[Archived]

David, I have had two Liberties with inverters and Lifeline batteries. I have learned a little about batteries and battery life and know what it takes to make it through the night.

First, after driving, even for an entire day I know my house batteries are not fully charged. Lifelines and I assume most AGM batteries require a bulk and absorb charge of 28.4 to 28.8 Volts and our alternators are only maintaining batteries as we drive at 27.7 (approximately). So to fully top off my batteries when dry camping at the end of the day I run the generator and allow the inverters to complete the charge. Failure to do so leaves the batteries at a charge of 85% for example, and if they don’t get routinely fully charged the sulfating of the plates remains and battery capacity is reduced.

A Classic has three batteries and depending on loads getting through the night without recharging might be difficult. Our Liberty coaches have a lot of phantom loads we cannot control or turn off. But we can turn off the circuits to the TV, water pump, and any other devices we will not use through the night like the microwave, coffee maker and aux compressor. If we use a lot of lights for reading, watch TV, run a shower, or a multitude of other current draining loads we should consider running the generator (and inverters) up until we go to bed.

On my 4 battery Elegant Lady I have 33% more power available so I can wake up with voltage down to 24.5 or above so I’m still OK, but as my batteries age I begin to see the morning voltage less and less.

But the key to maintaining batteries is to avoid discharges below 50% and to always top off the house battery charge at the end of a day of driving by being plugged into shore power or running the generator.

[Archived]

Well, things seemed to be working well on the way out here to Phoenix, the house alternator was charging well at the high 13s most of the way, though it did fluctuate up and down between high 12s and almmost 14. Toward the end of the trip seems like it stopped charging. Will see what happens on trip back today.

Even when it was charging on the way out seems like the ammeter never went above 50 or so. Is there some other regulatory system besides the integral Leece Neville regulator? The original alternator that I removed was fried.

[Art]

Do you have two alternators? One for the chassis batteries and one for the house batteries. I think you have two and not just a single one. Please confirm. We have just a single, massive 50DN alternator that supplies DC power to both the house and the chassis batteries through an isolator (big blue device with fins in the engine bay). While on our trip to Florida I noticed the house voltage meter at zero while driving. Eventually figured out it was the isolator, got a new one, and replaced it (pretty simple job). If you have two or more alternators, you might have a different problem.

How is the charging when you are plugged into shore power?

Like Jon posted, I have discovered that even with the entire charging system running as it should the alternator on the Detroit Diesel doesn’t bring the house batteries up to full charge and I need to run the generator if we’re not plugged into shore power at the end of the day if we’ve been running on the road for a few hours.

Do you let the WatchDog start your generator if you’re not plugged into shore power? If so, its likely starting the generator when the house battery voltage has dropped below the optimum level (which I think is 24.1 or 24.2 volts or 12.1 volts on a “12 volt coach” … Jon or Tom should quickly correctly me if I’m wrong. You should watch the voltage on the house batteries when you’re not plugged into shore power and probably start the generator BEFORE the WatchDog kicks in. Allowing the Lifeline AGM batteries to discharge below that magic number shortens their life.

The WatchDog was likely a wonderful piece of technology when our coaches were built 18 to 20 years ago. But as I understand it, there is better technology available for battery/generator management today that could be installed on our coaches when we upgrade the inverters/changers and their controls.

Another thing that shortens AGM battery lives is allowing them to fully discharge; especially more than once.

We’ve had our Lifelines for almost five years. They don’t last as long has they originally did, or even did a year ago. I’ll be taking steps on the next set of Lifelines to make them last longer.

[Ronald]

David, the Classic with its 2 alternators uses the smaller of the two alternators for the house because the large 50DN output is needed for the over the road air power requirements of the chassis.

Unfortunately the small alternator has an internal regulator that is not adjustable.

As to why it is failing or has failed I cannot answer, but the key to a healthy alternator is to keep the loads minimal because they generate heat when working and heat is the enemy. One possibility is if your 3 house batteries are being nearly depleted overnight, with every start up the alternator is putting out a lot of current, more so if you are not topping them off after a day of driving with the generator or shore power supplying power to the inverters.

Our coaches are energy hogs and we have a lot of phantom loads we not only are unaware of, but we have no way to turn them off to reduce the draw on batteries overnight. We have burglar alarms, there is power to the TVs, we have clocks, and all sorts of devices that are powered from the house batteries.

Then if the house batteries are not topped off after driving all day they begin to lose capacity and the loss of capacity continues through their life. I am in the habit of connecting to shore power or running the generator after driving all day so the inverters can get power to do a bulk charge at about 14.4 volts in the case of the Classic and then dropping back to float. The alternator is likely limited to 13.6 to 13.8 volts which is only a maintenance charge.

[Bill]

Thanks for the information. Yes I have two alternators. The 50DN is 24 v and runs chassis and otr ac stuff and some diesel engine control system items via equalizer. The 12v Leece Neville which sits up on the fan drive right angle drive platform charges the house batteries.

During this trip out I left with fully charged batteries and it seemed like the alternator was keeping up with down the road loads essentially only the refrigerator and the misc parasitic loads. Toward the end of the second day of travel, the voltage started to fall and when it hit 12.6 I fired up the generator and ran it till I got to campground in PHX. Stayed on shore power while in PHX.

Left PHX today and as soon as I unhooked shore power, the house alternator was not charging per ammeter/voltmeter. Voltage stayed at 12.8 for a few hours, then 12.7 for a couple more, all the while showing about 25 amps discharge rate on the house batteries. When it got down to 12.6 around petrified forest NP I fired up generator. Ammeter showed immediate jump to charging rate 100+ amps and voltage about 14. Ran for a few hours till showed “full charge” on the inverter lights. Shut off generator. Voltage immediately dropped to 12.8. Shortly later while driving down road I glanced at volt/ammeter occasionally and for about a minute or two once, the system showed charging at 50 amps and 13.8 or so volts, then the needle fell down to high 12s and discharge on amp needle and has stayed there until we shut down at KOA in Tucumcari.

When I get home and find some free time will recheck wiring in area of the alternator and see if something is loose, check voltage at alternator terminals when running, etc.

One question I have is does the charging current from alternator pass through or is in any way affected by the inverter system? I recall reading past posts about how the AC feeds to the coach are sometimes affected by the inverter system in some older coaches. Could this be happening with the alternator output, or is there a “hardwired” connection from alternator output stud to the battery bank?

[Bruce]

If I interpreted your description of what is happening it sounds like the alternator is intermittent and your idea to check connections, etc. is a good one. The voltages and voltage drops you see would be exactly as I would expect as long as there was no charging. The discharge of 25 amps is not unusual and it indicates a load I would expect at 12V.

Any regulated charging current, whether it is from the alternator or inverters is going to be unaffected by charging from a second source. A regulator as the name implies controls how much charging current is applied to the batteries. So imagine you have a setting of 13.8V for the alternator and it is charging the batteries. Then you start the generator and the inverters have an initial charge rate of 14.4V and a float charge of 13.6V.

At that point the batteries are being bulk charged by inverters and the alternator is not doing any charging because its regulator is not seeing a voltage calling for a charge. Once the inverter bulk charge is satisfied it wants to go into float at 13.6V, and as the battery surface charge drops past 13.8V the alternator picks up the charging, and the inverter stops charging because its voltage requirement for float is being maintained.

There are a lot of conversions running the highways with generators running, inverters on, and the alternator(s) providing charging current all at the same time with no ill effects.

[joel]

Thanks for that excellent explaination Jon.

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1999 XLV X-6872,  liberty #440

[Archived]

I remember one of the common failures on your 50 DN alternators, was the wires at back side. Larger size wires are crimped to connectors then placed over threaded 50DN locations.

Test… to pull on each wire a couple inches from each connector. This test will explain intermittent charging issues.

In one case pulling on the wire we were able to remove it from crimp.

Engine shake is the reason for failure of a tight connection.

AL

[Archived]

The alternator in question is not a 50DN, but a smaller one with internal regulation. But it is true wires and connections could be the problem.