh5555

You just need to loosen the 2 brass nuts, then the fuse lifts out of its holder.

marleecamps

@rh5555 - yes, thanks, I did manage to extricate the fuse.  I am now on hold tryiing to locate a replacement.  I thought I had purchased extra fuses for everything, but this one was not on my list.

marleecamps

Thanks to everyone who has provided guidance, suggestions and encouragement so far.  I have ordered the replacement inverter fuse, which will arrive next Friday.  In the meantime, I have restored order to the camper and reconnected to shorepower to minimize any further damage to the batteries. A great learning day, for sure.

I plan to proceed with next week's camping outing as planned (electric hookup), and will reconvene with addressing this issue when I return and the new fuse is in hand.

Cheers, and happy Labor Day.

rh5555

@marleecamps:  I think we got wires crossed here.  My suggestion was to remove the fuse so there is no chance that the inverter is draining your battery, then wait an see if you still get low battery measurements.  If the battery now behaves normally, then the inverter is probably at fault.  The fuse itself is not the problem - it is almost certainly fine (unless you broke it when removing it).

marleecamps

@rh5555 - Ah!  Mixup undoubtedly on my end.  I will run out, repull the fuse, unplug electric cord and turn off battery.  Then wait and see.

pthomas745

Nice to have a spare, though.  The Stinger fuses are fairly common (check the product, though)

https://www.amazon.com/dp/B001JQCYWQ/?coliid=I6VRFOCOF17CG&colid=3DJSJON9VK2CS&psc=1&ref_=lv_ov_lig_dp_it

marleecamps

This is what I ordered - appears to be identical to the one I pulled out today.

ANL Fuse 150A 150 Amp For Car Vehicle Marine Audio Video System Gold 2 Pack (150 Amp) https://a.co/d/aejp3oG

marleecamps

So, 24 hours into our unofficial experiment (inverter fuse pulled, battery disconnect in off position, no electric connection), the history tab shows normal readings for past 24 hours. Yesterday's is skewed because I plugged in shorepower late aft for a couple hours.


Trend line: 


And my current state battery reading (Victron controller turned off for 30 mins) s this:


While this is only one day and hardly a robust statistical sample, it does seem to support the theory that the inverter may be draining the batteries. 

I am going to have to pause this experiment tomorrow morning so I can prep the camper for this week's outing and cool down the frig.  I will pick back up next weekend when I can get a few days of monitoring in. 

Denny16

Even without an AC load on the Inverter, Marlee, it will still quickly drain the battery, as it has a current draw unless it is turned off.  This is why I  keep the Inverter turned off, unless I am using it.
 Cheers 

marleecamps

@Denny16 - This is the most enlightening piece of information. I have NEVER once turned off my inverter using the switch in my bedside cubby since picking up my camper from the dealer over two years ago, including the past two winters when the camper has been stored for six months in cold MN temperatures - battery disconnect off but inverter switch on. (Not to be confused with the button above the 3-way frig which I turn on only for towing and turn off immediately upon reaching my destination.) If this was mentioned during my dealer walk-through, I certainly missed it. So, upon arriving home Friday afternoon, I did turn off that switch as part of my unhitch/home setup process. Battery disconnect turned to off position as usual.. No power hookup. My Victron app readings appear solidly in the normal range for the past two days. I have updated my departure prep checklist, as well as my home arrival checklist accordingly. Since my primary concern was the reported battery levels that occurred only when the battery disconnect was in the off position (sitting in my driveway, and potentially during storage), I assume I can technically consider my question answered. But it does still seem perplexing that my batteries were not completely dead when I picked up my camper each spring. Granted, I never thought to check their levels, but I do know that when I turned on the battery disconnect and pulled out the entry step, the little blue light came on - so there was still some power. And I learned yet more skills in using a multimeter to check actual battery level, as well as how to access the inverter fuse in its dedicated compartment under the passenger rear bunk. I also have a couple of spare fuses in my toolkit. All good things. If anyone has any additional insight or suggestions to add, I am all ears.