Will my coach batteries charge from the truck altenator while driving

[Flame]

Heading out on 4,000 mile trip. 1998 Concourse v-10 triton Ford. Just to be sure...will my truck alternator keep my coach batteries topped off while driving? I also have the original tiny solar charging system still hooked up too. I have replaced and updated/upgraded my inverter and installed a new Coleman controller. Question #2...at recommendation of my stepson we purchased a small inverter to plug in to the cigarette lighter to run our laptop off of while driving. HE SAID just plug laptop into the inverter using the 110 volt regular cord. My concerns is it will run my batteries down too much? we will be gone about 2 weeks but will be staying in motels at night. I can take laptop in each night and charge it up. I will not be anywhere to plug in to shore power to recharge my coach batteries and don't want them going dead on me!! Just getting nervous as this will be our longest trip ever!! Please advise! Thanks.

[caconcourse]

Assuming your battery separator is working properly, your alternator will charge you coach batteries while driving. Driving should be just as effective as plugging into shore power at recharging the coach batteries.

Using an inverter plugged into your cigarette lighter socket to power your laptop while driving should not drain any batteries. It will effectively be powered by your alternator.

We've made three trips of over 12,000 miles and about 6 weeks each and no hotels, so your trip should not be too demanding.

Hope you have a great experience.

[Flame]

Thanks sooo much Clay!! We are so excited!! Heading to New York and over to New England and back down the East coast to Texas!! Had this planned last year and had to cancel because wife had a braintumor surgery!! God has blessed us with her almost full recovery and we are good to go this year!! God is GREAT!!

[BobW9]

So long as you're not using lots of battery in the coach each evening, you'll be fine.

But I do have to disagree with Clay about how quickly the coach will charge off the alternator vs the charger/converter in the coach when on shore power. The alternator does not have the charging cycle for deep cycle batteries, it has a charging cycle designed solely for engine starter batteries. One that is even worse than the original Magnetek that was in my 2000 Concourse. Off the alternator, I found when starting with my batteries down at like 60% it took over 10 hours driving to get them back near 95%. But I planned for most of my driving between campsites at more like 2-4 hours. That is why I first bought a Battery-to-Battery charger in 2014 shortly after buying my Concourse. With the 50A B2B it charged up fully in just a few hours driving, even faster than the newer Magnetek I also installed for when on shore power.

Enjoy your trip!

[caconcourse]

Bob,

That's interesting information on your alternator charging experience. I never paid close attention, but it seemed our batteries were always charged after a long day of driving, which for us was usually 4-6 hours. Except when we ran the refrigerator on DC while driving and forgot to turn it off when parked once or twice. When I realized how inefficient the DC mode was, we just started leaving the fridge off while driving, and the batteries seemed to charge up fine. The Chinooks came with high output alternators, presumably for that purpose. As for a charging algorithm, I think the alternator just pumps out at a constant high voltage, which should be like bulk charging the deep cycle batteries. We also have solar assisting the charging while driving, but it's a pretty small contribution. I installed a new DC-DC converter to charge our new Lithium batteries, so it works like your B2B charger, but limited to 30Amps in my case. That was to prevent overloading the alternator, since the lithiums could suck as much as 100Amps if it were available.

[BobW9]

If you have a ScanGauge or something like it, which plugs in to your OBDII port, you can watch the voltage the alternator is running at. Or even a USB charger that plugs into a car's port which has a voltage LED on it (I have one I use for charging my phone, though they made the LED such a pale blue I can only really see it at night).

With a new 200A alternator I put in a couple years ago, I can tell how far down my engine battery was just by watching the voltage - it starts around 14.4 volts usually and how long it takes to drop down to an average of 13.8 tells me how far down the battery was. If I haven't driven it in a week or so, it might be 10-15 minutes at 14.4, then starts down. If its been 2 weeks (or if my car alarm was on) it might stay at 14.4 volts for half an hour or longer. I don't think I've ever seen it above 14.2V for more than an hour, but I may just have never noticed. Except, I did once have it at 14.4 for a long time and got concerned, and when I looked around under the hood I found that one of the cables on the battery was loose, and very hot. Tightened it back up, and the voltages were normal again. I think that's the only time that I've really been glad I have the ScanGauge, and have a tendency to monitor things.

The voltage being output does go up and down while I drive, and down a bit when at a full stop (though not much, compared to my old 120A alternator which dropped the voltage quite a bit when the engine was idling). Even after driving for hours, I've noticed the voltage is usually at 13.8, sometimes dropping to 13.6, and sometimes up to 14.2, but never for long. It doesn't seem to have a sophisticated charge cycle, but there is definitely a cycle - it never stays at a level that would be really good charging for a deep cycle battery. But it also doesn't stay high, above 14 or 14.2, which longer term would be quite bad for a deep cycle battery that is nearly fully charged, so that's good.

That voltage cycle will charge your coach batteries eventually, its not like 13.8V is so low. And depending on how far down they were, a few hours driving might be pretty good (especially if you're not watching a battery monitor to see if they are at 90% vs 100%).

But for someone that does a lot of dry camping and uses lots of electricity each day, the difference for getting low batteries up near 100% in a few hours driving really does need a B2B. Or if you have a really large lithium system, you could add a second heavy duty alternator who's entire output would go to charging the coach (some van outfitters now are doing that, because they're putting in 400AH, 600AH, and larger, lithium systems).

By the way, I highly recommend getting an OBDII monitor like the ScanGauge II (there might be better ones out there now, I haven't looked in years, since I have mine). It can display 4 gauges at once. i usually have mine showing transmission fluid temperature, engine coolant temp, voltage, and RPM's. It also has a trip computer to give you average MPG on fillup, average cost of gas during your trip, though I don't bother with that too often. Oh, and will show any error codes from the vehicle CPU.

[Flame]

Thanks guys! Always great info.