02-23-2018, 01:41 PM
Gurus,
I arrived at my coach after a two week absence and found the start battery dead...as in doornail. When I got the coach five years ago, I went through three sets of engine batteries in the first year. After I switched to AGM batteries, the problems seemed to smooth out....until this week! (frown face). I thought...oh no the gremlin is back.
I merged the start batteries with the house batteries, but did not have luck starting the coach. (After waiting a while with the batteries merged, I finally was able to start the engine). There is a possibility that my inverter had the charging function set to OFF. I have an Xantrex echo charger and when I looked at it while charging the batteries, I saw that it had a green light which means it is charging the engine batteries. (Green blinking means that it does not sense enough voltage in house batteries to charge engine bats)
I went through a charge cycle with the inverter. The Magnum cycle is Bulk Charge->Absorb Charge->Float Charge->Full Charge. This takes several hours.
So Starting from Full Charge I took a few measurements. With the batteries not merged.
House Battery = 13.4 volts. Engine Batteries = 12.5 volts. It kept these measurement overnight. I did notice that the light on the echo charger was blinking this morning. Hmmmm.
Puzzler....Why did my engine battery go dead in the first place? With Richard's help we developed three possible theories. 1). The echo charger is bad and not charging the bats. 2). The batteries are toast and cannot take a charge and 3) There is a ground problem.
Tick Tock, what's the answer? (Turns out this is a trick question, because it turned out to be none of the above)
Before we get to the answer, here is some theory on the echo charger....
From Xantrex manual:
This means that the Echo Charger essentially follows the charge cycle of the house batteries. When they are charging they will be typically higher than 13 volts and the echo charger will come on. When you are using them, they will fall below 13V and the echo charger will turn off.
In order to understand my situation, I disconnected shore power and ran the microwave for a while. When I reconnected to shore power, the inverter sensed voltage less than 12.8 volts and started a charge cycle. During a charge cycle you will see close to 14V going to the house batteries. I went back to the Echo Charger and expected to see a green light. Nope....still blinking.
So at this point (with a charge cycle going) I measured 12.5 Volts at the engine batteries and 13.4 at the house batteries. Hmmm... Why wasn't the echo charger coming on?
Answer: I followed the wires from the fuse block labeled "Echo Charger" up to the echo charger. The wire labeled Start Battery measured 13.4 volts and the wire labeled "House Battery" measured 12.5 volts. Wait!!!! that is backwards. I unbundled the wires and found two splices in the wires. Someone / somewhere along the way replaced the echo charger and got the orange and red wires reversed. This echo charger has never worked because it was wired wrong. When I saw the solid green light it was because the batteries where merged and it sensed >13Volts. I rewired by swapping the house and start wires and then re-tested. The green light came on during the charge cycle.
Lessons learned: 1) If the house batteries are less than 13V, the echo charger will blink and will not charge your start batteries. 2) Just because you see a green light on the echo charger, do not assume everything is ok. If the batteries are merged and charging, the green light would come on with incorrect wiring. 3) It helps to not merge your batteries when troubleshooting. 4). Don't be a doofus like me and randomly turn off your charger unless you really mean to. 5). You don't need to merge your batteries to keep the engine batteries charged if you have a properly wired and operational echo charger.
I arrived at my coach after a two week absence and found the start battery dead...as in doornail. When I got the coach five years ago, I went through three sets of engine batteries in the first year. After I switched to AGM batteries, the problems seemed to smooth out....until this week! (frown face). I thought...oh no the gremlin is back.
I merged the start batteries with the house batteries, but did not have luck starting the coach. (After waiting a while with the batteries merged, I finally was able to start the engine). There is a possibility that my inverter had the charging function set to OFF. I have an Xantrex echo charger and when I looked at it while charging the batteries, I saw that it had a green light which means it is charging the engine batteries. (Green blinking means that it does not sense enough voltage in house batteries to charge engine bats)
I went through a charge cycle with the inverter. The Magnum cycle is Bulk Charge->Absorb Charge->Float Charge->Full Charge. This takes several hours.
So Starting from Full Charge I took a few measurements. With the batteries not merged.
House Battery = 13.4 volts. Engine Batteries = 12.5 volts. It kept these measurement overnight. I did notice that the light on the echo charger was blinking this morning. Hmmmm.
Puzzler....Why did my engine battery go dead in the first place? With Richard's help we developed three possible theories. 1). The echo charger is bad and not charging the bats. 2). The batteries are toast and cannot take a charge and 3) There is a ground problem.
Tick Tock, what's the answer? (Turns out this is a trick question, because it turned out to be none of the above)
Before we get to the answer, here is some theory on the echo charger....
From Xantrex manual:
Quote:When the input voltage is 13.0/25.5 volts DC or higher, echo-charge automatically switches ON. The LED glows a steady green. When the input voltage is lower than 13.0/25.5 volts, the echo-charge automatically switches OFF, and the LED blinks green. The output voltage of echo- charge is limited to 14.4/28.8 volts. When it reaches 14.4/28.8 volts, the charge current will decrease, maintaining a float condition. The starter battery will be fully charged without overcharging.
This means that the Echo Charger essentially follows the charge cycle of the house batteries. When they are charging they will be typically higher than 13 volts and the echo charger will come on. When you are using them, they will fall below 13V and the echo charger will turn off.
In order to understand my situation, I disconnected shore power and ran the microwave for a while. When I reconnected to shore power, the inverter sensed voltage less than 12.8 volts and started a charge cycle. During a charge cycle you will see close to 14V going to the house batteries. I went back to the Echo Charger and expected to see a green light. Nope....still blinking.
So at this point (with a charge cycle going) I measured 12.5 Volts at the engine batteries and 13.4 at the house batteries. Hmmm... Why wasn't the echo charger coming on?
Answer: I followed the wires from the fuse block labeled "Echo Charger" up to the echo charger. The wire labeled Start Battery measured 13.4 volts and the wire labeled "House Battery" measured 12.5 volts. Wait!!!! that is backwards. I unbundled the wires and found two splices in the wires. Someone / somewhere along the way replaced the echo charger and got the orange and red wires reversed. This echo charger has never worked because it was wired wrong. When I saw the solid green light it was because the batteries where merged and it sensed >13Volts. I rewired by swapping the house and start wires and then re-tested. The green light came on during the charge cycle.
Lessons learned: 1) If the house batteries are less than 13V, the echo charger will blink and will not charge your start batteries. 2) Just because you see a green light on the echo charger, do not assume everything is ok. If the batteries are merged and charging, the green light would come on with incorrect wiring. 3) It helps to not merge your batteries when troubleshooting. 4). Don't be a doofus like me and randomly turn off your charger unless you really mean to. 5). You don't need to merge your batteries to keep the engine batteries charged if you have a properly wired and operational echo charger.
Bill Johnson
Birmingham, Alabama