Battery surprise!

[adamdegraff]

Hey All,
When I took possession of my coach, almost exactly one year ago, I bought brand new coach batteries and chassis batteries. The coach batteries were impressive. (6 big Lifelines... I think 4D, but I'd have to check to be sure.) They would run what they were supposed to run in my coach for 12-16 hours without causing the Auto Gen Start to kick on. This was true in the dead cold of winter and the heat of summer.

9 months later, the batteries were still doing OK, though I was down to like 10 hours of regular usage time.

10 months, down to 8 hours.

11 months, down to 6 hours.

12 months, down to 4 hours

Almost 13 months, about 3 hours.

Keep in mind that my usage "style" has not changed. They just won't hold the charge as long. Visual inspection reveals clean, well connected battery cables. Though, the batteries are packed in there tightly and it is difficult to tell for certain. No green corrosion is visible. The charge from the Alternator and the Generator both test as the same as they did before. The alternator, around 26 volts (always been that way), the generator is at 27.7 or so.

I really thought that by going with what I thought were top of the line batteries, they would last a little longer. I guess I expected some decrease in battery life as the years past. But not such a significant difference by the month.

Any thoughts? Should I have gone with a different battery / brand?

Thanks!

Adam

[jack14r]

I have heard that AGM and gells have some memory,I don't know if it is true.I was told that 3 discharge cycles along with 3 complete charges would wipe out the memory.I have always wondered if it was true.

[Jon Wehrenberg]

Adam,

This link is worthwhile reading. it will give you a better understanding on your batteries, battery charging, and specifics about charging rates and the general care and feeding of batteries.

There are a lot of factors that influence the life of a battery. The voltage when your autostart is initiated for example influences the number of life cycles on your batteries. Other factors also determine your battery life such as charge voltages and rate of charge. All of this information is in this link:

http://www.windsun.com/Batteries/Bat...ery%20Charging

But before assuming your batteries are no good you need to do some checking. First determine that using a battery tester. You will need to remove the cables and test each battery individually because if you do have a failed battery nothing you learn in the link above will help. If the batteries test OK (make sure you use a tester sized for the batteries) all you may need to do to bring some life back into them is to give them an equalization charge. Your inverter handbook can help you do that.

Our batteries are our direct link to a life of ease in our coaches. They are a consumable item and have a life span. We can influence that to a great extent. We can use and charge them in the most beneficial manner, or we can abuse them. The key is in making sure the inverters are programmed for the specific type of batteries, that the inverters are set at a charge rate that does not exceed the best rate, and that we comromise by not allowing an especially deep discharge before recharging.

My guess is you have a bad battery, but it could be you also may have some errors in how the inverters have been programmed.

[Joe Cannarozzi]

Do AMG and gel type need to be desulfated periodically like wet cells.

What is even more alarming to me is I would think that someone full-timing could get more life from batteries due to frequent use than others who don't.

[adamdegraff]

Jon,
just to be clear, if I disconnect all six batteries to test them, do I then have to remove them from the bus? (huge difference in time!) Or would I be able to get a tester to each of them? (I know.. you can't see my battery compartment, but I think all Marathon's are the same.) Where does one obtain a battery tester like this? Is it something I can get done at any old RV dealer?

I will take a look at that link and report back.

Thanks for your post and all of your help!

~Adam

[Jon Wehrenberg]

Adam,

The batteries can remain where they are as long as you can get at the terminals.

Here is the tester I use:

http://www.nationaltoolwarehouse.com...qx/product.htm

There are many on the market. I selected that one because it goes up to 2000 CCA.

You don't have to buy a tester if you can drive the bus to a battery place like Batteries Plus. They can do the test. Of course you will be sitting in the parking lot disconnecting cables drawing attention. This might be heresy, but if your batteries are ventilated well, and easily accessed so you can check and service them lead acid are robust, cheap and give good life. I would not consider them unless accessing the caps is easy and the compartment has plenty of ventilation however.

Joe,

AGM can be given an equalization charge 2 to 4 times annually. I don't think all gel cell batteries can take the voltage of an equalization charge.

[truk4u]

Adam,

The life of the batteries are based on cycles. For someone like yourself, being full time and using the bus as it was intended, I think you will probably use up the life of your batteries much sooner than most of us. This is my own opinion, but if you think about it, every time you hook to shore power or run the generator, your batteries get a bulk, absortion charge then go to float. I think all these cycles add up and take the life out of the batteries. On my Marathon, I used to change the Trace settings so I didn't get a bulk charge when plugging in after running all day since the batteries were fully charged.
I also discussed Equalization with LifeLine for AGM's and they didn't recommend it, but maybe it can't hurt.

I have been using this Battery Load Tester for 10 years and just replaced it this week for another of the same brand. It's 49.00 at NAPA.

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[adamdegraff]

OK, I'm looking at my heart interface freedom 25 inverter/charger manual. A few questions.

1. I have two inverters... like everybody else I suppose. Do both inverters charge the batteries? Or is just one used to do that. I assume they are both set up for that.

2. I see that the dip switches can be set for different types of batteries. Wet cell cold, wet cell warm, gel cell cold, gel Cell warm. I have AGM, Lifeline 4D's. I assume mine should be set for one of the Gel settings. I have 8 options to choose from and it does tell me, for each battery type, the folloiwng specs:

what the Bulk Voltage/Max time is
the float voltage
and the Equalize Voltage.

I assume, somewhere, for Lifeline 4D's, there is a chart telling me what they should be set at, thus assisting me in choosing the setting?

Thanks!

Adam

[garyde]

Hi Adam. From what I remember, my Lifeline batteries came with a chart indicationg recommended rate of charge. Since I had Gel batteries previously, the new AGM's were the same rate of charge.
When I removed my old Gel batteries, two batteries were bad, reading 11 volts.

[Jon Wehrenberg]

Adam, The short answer is that gel and AGM batteries have two different charging protocols. AGM are tolerant of charging cycles like those of lead acid (flooded cell), but gel battery charging voltage limits are lower.

The manufacturer's charging instructions are to be considered the gospel, but in general you can bulk charge AGMs at around 14.25 volts (28.5 if set up as a 24 volt system) but should limit gel cell batteries to around 13.8 (27.6 for a 24 volt set up). An equalization charge will be somewhere around 15.2 volts, a definite no-no for gel cell batteries. Float or absorbtion voltage should drop down to around 13.7 (27.4) volts.

The rate of charge expressed in amps is dependent upon how you use the coach. "Dry" camping probably dictates a high rate of charge so the generator can fire up as needed, slam a charge into the batteries and shut down quickly. Using that rate of charge if connected to shore power however may trip the shore power breakers if you are also running some AC units, so setting the dipswitches like everything else in our coaches is a compromise.

I am guessing here, but if your dip switches are set for gel, you may not have been getting an adequate charge.

Both your inverters do carry the responsibility for charging your batteries. However, it sounds like we have the same inverters and set up, and if so I have noted that one of mine predominantly carries the charging load. If you want to verify both are working however, turn off the small inverter switch in the remote panel on the one handling the charging, wait a few seconds (there is a delay built in) and see if the other one picks up the charging load. When you turn the switch back on the other inverter may retain the charging workload. I suspect the reason is for slightly different values in the sense circuits of the inverters.

Your first step is a battery test. let your generator run a long time until with no DC loads (like lights) your DC current is showing the lowest value. That would indicate the batteries are as charged up as they are going to get. Then disconnect the cables and test them. It may be that you need to give them an equalization charge (I think that is dip switch number one, which should only be on for this purpose. Check the book), or it may mean there is a bad battery.

As Truk pointed out however, batteries are consumable. There is a direct correlation between battery life based on depth of discharge and number of cycles. We use our coach different than you do, so our depth of discharge is minimal. As a result my 4 1/2 year old batteries still show a 25 volt charge in the morning after sitting all night in a rest area without running the generator at all during the night. But my "dry" camping events during those 4 1/2 years can be counted on my fingers. We are either driving, or plugged into shore power so our depth of discharge under normal conditions is almost nothing. You may have deep discharge conditions depending on the auto start voltage, and your batteries may only last 1000 cycles.