Battery Drain when Boondocking 2019 Forza 34T

[BHOUSE2]

Forza 34T 800AH of batteries. I start with batteries fully charged at 13volts. 10hrs later, I'm at 11.9volts. All I have running is the fridge @ -3amps and Cpap @ -1.5amps. Every once in a while the monitor shows a -35amp draw but nothing is on. Any help would be greatly appreciated.

 

[Eagle5]

Greetings BHOUSE2,

1. Are the batteries Lead/Acid?
2. What Group Size are the batteries?
3. How many batteries do you have?
4. How old are they?

Welcome to the forum.
Eagle5

 

[Morich]

Lots of details missing to really take a look at how and what might be happening! First might be that we don't know what year the Forza might be. Different years tend to have diffferent features and electrical use. One of the big items can be what type frig as some need 12VDC or 110AC made by an inverter. Then if what we normally think of as boondocking, I would assume there is some water used? Is the pump going on/off when the amp draw increases? But also if the batteries are reading 13 and they are lead acid, that indicates it is not a true voltage as it is above what lead acid will maintain! Getting what is called surface charge from recent charging! Not actually possible to have "nothing on" if we don't totally disconnect the batteries as safety items are normally left on! The monitor panel itself draws power. If the lights are on, it is drawing power!
One of the really common mistakes with battery use is how tricky they can be when they look so simple. One easy thing to get wrong is when we see the voltage at higher than real. If we draw the batteries down and do some charging until we see 13 or so, it is easy to start the next night with them being almost flat when we thought they were more than charged!
It is sometimes decribed as what might happen if we were filling a barrel with thick syrup. If we look in the hole at the top, we may see lots of syrup if we look while filling or too soon after. If we really want to know how much syrup (or power), we have to give it time to settle for several hours! Lead acid are slow to charge!

 

[BHOUSE2]

Greetings BHOUSE2,

1. Are the batteries Lead/Acid?
2. What Group Size are the batteries?
3. How many batteries do you have?
4. How old are they?

Welcome to the forum.
Eagle

Forza 34T 800AH of batteries. I start with batteries fully charged at 13volts. 10hrs later, I'm at 11.9volts. All I have running is the fridge @ -3amps and Cpap @ -1.5amps. Every once in a while the monitor shows a -35amp draw but nothing is on. Any help would be greatly appreciated.

2019 Forza 34T
Lead acid batteries
New as of 3/24
BCI No.31
Napa 8231 Deep Cycle Marine
Factory Whirlpool fridge 110volt 3amp

 

[BHOUSE2]

4 batteries @ 200ah ea totaling 800ah. I appear to be using 400ah in a 10 hour period with only 2 items running that total 5ah usage. That should put me using a total of 50ah give or take. Before use I Charge the batteries for a minimum of 2hrs till the charger floats. I let them rest for an hour before use. Usually reads 13 to 12.9 after that.
I'm fairly experienced with electrical work. Everything checks out except for the -32 to -36 amp draw that pops up on my monitor occasionally. All batteries have been load and voltage tested.

 

[Morich]

I would suggest longer charge time to get them fully charged as they are slow and that may explain why they seem to go down way too quick!
But it is often true that corrosion on connections can drive us crazy on RV. But monitors are not good for much more than quick checks as they can add various other questions to the problem. Something as simple as a pinched wire can throw us into fits if it changes every time we push a button.
Any reading above 12.8 is not an accurate reading on lead acid!

 

[wahoonc]

What type of fridge? Three amps sounds like a low draw to me. The high draw you see occasional could be the fridge compressor kicking in, if you have that type.

Aaron

 

[RayIN]

Do not turn on the inverter until its use is required, it consumes battery power even when in standby mode.

 

[Eagle5]

Sorry for not writing back sooner; I have been away from the keyboard.
I believe one of your four batteries is bad and causing an intermittent dead short. I would take the four batteries into a auto parts store and have each one load tested.
Eagle5

 

[Eagle5]

Hi BHOUSE2,
In re-reading your response, I now see that you did indeed load-test all four batteries. So, I guess I would recommend that you pull the fuses to everything except the fridge and the inverter. If that solves the problem, then reinstall half of the fuses to see if the problem returns. An intermittent drain is going to take time to find.
Eagle5

 

[creativepart]

Something doesn’t add up.

There are no 200 amp hour Group 31 LA batteries. The Napa 8231 Deep Cycle Marine battery you listed Is 105 ah. So, four of those is 420ah, not 800 ah. Perhaps you’re looking at Cold Cranking Amps of 200 and mistaking that for your amp hours. But that battery’s spec sheet clearly states that the amp hour rating is 105ah.

If you have a residential fridge that runs on 110v via an inverter then you should expect to power just the fridge for a bit over 12hrs and be down to ~30% SOC. Add in the CPAP and you are easily depleting your batteries.

I know this from experience because I had a 2017 Winnebago Adventurer with 4-100Ah Napa batteries, a 2000w Magnum inverter and a lovely Whirlpool 3-Door residential fridge and just running the fridge on inverter overnight would use about 70% of the battery’s SOC.

 

[creativepart]

Something else to be aware of… a fully charged LA 12v battery is 12.7-12.8 volts-not 13v. When the battery is being charged, the charger, which is likely the Magnum MS2012 inverter charger, will apply 13-14v to bring the batteries up to their max voltage of 12.7v.

However, while charging, your battery monitor will indicate that 13+ volt charging voltage even while the battery is not yet fully charged. So, it’s highly possible and likely that you “think” the batteries are charged because the monitor shows 13v. But you are not starting the night with “fully charged” batteries to begin with.

Lastly, when your charger applies this higher charging voltage you can unplug from shore power, turning off charging, but the battery will hold a surface charge and show ~13v even when the batteries are really at 12.5v or lower. But the moment a load is placed on the batteries the voltage will sag to or even below its actual voltage.

 

[bigbAZ]

I appear to be using 400ah in a 10 hour period with only 2 items running that total 5ah usage.

The fridge alone is pulling close to 30 amps from the batteries not counting inverter losses. (115V X 3a=345watts/12V=28.75a)

 

[Morich]

And that figure is not adding the things we really are not likely to turn off! Bottom line in my thought is that boondocking is one of the things most who have come up through tent camping are not fully ready to agree to the compromise that has to be made. Either we have to invest quite a lot and do a fair amount of work to get the correct changes made or we have to adapt what we do to fit what we have. For many of us, that adaptation means going without the modern convenience items we bought the RV to have.
If we expect to not use electrical nor running water, we may be able to get by for an overnight. But that also means losing a few things that we have grown to think of as necessary! Things like the light under the step, cell phone chargers and TV? Go to bed when it gets dark and use lots of covers when it gets cold?
Possibly it works but not the level many of us expected.

 

[creativepart]

The fridge alone is pulling close to 30 amps from the batteries not counting inverter losses. (115V X 3a=345watts/12V=28.75a)

We saw ~50 amps from the fridge in 12 hours (overnight) for the exact same fridge/inverter/battery combination.

 

[RV_Lee]

Pretty sad they are putting residential fridges in RVs that require the inverter to be on (that uses power on its own) and equipping them with weak lead acid batteries that wont even run said fridge for 24hrs.

Winnebago is big enough to buy lithium batteries in bulk for pennies on the dollar

 

[bigbAZ]

We saw ~50 amps from the fridge in 12 hours (overnight) for the exact same fridge/inverter/battery combination.

It used 50 amps in 12 hours or it drew 50 amps while running?

 

[creativepart]

In our Class A, before we changed from 400ah of LA batteries to 460ah of Lithium batteries we could not camp without power for more than 12-14 hours without running the generator to recharge the batteries. We were forced to run the Generator first thing each morning for about 2-hours. Then each lunch time for an hour and evenings for 2-2 1/2 hours.

This is with 300w of solar as well. But we didn't really count on solar. Running the gen while preparing meals morning, noon and evening not only recharged the batteries but also keep meal prep from further depleting the batteries.

Even with the Lithium we need to run the gen about 3 1/2 hours a day spread out at meal prep times.

Mind you, we tried out best to not drop much below a 50% State of Charge very often. So, using 200ah or less was our daily goal.

 

[Eagle5]

amp-hours is for total energy used
amps is for power

 

[creativepart]

Pretty sad they are putting residential fridges in RVs that require the inverter to be on (that uses power on its own) and equipping them with weak lead acid batteries that wont even run said fridge for 24hrs.

Winnebago is big enough to buy lithium batteries in bulk for pennies on the dollar

Back then (2017-2022) when you got a residential fridge you automatically got a 2000w Inverter Charger, 200w of Solar and 400 ah of LA batteries. It was a complete package. If you got an RV fridge you got no solar, 200ah of LA batteries and a 1000w Inverter with a standard RV Converter.