Battery gauge reliability?

[Skyhigh]

Is the gauge that comes with the Hawk that displays battery life and water level accurate? I'm sure the water level was right but I put in a fully charged blue top Optima and the gauage only read 3/4 full. I then drove to the campsite for an hour with the battery plugged in to the truck and when I got there it showed half full and then stayed at that reading for the three days that we were there. Is this common with these gauges?

 

[Mark W. Ingalls]

My meter is pretty accurate, as long as I turn off everything before using it.

Sorry to hear about your problem, Sky.

 

[Skyhigh]

Does this gauge seem to work for everyone else? Maybe I got a dud. Seems to me after three days of using the furnace and lights the gauage should move.

 

[Ted]

battery guage

Skyhigh,

Maybe your guage is faulty. Our rig is about five years old now. When new, it had the Optima battery that FWC uses as a standard. When starting out on a trip or after driving a while, the gauge would have a green light. If we ran the lights (not fluorescent) a while, it would read yellow. If the heater was running, it sometimes would even read red.

Like Mark said, it would depend on weather something was running. So try this - while holding the button to the gauge on, turn on an appliance like the heater. When the fan kicks in, the guage reading should go lower. Then turn the heater off, and it should read higher.

By the way, after about four years we found the Optima drained very easily. Upgraded to a Lifeline AGM and have had no lack of power since. We'll see if that is still the case after a few years.

Ted

 

[Skyhigh]

My bad. The gauge is fine, my 30A fuse was blown and the optima held its charge so well the gauge didn't move even after running the furnace for three nights. I replaced the fuse and charged the battery and everything is in working order.

 

[Jack]

Battery Gauge

Bottom line, get a $10 digital voltmeter from Radio Shack, print out a battery charge voltage chart, and make your own measurements (the 12V outlet is a lot easier to get to than the battery).

The gauge is almost for sure just a simple voltage divider network. I checked my gauge when I was having problems with the Optima and found that the Fair LED comes on at about 12.1V, which is about 40% of full charge. The alternator puts out over 14V and by the time the juice reaches the battery, you will find it is between 13.5V and 14V, so the Charge LED comes on a bit above 13V. There are a number of sites that have battery charge tables (http://www.e-marine-inc.com/articles/battery_charging.html has a lead-acid table, which should be similar to the Optima). To measure voltage, turn off all 12V appliances and lights (the gas monitors probably won't make much of a difference). Also, the voltage will be a bit higher just after charging, so run some appliances for 10 or so minutes before making a reading.

The Optima actually failed, but the effort to get a warranty replacement was so onerous that we just ditched it (recycling center) an bought a higher rated Interstate (which I think FWC now uses).

Some other tips. You want to avoid completely discharging even a deep-cycle battery (that happened inadvertently to our Optima, which killed it). Also, if the battery is very low, the battery separator switch may not engage the alternator to recharge it. You can use a jumper to override the switch or use shore power to recharge.