# how long without EHU



## timofleeds (Sep 12, 2006)

Could anybody tell me how long we would be able to run Truma blown air heating on low setting without electric hook up, before having to run the engine to recharge the leisure battery. Our truma is gas only but the fan runs from the 85a/h leisure battery.

Thanks, Tim


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## sprokit (May 1, 2005)

timofleeds said:


> Could anybody tell me how long we would be able to run Truma blown air heating on low setting without electric hook up, before having to run the engine to recharge the leisure battery. Our truma is gas only but the fan runs from the 85a/h leisure battery.
> 
> Thanks, Tim


Tim

Don't know whether this is of any help - I have two 110 AH batteries, so 220 AH in total, - Last winter I had the heating on permanently, set to 10 degrees to prevent the Truma "dump" valve opening and to keep the van aired.

We do use the van during the winter, so the batteries get a regular charge, however, the longest period without a hook- up or charging run was about 5 weeks, there was still plenty of life in the batteries after this period.

I'm doing the same this year, so, fingers crossed, I won't have any problems with frozen pipes / tanks etc.

HTH

Keith (Sprokit)


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## DiscoDave (Aug 25, 2008)

with a good quality 85Ah leisure battery and the truma fan running at full speed, which if memory serves will be just less than 1 amp, in theory you should be able to get 85 hours use from it.

but with all the losses of energy and temperature effects it will be less. the question is really how long do you need it to run?

has your fan got an auto setting? this will adjust the speed of the fan and therfore the power used depending upon the heat out put from the fire, ie if you turn the gas setting down the fan will slow down too!


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## timofleeds (Sep 12, 2006)

Hi thanks for the replies, I would like to leave the heater on overnight and most of the next morning, we will be in northern France so the weather could be quite cold. From your replies it looks as though I will be ok.

Thanks Tim


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## spykal (May 9, 2005)

timofleeds said:


> Hi thanks for the replies, I would like to leave the heater on overnight and most of the next morning, we will be in northern France so the weather could be quite cold. From your replies it looks as though I will be ok.
> 
> Thanks Tim


Hi Tim

Why not give it a try overnight before you go ( or for the required number of hours...a simulation :wink: ) , that way you will know for sure. I am not exactly sure how your truma works but you may be able to set the blown air running with no gas turned on.

In this I am assuming that you can hook the van up to the mains after the test to fully recharge the battery ... but not something you can easily try if your van is stored away from home with no hook up available.

Mike


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## Zebedee (Oct 3, 2007)

Hi Tim

Do you really need to use the fan?

I know the lavvy will be cold if you don't, but if your heater is similar to ours it will work fine for the main hab area when delivering only convected heat.


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## Boff (May 10, 2005)

Hi Tim,

which model of Truma heater is it? 

Best Regards,
Gerhard


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## timofleeds (Sep 12, 2006)

Hi Zebedee and Gerhard, I think the fan come son automaticaly, sorry I do not know the exact model but will find out and let you know.

Thanks Tim


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## Andysam (May 10, 2005)

DiscoDave said:


> with a good quality 85Ah leisure battery and the truma fan running at full speed, which if memory serves will be just less than 1 amp, in theory you should be able to get 85 hours use from it.
> 
> but with all the losses of energy and temperature effects it will be less. the question is really how long do you need it to run?
> 
> has your fan got an auto setting? this will adjust the speed of the fan and therfore the power used depending upon the heat out put from the fire, ie if you turn the gas setting down the fan will slow down too!


You won't get 85 hours from a 85aH battery running at 1 amp. More like 60. Even so, deffo enough for an overnight stay.


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## timofleeds (Sep 12, 2006)

Hi Gerhard my truma is the C4002 model.

Regards Tim


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## DABurleigh (May 9, 2005)

1.3 A average consumption I believe, so just over 30 hours with a fully charged battery depleting it to no less than 50% to maximise its life.

Dave


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## Boff (May 10, 2005)

Hi!



timofleeds said:


> Hi Gerhard my truma is the C4002 model.





DABurleigh said:


> 1.3 A average consumption I believe...


1.3 A average is correct, however only while the system is running. The C4002 has however full thermostatic control, so heater and fans will only switch on on demand.

To my experience, with outside temperatures constantly just below freezing and inside temperature at a cosy 20 degrees C, the system will run for about 8 hours a day. Means an average consumption of 10.4 Ah per 24 hours. It depends a lot on the actual temperature difference between in- and outside, and the thermal insulation of the van, but 1-2 nights in a row without hookup should be - regarding the heater - no problem.

Best Regards,
Gerhard


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## 101405 (Oct 15, 2006)

IF your batts are getting a bit low. Why not start your engine and run it to Charge your batts up, It will run for ever . it wont overheat because the cooling fan will cut In , It does not have to be driven, and it wont do any harm. Of course you can't run it next to another M/H . It always beats me why people dont do this?


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## Andysam (May 10, 2005)

Idling an engine from cold is not a good idea. Smaller engines like gennies are fine as they quickly heat up, but modern energy (heat) efficient engine will struggle to get to optimum operating temperature. Yes they will work but a lot more strain is placed on the oil and internals than if you simply started up and drove away.

Of course the simple answer is to frequently change the oil to maintain a good level of protection.


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## vicdicdoc (May 14, 2005)

timofleeds said:


> . . " before having to run the engine to recharge the leisure battery. . ."Thanks, Tim


Rather than run your vehicle engine - get yourself a small generator - less fuel being used and no wear on the engine just idling !

[look in the 'Accessories For Sale' - there's one for sale right now !


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## AberdeenAngus (Jul 26, 2008)

silversurfa said:


> IF your batts are getting a bit low. Why not start your engine and run it to Charge your batts up, It will run for ever . it wont overheat because the cooling fan will cut In , It does not have to be driven, and it wont do any harm. Of course you can't run it next to another M/H . It always beats me why people dont do this?


Can be quite bad for an engine especially a large diesel to leave it on light load (i.e. tickover) for a long time.
Can cause 'glazing' of the cylinder walls which will give problems later on.

It's also pretty inefficient to run a vehicle engine just to spin an alternator.

Better to buy a gennie


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## raynipper (Aug 4, 2008)

Hello Timofleeds,
Where in Northern France? If you have a long enough lead you can plug into us.

Ray. Portbail.


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## Boff (May 10, 2005)

Hi!



silversurfa said:


> IF your batts are getting a bit low. Why not start your engine and run it to Charge your batts up, It will run for ever [...] It always beats me why people dont do this?


I know from experience that in my van - which admittedly is relatively well-insulated - having a Truma C3402 (predecessor of C4002) and a 100 Ah leisure battery, two nights in a row are absolutely no problem even at outside temperatures constantly below -10 degrees C. And, if being rather conservative with lights, laptop etc. then even 3-4 days. (Certain, heat-producing indoor activities are anyway better done in the dark... :wink: )

But then the _option_ to run the engine in a real *emergency* (like being stuck in snow for several days far from hookup) is what keeps me from buying a genny. I am fully aware that this would be no good for the engine, but as said it is only a last resort. Which I so far never had to refer to.

Best Regards,
Gerhard


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## Andysam (May 10, 2005)

I'm in total agreement Gerhard- no problems at all with HAVING to run the engine in a need situation. Far better that than freeze. But I admit I'm a genny junkie if I'm not moving for 3 days. (Although I can't remember the last time we didn't move the next day!)


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## timofleeds (Sep 12, 2006)

Hi Ray, not sure where we will end up, it depends on the weather really.
If it is dry and bright probably the coast if not inland possibly Rouen. thanks for the offer but my EHU cable is only 25mtrs.

Regards Tim


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