Charging batteries with the engine

[Redram99]

Hi all.

I have a 2011 triple e senator 25d. Great motor home. E450 v10.

Just curious, what is the output of the alternator vs the standard converter?

It seems to charge the house batteries off the engine alternator very quickly.
Would that be nearly as economical as running a 4000 Onan?

Thanks.

[pnichols]

Redram99 wrote:
Thanks Pnichols. This is what I wanted to know. I’m not very good with electrical. In an hour, you can get a solid charge back into your batteries by idling the v10. I usually idle it up to 1000 rpm.

Wow. Engine abuse!!! Haha. From idling.

I’m in northern British Columbia where it is consistently -30 for extended periods. Our vehicles idle a lot! Doesn’t really seem to bother them much. Just the new diesels are a pain in the ass. No catastrophic failures that I know of on gassers.

I imagine the lifespan reduction of my v10 spinning at 4000 rpm wide open for 3-4min straight climbing a long hill is a bit higher than idling for 1 hour charging batteries. If not, it’s something I’m ok to do to the engine.

Burning more fuel than running the Onan... worth it in my opinion not to have to listen to that thing hammer away down there. Plus I can use the heat or a/c.

I found out what I wanted to know.

Thanks for the input!!

Nicely stated summary of the results of your original inquiry into using one's main RV engine here and there for added camping convenience and practically.

IMHO, it appears that there's a lot of "Old Wives Tales" and "Urban Legends" scare tactics going around concerning idling of a modern gas vehicle engine.

Here's some more comments/observations:

- I have a large roll-around wheeled backup generator for power outages at our home. I has a smart mode where it drops down to an idle when the load on it is low enough ... in order to reduce noise and fuel consumption whenever possible. I guess the manufacturer didn't realize that too long in it's idle mode might ruin it. 😉 (P.S. It's NOT an inverter generator.)

- How about today's Honda inverter generators? Are they ruining themselves by too much low speed running when the loading on them is low? 😉

- We idle our 2002 daily driver sedan's 290 HP V8 all the time to keep one of us warm or cool in parking lots while the other one is shopping. So far it's got over 180,000 miles on it's engine and it still runs like a Swiss Watch ... getting 25-27 MPG on the open road and burning no oil. 🙂

- I don't understand a wacky conclusion by someone above implying that just because V10 powered emergency vehicles can tolerate engine idling for hours doesn't mean V10 motorhome engines can. :h

There is only one VALID reason to not idle your RV engine for battery charging - it's not good for the air surrounding Mother Earth. I admit to being a bad boy, in this respect, whenever I use the V10 for battery charging instead of: The Onan, the Honda, some solar, a wind generator, or a fuel cell. 😞

[Photomike]

Redram99 wrote:
Thanks Pnichols. This is what I wanted to know. I’m not very good with electrical. In an hour, you can get a solid charge back into your batteries by idling the v10. I usually idle it up to 1000 rpm.

Wow. Engine abuse!!! Haha. From idling.

I’m in northern British Columbia where it is consistently -30 for extended periods. Our vehicles idle a lot! Doesn’t really seem to bother them much. Just the new diesels are a pain in the ass. No catastrophic failures that I know of on gassers.

I imagine the lifespan reduction of my v10 spinning at 4000 rpm wide open for 3-4min straight climbing a long hill is a bit higher than idling for 1 hour charging batteries. If not, it’s something I’m ok to do to the engine.

Burning more fuel than running the Onan... worth it in my opinion not to have to listen to that thing hammer away down there. Plus I can use the heat or a/c.

I found out what I wanted to know.

Thanks for the input!!

If it is something that you want or need to do look at adding a larger charge cable or if you want to get crazy running an inverter off the engine to a 3 way charger for the house battery. I know in the real cold that running the vehicle can also help to warm up the fluids and to make sure that the vehicle battery is topped up, not that in Canada we ever have to do this :B

[Redram99]

Thanks Pnichols. This is what I wanted to know. I’m not very good with electrical. In an hour, you can get a solid charge back into your batteries by idling the v10. I usually idle it up to 1000 rpm.

Wow. Engine abuse!!! Haha. From idling.

I’m in northern British Columbia where it is consistently -30 for extended periods. Our vehicles idle a lot! Doesn’t really seem to bother them much. Just the new diesels are a pain in the ass. No catastrophic failures that I know of on gassers.

I imagine the lifespan reduction of my v10 spinning at 4000 rpm wide open for 3-4min straight climbing a long hill is a bit higher than idling for 1 hour charging batteries. If not, it’s something I’m ok to do to the engine.

Burning more fuel than running the Onan... worth it in my opinion not to have to listen to that thing hammer away down there. Plus I can use the heat or a/c.

I found out what I wanted to know.

Thanks for the input!!

[Lwiddis]

“as I understand that various emergency response vehicles with a V10 sit with their engine idling for hours at incident sites”

Who wants to buy a used emergency vehicle that idled for hours and hours and hours? Or an RV? Justify your engine abuse by the engine abuse of others?

[pnichols]

Desert Captain wrote:
The occasional use I described does no harm and gives the owners of gassers a valuable option, one that is not open to the folks with the popular Mercedes {or other similar diesels}. It was hardly "overstated" and is in fact correct.

Re-read my post and you will see that in the last 4.5 years I have had the need to use this technique twice. Nowhere did I recommend making this a regular event but merely pointed out this valuable option. Also as noted above emergency vehicles {often large gassers, typically V-10's} routinely sit idling for hours.

D.C. .... well put!

We used our RV's V10 alternator for drycamp battery charging this past January in Quartzsite. I idled the engine for about an hour for a fast partial charge of our AGM batteries. We could have used the Onan or Honda, but I was both lazy and wanted complete quietness so I just fired up the V10 and let it idle.

Once in the Texas Panhandle in August we idled the V10 for awhile so we could run both the roof top A/C via the Onan and the dash air for a fast cool-down in extreme heat.

This is a very nice additional choice for V10 motorhome owners. :C

[Desert_Captain]

The occasional use I described does no harm and gives the owners of gassers a valuable option, one that is not open to the folks with the popular Mercedes {or other similar diesels}. It was hardly "overstated" and is in fact correct.

Re-read my post and you will see that in the last 4.5 years I have had the need to use this technique twice. Nowhere did I recommend making this a regular event but merely pointed out this valuable option. Also as noted above emergency vehicles {often large gassers, typically V-10's} routinely sit idling for hours.

:R

[valhalla360]

ronfisherman wrote:

valhalla360 wrote:

Desert Captain wrote:
One of the many advantages of a large gasser vs the Mercedes {or other diesel} is the ability to let the gasser idle for extended periods of time. {Don't even think about trying this with a diesel}.

This bit of wisdom is at best overstated and in many cases flat out wrong.

It's not good for either gas or diesel to only be run at idle, so if you are boon-docking for months on end and the only use is an hour a day of idling, it causes problems. Basically the engine doesn't get hot enough to burn the fuel cleanly and carbon deposits can coat the cylinder and score the piston.

As long as you periodically get the engine up to full operating temperature, those carbon deposits get burnt off before they are enough to do any damage. So if you drive out for a long weekend, run the engine to charge for a couple hours on saturday and then drive back at the end of the weekend, no issues as the engine will reach operating temps during the drive. Even a stray week won't have any measurable impact. (look at truck stops where historically they would just idle the engines all night long and get 500-1000k miles out of an engine because the next morning the engine gets up to temp and addresses the issue).

Still not the best option if you have a generator or other source to charge with but this is rarely a consideration.

The problems with idling is with engines that have DEF and DPF exhaust systems. Those that idle long times have problems with the DPF plugging up.

Again, if you are doing it for weeks on end, it can be a problem. You can also run into issue with condensation rusting out the exhaust.

But as long as you get it up to temp periodically, that largely sorts itself out.

[ronfisherman]

valhalla360 wrote:

Desert Captain wrote:
One of the many advantages of a large gasser vs the Mercedes {or other diesel} is the ability to let the gasser idle for extended periods of time. {Don't even think about trying this with a diesel}.

This bit of wisdom is at best overstated and in many cases flat out wrong.

It's not good for either gas or diesel to only be run at idle, so if you are boon-docking for months on end and the only use is an hour a day of idling, it causes problems. Basically the engine doesn't get hot enough to burn the fuel cleanly and carbon deposits can coat the cylinder and score the piston.

As long as you periodically get the engine up to full operating temperature, those carbon deposits get burnt off before they are enough to do any damage. So if you drive out for a long weekend, run the engine to charge for a couple hours on saturday and then drive back at the end of the weekend, no issues as the engine will reach operating temps during the drive. Even a stray week won't have any measurable impact. (look at truck stops where historically they would just idle the engines all night long and get 500-1000k miles out of an engine because the next morning the engine gets up to temp and addresses the issue).

Still not the best option if you have a generator or other source to charge with but this is rarely a consideration.

The problems with idling is with engines that have DEF and DPF exhaust systems. Those that idle long times have problems with the DPF plugging up.

[valhalla360]

Desert Captain wrote:
One of the many advantages of a large gasser vs the Mercedes {or other diesel} is the ability to let the gasser idle for extended periods of time. {Don't even think about trying this with a diesel}.

This bit of wisdom is at best overstated and in many cases flat out wrong.

It's not good for either gas or diesel to only be run at idle, so if you are boon-docking for months on end and the only use is an hour a day of idling, it causes problems. Basically the engine doesn't get hot enough to burn the fuel cleanly and carbon deposits can coat the cylinder and score the piston.

As long as you periodically get the engine up to full operating temperature, those carbon deposits get burnt off before they are enough to do any damage. So if you drive out for a long weekend, run the engine to charge for a couple hours on saturday and then drive back at the end of the weekend, no issues as the engine will reach operating temps during the drive. Even a stray week won't have any measurable impact. (look at truck stops where historically they would just idle the engines all night long and get 500-1000k miles out of an engine because the next morning the engine gets up to temp and addresses the issue).

Still not the best option if you have a generator or other source to charge with but this is rarely a consideration.

[pnichols]

theoldwizard1 wrote:
I will repeat, YOU WILL NEVER BE ABLE TO FULLY RECHARGE HOUSE BATTERIES FROM A VEHICLE CHARGING SYSTEM ! To properly recharge them, you need a 3 stage charger.

Nope ... not true.

Our RV's 230 amp hour AGM battery bank - when discharged down to around 12.1 volts - can be completely recharged by our Ford E450's 130 amp alternator in 4-5 hours of driving.

I have watched this happen time and time again on RV trips because right on the cab dash I have installed a coach battery system 4-place digital voltmeter and coach battery system 3-place digital ammeter (the ammeter shunt is mounted right close to the batteries). After 4-5 hours of driving, the ammeter reads zero current flow - meaning the coach battery bank is neither receiving current from, nor delivering current to, the RV's 12 volt system. I've installed the ammeter and it's shunt such that negative readings mean that current is flowing out of the RV batteries and positive readings mean that current is flowing into the RV batteries.

In my earlier post above I explain in more detail how effectively our V10 engine's 130 amp alternator can be used to help charge our RV batteries when camped.

[BFL13]

"To properly recharge them, you need a 3 stage charger."

No, you need a single voltage charger that is set at the specified Absorption Voltage (Vabs) for that battery. Leave it on until amps taper to zero and you are now properly charged.

You can then put the battery on a maintenance charge at its specified voltage for that.

Your single voltage charger at the proper Vabs will take the battery through its Absorption Stage and perhaps a Bulk Stage before that. (But not necessarily--whether there is a Bulk Stage depends on the charging rate--charging amps vs bank AH capacity-- and the starting SOC.) You could be where the battery goes straight to its Absorption Stage.

If you wish to argue about that, we should take it to the Tech Issues forum.

[RasMouSein]

My two cents 🙂
My Honda Pilot alternator charge at 14.2v 🙂
I'm always suprised when plugged and at idle looking at my trimetric and showing 10+amps of charging.
I have yet to check amps when battery is low.

[theoldwizard1]

Oldtymeflyr wrote:
Depending on the state of charge of the battery, it will take hours to charge a battery with an engine idling at say 750 rpm. Even a half charged battery will take hours to properly charge, that is to bring it to as similar state of charge after a days travel on the road.

I will repeat, YOU WILL NEVER BE ABLE TO FULLY RECHARGE HOUSE BATTERIES FROM A VEHICLE CHARGING SYSTEM ! To properly recharge them, you need a 3 stage charger.

[pnichols]

When drycamping I partially recharge our Class C's two paralleled 12V 115 amp-hour batteries (230 amp-hours, total) at times using our 2005 E450's V10 alternator. When the batteries need recharging, I often idle the V10 for about an hour to put heavy current into them before I use the stock converter for several hours powered by either our built-in 4KW Onan or our small 650W portable Honda. I've seen initial recharging current from the alternator as high as 80 amps while the V10 idles.

Our alternator is rated at 130 amps at full spin speed and up to 75-80 amps at engine idle spin speed. This is also shown on Ford's performance graph for the E450's 130 amp alternator. The alternator is over-driven by it's pulley, so it spins much faster at all times than the engine does. I suspect that at some point V10 engines later than our 2005 may have shipped stock with only a 120 amp alternator - but I'm not sure on this.

I don't think that the V10 is harmed by idling, as I understand that various emergency response vehicles with a V10 sit with their engine idling for hours at incident sites. However, we do use top tier synthetic oil in our V10 - if that counts for anything.

Especially in very noise senstive camping areas (such as around tent campers), partial recharging via the idling V10 is our quietest way to recharge. In those situations we skip further/full recharging via either the Onan or Honda because of their noise level being above that of the idling V10. The idling V10 noise is only a low whisper just outside the motorhome and can't be heard a few feet away. The idling V10 supposedly consumes around 0.7 gallons per hour when idling, the Onan probably consumes around 0.3 gallons per hour when powering just the stock converter for our battery charging, and the portable Honda consumes around 0.1 (one tenth) gallons per hour when powering just the stock converter for our battery charging. So, idling of the V10 is the most expensive way to put some amp hours back into our batteries - but we use it only sparingly to do this and we always use it in the special situations when ultra-low noise is the name of the game. We don't have solar, but even if we did it would not work in many of the very quiet and shaded camping spots we find ourselves in. Our RV batteries are AGM, so they charge faster than liquid acid batteries do regardless of the charging technique used (because of their lower internal resistance).

For what it's worth, decades ago the original owners of our very first Class C motorhome (a 1969 model Chinook) used to regularly idle it's GMC V8 to recharge it's coach battery and that V8 was of course still strong years later. RV generators were rare back then and RV solar was non-existent back then.