Erratic black tank level sensor

[Frans]

The black tank level sensor in our 2022 Coachmen Beyond behaves erratically when in normal use. The panel shows empty or something at 20% or less untill it's almost time to dump, then the panel suddenly jumps to 80% or higher. After emptying we always refill with water to 80 % or more for flushing, and when we do that the panel indicates the level neatly in 5% increments as if nothing was amiss.

Anyone here has seen this problem of have suggestions?

 

[Larry-NC]

Not that exact problem

The black tank level sensor in our 2022 Coachmen Beyond behaves erratically when in normal use. The panel shows empty or something at 20% or less untill it's almost time to dump, then the panel suddenly jumps to 80% or higher. After emptying we always refill with water to 80 % or more for flushing, and when we do that the panel indicates the level neatly in 5% increments as if nothing was amiss.

Anyone here has seen this problem of have suggestions?

Most of us have not seen that exact problem. Most RVs have an older style sensor-and-gauge arrangement. The older style has three sensors mounted at different heights on the sidewall of the tank. The four LEDs associated with them indicate:

• Full
• 2/3 Full
• 1/3 Full
• Button is being pressed

in conjunction with the button being pressed. These older sensors can be confused by toilet paper or solid waste clinging to them.

It sounds like you have a continuous, float-based system like the fuel gauge in a car/truck. It also sounds like the float movement might be inhibited by toilet paper or something. Is the problem solved by using the Black Tank Flush feature, that sprays down the inside of the tank? Are you using RV toilet paper or some of that fancy residential stuff?

 

[Frans]

I only use RV tp. The problem isn't there after I dump and refill with clear water; then the panel goes up by 5% at the time. The pattern is very consistent: irrational levels while using the toilet, nice 5% increases when filling for cleaning with clear water after dumping.

 

[D W]

During camping season I always maintain my black tank with a dose of Walmart branded RID-X. We use regular TP and never have a problem with sensors or flushing. Once in a while we'll drop in a WALEX Porta-Pak deodorizer if we encounter some smell.

 

[MGD1961]

I only use RV tp. The problem isn't there after I dump and refill with clear water; then the panel goes up by 5% at the time. The pattern is very consistent: irrational levels while using the toilet, nice 5% increases when filling for cleaning with clear water after dumping.

Oh boy. Here we go with the toilet paper again. Just make sure it has no cotton fiber and is septic safe like Scott’s 1000

I doubt there is a float. I could be wrong. If your tank gauge is sensitive enough to use 5% increments it is probably a linear resistance sensor identified by a copper band or a number of strips stuck to the side of the tank with a wire at the top and bottom. They “or some” work on the resistance change in the copper alloy foil due to a temperature difference at any given level in the tank. If the temperature difference is too close to ambient they don’t work well. That would explain why when you fill the tank with cold(fresh) water it works more accurately.

Solid materials may affect this I suppose. Next time it acts up dump a bag of ice in it and see what happens.

I would be interested in seeing a picture of the panel so we know what it is.

 

[Larry-NC]

Uhh...

I only use RV tp. The problem isn't there after I dump and refill with clear water; then the panel goes up by 5% at the time. The pattern is very consistent: irrational levels while using the toilet, nice 5% increases when filling for cleaning with clear water after dumping.

Uhh, you're not making waves, are you?

What would you expect to happen if you make waves?

 

[Chuck_S]

Toilet paper is toilet paper. I'm sure "not septic tank safe" TP exists but I've never seen it and I'm curious enough to read the labels. (Yes, I have no life. ) "RV" type is merely single ply -- and you have to use twice the length to match the performance of normal TP.

Time for my Odorlos and enzyme recommendation again?

-- Chuck

 

[BDenn]

Black water tank sensors

I have 3 sensors on mine. Found loose corroded connections on sensors. Cleaned them off, put battery protection cleaner on. Use it every year worked. Found loose ground wires everywhere on chassis.

 

[MGD1961]

I have 3 sensors on mine. Found loose corroded connections on sensors. Cleaned them off, put battery protection cleaner on. Use it every year worked. Found loose ground wires everywhere on chassis.

OP stated his gauge reads in 5% increments. The type with 3 sensors would only read empty, 1/3, 2/3, and full.

 

[BDenn]

Loose or corroded ground or supply wires could apply.

 

[TitanMike]

RV tank OE sensors can be erratic for several reasons. When bridged with TP is #1. Any liquid "wetting" thevtank wall between sensors is another and is usueally intermittent. Can be caused by "splashing" when toilet is used or any wave action from RV movement.


I don't pay much attention to black tank gauge. With water off (city water or pump) I just push down the pedal and use a flashlight to see how much gap there is between dump tube and level of contents. This method has never failed me.

 

[MGD1961]

It might be nice if the OP were to chime in rather than us all talking amongst ourselves to clarify a thing or two.

I will reiterate. If his panel reads in 5% increments this is not a 3 sensor system. The OP stated twice that it reads in 5% increments. If so it has to be something like this

https://www.rvupgradestore.com/Garnett-Technologies-Model-709P3W-SeeLeveL-II-p/709-P3W.htm

Toilet paper or a big fat constitutional doesn’t get stuck on this type nor would it be affected by a wetted surface. They work on a totally different principle.

 

[LivingToCamp]

I don't pay much attention to black tank gauge. With water off (city water or pump) I just push down the pedal and use a flashlight to see how much gap there is between dump tube and level of contents. This method has never failed me.

X2 ^^^
My sensors stopped working about a year after I bought my TT. To make it easier to see the end of the dump tube, I used an old small paint brush taped to a stick and painted the end of the dump tube white.

 

[MGD1961]

X2 ^^^
My sensors stopped working about a year after I bought my TT. To make it easier to see the end of the dump tube, I used an old small paint brush taped to a stick and painted the end of the dump tube white.

Only problem is in many cases the end of the dump tube is not the top of the tank but I like that idea. It’s probably close enough

 

[Frans]

Contacted Coachmen support a week ago; so far, no response.

 

[Bob K4TAX]

The OP where it is said "behaves erratically when in normal use." I'd say this is normal for that style of tank monitor.

 

[Couick]

my gauge reads funny till it drys off

 

[jlynn721]

The black tank level sensor in our 2022 Coachmen Beyond behaves erratically when in normal use. The panel shows empty or something at 20% or less untill it's almost time to dump, then the panel suddenly jumps to 80% or higher. After emptying we always refill with water to 80 % or more for flushing, and when we do that the panel indicates the level neatly in 5% increments as if nothing was amiss.

Anyone here has seen this problem of have suggestions?

Don’t even use the tank meters. They are historically inaccurate. Most people figure out that they need to dump every 1, 2, or 3 weeks (depending on # of people and how frugal you are with water use.


I boondock (mostly alone) and can go 3 weeks without dumping. If it’s been 2 weeks and a dump is convenient, I dump.

If you are in a FHU spot for a long time, dump every 2 weeks.

I will dump and flush the tank, and the meter may show 1/2 full. They are garbage.

 

[MGD1961]

Why. If these tank gauges are such junk do we as consumers continue to accept this as just the way it is ?

 

[5picker]

Why. If these tank gauges are such junk do we as consumers continue to accept this as just the way it is ?

I have had about 15-16 R/Vs through the years, none of the sensors/gauges worked well. I have complained to the manufacturers and to factory reps beginning with the 1st one in the late '60s and taken several of them in to have the issue addressed (early on, until I learned) That's 40+ years of complaining.

Short of just not buying a R/V, what is your suggestion that a consumer can do?