Battery depletion rate 3% or more per day... with EVERYTHING off?

[Snackchaser]

On 6/3/2024 at 4:32 PM, Dave and Kimberly said:

 It's not a real big deal but I can't figure out what I'm missing.  

I decided to chime in on this because I don’t think you’re missing anything, your discharge rate is perfectly correct!

All the given advice is good, but it’ can be a bit miss-leading to fully understand whats going on.  I hope to provide a better explanation, and show you a simple and very accurate way to check your “parasite” loads, which I’ll refer to as normal “stand-by” loads.

Your 390 amp hour battery with a daily discharge rate of 3% equates to a loss of 11.7 amp hours over a 24 hour period.  This further equates to a stand-by load of 0.48 amps, which is not overly excessive considering all the electronic devices in the Oliver.  Devices with memories, remotes, touch lights, rain sensors, USB ports, electronic boards, etc., can each draw milliamp currents even when turned off, and they do add up quickly.

I took some current readings from my own trailer to show you what I mean.  It’s the same year as yours and it also has a 390 amp hour battery.  Remarkably, the values add up to exactly the same current as your calculated load.  But more importantly, it shows that there is no single extraordinary load:

• Fuse 2, Various electronics = 0.117 amps
• Fuse 4, Furnace = 0.012 amps
• Fuse 5, Main lighting = .003 amps
• Fuse 6, Fans = 0.016 amps
• Fuse 7, Water heater = 0.113 amps
• Fuse 8, Radio = .204 amps
• Fuse 9, USB outlets = 0.007 amps
• Fuse 10, USB outlets = 0.009 amps
• Total = 0.481 amps

These measurements were done with a precision multimeter having a resolution of 3 decimal points.  My Victron shunt has a resolution of 2 decimal points and it showed a lessor current of 0.42 amps.  My Clamp-on Amp Meter has a resolution of 1 decimal point, and it showed a higher current of 0.5 amps.  This demonstrates how subjective and inaccurate some of these measurement methods can be when dealing with such small milliamp values.

Another potential misconception is that the Lithionics BMS App will provide the overall charge and discharge values.  It’s only true to the extent that it provides values for the battery selected, but not for each battery combined.  For example; the 390 amp hour package consists of three 130 amp hour batteries.  If the overall load is 3 amps, then the App will show each battery discharging at 1 amp.  Additionally, it’s only accurate to 0 decimal points so it won’t show anything less than 1 amp.  This is another good justification for installing a Shunt.

There are a number of ways to measure stand-by or parasite current, but the easiest and most accurate way is with an inexpensive Multimeter through the fuse box.  It will show the load of each circuit, but not each component on the circuit.  Thats okay because some of the individual component loads are too small to be accurately measured anyway.   

• Caution:  When using the ammeter function, the meter is in-line with the circuit.  This means that the current is running through the leads and meter.  So don’t use it with loads greater than it’s rated maximum current, which is typically 10 amps.

Before testing, make sure that everything is off including the inverter/charger and solar (Solar switch is in the street side overhead cabinet.)   Make sure shore power is unplugged too.  Pull each fuse one at a time and the red LED “blown fuse” indicator will light-up if there is any load.  Put your ammeter leads on each leg of the fuse socket and read the current.  Add up the values and you will have an accurate overall stand-by load.  FYI, the inverter/charger does not go through the fuse box, but it will add another 0.2 amps load if left on.

I keep my trailer undercover without shore power and the batteries also discharge rather quickly.   In fact the shunt screen shot below shows that it will discharge in 10 days.  I considered adding a battery master switch, but it wasn’t a viable option for a number of reasons which is why I believe that Oliver doesn't install them either.  I ended up getting an auxiliary solar panel, with charge controller, and I mounted it on the roof to keep the batteries at 100%.  It was better than running an extension cord and risking complete discharge mishaps.

Hope this helps

Cheers, Geoff

[Geronimo John]

On 6/9/2024 at 2:32 AM, Dave and Kimberly said:

I'm not familiar with another fuse panel in the attic?  Do you mean the rear storage space (above rear window) where the EMS, TV antennae on/off area?

I'm not familiar with the wiring on your trailer, but for many years YES, there is a fuse panel in the Attic, right side.

[Geronimo John]

20 hours ago, Snackchaser said:

I considered adding a battery master switch, but it wasn’t a viable option for a number of reasons which is why I believe that Oliver doesn't install them either

Geoff: 

What a great post.  It certainly sheds a technical light on the amp draw issue.  Knowledge is good.

Speaking of which, would you please elaborate further on not installing a high quality Battery Master Switch?  There are some owners who are on the fence in this regard, and your perspective would be beneficial.  

Thanks,

GJ  

[Snackchaser]

1 hour ago, Geronimo John said:

Geoff: 

What a great post.  It certainly sheds a technical light on the amp draw issue.  Knowledge is good.

Speaking of which, would you please elaborate further on not installing a high quality Battery Master Switch?  There are some owners who are on the fence in this regard, and your perspective would be beneficial.  

Geromino John, thanks for the kind words.  Sure I can elaborate why I haven’t installed a Master battery switch, and I’ll also provide a better solution if the objective is to switch off all the stand-by loads when the trailer is in storage.

The battery switch will add resistance to the circuit from the additional cable length needed to reach the switch, and through cable lugs and switch contact resistance.  Granted it’s not much, but anyone who has ever dabbled with cable resistance knows that it doesn’t take much to create a voltage drop, particularly in high amperage battery systems like the Oliver.   Voltage drop impacts the systems efficiency and it means your creating heat and burning watts.

I don’t think there’s an optimum place to install a switch given the stiffness and limited bending radius of the size cable that you would need.  It's best to keep the cable as short as possible and that really limits the mounting options.

I haven’t see a compelling reason to install a huge battery switch.  I’m in and out of the trailer enough where it would be an unnecessary burden to turn the battery off.  The only reason I can think of for installing a switch, is to shut off the stand-by loads while in storage.  I personally think stand by loads are not a significant concern.  There are not many scenarios where solar or shore power is unavailable and, if so, there are other solutions.  

If there is a desire to shut off the stand by loads while the trailer is in storage, then simply shut off the DC breaker that supplies the DC fuse panel. It’s located next to the inverter.  You can see from my previous post that all the primary loads are fed by the DC fuse box.  However, I’d recommend re-powering the CO2 detector so that it always stays energized.

Hope you find this useful!

Cheers, Geoff