battery charge question

bidhounds wrote:
It does charge on shore power. What I researched made me think that it doesn't charge as fast while driving especially if there are sources draining it. I just wanted to ask the community.

Yes, it charges pretty good while driving. Remember, your kids DVD and Phone/tablets are NOT pulling that much DC amperage. Your Headlights/clearance lights pull more than their electronic toys. BUT, ANYTHING that is ON in the motorhome(chassis or coach) will cause the chassis Alt. to take LONGER to charge the battery banks.
So, the priority of the chassis Alt is the chassis battery(s). Remember, IF you have been plugged into shore power and then disconnect and leave, the coach batteries are already fully charged. That leaves the Chassis Alt to just replenish the juice used to start the chassis engine, then bring the chassis to full charge and that depends on what state it was in when starting. But usually less than 1 hour of traveling will fully charge the Chassis. But, there is still more than enough current going to the coach system to run your kids electronic appliances. But to answer your question as I outlined above. It does NOT charge as fast when you do have 12 volt draws on the system. The RV systems are NOT like a Auto vehicle charging system where electronic appliances may cause a draw even in transit. Doug

wolfe10 wrote:

Gjac wrote:

bidhounds wrote:
We didn't drive the hours that you mention. If I wanted to increase charging amount it sounds like a different alternator is the way to go?

This might not be the case. When my stock alternator failed it was replaced with a 180 amp alternator because I was on the road and a std replacement could not be found. I thought that it would charge the batteries much faster. I would read 14.2 v to the chassis and thought all was well. When I installed a cheap volt/ammeter with a shunt I was only reading 5.5 amps going to the 2 6 volt chassis batteries from the alternator at 50% SOC. So I'm not sure if it has to do with the starting battery having to be charged first or thin wires as waxmen described was limiting the charge rate. Maybe someone on here can explain what is happening.

Indeed, you need to troubleshoot this. See where the voltage loss is-- I say voltage, as 14.2 VDC at a 50% discharged battery will show way more than 5.5 amps. Could be small wire size. Do you have a diode-based battery isolator? If the alternator does not have an external sense wire to the battery side of the isolator, you will be looking around .7 VDC across the isolator.

Let us know what you find.

I have 2 mechanical isolators(not diodes) which I recently replaced. One for chassis and one for house. By sensing wire I assume you mean the small wires going to the isolators,( I have 2 small wires going to each isolator.

Hi,

I'd consider solar a better option. It works all the time that the sun shines. It is a one time cost.

There are add on devices for alternators. Essentially they add external diodes that can be located away from the heat of the engine.

Gjac wrote:

bidhounds wrote:
We didn't drive the hours that you mention. If I wanted to increase charging amount it sounds like a different alternator is the way to go?

This might not be the case. When my stock alternator failed it was replaced with a 180 amp alternator because I was on the road and a std replacement could not be found. I thought that it would charge the batteries much faster. I would read 14.2 v to the chassis and thought all was well. When I installed a cheap volt/ammeter with a shunt I was only reading 5.5 amps going to the 2 6 volt chassis batteries from the alternator at 50% SOC. So I'm not sure if it has to do with the starting battery having to be charged first or thin wires as waxmen described was limiting the charge rate. Maybe someone on here can explain what is happening.

Indeed, you need to troubleshoot this. See where the voltage loss is-- I say voltage, as 14.2 VDC at a 50% discharged battery will show way more than 5.5 amps. Could be small wire size. Do you have a diode-based battery isolator? If the alternator does not have an external sense wire to the battery side of the isolator, you will be looking around .7 VDC across the isolator.

Let us know what you find.

bidhounds wrote:
We didn't drive the hours that you mention. If I wanted to increase charging amount it sounds like a different alternator is the way to go?

This might not be the case. When my stock alternator failed it was replaced with a 180 amp alternator because I was on the road and a std replacement could not be found. I thought that it would charge the batteries much faster. I would read 14.2 v to the chassis and thought all was well. When I installed a cheap volt/ammeter with a shunt I was only reading 5.5 amps going to the 2 6 volt chassis batteries from the alternator at 50% SOC. So I'm not sure if it has to do with the starting battery having to be charged first or thin wires as waxmen described was limiting the charge rate. Maybe someone on here can explain what is happening.

Since the alternator/VR system does not "meter"/taper the charging voltage as the SOC rises it is not a good idea to recharge a deeply discharged house battery via this method.

Easy to boil off the electrolyte that way.

It is expected that the chassis battery will never be deeply discharged so no harm no foul for using a fixed voltage charge method.

We didn't drive the hours that you mention. If I wanted to increase charging amount it sounds like a different alternator is the way to go?

There are many things involved in charging.. First 2 days with no charge and the RV occupied is a LONG TIME unless you have done a SERIOUS upgrade of the 12 volt storage system..

But the alternator has, as its primary duty, the charging of the chassis battery, leads to said battery are generally very heavy duty, Then you find an "Isolator" and leads from there to the house battery are often both long and smaller.. this limits the Alternator's abililty to provide charge to these batteries. IT WILL CHARGE THEM, if you drive like 8 to 12 hours a day, but it takes a long time to do it.

In fact, Four to Six is kind of the minimum charge time for most batteires, Some can charge a bit faster (Say 3 to 5) but for most its 4-6.

How far did you drive each day?

Nomadac wrote:
Some MH's do not charge the house batteries with the alternator. Some models of Travel Supreme did not, until later when the installed a B.I.R.D. in the line and then it would only charge if the chassis batteries were at full charge.

This is about the ONLY Motorhome that had such a non charging system. Doug

You have a Winnebago product. Older Winne's, you have a switch on the dash area labeled---MOM/DUAL. MOM(momentary) push that side and it is spring loaded. THAT engages the charge solenoid to boost to start the chassis engine if the chassis batteries are low or dead. To CHARGE BOTH battery banks you MUST have that switch in the DUAL position(locks in that position). See if your 2007 has that switch. Doug