Using high-idle to recharge house batteries.

[arctictraveller]

Originally Posted by LenS

Many of the better 3 stage chargers have desulfation cycles built into them. So does the Renogy MPPT solar charge controller.

Agreed, My Renogy does, but only every 21 DAYS, not hours. I wonder if that's a misprint?

[carringb]

Extended idling of new diesels can foul the DPF however fast-idling reduces the problem, especially if any extra load helps it run hotter. The important thing is decent highway drives between long periods of idling. So, probably won't be a problem in a camper but ambulance operators still struggle with their emissions systems.

[LenS]

Originally Posted by arctictraveller

Agreed, My Renogy does, but only every 21 DAYS, not hours. I wonder if that's a misprint?

The literature that came with my 2015 solar cells also states 21 days.

Have seen recommendations of monthly to 1-2 times a year.

[derJack]

Originally Posted by Wrinkledpants

The Sprinters come from the factory with a 200 amp alternator with an option of a second alternator. If high-idle is used to ensure 200 amps are put out, how long would it take to recharge a 200 Ah battery if it's at 50%?

The 2nd alternator option is 280 amps for a total of 480 amps at high idle. Does this drastically reduce charge times, or is there a point of diminishing return in regards to how current a battery can take during a charge?

It's NOT that easy!

I doubt that the alternator in general goes up to 100% with high Idle on a German car.
Die to fuel efficiency most secondary Engine parts are set to save energy. Most alternators in German cars only charge of needed, not in general.

I would suggest to check this first before planning on this.

[arctictraveller]

Don't become discouraged. It may seem like there are no good solutions, but every one of us with house battery systems faces the same challanges. The reality of it is that most people don't get a full 100% recharge each day unless they have small loads and batteries, drive many hours, have lot's of solar and sunshine, or a generator or shore power. When you first begin recharging, the acceptance rate allows a high current to flow before it begins to taper off. This is where a high amp alternator or two can really help. Once the current drops way off at say 80% recharge, the advantage of big alternators is lost, unless your also using your microwave or other 110v loads through your inverter. If you only make it to say 85% recharge each day, you will still have a fully functioning electrical system, but slightly shorter battery life. So, based on your expected loads, install the biggest battery and charging system you can (afford and/or fit) Then manage your loads and enjoy having a silent power supply while you camp.

[COkid]

As others have stated, there are many variables that affect the charging rate. My experience matches Arctic Traveller's.

I have a V6 Sprinter with the high-idle option, 440 Amp-hr battery capacity, an auxiliary alternator, and a 3-stage voltage regulator for the auxiliary alternator. I can go from about 70% SOC to 90% SOC in about an hour. If I get decent sunshine for the solar panels and drive every-other day, I don't need to idle at all. When I do idle, it is for an hour or less.

Hope this helps,
Alan

[daveb]

I finally got around to installing a XP-270 alternator with a Balmar MC-612
regulator on my Ford. Don't know if a sprinter can use something like it...probably not in regard to the warranty but might be worth looking into.

[arctictraveller]

Originally Posted by daveb

I finally got around to installing a XP-270 alternator with a Balmar MC-612
regulator on my Ford. Don't know if a sprinter can use something like it...probably not in regard to the warranty but might be worth looking into.

Do you have enough experience to determine if it has shortened your recharge times? My guess is that it has or will.

[JoeH]

Originally Posted by arctictraveller

Do you have enough experience to determine if it has shortened your recharge times? My guess is that it has or will.

My seat-of-the-pants-measure-meter tells me that my XP250 alternator bumps up the house battery way faster when idling than the stocker ever did. The OEM alternator on a 6.0 psd is not up to the task for what we ask with our accessories and inverters. The OEM Ford alternator does 65 amps at idle versus the 180 that the XP270 does that Dave just installed.

[arctictraveller]

Originally Posted by JoeH

My seat-of-the-pants-measure-meter tells me that my XP250 alternator bumps up the house battery way faster when idling than the stocker ever did.

That's exactly what I would expect. Once you begin driving for a while, the benifit of the bigger alternator is probably a bit less.