House Battery Charge While Underway

"prstlk"......Simple answer. The Magnum inverter on your motor home has an on/off switch. It's right there on your control panel, on the left side, black buttons. The reason it's on while you're driving is that you have it turned on. You can easily turn it off, unless there is something you want to run on 110 volts while driving from point A to point B. Leaving it on is not detrimental to your coach operation. But it has nothing to do with your battery charging.

When you start your generator in the morning, it will go through the charging phases that "FIRE UP" described. Starting with BULK, usually after about 20 minutes or so (depending how much you drained your batteries) it will go to ABSORPTION, and once they're fully charged, they will go to FLOAT. While doing this, there will be a number in the window, like 91. My understanding is this is the number of amps required to bring you back to zero (Float Charging). The number will drop as you near fully charged. My previous coach (05 Diplomat) typically took about 2 hours, after evening battery use, to come back to full charge.

Caution....Typically, you wake up each morning and start the generator. You run it until you're fully charged. On the morning that you're breaking camp and leaving, many don't run the generator and just drive off, allowing the engine to charge the batteries while on their way home or to the next campground. This practice is hard on the alternator. You'll be working it hard to recharge those batteries that might be pretty low. You're better off to run the generator, at least while your breaking camp, to give the batteries a jump on charging.

Start your engine, wait about 2 minutes and then measure both battery banks voltage. You'll likely find that the isolation solenoid is not working and failure of the contacts is common.

Scott, The ME2012 fourth stage is No Charge and is automatic. This occurs with fully charged batteries and minimum draw. The fifth stage is Equalize and is manual.

You probably have a BIRD device not doing its job. Bi directional Relay Delay.

Look inside your battery compartment and see if there is a large solenoid mounted on the back wall. Be careful because the thing can get very hot to the touch if plugged into shoreline, generator running, or the engine running for several hours.

The solenoid would have large battery cables on each side of it and two small wires. One may be violet.

Plug into shoreline, start the generator OR start the engine. Do not run the generator and the engine at the same time because there may be a defeat function under those conditions.

Now use a 12 volt test light or a meter to see what is happening on the violet wire. It should light the test light and show 13.5 volts or more. If it does, you need to measure the voltage on each side of the solenoid where the large wires are. IF the voltage is not exactly the same, the solenoid needs to be taken apart and repaired or just replace it with one with silver contacts.

If you get this far I can steer you to the right part number and supplier.

A "Well Done" to Scott.

Thanks, hope the OP can digest it.

Bill

prstlk wrote:
Once again I come to the best wisdom source to be found.

07 Holiday Rambler, 4 6v house batts, Magnum controller, Magnum inverter 2012.

Situation is, when we dry camp we run the gen for 2 hours when we stop, and another 1 hour in the morning. (might be more if we need the air)

Question is this. Should the house Batts not recharge from the engine alternator if we are driving from A to B for 300+ miles?

We have found looking at the control panel we are inverting going down the road.

Is there something we need to do different with the controller?
I find it hard to believe that after 300 mi we should arrive without fully charged house batts.

Thanks for all you do, you are all the best!

Well Sir,

First off, if your Magnum 2012 inverter is the same exact unit as we have, a Magnum 2012ME, it is an "INVERTER/CHARGER". And with that, that inverter/charger is basically a 4-stage battery charger. It normally uses three of those stages for normal charging.

1. Bulk Charging for massive amount of amps due to low battery voltage condition
2. Absorbsion Charging for mid-level charging as thing simmer down from the higher rate of, Bulk charging.
3. Float charging for when things are topped off and, your batteries are done with the heavy charging.

The "fourth" charging section is for EQUALIZING. That is rarely used and, based on your remote controller for that Magnum 2012, you have to MANUALLY setup the Equalizing stage.

Now, all of this primarily is for house batteries. Many coach builders, for some odd reason, other than they (the builders) were/are cheap, did not setup the coaches for chassis battery charging, from either shore power or, generator power. That task is mainly taken care of from the engines alternator. But, there are simple and semi-inexpensive remedies for this.

1. Trik-L-Start, a simple unit that normally runs around $35-$50, depending on where and when you buy it. IT is a little box that simply ties the charging system from your inverter/charger to your chassis batteries. It IS NOT A BATTERY CHARGER! It simply "DIVERTS" some of the battery charging intended for your house batteries, over to your chassis batteries, while being plugged into shore power or, generator power. However, that unit will only allow maximum of 5 amps to the chassis batteries.

2. Amp-L-Start, a bigger, more modern version of Trik-L-Start with much of the same function and setup.

3. A dedicated, 3-stage, battery charger, hard wired into your coaches electrical system, that's setup for charging ONLY the chassis batteries. I like and use this system because, it's totally isolated from the coach battery charging system. So, if anything should go wrong with the inverter/charger, your chassis batteries will still be on charge and get you out of your predicament.

This is a preference thing. Choose what suits you.

Now, as for your engine charging your house batteries while driving down the road. About 99.9999999999% of all coaches made, both in the past and, today, WILL charge both sets of batteries, while driving down the road, with the engines alternator. Now, just how it does it, for your particular coach/chassis, may and, quite possibly will be, different from other makes and models. Contrary to popular belief, THEY'RE NOT ALL THE SAME IN THIS SITUATION.

On many, you have what's called an Auxiliary Start Solenoid. That solenoid is used to link both the house batteries and, chassis batteries together for starting the main engine, should the chassis batteries be too low to crank the engine.

But, that solenoid has dual duty in many of the coaches. It will also, through the ignition wiring, tie the two sets together, and let the alternator do all the charging while your driving down the road. That solenoid will NOT CLOSE during normal cranking, unless you use your switch on the dash for "Auxiliary battery Start". (however its worded on your coach)

Now, basically, that's a mechanical link-up, between the two sets of batteries. There's NO THINKING of any electrical computer boards, circuit boards, BIRDS, or anything else. It simply closes AFTER the engine is started and, you are now sending alternator charging, through that solenoid, to your house batteries.

On other coaches/makes/model/engines/fuel types/ etc. there will be different systems that link the alternators charging to your house batteries. You will have to determine, just which system you have and, therefore be able to determine, if, you have a defective system or, component of that system.

So, to answer your question, should your 300 miles of driving, have charged your house batteries, YES! That is of course, if, your system, whichever one you have, is working properly. If it's not, then no.

One more thing. No, you should NOT BE INVERTING, while driving down the road unless, you have a need to. That is, if you're in need of 120VAC for some appliance, a residential fridge, a crock pot, (we've done that a few times for having a prepared meal at the end of a days drive), a TV or so for the little tykes in the back of the coach, etc.

But, if you're not in need of 120VAC while driving, NO your inverter does NOT NEED TO BE INVERTING. It has nothing to do with charging either set of batteries, while the main engine is running.

Scott

prstlk wrote:
We have found looking at the control panel we are inverting going down the road.

What is the wattage you are inverting?
Consider turning the inverter off but should be OK for a small tv of 100 watts or less.

Do verify house battery voltage jumps from ~12.5 to 13.5+ when running down the road. Use a voltmeter direct on the battery terminals.

The intellect brain box controls what the alternator is charging. when the chassie batteries are 13 volts or higher, and 1 volt above the house batteries, the brain box will close the relay between the two sets of batteries then the alternator will charge all batteries as one. If there is any voltage on the generator out put to the inverter it will charge the house batteries. and the brain box will never close the relay between the house and chassie batteries so the alternator can charge the house batteries

If your Rambler is similar to our Tiffin, you should have a solenoid that connects the house batteries to the chassis batteries when the ignition is on thus allowing the house batteries to receive a charge from the alternator just like the chassis batteries. On our coach this solenoid is a high failure item ( we have replaced ours twice in the last four years).

My impression is that the engine alternator is mainly concerned with the charge status of the chassis battery, so, as soon as that battery is charged up the alternator starts cutting back on it's output. A few hours at the reduced voltage might not be enough to fully charge the house batteries. I suppose something could be rigged up to keep the alternator at a higher output level.

We are not running a residential fridge and it is set on LP while we are going down the road. Nothing else is on - lights or AC. Exception to this is the fantastic fans - they are both on low.

While we were driving today my wife went back and checked it and it said we were inverting.

Not sure why we are not charging while we are running down the road.