Battery question?

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RipVan

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Jun 20, 2013
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277
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WI
In replying to an associated thread I had a question of my own. Instead of hijacking that thread, I started anew.
In between camping trips during the Summer months, I keep my x210 parked on a pad in my yard. It’s close enough to my house to allow for running an extension cord out to it. I have an adapter that allows me to hook up to the 30 amp plug. I don’t power any high draw 120 volt items (A/C, heater etc). But I do keep the Dometic fridge in the “Auto” mode.
I’m of the belief (please correct me if I’m mistaken) that while on “shore power”, the WFCO 3-stage Power Converter / Center essentially functions like a “smart charger” and keeps the battery topped up. I don’t seem to be having battery issues. I bought a new battery when I purchased the camper back in ‘13. Replaced that one in ‘18 and just replaced that one earlier this month. I do pay attention to electrolyte levels and keep the camper battery on a charger (smart type) over the Winter. I’m satisfied with getting 5-6 years out of a battery. Am I correct in thinking that the WFCO Power Center is keeping the battery charged during the Summer?
 
You are correct that the WFCO charger is designed to drop into 'float mode' (3rd stage) to maintain the battery at full charge. In float mode the converter is basically a trickle charger. I did that for years with mine with no problems before the converter finally died and I replaced it with a Progressive Dynamics.
WFCO chargers do have a reputation for not dropping into float mode and staying in the full charge 2nd stage which can shorten the battery life, so you'll want to keep an eye on it.
 
LJAZ said:
You are correct that the WFCO charger is designed to drop into 'float mode' (3rd stage) to maintain the battery at full charge. In float mode the converter is basically a trickle charger. I did that for years with mine with no problems before the converter finally died and I replaced it with a Progressive Dynamics.
WFCO chargers do have a reputation for not dropping into float mode and staying in the full charge 2nd stage which can shorten the battery life, so you'll want to keep an eye on it.
Click to expand...
How can I tell if it doesn’t drop into “float mode”?
 
If there is no load on the battery then the float charge should be about 13.2 volts. Absorption charge (stage 2) will be 13.6 v. The battery will have to be at full charge for a day or so before it drops to 13.2. Also if there are loads on the battery that may kick it out of float mode. What I did was keep in eye on the water level - I have lead/acid batteries - and as long as it the level didn't drop very fast.
Just a thought, if you are running the fridge that may be enough to keep the converter in second stage which is probably ok as float mode may not be enough to keep it fully charged.
 
LJAZ said:
If there is no load on the battery then the float charge should be about 13.2 volts. Absorption charge (stage 2) will be 13.6 v. The battery will have to be at full charge for a day or so before it drops to 13.2. Also if there are loads on the battery that may kick it out of float mode. What I did was keep in eye on the water level - I have lead/acid batteries - and as long as it the level didn't drop very fast.
Just a thought, if you are running the fridge that may be enough to keep the converter in second stage which is probably ok as float mode may not be enough to keep it fully charged.
Click to expand...
Pretend for a moment that I’m not fully cognizant of the inner workings of battery maintainers ;). When I test for the voltages mentioned above, should the battery be “out of circuit”? Also, yes, I have the fridge running (back up beer supply needs to be kept cold) :rolleyes:. When on “shore power” and in “Auto” mode, does the fridge use 120v AC or converted 12v DC from the WFCO Power Center? If it uses DC power, I guess that would be considered a load. I’m sure that the Radio/DVD player has a small draw even when off. That prolly applies to the gas leak detector too. It would have been nice for WFCO to have some sort of indicator to show the “stage”.
For now, I guess that I’ll keep an eye on the electrolyte leves and monitor voltages. Thanks for the info :).
 
This calculator can be used to help you understand battery draw and how little amount of watts it takes to drain a battery. Definitely worth playing around with. Some aftermarket power centers do have a display to tell what charging phase it is. I always end up adding a battery monitor to which camper I currently own so I can monitor this. But I agree that it would be nice if it was on all rv's.

https://calculator.academy/battery-run-time-calculator/
 
RipVan said:
Pretend for a moment that I’m not fully cognizant of the inner workings of battery maintainers ;). When I test for the voltages mentioned above, should the battery be “out of circuit”? Also, yes, I have the fridge running (back up beer supply needs to be kept cold) :rolleyes:. When on “shore power” and in “Auto” mode, does the fridge use 120v AC or converted 12v DC from the WFCO Power Center? If it uses DC power, I guess that would be considered a load. I’m sure that the Radio/DVD player has a small draw even when off. That prolly applies to the gas leak detector too. It would have been nice for WFCO to have some sort of indicator to show the “stage”.
For now, I guess that I’ll keep an eye on the electrolyte leves and monitor voltages. Thanks for the info :).
Click to expand...

You should check the voltage at the battery with everything connected. The reading then will be whatever voltage the converter is putting out. As for the fridge I was assuming that it was running on 12V DC from the converter but I have to admit that I'm not sure if that's correct.
 
herdbull said:
This calculator can be used to help you understand battery draw and how little amount of watts it takes to drain a battery. Definitely worth playing around with. Some aftermarket power centers do have a display to tell what charging phase it is. I always end up adding a battery monitor to which camper I currently own so I can monitor this. But I agree that it would be nice if it was on all rv's.

https://calculator.academy/battery-run-time-calculator/
Click to expand...

Thanks! Using the calculator does require one to know the power draw for all of the devices on the circuit. Product info that’s not always readily available and may vary with things that don’t run continuously. Prolly more important for the “boo docking” crowd. Nevertheless, thanks!
 
LJAZ said:
You should check the voltage at the battery with everything connected. The reading then will be whatever voltage the converter is putting out. As for the fridge I was assuming that it was running on 12V DC from the converter but I have to admit that I'm not sure if that's correct.
Click to expand...
Got it! I keep my battery box secured with a wrap around cable lock so it’s a bit putsy to get at the connections ;(. I may hook up a connector that will allow easier access to the terminals for “spot checking” the real time charging voltage.
I do have the original Installation/Operators Manual for my WF-8945NN WFCO ULTRA Distribution Panel. It’s more focused on the installation and not so much on actual use. I’m guessing that the expectation is that it does its job “automatically” and is not prone to fail. The guide does mention “CAUTION: If the converter cycles into the bulk charge mode more than once during a charge cycle check the battery(s) to determine if it has a bad cell.” What’s not described is how one knows if that is happening? I just bought a new battery last month so a “bad cell” is unlikely (but I guess, still possible). I’ll see if I can make the unit function in all three (Bulk, Absorption and Float) modes. I’ve got “bigger fish to fry” currently, so it may be a while before that gets done ;).
 
RipVan said:
Thanks! Using the calculator does require one to know the power draw for all of the devices on the circuit. Product info that’s not always readily available and may vary with things that don’t run continuously. Prolly more important for the “boo docking” crowd. Nevertheless, thanks!
Click to expand...

not necessarily. You can alter any of the (3) values in the calculator. So if you know it lasts say 72 hours, input 72 hours. And you know the battery amp hours is 100 so you enter that figure. Actually for lead acid you would enter 50amp hours because you never want to go below half of the battery capacity. For lithium I think you have a higher drain available and I believe it's 80% so you enter 80amp hours. This will give the draw in watts. Even with the fridge on propane it still draws like 5-6 watts or more for the electronic board.
 
Basic algebra then, if two values are known, the third can be found. I still think it applies more to those that “boondock” but its nice to know how to do it if needed. We always try to have, at the very least, electrical hook ups. Water hook ups are a bonus as well as sewer at the individual site. Most of our recent trips have been electric only. Bottom line, calculating what’s left in my battery is not likely something that I’ll need to do on any kind of regular basis. That said, it’s good to know that there’s a way to do it ! Thanks
 
Coupla things.

My frig has no "12V mode" and won't operate in "AC mode" unless plugged in to shore power or the gen set. I've always assumed the circuit board runs on 12V from the batteries so it can work either way but the heater needs 120VAC.

Add a hardwired voltage gauge to determine what mode the converter is in (and what shape your batteries are in). As LJAZ says, if you read 13.2VDC it's probably float charging. If you read 13.6VDC, you're in "stage 2."

A fully charged lead acid battery with no load should read about 12.7VDC. And when you see around 12VDC, your battery is about 50% discharged. (Lithium batteries are more linear and maintain a higher voltage which is pretty much all I know about lithium batteries.)
 
Why does your heater need 120VAC? Is it an electric plug-in heater and not a factory furnace?
 
Sorry. "heater" was shorthand.

A compressor cools the refrigerant in the fridge you have at home but RV fridges don't have compressors because compressors are huge (electrical) power hogs.

An absorption fridge doesn't need a compressor. It works by heat and the chemical reactions of water and ammonia. It seems non-intuitive that the fridge needs heat to trigger the cooling process but the evaporator combines the ammonia with hydrogen gas, causing it to evaporate into a cold vapor. The energy required to evaporate it is created by an electric heating element or by a propane fire.

The cold vapor moves to the interior cooling coils and then back into the absorber where it mixes with water, and the process repeats over and over again.

FYI, one reason so many RVs burn is because their fridges have a little fire running whenever they are actively cooling on propane.
 
NorthPuffin said:
Coupla things.

My frig has no "12V mode" and won't operate in "AC mode" unless plugged in to shore power or the gen set. I've always assumed the circuit board runs on 12V from the batteries so it can work either way but the heater needs 120VAC.

Add a hardwired voltage gauge to determine what mode the converter is in (and what shape your batteries are in). As LJAZ says, if you read 13.2VDC it's probably float charging. If you read 13.6VDC, you're in "stage 2."

A fully charged lead acid battery with no load should read about 12.7VDC. And when you see around 12VDC, your battery is about 50% discharged. (Lithium batteries are more linear and maintain a higher voltage which is pretty much all I know about lithium batteries.)
Click to expand...
Since the consideration of the various power draws is part of this “battery” thread, a detour into fridge operation is appropriate. While Dometic RV refrigerators aren’t the only brand in use, they are very commonly the brands in the FF lineup. In reading thru my Dometic User Manual, I’ve learned that there are several variations with different features. All seem to have at the very least, a “propane” mode and an “electric” mode with the electric mode having the possibility of 12v DC and/or 120v AC in some of the models. Mine, a RM2551, is propane or 120v AC. The control panel allows for “Auto” or “Gas”. In the Auto mode, 120v AC is used by default. If not on “shore power” the system automatically switches to propane. In the Gas mode, the manual doesn’t specifically discuss it but I’m thinking that the initial ignition of the propane heater must use a tiny draw from the 12v circuit. (Not totally unrelated but the same logic must apply to the ignition of the propane water heater). There is a model that has a 12v DC only mode. At first I was a bit disappointed that mine didn’t have that function but changed my mind after learning that mode rapidly depletes the onboard battery.
Getting back on topic, the in-line voltage gauge hardwired into the system sounds like something that I would like to do!
 
My WFCO fried my marine batteries and I added a separate DC-DC charger to properly charge the batteries and replaced them with two 100 Ahr gel cells. Thus far it is a huge improvement and does not overcharge the gel cells.
 
RE: WFCO 3 stage Power, I’ve yet to get a hardwired voltage monitor but I did check the system (at the battery) with my Harbor Freight multimeter. While plugged in to “shore power” I’m reading ~13.6v +/- across the battery terminals. I believe this shows the system to be in the “absorption mode”. When disconnected from “shore power”, the voltage across the terminals reads ~12.8v +/- showing the battery to be full charged. In reviewing the WFCO material that I have, it seems that the Power Center is functioning as it should. As to current draw while my camper sits on the pad in my yard, the sound system is powered but off. The gas leak detector is active. The Dometic fridge is in the “Auto” mode that I believe preferentially runs in the 120v AC mode when on “shore power” i.e. no draw on the 12v DC system. What I don’t know is if the Power Center ever jumps up to the “bulk /14.4v” mode or drops to the “float / 13.2v” mode? The current draws from the sound system and the gas monitor are relatively low preventing excessive voltage loss and the jump into “bulk” mode but perhaps variable enough over a 44 hour period to prevent dropping into “float” mode. Do monitors like the ones suggested by herdbull track voltage and current over time? I guess that would be a good reason for me to invest in one.
 
The Victron monitors store more information than the cheaper ones. But I find the Victron to be a bit of overkill. The other monitor(s) that I've been talking about will keep track of total amp/hrs consumed over time. Which is more important than voltage. As you draw more amps off of the battery it tracks that in real time. If you then start charging it adds them back in. If that makes any sense. Yes, my display does also show the current draw in watts.

They are very easy to set up and very accurate as they use a shunt to track amps in/out. I too have noticed if/when I start my generator and hook up to it that it never goes into bulk mode or the 14v+ mode. I think the batteries have to be pretty depleted to get that mode to kick in. I've been too chicken to let things go for a few days while boondocking to see if I can it to kick into that mode. I usually just throw the 100w solar charger on it for 3-4 hours and batteries are at 100%. I almost just went ahead replaced my WFCO because it never went into bulk mode. But here it seems my batteries have just never needed it.

On a side note, give them batteries a good few hours to settle after a charge to get an accurate reading on them with no load. They will always read high right after disconnecting from a charging source. Also watch the fluid levels.

If you're plugged in to shore power there will be zero draw on the batteries. If they are 100% when you plug in they will basically just receive a small trickle charge when needed or if needed. Things like the radio consume about 1-1.5w when turn off but still hooked up. I put a switch in my power lead to the radio so I can completely turn it off. You lose presets and the clock memory but that's no big deal for me. The gas monitor is also like a 2w draw.
 
herdbull said:
The Victron monitors store more information than the cheaper ones. But I find the Victron to be a bit of overkill. The other monitor(s) that I've been talking about will keep track of total amp/hrs consumed over time. Which is more important than voltage. As you draw more amps off of the battery it tracks that in real time. If you then start charging it adds them back in. If that makes any sense. Yes, my display does also show the current draw in watts.

They are very easy to set up and very accurate as they use a shunt to track amps in/out. I too have noticed if/when I start my generator and hook up to it that it never goes into bulk mode or the 14v+ mode. I think the batteries have to be pretty depleted to get that mode to kick in. I've been too chicken to let things go for a few days while boondocking to see if I can it to kick into that mode. I usually just throw the 100w solar charger on it for 3-4 hours and batteries are at 100%. I almost just went ahead replaced my WFCO because it never went into bulk mode. But here it seems my batteries have just never needed it.

On a side note, give them batteries a good few hours to settle after a charge to get an accurate reading on them with no load. They will always read high right after disconnecting from a charging source. Also watch the fluid levels.

If you're plugged in to shore power there will be zero draw on the batteries. If they are 100% when you plug in they will basically just receive a small trickle charge when needed or if needed. Things like the radio consume about 1-1.5w when turn off but still hooked up. I put a switch in my power lead to the radio so I can completely turn it off. You lose presets and the clock memory but that's no big deal for me. The gas monitor is also like a 2w draw.
Click to expand...

Good info! Thanks:cool:
 
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