Keep battery fluid from boiling out while plugged in for winter?

[Patrick]

Hello all,

I am prepping my Dynasty for winterizing.  I will leave it plugged in to 30 amp power for the winter and plan to have a small electric heater running inside to keep it dry. I will have a cover over it as well as it rains here all winter long.

How do I best keep the batteries from overcharging and boiling out of fluid over the winter? Disconnect them? If I turn off the battery switches will the AC plugs still work?

Appreciate your advice.

[cbr046]

I'd turn off the engine and coach battery switches and connect a battery maintainer to each 12V battery set (2 maintainers).  That will allow them to keep their charge without overcharging.  No re-wiring of cables necessary. 

Just my opinion, not the words of a battery expert.

- bob

[vito.a]

I don't understand why they would overcharge? 

Your Trace inverter reduces the charge current as the house batteries approach full charge until they are just maintaining.   

Some of your 120v AC outlets are powered by the shore power panel and a few are powered by pass through from the inverter.  

If you do not keep your batteries charged, they can freeze which will swell the cases and ruin them.  

What is your plan to keep your chassis (engine start) batteries charged?

[Ivylog]

Your inverter/charger is a smart 3 stage charger…not going to boil the water out of the house batteries. You need to confirm it also charges the engine batteries… pretty sure it should.

Rarely do I disagree with Vito, but in my 04 Dynasty, all of the outlets (except washer/dryer) are powered through the inverter. One small electric heater will not pop the hard to find breakers on your inverter that feeds the outlets so it should be OK.

Edited October 17, 2021 by Ivylog

[Joel & Susanna]

Regarding the question for keeping the chassis batteries up while in hibernation, could a temporary fused jumper be clipped on between the chassis and house batteries positive terminals allowing our inverter to keep all the batteries up? They do share a common ground. I’ve thought about this but have not done it but... My chassis batteries are two sealed 12’s in parallel, house are four 6’s in a series parallel confit like most others. What could be the down side?

[Ivylog]

A 04 Cheetah probably has a BIRD and BigBoy boost solenoid (located in the RRB) that automatically connects the two. The contacts in the BigBoy are known for corroding and not connecting  them together…fairly easy to clean. Easy enough to put a jumper on the 2 large lugs on it.

[jacwjames]

I have always kept my Windsor plugged in and the battery disconnects on.  My last set of batteries lasted ~9 years.  I make sure to check the water level, use distilled water to top off. 

The only outlets I have not passed through the inverter is the one behind the refrigerator, the washer/dryer/and the block heat.  None convenient to use use inside the coach for a small heater. 

I did rewire refrigerator oultet and added an outlet in the bedroom TV box that could be used for a small heater if I wanted to shut the batteries down.   You could also consider pulling a separate extension cord into the coach to run a block heater completely shutting power down going to the coach. 

[StephenW]

I keep my 01 Dynasty plugged in to 30 amp shore power with 2 electric heaters and a dehumidifier plugged in to keep the coach warm and dry.  The inverter has a pass through for the 110v power and the inverter 3 stage battery charger keeps house and chassis batteries charged.  I also do a regular check on the battery water level. I would highly recommend the dehumidifier to keep things dry.

[Bob Jones]

I would not be concerned about the batteries over the winter. Typically they gas and use water in relation to how much they are used, ie, charged and drained, charged and drained. Unless they are being over-charged, which is unlikely. If you want to ensure all is OK just check/top off the batteries before leaving it and also check the voltage with a multimeter when they are fully charged. That will tell you if they are overcharging and give you the peace of mind that they won't boil dry. 

I suspect you'll find that when you come back to it next year the battery water levels are much the same as they were when you parked it. 

[Gary Cole]

All of this talk about using unattended portable space heaters is scary. Lot of recalls over the years. Ask your local fire chief what he thinks about space heaters. You are trusting that a 7 cent Chinese thermal snap switch will work in the event of an air circulation failure or that it is even within 100 degrees of its claimed rating. There are space heaters available with a low heat density such that they do not require air circulation. A little more expensive but much safer.

I do charge both battery sets from the front bay with a jumper so long as the standing voltage of the chassis and house batteries is very nearly the same. When that voltage starts to drift due to age and use factors I use individual chargers. After experiencing a near battery event which my inverter did not detect, battery temp reached 170 degrees and was still climbing when I noticed the heat when walking around the vehicle, I decided that a small 115 V 10A  3 stage charger is probably a safer option when the coach is in dry dock. Also be aware that some advertised 3 stage chargers are fake. I now verify a new chargers amp and voltage output through a complete charge before I leave it unattended on a battery which I have grown fond of.

 

Edited October 19, 2021 by Gary Cole
having trouble spelling unattended

[lusgi]

if i leave batteries for extended time i make sure they are fully charged and then disconnect them.

[cbr046]

2 hours ago, lusgi said:

if i leave batteries for extended time i make sure they are fully charged and then disconnect them.

They will still self-discharge, and faster in cold weather.

- bob

[Bob Jones]

On 10/18/2021 at 5:26 PM, Gary Cole said:

All of this talk about using unattended portable space heaters is scary. Lot of recalls over the years. Ask your local fire chief what he thinks about space heaters. You are trusting that a 7 cent Chinese thermal snap switch will work in the event of an air circulation failure or that it is even within 100 degrees of its claimed rating. There are space heaters available with a low heat density such that they do not require air circulation. A little more expensive but much safer.

Agreed. My uncle lost a unit due to a 'space heater' - it nearly set his house on fire in the process. That is why I only run an oil-filled radiator-type heater (also for the lack of noise). Asking a fire chief is sage advice, I can just imagine what he would say about them. 

[Chargerman]

3 hours ago, lusgi said:

if i leave batteries for extended time i make sure they are fully charged and then disconnect them.

I do the same. The amount of charge they will loose is very minimal. After leaving mine disconnected for 4 Winter months last year in New England I put them on a digital charger prior to connecting them. Each one was at approx 95% of full charge. 

[StephenW]

I agree with Bob Jones as I only use oil filled radiator type heaters in my coach.

[Rich Cutler]

I rely on my inverter charger system, but I check it monthly for water level.  I do add water the 6v wet cells after the season.   Seems like it always takes a gallon of distilled water to bring the four batteries back to full level.  Same during summer storage as well.  I just assumed that was standard as my previous Endeavor was the same.   I never let the plates get exposed.   I assume that would be the kiss of death for a battery.   

[Chargerman]

8 hours ago, Rich Cutler said:

I rely on my inverter charger system, but I check it monthly for water level.  I do add water the 6v wet cells after the season.   Seems like it always takes a gallon of distilled water to bring the four batteries back to full level.  Same during summer storage as well.  I just assumed that was standard as my previous Endeavor was the same.   I never let the plates get exposed.   I assume that would be the kiss of death for a battery.   

I’m surprised to read that you’re batteries require so much water. Do you see any signs of the batteries boiling over? I used to see this and ended up finding that my charge rate was set too high. After adjusting it my batteries and the compartment stay clean and my battery water consumption has gone WAY down. 

[Rich Cutler]

Steven,

How do you adjust the charge rate.  It does not take long after returning from a trip to reach float.   The inverter appears  to operate properly  and I have all loads off during storage including the inverter.  The generator normally runs during travel for the AC units.   Therefore, no battery load and they last a minimum of 6 years.  Biggest load is boondocks at convention when the refrigerator,  rf18, runs off the inverter.

[Chargerman]

Before considering changing the charge rate are you seeing evidence of your batteries boiling?

[Rich Cutler]

I do not see evidence of boiling in the batteries, just level lowering over time of months of about three.  It takes a gallon of distilled water to refill all four batteries.  Others do not appear to add water at all.

[Chargerman]

It was obvious on mine that the charge rate was too high. I have 8 House batteries and the battery trays were a mess. My charge rate was set at 90% and I changed it to 80% after reading about suggested settings on the forum here. I’m sorry but I am not near my Coach presently to give you the details on how it is set but mine was in the EMS controller. I know it wasn’t hard to find the setting and change it. Hopefully you have your controller manual and can check what your current setting is. 
I also have put 2 oz of mineral oil in each cell which will also help to reduce water loss significantly. I know that I do not add more than a few ounces of water per cell in a year. I maybe add 1/2 gallon a year total to the 8 batteries. 

[Bob Jones]

Wouldn't it be easier to just use a multimeter on the batteries to determine what the actual voltage is at the battery before making decisions?

[Rich Cutler]

I check with Hydrometer, and all OK.  Voltage when connected to power is always OK unless the very occasional boondock, then it will drop as low as 11.6.     I cannot recall the peak voltage the batteries reach, but I do recall it to be correct.