When do you replace the chassis battery(s)?

[b-Bota]

Yesterday I turned the ignition to acc. to dump the air suspension. I got busy doing some other things and completely forgot to turn the ignition off. This morning I found the chassis batteries dead. I disconnected the batteries from each other and attempted to charge each battery. The batteries are sealed and would charge no more then 64%. When I tried to start the MH the motor turned very slow and the batteries drained quickly. We purchased the 2005 DP MH about six weeks before. I suspected the batteries were the original factory batteries, however they always started the MH easily every time. Now I have no doubt that the batteries would have failed on the first really cold Michigan morning.
When my car battery fails I just jump start it (or call AAA) and take it to Sears (or Sam's Club) and have the battery replaced. Finding replacement batteries for the MH and then installing the heavy batteries was a chore. Something I wouldn't want to do on the the road and/or in cold weather. I have come to the conclusion that I should have changed the batteries before they failed. Because I am inexperienced with these heavy duty diesel batteries my question is, when do you change the chassis battery(s) on your MH.

[TeJay]

That's a difficult question to answer. If the B+'s (batteries) are charged regularly they should last at least as long as the warranty. A 60 month B+ 5-years, 72-month B+ 6 years and so on. Most warranties are prorated so if they fail before their time you will get some $$$ back.

Here's what I would do. As I previously stated B+'s need to be at least trickle (slow) charged monthly because they will loose their charge just sitting around. If they stay in a discharged state for long periods they will sulfate or be less likely to accept a charge when it is attempted. So if you run your generator monthly as recommended then the coach B+s will get some charge.

As you get towards the end of their life you can have the B+s load tested at almost any shop. A load test does this. First the B+ is charged by a known good B+ charger. In other words they don't rely on your charging system to charge the B+ because it might not be working up to standards. It should be charged until the B+ charger says that it is fully charged. Then a carbon pile rheostat is is used to apply a load (current drain) to the B+. There may be some different loads placed on some B+'s but on a standard car/truck B+ they will apply a load of 1/2 the CCA (cold cranking amperage) rating for the B+ for 15 seconds. The B+ will test good if it can maintain that load for at least 15 seconds and still keep the B+ voltage above 9.6 volts. If the voltage falls below that the B+ will not hold a sufficient charge to remain in service.

It's kind of like this. Voltage is pressure and current is the flow of electrons. If you want to test a water pump to see if it is working properly you set up a test to see if it can fill up a certain sized container in a certain amount of time while still maintaining a certain pressure. A small trickle of water over 10 hours won't put out a fire but if you need 1,000 gallons in 10 minutes then you need pressure.

Sorry, I just can't give a simple explanation. It's just not in my nature.

TeJay

[Muncie_6spd]

I normally change batteries at least every 5 years. I tried keeping the one in my wifes car longer than that but after having it load tested by my dealer at 5 years old and being told it was fine it ended up going dead a few months later.
Good Sam had it jump started within 15 minutes and I had it replaced immediately afterwards.

The chassis batteries in my MH are now 5 years old and will be replaced shortly just to be safe.

Mike

[Medico]

Generally I change batteries when they do not crank as they should. In your case, the 8 year old batteries will not do so. Even if you have a booster switch which connects the house batteries, this is not meant for a replacement for good chassis batteries.

I think it's time to replace yours, sorry!

[jenandjon]

I use to run em till they were completely shot. Now older and with a family I don't want the wife and kids stranded so I change at 5 to 6 years unless I notice its weak then sooner.

[clyon51]

Starting batteries can last 10 years if not allowed to ever fully discharge and are always kept in a charged state. Unlike a deep cycle, after about 10 full discharges, they will be useless.

We don't know their history, but from what you describe they are shot, especially if they are 8 years old.

I'm very picky on battery maintainance and all my batteries go on chargers if used and fully charged once a month. As far as my coach, it stays plugged in 24/7 and maintains the chassis batt, so I don't think about it much before 8 years. 5 years is a good rule of thumb to at least have them load tested.

[Lloyd in S.C.]

I maybe adding what you already know..............

Starters are expensive. Cranking the engines with less than fully charged batteries is no good for the starter. Considering labor/time to change them, batteries are a no brainer.

Stinks that you goofed and killed them, but the high road is get some new batteries.

PS : I did the same a few months ago with one of my motorcycles, got side tracked and left the key on for over 2 hours. It cost me a battery as it would not accept a full charge on a 3 year old battery. (i've been getting 5 years out of them by leaving a tender on them whenever not using)

L.

[b-Bota]

Thanks to everyone for sharing their wisdom. I have replaced the chassis batteries and am ready to hit the road.