Battery water usage

[RonaldNC]

I leave my motorhome plugged in when not in use. I like to do this so that I can be sure that the two house batteries are in peak shape when I hit the road. My coach also has an EMS that is supposed to maintain the batteries, without boiling them dry.

I check the battery water occasionally and find that I am adding about 1/2 to 1 cup of distilled water to the batteries per month. Is this normal, or is my EMS/charger boiling the batteries?

Ron

[Guest Wayne77590]

Ron,

I have run into the same problem. I carry distilled water and keep it topped off.

[wolfe10]

Ron,

You don't say what size batteries you have. If group 24 or 27 that is on the high side unless you are in really hot conditions. If 8D's or other larger batteries, you are in the "normal" range.

But, do yourself and your batteries a big favor and VERIFY voltage. If you have a smart converter, smart charger or smart inverter/charger, do this at least 24 hours after plugging into shore power to insure that it has gone into FLOAT MODE. Use a digital voltmeter (available at Radio Shack, Sears, etc starting under $25). In the summer, 13.0-13.2 VDC is ideal with 13.5 VDC being at the high end of acceptable.

If you have a smart inverter/charger, be sure it is properly programmed for high temperatures. The charger's owners manual will cover this.

Brett Wolfe

[Guest Wayne77590]

I talked to the service manager where I bought the MH today and he said that it was normal for the house batteries to use water because they are under constant charge. He also said to check the electrolyte with a hydrometer to see if there were any weak cells. If the specific gravity is down on one cell it will cause the water loss from trying to keep the weak cell charged.

Anyhow, that's what he said.

[PIPEWRENCHGRIP]

I too had a lot a battery water usage. I bought a new Monaco Diplomat last July. Our first major trip was to south Texas for the winter. After being set up and hooked up to power for a month or so I opened the battery compartment to find the snaps on the hold down straps coroded off and a various other items badly coroded. I promptly got to an automotive store and bought some spray battery cleaner and protectant. On checking the battery cells I found them to be low. Needless to say I was confused. I even asked a service tech at an RV deadership about it, his comment was that happens all the time!!! I bought a new snap for the battery strap and ignored the problem hoping it would go away, it didn't, next time I opened the battery compartment door, I found the same problem. Then I started studing the problem seriously. After studying my Energy Management owners manual, I found the the batteries were being charged at a very low rate. So I determined that the batteries were being discharged all day long and the evening when we are using 12 volt power. Then they would charge all night long, then again discharge during the day. This going on day in and day out is a lot of discharging and charging thus cooking out the electrolite.

To solve the problem, I simply set the EMS system to charge the batteries at the recommended rate. If I remember correcty that was 85 amps max. This keeps the batteries near fully charged even when we are using the 12 volt systems.

I checked the battery water before we left on 6 wk trip in mid July, and then again Midway through our trip. The water was down only slightly. When we got home the first of Sept. I added a few ounces to ea cell. and NO COROSION. HAPPY HAPPY

BILL

[wolfe10]

I too had a lot a battery water usage. I bought a new Monaco Diplomat last July. Our first major trip was to south Texas for the winter. After being set up and hooked up to power for a month or so I opened the battery compartment to find the snaps on the hold down straps corroded off and a various other items badly corroded. I promptly got to an automotive store and bought some spray battery cleaner and protectant. On checking the battery cells I found them to be low. Needless to say I was confused. I even asked a service tech at an RV dealership about it, his comment was that happens all the time!!! I bought a new snap for the battery strap and ignored the problem hoping it would go away, it didn't, next time I opened the battery compartment door, I found the same problem. Then I started studing the problem seriously. After studying my Energy Management owners manual, I found the the batteries were being charged at a very low rate. So I determined that the batteries were being discharged all day long and the evening when we are using 12 volt power. Then they would charge all night long, then again discharge during the day. This going on day in and day out is a lot of discharging and charging thus cooking out the electrolyte.

To solve the problem, I simply set the EMS system to charge the batteries at the recommended rate. If I remember correcty that was 85 amps max. This keeps the batteries near fully charged even when we are using the 12 volt systems.

I checked the battery water before we left on 6 wk trip in mid July, and then again Midway through our trip. The water was down only slightly. When we got home the first of Sept. I added a few ounces to ea cell. and NO CORROSION. HAPPY HAPPY

BILL

Bill,

What converter, charger or inverter charger do you have?

What is voltage at the battery when charging? If smart charger, what is voltage at float stage (after charging for over 24 hours)?

Why would you ever have it set to NOT charge all the time you are on 120 VAC, and at the proper voltage (assuming your charger or inverter/charger is programmable)?

The only exception would be times that your 120 VAC shore power is not adequate to supply charger and you other 120 VAC appliances . (i.e. you are plugged into less than 50 amps and yet want to run lots of appliances).

Brett Wolfe

[PIPEWRENCHGRIP]

Bill,

What converter, charger or inverter charger do you have?

What is voltage at the battery when charging? If smart charger, what is voltage at float stage (after charging for over 24 hours)?

Why would you ever have it set to NOT charge all the time you are on 120 VAC, and at the proper voltage (assuming your charger or inverter/charger is programmable)?

The only exception would be times that your 120 VAC shore power is not adequate to supply charger and you other 120 VAC appliances . (i.e. you are plugged into less than 50 amps and yet want to run lots of appliances).

Brett Wolfe

I'm away from my unit right now, so I can't tell you the make and model of my charger inverter. I bought this RV new and the charging system was apparently set at the factory or by the dealer. I assumed that it was ok untill I started having problems. I'll get back home on Tues and chech out the Inverter Charger etc.

[wolfe10]

I'm away from my unit right now, so I can't tell you the make and model of my charger inverter. I bought this RV new and the charging system was apparently set at the factory or by the dealer. I assumed that it was ok until I started having problems. I'll get back home on Tues and check out the Inverter Charger etc.

Bill,

If it is one of the "smart" inverter/chargers, be sure to run through the programming steps (in the old days it was called "setting the dip switches" as you physically had to move small switches). On most units, this programming is done from the inverter remote.

These things are smart enough to REALLY do a good job if(and only if) you "tell them what you need".

Programmable issues include:

Battery bank size (in amp-hrs): A charger programmed to charge a 120 amp-hr battery bank would not work well on a 400 amp-hr bank and visa versa.

Type of battery: Wet cell, AGM or gel. Each is different.

Temperature: Many allow you to tell them ambient temps (wide range) if programmed for winter and run that way in the summer it WILL overcharge the batteries.

All this information should be in your inverter/charger's owners manual.

Brett Wolfe

[garykd]

Hi Ron,

Consider doing what Wayne posted. Checking the specific gravity of each cell will confirm or rule out a bad cell or two. Once a cell goes bad, boiling will start. Maintenance (adding water and cleaning the compartment) will be constant. Your auto parts store will have a tool that you can make this check. Fill the batteries with distilled water. Then fully charge the batteries. Allow the batteries to set (with no drain) for 24 hours after charging is removed. Remove the coach connection cables to ensure there is no drain. If the cells check good, make the check again after several days (up to one week). Without a drain, the batteries should hold their full charge for at least a week.