Nite time generator

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

wls

Member
Joined
Nov 6, 2005
Posts
15
Location
Mid-Michigan
Was wondering if you have to use the generator all night, if your just using the furnace, will the battery last that long. This would be for winter camping, like 15-30 degree nights. Thanks
 

Lowell

Well-known member
Joined
Aug 15, 2005
Posts
2,221
Location
Tempe, AZ
I would expect your battery to last for at least several nights.  We have camped with night time temperatures in the 30's in our old Coleman pop-up and the battery lasted for over 4 nights while running the furnace.    Many campgrounds do not allow the use of generators after 10 PM.  But if you use a generator to recharge the battery during the day, you should be able to get through the night.
Jake
 

Carl L

Moderator Emeritus
Joined
Mar 14, 2005
Posts
7,239
Location
west Los Angeles
The battery?!? ?How many do you have?? ?How old are they?? ?Have they ever been discharged to zero?? ?How high do you set your thermostat?? How big is your rig?? In short, the answer depends on a number of factors.? ?

Simplest way to find out is to try the rig out at home.? Charge the batteries full.? ?Run the furnace overnight off shore power.? Check the charge on the battery the next morning with a voltmeter.

However, boondocking without shore power in sub freezing temperatures? -- that does seem a bit severe.?
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
73,911
Location
At our Silver Springs FL home
An RV furnace really sucks the juice from the batteries if you keep the rig warm like you are accustomed to at home. The furnace fan runs a lot and it is a electrical hog, typically several amps/hour. One 85 amp-hour battery (that's a typical Group 24 size) will probably get fully discharged by EARLY morning, because you can only count on about half the rated amount unless the battery is brand new and fully charged.  And after the first night, you probably cannot fully recharge the battery (it takes 8-12 hours to reach 100% charge again).

If you let the rig get cold, say 50 degrees and then turn up the heat in the morning, your furnace won't run anywhere near as much and thus use far less electricity.

If you have room, get the larger Group 27 or Group 31 batteries - they have a capacity of 105-120 amp-hours,
 

Bob Buchanan

Well-known member
Joined
Mar 3, 2005
Posts
3,038
Location
Philadelphia, PA
wls said:
Was wondering if you have to use the generator all night, if your just using the furnace, will the battery last that long. This would be for winter camping, like 15-30 degree nights. Thanks

As mentioned, if you set your thermostat down to around 50 degress, you should be OK. I do that all the time when boondocking in Northern Nevada -- such as around the Reno/Tahoe area.  Not sure of the type of rig you have, but if your Genset starts from the same battery that powers your furnace -- the disappointment of getting out from under the covers and running to the Genset start button to begin recharging only to find it won't start because the batteries are too low is not a fun way to start the day.

In my rig if the batteries are too low to start the genset, I can then start the rig engine, which in turn allows me to start the Genset. If the rig engine won't start, I can jump start using my Jeep tow battery. If that won't start, I have an auxilliary start battery that I keep in the back of the Jeep. Point is, if you are like me and don't like super cold AM's, you are wise in bringing up this question.  :)

There are company's that make DC electric blankets that I have considered. Not sure of the power they draw, but if they take less than the ever running furnace fan, it might lessen the amount of battery drain.
 

wls

Member
Joined
Nov 6, 2005
Posts
15
Location
Mid-Michigan
Carl Lundquist said:
The battery?!? ?How many do you have?? ?How old are they?? ?Have they ever been discharged to zero?? ?How high do you set your thermostat?? How big is your rig?? In short, the answer depends on a number of factors.? ?

Simplest way to find out is to try the rig out at home.? Charge the batteries full.? ?Run the furnace overnight off shore power.? Check the charge on the battery the next morning with a voltmeter.

However, boondocking without shore power in sub freezing temperatures? -- that does seem a bit severe.?
I just got the 5th wheel, it has one battery, would like to keep it reasonably warm in there, say 65-70. Its a 37' sandpiper, I may hook another battery up to the exsisting one. But I have another problem that is keeping me from finding out how long it will blow hot air on a battery. I will stat another post for that, stay tuned in :) Thanks for all the help.
 

Karl

Moderator Emeritus
Joined
Mar 3, 2005
Posts
5,154
Location
Elkhart Lake, WI for the summer. Work at Road Amer
Gee Bob,
You mean you don't have a couple hundred "D" cells? you can rig in series/parallel to back up your backup-backup battery scheme ;D ;D ;D

Electric blankets (or in my case an electric matress pad) are great! However the newer 110V types with electronic controls will NOT work properly on modifed sine wave inverters; you must either use a pure sine wave inverter or an inductor/capacitor to get them to do their job. DC blankets are certainly an option, but rather expensive and need additional 12V wiring. Personally, I'd prefer a warm body - easily transportable, don't require electricity, but you do have to feel feed them a few times every day ;D?
 

Carl L

Moderator Emeritus
Joined
Mar 14, 2005
Posts
7,239
Location
west Los Angeles
I just got the 5th wheel, it has one battery, would like to keep it reasonably warm in there, say 65-70.

If that battery is the  standard group 24 or 27 battery, the short answer to your original question is that it will not reliably last overnight at the temperatures you cite.

Batteries lose efficiency with declining temperature and if exhausted are subject to freezing.  To keep a trailer that warm in subfreezing temperatures, you will essentially run the furnace all night.  At the very least you will need a second battery.  IMHO, shore power is a better solution.

BTW I am talking about true single-purpose deep cycle batteries.  Dual purpose cranking/'deep cycle' batteries are even less capable of your requirements.
 

RLSharp

Well-known member
Joined
Mar 3, 2005
Posts
1,810
Location
Rochester, NY summer; Tucson, AZ winter; otherwise
Karl said:
Electric blankets (or in my case an electric mattress pad) are great! However the newer 110V types with electronic controls will NOT work properly on modified sine wave inverters; you must either use a pure sine wave inverter or an inductor/capacitor to get them to do their job.

Karl,

Can you provide a schematic with component values for an inductor/capacitor device to make an electric blanket with electronic controls work on a modified sine wave inverter? We have a new electric blanket which does not work except on shore power--we really need it more while boondocking to cut down on furnace usage. I don't want to buy a pure sine wave inverter just for boondocking.

Thanks.

Richard
 

Bob Buchanan

Well-known member
Joined
Mar 3, 2005
Posts
3,038
Location
Philadelphia, PA
>> You mean you don't have a couple hundred "D" cells? you can rig in series/parallel to back up your backup-backup battery scheme
====
I thought of that, Karl, but ran out of space.  ;D  However, whatever it takes to avoid not having a heat source with sub freezing temps around my rig.  I'm more into "Just Right" vs. too hot or too cold.

>> DC blankets are certainly an option, but rather expensive and need additional 12V wiring.
====
I hear you about the 12V wiring -- but it would seem worth it to have 12V plug installed in a bedroom -- if only for that purpose if boon-docking in freezing climates. I looked at one blanket that drew 4.2amps. That seems a lot more efficient than the draw from the batteries via an inverter.

>> Personally, I'd prefer a warm body - easily transportable, don't require electricity, but you do have to feel feed them a few times every day.
====
Hmmmmm. I keep having to remind  you that this is a family oriented forum -- or were  you referring to your cats?  8) :)?
 

Karl

Moderator Emeritus
Joined
Mar 3, 2005
Posts
5,154
Location
Elkhart Lake, WI for the summer. Work at Road Amer
4.2 amps sounds quite reasonable - should be able to run quite a few hours at that rate.

>> Personally, I'd prefer a warm body - easily transportable, don't require electricity, but you do have to feel feed them a few times every day.
====
Hmmmmm. I keep having to remind  you that this is a family oriented forum -- or were  you referring to your cats?   

Of course I was talking about my cat. Hercule likes to sleep under the covers at my feet - but he does snore occasionally :-\
 

Karl

Moderator Emeritus
Joined
Mar 3, 2005
Posts
5,154
Location
Elkhart Lake, WI for the summer. Work at Road Amer
Richard,

I will do that, but it will take a little time to work out the calcs. I did mine kind of hit-or-miss using an old 5mF. motor capacitor and the transformer from an old 10A battery charger. It's a little more complicated than that because you need a diode and MOSFET to control the charge/discharge of the inductor/capacitor along with a 555 timer set for 120Hz by way of the var. resistor. For the MOSFET, a Motorola MTD6N15 (6A, 150V) will do the trick nicely.

OOPS! Add a 1uF cap. between pin 6(2) of the 555 and ground. Sorry about that.

Ignore above. Schematic corrected.
 

Attachments

  • Blanket.doc
    46 KB · Views: 25
Top Bottom