Battery surprise!

[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.

[jelmore]

Jon and others,

Do you know about "power sharing"? I've always had a bit of a hard time getting my head around charger, inverters, batteries, amps and voltage but I'm coming along. In the dip switches, there's one that controls power sharing and from what I read, if enabled, you can set the charge rate to unlimited and the charger will adjust how much is going into the batteries based on the AC loads, and that is supposed to keep the breaker from being overloaded. Do you know about that power sharing feature or do you use it? I like what you said about fire the generator and get the batteries back up quickly, but I think the way I (and you?) have the inverters set up, one provides a fair amount of charge and the other only a small amount. If power sharing works as I described, the Liberty's instructions of unlimited power available to the charger makes sense. I guess it's easy enough to try, it would just be a tripped breaker. I just haven't done that.

[Joe Cannarozzi]

When checking the batteries immediately after a charge they will show a higher voltage than they really are. You have to wait 3 or 4 hours after the charge cycle is over to give them sufficient time to rest and come down to the actual voltage.

I have charged batteries 1 at a time and a bad battery will really show up if you check it the next day, occasionally some dropping 2 or 3 volts overnight.

The longer you let them rest after charging but before checking the more definitive results you will see.

Kinda tough to do when your living on board and moving around every other day.

If your house is 12 volt you can unhook 1 at a time from the bank and still use everything. You may have to buy 2 longer battery cables so you do not have to remove the batteries, so when you disconnect one of the middle ones you can re-hook the 2 on either side of it together.

Be careful wear gloves and glasses

[jelmore]

Never mind on my comments. I just reread the manual and am confused again. On the Freedom 25 units, there's also the issue of how they are wired into the source AC that affects power sharing.

[Jon Wehrenberg]

Jim,

The power sharing phrase has been used in many different contexts. I have given up on trying to determine what it means.

Some coaches are set up so the inverters "know" how much shore or generator power is available and the inverters adjust their current draw for charging so as to not trip a shore power breaker. But not all coaches are set up that way, not all inverters have that capability and not everybody considers that feature power sharing.

Adam's inverters and remote panels sound exactly like what mine has and if I am correct he has to manually set rates of charge. He has no control over which inverter is doing the battery charging. It could be one or both.

[adamdegraff]

Jon,
it does sound like we have the same set up. If I do go ahead and do an equalization, could I do it with the generator only? That is... that manual says it takes 8 hours. Could I just turn the gen on before I go to sleep, flip the #1 switch on then off to trigger an equalization, let it do it's thing and see what the verdict is tomorrow? I do NOT have gel cells. I have 6, 4D Lifeline AGMs. They are a bitch to reach. Even to unhook all the cables would be a multi-hour, warm weather job. Something that won't be in the cards for a while. For now, the best I could do would be to re-inspect for tight, corrosion free connections and, advice pending, run an equalization, and, make sure after that, that my dip switches are set for the proper charge. I just assumed that since Marathon replaced the batteries, that they would have set the inverters up correctly. In fact, I know that the previous coach batteries were also Lifelines. That is not to say thought that the settings were correct.

Am I correct that to check the remote panel switches, all I need to do is unscrew the panel and take a look? I'm a little afraid :-)

~Adam

[Joe Cannarozzi]

Adam you may be learning maintenance cycles here. It is getting close to a year now. That overnight may help with the gen as you questioned. If not you need to check your batts. Is the house 12 volt?

You went from being pretty good to terrible in a matter of 60 to 90 days (some pretty good record keeping too) That is a sign of a possibly bad apple in the bunch.

I would want to know if there is a week battery in the bank dragging the others down. If there is, the earlier you yank it the less harm it does the rest.

I think full timing as you do, frequently on Batts, isolating and then load testing each one separately at once a year should be on the list.