Inverter question

[prstlk]

We have a 2007 Holiday Rambler DP with an Onan 8500 Generator and an inverter.

The way it is set up through the Magnum Energy panel inside, our batteries do not charge as we are going down the road. The only way to charge them is to start the generator and run it for 2 or 3 hours or plug into shore power.

We called the manufacturer of the panel and they told me that I was to start the coach and go back and look at the panel. If it says “inverting” then it is not charging while the engine is running. This is in fact what it says. He basically told me that some charge while going down the road and some don’t and that it depends on how the MH manufacturer set it up.

Can someone tell me what I would need to do to have the batteries charge while the engine is running and we are moving?

[jyrostng]

I've seen 2 ways they charge the house batteries while moving. One is the same relay the Aux button energizes, it energizes when the key is on joining the batteries together so the house batteries charge.

The other is a solid state isolator block with the typical one way diode inside, it lets the current only go from the alternator to the house battery, it blocks the current the other direction so the house CKT. can't run down the starting battery.

[FIRE_UP]

pianotuna wrote:
Hi Fire Up,

I've seen 193 amps being drawn on the Magnum 3012. When that happens with the engine running it most certainly exceeds the possible output of the alternator.

My microwave draws 1591 watts / 12.8 volts =~ 124 amps. This number also exceeds the possible output from the alternator.

A 2000 watt inverter, if pushed HARD may drop the voltage to 11.5 so the amps drawn would be about 173 amps.

FIRE UP wrote:


I'm not the sharpest tool in the shed but, aren't most modern class A coaches, especially diesel ones, equipped with at least a 160 amp alternator? If that's the case, and, if the chassis batteries are in good shape, then the alternator can provide anything needed to not only "bring up" but, top off, the house batteries while driving.

Now, lets say you have a 2000 watt Inverter/Charger. Typically that would mean that, that inverter is capable of 2000 watts of A/C output, correct? In my basic knowledge of electrical application and the "ohm's law" theory and all that, "Amps x Volts = watts", correct? So, in reverse, Watts ÷ volts = amps, correct?

So, 2000 (watts) ÷ 13 (average volts) = 153 amps. Now, just because the numbers say that a 2000 watt inverter is capable of 153 amps, that doesn't mean it will actually supply that much amperage, correct? So, let's just cut that number in half, for a more realistic number. Say, around 75 amps.

So, with all that goble-gook being said, according to one of the statements above, the panel on the coach, would have to show a supply of at least as high or higher, than say around 75 amps, in order for the load, to overtake, what would be supplied to the house batteries, in order for a "discharge" or "no-charge" set of numbers to be displayed, correct?

Again, I am by far, no expert in any of this. But, the statement that the panel COULD show a house battery NO-CHARGE situation, due to the Inverter/Charger actually inverting THAT MUCH amperage while driving, sure seems highly unlikely to me. And, if that COULD possibly be the case, what in the world, could demand that kind of amperage, on COACH while driving down the road? I mean, even a micro-wave on full throttle for cooking something sure as heck don't draw 75 amps, does it?
Scott

My numbers and calculations are primarily based on some "assumption" and kind of logic. Of course, both ways of thinking CAN be way off. In reality, I've never even thought that, there can be that much draw on the inverter. On ours, a Magnum 2012ME (not year) it's a 2000 watt unit. I guess I've never really taxed my batteries that much.
Scott

[jyrostng]

the OP question was : "Can someone tell me what I would need to do to have the batteries charge while the engine is running and we are moving?"

I only run the tv, sat box and dish, a few cell chargers, I had the same problem, the batteries were low after driving all day, the 120v heater on the fridge was on all the time if we didn't have it switched to gas. A 70 amp isolator has done fine for keeping the house batteries charged.

[pianotuna]

Hi Fire Up,

I've seen 193 amps being drawn on the Magnum 3012. When that happens with the engine running it most certainly exceeds the possible output of the alternator.

My microwave draws 1591 watts / 12.8 volts =~ 124 amps. This number also exceeds the possible output from the alternator.

A 2000 watt inverter, if pushed HARD may drop the voltage to 11.5 so the amps drawn would be about 173 amps.

FIRE UP wrote:


I'm not the sharpest tool in the shed but, aren't most modern class A coaches, especially diesel ones, equipped with at least a 160 amp alternator? If that's the case, and, if the chassis batteries are in good shape, then the alternator can provide anything needed to not only "bring up" but, top off, the house batteries while driving.

Now, lets say you have a 2000 watt Inverter/Charger. Typically that would mean that, that inverter is capable of 2000 watts of A/C output, correct? In my basic knowledge of electrical application and the "ohm's law" theory and all that, "Amps x Volts = watts", correct? So, in reverse, Watts ÷ volts = amps, correct?

So, 2000 (watts) ÷ 13 (average volts) = 153 amps. Now, just because the numbers say that a 2000 watt inverter is capable of 153 amps, that doesn't mean it will actually supply that much amperage, correct? So, let's just cut that number in half, for a more realistic number. Say, around 75 amps.

So, with all that goble-gook being said, according to one of the statements above, the panel on the coach, would have to show a supply of at least as high or higher, than say around 75 amps, in order for the load, to overtake, what would be supplied to the house batteries, in order for a "discharge" or "no-charge" set of numbers to be displayed, correct?

Again, I am by far, no expert in any of this. But, the statement that the panel COULD show a house battery NO-CHARGE situation, due to the Inverter/Charger actually inverting THAT MUCH amperage while driving, sure seems highly unlikely to me. And, if that COULD possibly be the case, what in the world, could demand that kind of amperage, on COACH while driving down the road? I mean, even a micro-wave on full throttle for cooking something sure as heck don't draw 75 amps, does it?
Scott

[Bill_Satellite]

We don't even know if the OP's batteries are being charged while driving. His concern was that when unplugged the inverter reads inverting but the batteries are not being charged. We really, really need to hear back from the OP as everything else is speculation.

[MrWizard]

the one thing the OP needs to understand
is that the Magnum inverter/charge combo
has absolutely NOTHING to do with the alternator
no matter what the tech on the phone told him

he has a break down in the chassis to house charge circuits

loose connection, bad isolator charge control, or one side of a dual output alternator that is out, blown fuse in the alternator to house batteries circuit

yes.. if the inverter is on powering a heavy load, it will suck on the batteries
and INVERT mode is normal IF there is no 120vac coming in

he didn't say but i wonder if it is an ALL ELECTRIC coach
{ if so he has to have the inverter on or generator on when not plugged in }
and blew out something on the chassis charge input side

[jyrostng]

On mine, the relay in the box under the hood was bad, rather than take the box apart and change the relay, I added this battery isolator under the box and ran heavy duty wires to the bad relay terminals to it. orielly isolator

[crasster]

Sounds like an isolator issue. Check all wires going to the isolator.

[MrWizard]

My inverter draws between 104 to 120 amps when powering the MW depending on the battery SOC
At 100 percent charged batteries it's easy to pull 120 amps
The coffee maker pulls about 80 amps

An add on inverter for whole house, could easily be pulling 100 amps running the heating element in the water heater

It's all a matter of wiring and power management

Now if the inverter is actually turned off

I don't know where his power is going

Has the alternator been tested and verified

All batteries tested

The dash/chassis a/C checked, clutched not engaged or shorted
There are many thing that can pull heavy power

[FIRE_UP]

SCVJeff wrote:

pianotuna wrote:
Jeff,

If the inverter is on, it may be that the engine charging path may not be able to keep up with the load. That would cause the house bank to discharge while driving. That makes it appear as if the alternator doesn't charge the house bank.

Of course, unless special efforts are made, alternator charging is about the starter battery, not the house bank.

SCVJeff wrote:
What I'm missing here is the "Inverting" comment.. That has nothing to do with the charge process, and is a user select manual button push.

that I'll agree with with, but I've not seen an inverter go into invert mode without being turned On

I'm not the sharpest tool in the shed but, aren't most modern class A coaches, especially diesel ones, equipped with at least a 160 amp alternator? If that's the case, and, if the chassis batteries are in good shape, then the alternator can provide anything needed to not only "bring up" but, top off, the house batteries while driving.

Now, lets say you have a 2000 watt Inverter/Charger. Typically that would mean that, that inverter is capable of 2000 watts of A/C output, correct? In my basic knowledge of electrical application and the "ohm's law" theory and all that, "Amps x Volts = watts", correct? So, in reverse, Watts ÷ volts = amps, correct?

So, 2000 (watts) ÷ 13 (average volts) = 153 amps. Now, just because the numbers say that a 2000 watt inverter is capable of 153 amps, that doesn't mean it will actually supply that much amperage, correct? So, let's just cut that number in half, for a more realistic number. Say, around 75 amps.

So, with all that goble-gook being said, according to one of the statements above, the panel on the coach, would have to show a supply of at least as high or higher, than say around 75 amps, in order for the load, to overtake, what would be supplied to the house batteries, in order for a "discharge" or "no-charge" set of numbers to be displayed, correct?

Again, I am by far, no expert in any of this. But, the statement that the panel COULD show a house battery NO-CHARGE situation, due to the Inverter/Charger actually inverting THAT MUCH amperage while driving, sure seems highly unlikely to me. And, if that COULD possibly be the case, what in the world, could demand that kind of amperage, on COACH while driving down the road? I mean, even a micro-wave on full throttle for cooking something sure as heck don't draw 75 amps, does it?
Scott

[SCVJeff]

pianotuna wrote:
Jeff,

If the inverter is on, it may be that the engine charging path may not be able to keep up with the load. That would cause the house bank to discharge while driving. That makes it appear as if the alternator doesn't charge the house bank.

Of course, unless special efforts are made, alternator charging is about the starter battery, not the house bank.

SCVJeff wrote:
What I'm missing here is the "Inverting" comment.. That has nothing to do with the charge process, and is a user select manual button push.

that I'll agree with with, but I've not seen an inverter go into invert mode without being turned On

[kdk]

I am pretty sure your charging system is the same as my 06 Ambassador which uses the "boost rely made by Trombetta" to tie the chassis and coach batteries together while the engine is running. Check the voltage on the large terminals with engine is running, voltage should be the same. If not have somebody depress the boost switch, now if the voltage is the same you know the relay is good and the bird circuit board has failed. Now if the chassis side of this relays voltage is higher than the house battery side the relay has failed. Trombetta has 2 versions of this relay. The upgraded version has silver contacts instead of copper. If I recall it cost around $45, call them for more info. Hope this helps, PM me if I can be of further assistance.
Blessingd; Keith

On edit; with the engine off have someone depress the boost switch, you should hear and feel the relay engage, but just because you hear or feel this the relay engage it still could be bad as mine was. With battery cables disconnected and the boost switch depressed you should read continuity through the terminals.

[Bill_Satellite]

prstlk,
Hopefully you will come back and re-visit your problems. What you should know by now is that if you are not plugged in or running the generator the Magnum panel should be showing Inverting. That is correct. The inverter drains your batteries of 12V power to create 120V power when there is no other power source available. Plugging the coach in or starting the generator would then supply 120V power to the inverter and that power would be used to charge your batteries but you will no longer be inverting as it is not necessary.
If you are certain that your house and/or engine batteries are not being charged then there is an issue related to the engine alternator which is where the replenishing power would come from while you are driving. There are a number of folks here who have given good advice on how to check to see if your batteries are gaining or losing voltage with the engine running and once you have a handle on that you should be able to figure out what is or is not working properly.

[JimM68]

I just replaced the "trombetta" relay in my 08 knight for exactly the same symptom.
It's located on the back wall of the battery bay.