AGM House Battery Charge/Discharge

Liberty WatchDog,

Is factory set to start the generator at 11.15 volts. I asked one of the Liberty's techs, and this setting is unchangeable.

Mike

Imre,

I have installed 4 of the PowerPulse units on the AGMs in my coach. The batteries are only 1 year old, so it is premature to report on their life.

I have spoken with other owners who have installed PowerPulse and they love it. The installation is simple, takes about 10 minutes.

With batteries costing upwards of $3,000, PowerPulse seems like a good investment to me. Mine were about $80 each X 4 = $320 (10%). I'll pay 10% if the battery life is doubled.

Mike,

On the Liberty Watchdog you can alter the start voltage.

The wire that carries the voltage the Watchdog sees as the starting voltage passes through a fuse located on a fuse strip in the electric bay. I think it is a 1 amp fuse.

To make the watchdog start at a higher voltage, all that is required is to add a small resistance in that circuit so when the house voltage is at your target voltage the Watchdog sees its programmed start voltage. I'm sure a few minutes with a soldering iron would get the job done.

Hmm, seems that Liberty and Marathon are pretty close in their battery discharge scenerio's for auto start.:rolleyes:

I think Liberty and Marathon have both done a great job of analyzing the entire concept of battery charging and have probably both concluded the small trade off in potential loss of battery life due to deeper discharging is offset by the reduced number of autostart cycles and length of time between those cycles.

While I resist relying on the autostart I can understand why it was set up that way and the success of the concept has certainly been proven.

It sounds like the only difference between the two converters is one has a fixed voltage level and the other offers an opportunity to adjust the starting voltage level.

Another interesting point just to drive everyone more crazy, is the Webasco and pumps are designed to operate at a range of 10 - 14 VDC. So if that is the case, then our flame throwers should have no problem running at the Liberty/Marathon discharge rates of 11.15 and 11.40.:eek:

This should get Mango deep into the technical manual for Webasco!:D

IMRE,

You need to learn more about Liberty.

When we drive down the road our bus OTR AC keeps us so cool if we did not adjust the knob upwards they would have to thaw us out so we could register in a campground. Our bus AC system does a great job and for my wife and I it is a necessity. Others prefer differnt systems and that is fine.

When we stop and hook up or rely on our generator we use our Cruise Airs.

End of story.

When I am in a campground that cannot supply me with the 50 amp power I am connected to, I have no problem whatsoever running my generator as long and as much as required.

I admit my coach is not set up to run AC units from inverters, but I never can envision wanting to do that anyway. If I need AC I intend to be plugged in or to run my generator. Others may have a different opinion.

Imre,

You don't run the cruisairs all day on inverter, there good for a few hours as needed in between stops or whatever. One good example is stopping to eat or take a break, it's great to just let 1 or even 2 A/C's run off the inverters and then the house is charged back up while driving. I look at it as a temporary short term option instead of running the gen for an hour or two. While driving I can run 2 A/C's indefinately, but I haven't had to do that, my dash air freezes my knee off. Western desert in the summer probably has everyone using the cruisairs while driving. That's one big plus for OTR like Jon has.

If I need A/C long term and there's no shore power, the ole gen will run 24/7 if needed. Mine is so quiet and exhausting out the roof that I doubt it would piss anyone off. Besides, if I'm in a campground paying for 50 amp and it's whimpy causing low voltage to the cruisairs, I'll be on the gen making smoke all night if need be.

This has been a great thread.....our last comment!

AGM's do fail and they do wear out, especially if you discharge them 75% or if they are not properly charged. Servicing hundreds of installations over the years, on average, we’re seeing about 4-5 years life expectancy of an AGM. Gels and good lead acid battery last longer. The primary advantage of AGMs is quick charge time and no maintenance. Don’t get me wrong, they have revolutionized the charging business, but they are not a panacea. Hook them up to a standard charger or, worse, an alternator designed to charge a truck/bus starting battery and you’ll see just how quickly they fail. Although fairly new to the coach business (I think Newell said they have used them for three years now), these batteries have been in widespread use in the marine and other industries for a decade now.

Proper discharge levels and keeping the batteries at a proper, temperature compensated float voltage is the key to longevity. The telecom industry pioneered the use of AGM's and knows more about them than most businesses, and they stress proper float voltage as the critical variable. Sulfation occurs when a battery is allowed to remain discharged for extended periods of time, it’s combated by proper float voltage. The most common cause of failure in AGMs, by the way, isn’t sulfation, that’s more of an issue for flooded batteries, it’s chronic overcharging or high float voltage, which occurs when AGMs are charged w/out the benefit of temperature compensation.