Engine charging of coach batteries

[CanadianEmbassy]

I have a general question about how the (Class A) coach batteries are charged from the engine alternator while the engine is running.

I am not at all sure that they even are so charged, as I cannot see a linkage to either my batteries or at the converter, but if there is such a link where would it be and how is it electrically configured?

If such charging does take place, how fast is it and how quickly would a discharged (e.g. half discharged) battery take to become fully charged again?

My motorhome is a Triple E Embassy, but this question also relates to what is typical in class A motorhomes - if there is a 'typical'.

Thanks.

Paul.

[dougrainer]

YC 1 wrote:
It would not take much to install a solenoid activated by a wire that is hot when the ignition is on. Or if you have an aux start switch that works just run an ignition wire to that solenoid.

You run that Ignition wire to the COLD side of that Dash Boost switch. A LOT easier and a shorter run. Doug

[YC_1]

dougrainer wrote:

YC 1 wrote:
It would not take much to install a solenoid activated by a wire that is hot when the ignition is on. Or if you have an aux start switch that works just run an ignition wire to that solenoid.

That is what the Intellitec BIRD system does with a small control box. They use the same solenoid and depending on if the IGNITION wire is powered is how that module activates the solenoid. Doug

Yes, I am totally familiar with the BIRD systems. However if the op system never charged it is a simple task to add a solenoid. I have installed thousands of solenoids in 40 years in my business. I kept them in stock by the box full.

[dougrainer]

YC 1 wrote:
It would not take much to install a solenoid activated by a wire that is hot when the ignition is on. Or if you have an aux start switch that works just run an ignition wire to that solenoid.

That is what the Intellitec BIRD system does with a small control box. They use the same solenoid and depending on if the IGNITION wire is powered is how that module activates the solenoid. Doug

[dougrainer]

wolfe10 wrote:

YC 1 wrote:
It would not take much to install a solenoid activated by a wire that is hot when the ignition is on. Or if you have an aux start switch that works just run an ignition wire to that solenoid.

MAYBE!

If it is a CONSTANT DUTY solenoid, that could work.

But many boost solenoids are only intermittent duty and certainly not designed for constant duty.

Actually it is the other way. BOOST solenoids(usually called BIG BOY solenoids that are rated at 200 amps) have to handle a LARGE amp load to power the starter. Charge solenoids handle a very small amp load as the Alternator is charging 2 battery systems. Most of the silver solenoids(what some would call too small) can handle 100 amp loads, which is way less than what will go thru them when chassis systems charge both banks. Older motorhomes did use those 100 amp silver solenoids as a BOOST solenoid and usually after a few times of boosting would burn out and then fail. Most common cause of the emergency start not engaging when needed. For instance, some use a FORD solenoid when they replace a silver solenoid because they look identical. BUT, a Ford Starter solenoid is indeed for momentary power to the starter and the internal make up of the copper disc is different. That is why people should NEVER use a Ford type solenoid when replacing those solenoids. They are not rated for the same amp load. Doug

[wolfe10]

YC 1 wrote:
It would not take much to install a solenoid activated by a wire that is hot when the ignition is on. Or if you have an aux start switch that works just run an ignition wire to that solenoid.

MAYBE!

If it is a CONSTANT DUTY solenoid, that could work.

But many boost solenoids are only intermittent duty and certainly not designed for constant duty.

[YC_1]

It would not take much to install a solenoid activated by a wire that is hot when the ignition is on. Or if you have an aux start switch that works just run an ignition wire to that solenoid.

[Effy]

lonewolf80 wrote:
Effy, not to beat a dead horse but if the alternator didn't charge the batteries are you saying they would go dead while on the road and not be charged until you could hook up to shore power? Sorry to say that doesn't seem right.

Yes they would go dead. Pretty fast too as there was only one house battery. Your choices were to run the gen or plug in. You guys can keep asking, I'll keep telling you the same thing. It was tested with a meter and in real life. The engine did not charge the batts. (In case I haven't said that before). I am not sure if it came that way or was because of the BCC recall and by pass. But they did not charge from the engine. Did I say that already?

[dougrainer]

lonewolf80 wrote:
Effy, not to beat a dead horse but if the alternator didn't charge the batteries are you saying they would go dead while on the road and not be charged until you could hook up to shore power? Sorry to say that doesn't seem right.

Yes, they will. If NOT charging, then the normal 12 volt draws on the COACH side will deplete the COACH batteries. Now, to EFFY's statement about what the Thor dealer stated. Just because a "Dealer" states something, does NOT make it so. I would verify that statement with THOR and have THOR send it to me in writing. I fix things all the time that both the selling dealer and the So-Called expert at the Factory stated was normal. Now, 99 and 99/100 of motorhomes charge ALL battery banks when the engine is running. I have 37 years as a Motorhome Technician and except for one specific model of motorhome about 20 years ago(orphan now), I have NEVER seen a motorhome that did not charge both battery banks. Most of the time, the customer thought it was not supposed to, until I fixed his system. Now, some(very few) motorhomes have a dash switch that MUST be engaged to engage the coach battery bank to the Chassis system. OLDER Winnebago's(Itasca's) had such a switch. Do NOT turn on that switch and the coach batteries did not charge. YOU DO NOT HAVE TO ENGAGE THE TRANSMISSION TO CHARGE THE BATTERY BANKS! Doug

[lonewolf80]

Sorry double post.

[lonewolf80]

Effy, not to beat a dead horse but if the alternator didn't charge the batteries are you saying they would go dead while on the road and not be charged until you could hook up to shore power? Sorry to say that doesn't seem right.

[lonewolf80]

Effy, not to beat a dead horse but if the alternator didn't charge the batteries are you saying they would go dead while on the road and not be charged until you could hook up to shore power? Sorry to say that doesn't seem right.

[cj7365]

crasster wrote:
A good way to tell is have somebody get into the coach put and start it, put it in gear, and then put a meter on the batteries. they should be over 13V (or more). Then have the person park the coach, put and turn it off and if the batteries then immediately sink some in voltage (like 12V) then they are charging.

The house batteries will charge even when the trans is in park, the engine just needs to be running

[Dale_Traveling]

This works for me,,,

[Effy]

tderonne wrote:

Effy wrote:


Yes, I checked, no it did not charge them. Brought it to my dealer's attention and they verified.

Seems to disagree with the 2012 Thor Ace owners manual (p 78):

Battery Isolator Controller

When the motor home engine is not running, the chassis and auxiliary batteries are kept separated from each other within the electrical system through the use of a battery isolating controller. The controller prevents the auxiliary batteries from discharging the chassis battery when the motor home is parked.

Some additional characteristics of the isolator system include:
1. Delays connecting the auxiliary batteries to the charging system for approximately 15 seconds, to allow the alternator time to reach full charging ability.
2. After this initial time delay, if the alternator has come up to full charging ability, (13.2 Volts) the isolator will electrically connect the
auxiliary and chassis batteries together for charging.
3. If the charging voltage drops below 13.2 Volts for a period of 4 seconds due to low idle speed and or excessive load, the isolator will disconnect the auxiliary batteries until the voltage returns to a level of 13.2 volts for about 10 seconds.
4. In the event the automotive battery is discharged, it will be necessary to press and hold the Start Switch located in the dash

Disagree all you want. They didn't charge. As noted before , likely the BCC recall that bypassed the disconnect. It was tested and verified. No charge from engine alt. I don't really care what the documentation says. Where's my beating a dead horse emoticon?