EPDM Coatings
rvupgradestore.com Composet Products PO Box Zone
Over The Network Custom Yacht Interiors

Author Topic: Charging house batteries using engine alternator  (Read 4120 times)

Sun2Retire

  • Photo moderator
  • ---
  • *
  • Posts: 1860
Charging house batteries using engine alternator
« on: November 07, 2015, 07:04:22 PM »
I've seen threads discussing the apparent fact that it's more efficient to charge batteries idling  the engine vs. using the gen set. According to Spartan I've got a 160A alternator. Any thoughts/knowledge on what the output would be at idle? Going to be dry camping for a few days this month and will likely have use for this knowledge. Thx
Scott
2005 Newmar Dutch Star 3810, Spartan, Cat C7 350 "OURVEE"
Eezrv TPMS, VMSpc, 800W Solar
2002 Dodge RAM 1500 Quad Cab "RTOAD"
Stowmaster towbar & Brakemaster

legrandnormand

  • ---
  • Posts: 1242
  • Retired and enjoying it since 1995
Re: Charging house batteries using engine alternator
« Reply #1 on: November 07, 2015, 08:13:14 PM »
If you use your GEN, you'll be able to run your A/C's, your microwave and run your water heater on electricity ! ;)
Normand
Trois-Rivieres, QC, Canada
2010 Gulfstream Independance, model 8367
2009 Smart Cabriolet

bucks2

  • Guest
Re: Charging house batteries using engine alternator
« Reply #2 on: November 07, 2015, 08:21:46 PM »
Yes..... and No. The big question is how big is your battery charger? The one in my MH charges at 100 amps, the one in my boat at 150 amps. Running 1 to 4 cylinders (depending on your genset) is more efficient than running 6 in my MH. My genset and charger are designed for charging deep cycle batteries for long periods. They are designed to put out power for hours on end. They are quieter than the main diesel engine. My MH alternator is designed to recharge for short periods of time or less than maximum charge for longer periods of time. My Beaver owners manual specifically warns against using the engine alternator to charge up deeply discharged house batteries. It specifically says to use the genset and inverter/charger to charge deeply discharged house batteries.

So I would say that the apparent fact is false.

Ken

Tinmania

  • ---
  • Posts: 411
Re: Charging house batteries using engine alternator
« Reply #3 on: November 07, 2015, 08:31:13 PM »
Another point is that you will not get anywhere near the amperage at the trailer connection that the alternator is capable of putting out. So if your plan was to just leave the trailer plugged into the 7-pin receptacle it would take a long time to charge the batteries.

Now if you connect directly to your tow vehicle battery while it is running, say with jumper cables, you are putting out a lot of amperage that, as pointed out, might not be good for deep cycle batteries.



Mike

Sun2Retire

  • Photo moderator
  • ---
  • *
  • Posts: 1860
Re: Charging house batteries using engine alternator
« Reply #4 on: November 07, 2015, 08:49:43 PM »
Aaaaannd.... there you have it. Genset it is
Scott
2005 Newmar Dutch Star 3810, Spartan, Cat C7 350 "OURVEE"
Eezrv TPMS, VMSpc, 800W Solar
2002 Dodge RAM 1500 Quad Cab "RTOAD"
Stowmaster towbar & Brakemaster

John From Detroit

  • ---
  • Posts: 19638
  • ^My New Home^
    • Diabetics Forum
Re: Charging house batteries using engine alternator
« Reply #5 on: November 08, 2015, 04:15:13 AM »
Is it more efficient to idle the engine or run generator.

A big block V-8, or V-10 Gasoline or a big diesel will burn fuel faster at full idle than the generator will at full load.
Plus the alternator is very low output at full idle in fact on some ewngines, if you are in neutral the alternator can't even keep up with the engine's needs.

Bottom line; Run Generator, it needs the exercise anyway.. UNLESS you have the problem I have just now.
(Generator tail pipe rusted out.. Replacement on order.. Just waiting for it, Should have next week I hope. Install will ve a very very very simple job).
Nothing adds excitement like something that is none of your business
My Home is where I park it.

Sam!

  • ---
  • Posts: 497
Re: Charging house batteries using engine alternator
« Reply #6 on: November 08, 2015, 09:10:55 AM »
For 2-3 day dry camping any two battery set up should hold you well with conservation. I think I have managed with one and using the generator to charge while using  the micro and tv.
1997 Serro Scotty 25' Diesel Cummins 4x4
2005 Dodge Ram 3500 Diesel SRW
2000 Tacoma Dezert trux
San Diegan

robertusa123

  • ---
  • Posts: 1507
Re: Charging house batteries using engine alternator
« Reply #7 on: November 15, 2015, 06:39:59 AM »
IV done it in a pinch.  But at ideal you not likely to get more then 20 amps of charge at the most. Which means 5 hr of ideling to get 2 100 amp batteries charged 1/2 way....
1996  26ft. 3 kids 2 dog and the wife too

garl02

  • Posts: 2
Re: Charging house batteries using engine alternator
« Reply #8 on: January 26, 2016, 10:23:52 AM »
Batteries have a maximum charge capacity called saturation.  Most lead acid batteries will only  take about 10 amps per hour.  You can push the rate higher, but all you do is cause heat.  The batteries will overheat and are potentially dangerous.  Gel cell batteries can take a higher charge rate, but cost twice as much.  Most modern converters float charge or will put out 10 amps drop to  lower charge rates as the battery voltage comes up.  The best thing to do is plug you unit in to 110 volts.  If you have 200 amp/hour batteries at 10 amps it will take 100 hours to fully recharge your batteries.  I purchased a Honda 2000 I generator and when dry camping run that for a couple hours per day and that takes care of keeping batteries charged.  It uses very little fuel and is very quiet.  It will run up to 8 hours on a gallon of fuel.  My Generac 5.5 burns .8 gallons per hour.  You would be better off running your generator than the engine of you unit. 

bucks2

  • Guest
Re: Charging house batteries using engine alternator
« Reply #9 on: January 26, 2016, 11:24:27 AM »
Batteries have a maximum charge capacity called saturation.  Most lead acid batteries will only  take about 10 amps per hour.  You can push the rate higher, but all you do is cause heat.  The batteries will overheat and are potentially dangerous.  Gel cell batteries can take a higher charge rate, but cost twice as much.  Most modern converters float charge or will put out 10 amps drop to  lower charge rates as the battery voltage comes up.  The best thing to do is plug you unit in to 110 volts.  If you have 200 amp/hour batteries at 10 amps it will take 100 hours to fully recharge your batteries.  I purchased a Honda 2000 I generator and when dry camping run that for a couple hours per day and that takes care of keeping batteries charged.  It uses very little fuel and is very quiet.  It will run up to 8 hours on a gallon of fuel.  My Generac 5.5 burns .8 gallons per hour.  You would be better off running your generator than the engine of you unit.

Is your 10 amp number referring to Bulk, Absorption or Float mode on your modern charger? Most sites I read, battery manufacturers and smart charger sites, state that up to 25% of amphour capacity is an acceptable charging rate. 10% is less than half that. Are you sure that's a maximum? Wouldn't the temperature sensor connected to the smart 3 stage charger keep them from overheating? Why do they put an inverter/converter/charger unit in RV's with a 100 amp charge capacity if a 400 amp battery bank can only accept 40 amps maximum?

When I do the math it comes out to 20 hours if you have 200 A/H batteries charged at 10 amps. And that assumes the batteries were totally flat, not a recommended practice. 100 hours seems awfully long, even taking into account a lower charge acceptance rate when almost completely charged.

Thanks, Ken


William52

  • ---
  • Posts: 812
  • Common sense is not common anymore.
Re: Charging house batteries using engine alternator
« Reply #10 on: January 26, 2016, 11:09:46 PM »
Aaaaannd.... there you have it. Genset it is
   The Alt. car, truck RV gas or diesel all the same is to power vehicle and maintain battery. But not a charger for heavy discharged batteries you will burn it up. Yes genset or solar. JS
2000 Pace Arrow M35N F53 V10 Ford  100,000 + miles purrs like a kitten. Yes I am old school.         2007 Honda VTX double dark side

BruceR

  • ---
  • Posts: 13
Re: Charging house batteries using engine alternator
« Reply #11 on: January 26, 2016, 11:56:15 PM »
Also, there's the voltage to think about, especially after running through some fairly small wiring and a trailer connection. Your battery will get a full charge at 14.4 to 14.8 volts -- at the battery. With a long cable run of undersized cable and a charge current of 10 amps, I doubt the charge voltage will make it out of the 13.x voltage range.
_______________________________________
2000 Chinook Concourse

rickst29

  • ---
  • Posts: 16
Re: Charging house batteries using engine alternator
« Reply #12 on: March 21, 2016, 01:47:33 PM »
Bruce is Right.
Without a special "Voltage Boost" device, the Alternator in the Truck/SUV cannot charge the Trailer Batteries. They will only provide power while the batteries are being discharged by the Fridge, and similar loads.

Purpose built devices are made by Redarc and Ctek. It is also possible to create a home-brew Voltage Boosting system, feeding into a Solar Controller, but it's (ahem) a bit more complicated. I've done that, and power from my TV into batteries is a bit less than 300W, during "Bulk" charging. I can charge my pair of "typical" SLA batteries from 50% to about 85% in 2 hours, either driving or idling in camp.
Trailmanor 2619 (hard-shell pop-up) 2006. 5K axle.
Danfoss Compressor Fridge (Dometic CR1110).
330W Solar @67V, Rogue 2024 MPPT.
280W "alternate Solar" @25-28V into Rogue. (From 4Runner, through Bargman).
2007 4Runner "Sport" with WDH (1000 lb bars), switchable 12V/24V Bargman, large Dog.

 

Hosted by Over The Network