Trauma Heater overload

[MykCamper]

I have been experiencing 12v overload cut outs recently and have now tied it down to the Truma heater.
It started off intermittently, now it cuts out the 12v system after a few minutes of use once up to temperature.
The Leisure batteries showing 11volts, then on reset it back up to 13.5 plus.
The water seems to get hot very quickly and the hot air fan is blowing very strong.
Has anyone ever experienced this phenomenon?
Mike

 

[wildebus]

I have been experiencing 12v overload cut outs recently and have now tied it down to the Truma heater.
It started off intermittently, now it cuts out the 12v system after a few minutes of use once up to temperature.
The Leisure batteries showing 11volts, then on reset it back up to 13.5 plus.
The water seems to get hot very quickly and the hot air fan is blowing very strong.
Has anyone ever experienced this phenomenon?
Mike

It sounds like a Truma Combi? Is that right? A model number might help to get help.

My own thoughts are if the Combi works in a similar way to the Ultrastore and Ultraheat, the only real 12V use is for the fan - maybe that is overheating and seizing causing an overload? What if you try using the heater without the fan?

 

[eurajohn]

It sounds like a Truma Combi? Is that right? A model number might help to get help.

My own thoughts are if the Combi works in a similar way to the Ultrastore and Ultraheat, the only real 12V use is for the fan - maybe that is overheating and seizing causing an overload? What if you try using the heater without the fan?

Other than physically disconnecting the fan, don't think there is any way to do that, I think that would then cause a fault to be registered by the system of the unit and shut the gas supply off.

 

[Okta]

Just a thought. The Combi draws up to 6.5A from the 12V system when working hard. If your leisure voltage drops to 11V it might indicate the battery is at fault. A heavily sulphated battery can rapidly drop and recover voltage but has little capacity to sustain power. Also fits with the problem starting intermittently and getting worse as the battery deteriorates. Not experienced the problem myself so just a guess.

 

[Davy]

I dont believe that the fan is powered by the battery. More likely the 240v/12v transformer in the charger.
However, if the battery is duff and is consumming too much current from the charger, then adding the 6.5A load from the fan may just tip it over.

 

[Okta]

I dont believe that the fan is powered by the battery. More likely the 240v/12v transformer in the charger.
However, if the battery is duff and is consumming too much current from the charger, then adding the 6.5A load from the fan may just tip it over.

As the voltage was dropping I assumed no hook up.

 

[wildebus]

Other than physically disconnecting the fan, don't think there is any way to do that, I think that would then cause a fault to be registered by the system of the unit and shut the gas supply off.

This is why knowing the Truma model can be helpful. On my Truma, the fan control on the heater is a separate control dial and can be turned off if you want.

I dont believe that the fan is powered by the battery. More likely the 240v/12v transformer in the charger.
However, if the battery is duff and is consumming too much current from the charger, then adding the 6.5A load from the fan may just tip it over.

As per the reply above. Different models may have different power sources. The fan on MY Truma heater IS powered by the battery and not by the AC or a transformer powered by AC.

 

[eurajohn]

I dont believe that the fan is powered by the battery. More likely the 240v/12v transformer in the charger.
However, if the battery is duff and is consumming too much current from the charger, then adding the 6.5A load from the fan may just tip it over.

I think you will find that all 12 volt services in the van are powered from the habitation batteries, if connected to EHU the inbuilt charger will maintain the state of charge of the habitation battery/ies.

 

[wildebus]

As the voltage was dropping I assumed no hook up.

Seems reasonable. Running heating on gas is perfectly doable with just the fan running off the battery.
Massive voltage drop for a fan use which implies a significant fault on the fan or batteries are bad?

 

[nabsim]

Just a thought. The Combi draws up to 6.5A from the 12V system when working hard. If your leisure voltage drops to 11V it might indicate the battery is at fault. A heavily sulphated battery can rapidly drop and recover voltage but has little capacity to sustain power. Also fits with the problem starting intermittently and getting worse as the battery deteriorates. Not experienced the problem myself so just a guess.

Although I don’t have any Truma gear the behaviour you describe is exactly what I had before I swapped out my battery’s. All apparently good but low capacity when drawn on

 

[MykCamper]

My 2 batteries are 3 year old, pair of premium 150ah from Alfa Batteries, been on hookup for 3 days prior to an hours drive 2 days earlier, 80 w solar panel had kept them topped up.
Never let the leisure batteries drop below 12.5 v when not in use.
Could I have a failing trip switch?

 

[Geek]

What SHOULD happen is that the Truma comes on and does a self check, then the flue fan starts up, followed a few seconds later by the burner. Then slowly the circulation fan ramps up as the burner produces more heat, until the fans are all going full pelt.

At this point, the current draw may be as high as 4.5A (maybe not the 6.5 as mentioned by others) and if the voltage at the Truma end of its power cable drops to less than about 11.7v, the Truma will cut out.

You battery should not drop to such a low voltage on such a small load. If it does, there are two possible reasons: the battery is flat, or the battery is worn out.

However, are you sure it's the battery? If there is a bad connection, that could be causing a voltage drop (and also could be preventing the battery charging properly). Check the voltage across the battery terminals themselves, not the connectors attached to them. If that's OK, look for a bad connection somewhere. If it's not OK, find out why the battery drops so low under load, and fix it.

In the meantime, to keep things running, you might try turning the thermostat down. If you request a temperature only a bit higher than the van is already, the Truma will start with less power. Over time you can turn it up a degrees or two as the van warms.

 

[Dave H]

My 2 batteries are 3 year old, pair of premium 150ah from Alfa Batteries, been on hookup for 3 days prior to an hours drive 2 days earlier, 80 w solar panel had kept them topped up.
Never let the leisure batteries drop below 12.5 v when not in use.
Could I have a failing trip switch?

Hi
I would doubt its the trip if the battery is dropping to 11v. Try applying a battery discharge tester or a known load like a headlight bulb to try the battery, which I think is the problem.

 

[Okta]

My 2 batteries are 3 year old, pair of premium 150ah from Alfa Batteries, been on hookup for 3 days prior to an hours drive 2 days earlier, 80 w solar panel had kept them topped up.
Never let the leisure batteries drop below 12.5 v when not in use.
Could I have a failing trip switch?

Are your batteries AGM, Gel or standard lead acid? Also what make and model of mains charger do you have? I am wondering whether your mains charger is looking after your batteries properly. At this time of year your solar is probably not contributing very much. Voltage can be a poor indicator of battery condition and solar charging, you need Amps too.

 

[TR5]

I dont believe that the fan is powered by the battery. More likely the 240v/12v transformer in the charger.
However, if the battery is duff and is consumming too much current from the charger, then adding the 6.5A load from the fan may just tip it over.

The fan supply has to come from the leisure batteries, otherwise it wouldn't work when not on EHU! I very much doubt the draw is anywhere near 6.5A if we are talking about a Truma Combi 4E or 6E - 4 amps maybe on full pelt.

 

[TR5]

My 2 batteries are 3 year old, pair of premium 150ah from Alfa Batteries, been on hookup for 3 days prior to an hours drive 2 days earlier, 80 w solar panel had kept them topped up.
Never let the leisure batteries drop below 12.5 v when not in use.
Could I have a failing trip switch?

Have you checked the terminals to the battery are secure? If not fully sealed units, have you checked the electrolyte and topped up as necessary? Have you checked the main fuse and holder to the batteries, to make sure it is not getting hot when under load, indicating weak or dirty connections? All these will cause an indication of low voltage, causing the Truma to trip out. If it goes off suddenly, it probably has an overheat trip as well, stopping it from working until it cools and resets.
You need to measure voltage at both ends to see where the issue is - it may well be a battery, but also may well be a poor connection somewhere.

 

[RoaminRog]

Can’t help you Mike, but hope you get it sorted quickly

 

[MykCamper]

What SHOULD happen is that the Truma comes on and does a self check, then the flue fan starts up, followed a few seconds later by the burner. Then slowly the circulation fan ramps up as the burner produces more heat, until the fans are all going full pelt.

At this point, the current draw may be as high as 4.5A (maybe not the 6.5 as mentioned by others) and if the voltage at the Truma end of its power cable drops to less than about 11.7v, the Truma will cut out.

You battery should not drop to such a low voltage on such a small load. If it does, there are two possible reasons: the battery is flat, or the battery is worn out.

However, are you sure it's the battery? If there is a bad connection, that could be causing a voltage drop (and also could be preventing the battery charging properly). Check the voltage across the battery terminals themselves, not the connectors attached to them. If that's OK, look for a bad connection somewhere. If it's not OK, find out why the battery drops so low under load, and fix it.

In the meantime, to keep things running, you might try turning the thermostat down. If you request a temperature only a bit higher than the van is already, the Truma will start with less power. Over time you can turn it up a degrees or two as the van warms.

Yes, I've had the heater on constantly for 10 hours at 14°, without mishap, came back from hiking, all's working fine for 3 hours,with lights on etc, thermostat upped to 20°, then the cutout, checked the LB reading, down to 11.5v, rebooted the system LB back up to 13.5v, with the Truma switched off.
Next morning LB reading at Max with sun on the solar, switch on Trama, ran for 30 plus minutes, water and air hot, then the cutout, LB reading down to 13v?
The hot air was blowing like a gale, never known it that strong!
I took particular care when fitting the replacement batteries using plenty of Vaseline on the terminals and sprung clamps.
They are Extreme gel batteries, 160 minimum cycles with 6 years warranty 115ah not 150ah as I previously wrote.
The battery condition indicator is showing All's well with LB?
Mike

 

[MykCamper]

Just booked my van into Todds at Lostock Hall, my local Truma specialist, engineer thinks that a circuit board is going on the blink, with the info I relayed.
Will post the results next week! :=)

 

[Okta]

Gel batteries should be capable of taking a hammering from time to time. A leisure battery reading of 13V means nothing if the solar is active, the solar controller will raise the voltage but could be sending two thirds of three fifths of sod all charge into the batteries.