TRUMA HEATING

[chris scantle]

How long can the heating run on a 70 amphour battery with a Truma C3402?

 

[VXman]

Someone more knowledgeable will respond soon I am sure but I would say not very long at all! 70amh is not very big and heaters use a lot or power.

My Truma doesn't runoff the battery at all (mains or gas only). Is this one designed to run off a battery?

 

[chris scantle]

sorry for the confusion, it is gas fired ,the leisure battery is 70ah. All works well but I am only getting about 10 hours before the red light flashes warning of low battery power, The battery is only 2 yrs old, so I don't think it is that.

 

[Davb]

This is probably a how long is a piece of string type question, as the main draw on the battery is the fan. If it's very cold then your fan and the heater is going to be running a lot more than in warmer conditions.

 

[VXman]

sorry for the confusion, it is gas fired ,the leisure battery is 70ah. All works well but I am only getting about 10 hours before the red light flashes warning of low battery power, The battery is only 2 yrs old, so I don't think it is that.

After more thought I did wonder if that was what was meant.

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[Figaro]

They do gobble up the amps via the fan so 10 hours maybe about right with other stuff your probably running ?
How are you charging the battery ?
Do you leave the heater on overnight, you might be better with a hot water bottle lol.
I'm sure the techies will be along to give more accurate information.
BTW

 

[Davb]

If you have a multimeter, try checking the voltage when the battery is charged and when the red light comes on and see if there is a significant drop in the voltage (i.e. less than 12 volts) If you haven't got a multimeter they are cheap to buy these days and well worth having.

 

[chris scantle]

Yes I understand that, I've checked the fan is running freely and it clicks in and out on the thermostat, I just want a ball park figure I don't want to take it to the repairers if there is no fault. What is strange is that although it cut out with the red light flashing (low battery?) when I started the van the charging indicator was normal, hardly charging at all and it all functioned perfectly after the drive home.

 

[chris scantle]

When the red light was flashing the battery indicating guage on the control panel showed very low voltage. I have a multimeter and will check it out but the battery has hardly been used since new.

 

[Gellyneck]

....... you might be better with a hot water bottle lol.

There are better alternative options!

ps to OP

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[Lenny HB]

It depends on the outside temperature, the wind speed, the van insulation & the size of the van.

The older C3402`s do take a bit more power than the modern versions.
A small amount of power it used by the combustion fan but most is taken by the main blow air fan.
On startup with the fan running full chat it will take about 5 5 amps once the van is up to temperature the fan speed will drop and current down to about 1.5 amps.

Depending on the conditions I stated above between 20 min to 1½ hours to get van up to temperature unless there is a very strong wind blowing sucking the heat out of the van then the fan will run continuously at full chat.

Example a well insulated 7m van no or very light wind outside temp 6°, at guess running for 5 hours about 7 to 10 ah.

Sounds to me like you battery has had it but you don't state what else is on drawing current, if you don't have LED lights you could be using 5 to 10 amps an hour on lights.

 

[chris scantle]

Thanks Lenny, there is only a ledlight on and it is a new battery and when I started the van there was no excessive charging of the leisure battery according to the charge/usage indicator. Thanks for the info about the amps. Just to clarify are you saying running it for 5 hours would take around 7 to 10 amphours?

 

[WillH]

Truma heaters are a bit fickle when it comes to voltage, it doesn't take much of a drop to bring up the fault condition.

 

[Lenny HB]

Just to clarify are you saying running it for 5 hours would take around 7 to 10 amphours?

Yes but depends on the conditions and your van.
If there is a howling Gale blowing it could take 28 ah.

 

[BouncyBoatFolk]

For the O.P. not forgetting, you only get 35 of those 70AHas a usable quantity. For the cost of a non fruitful workshop session you could buy and fit a tandem battery, giving an actual 70AH usable reserve.
Mike.

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[Figaro]

I have a multimeter and will check it out but the battery has hardly been used since new.

Maybe that's part of the problem, batteries don't like inactivity ?

 

[Lenny HB]

What is the tyre of battery & what is the charger/distribution unit in your van?
Just wondering if the battery is getting a full charge.

Also worth checking the wiring to the heater to see what sort of volt drop you are getting when the fan is running at full speed. On older vans you can get high resistance contacts on the connectors and it's not uncommon for manufacturers to fit undersize wiring.