Truma Combi 6 E - and the Battery

[Solomongrundy]

How much drain on the battery is my Truma Combi 6E when used during the cold winter evenings, without EHU, for a few hours?

There's a dial to allow power from the lowest setting of 1 to the highest of 5 and perhaps it's similar to the length of a piece of string on how hot we want the Motorhome and for how long.

Say it was on for three hours at maximum heat would any of the figures below show how much the battery was drained?

There are a lot of facts and figures on the Tech spec which mean b*gger all to me but may mean more to you technically minded guys/gals.

Power consumption (at 12v) Heating up boiler – Max 0.4 A

Power consumption (at 12v) Heating and boiler operation – 0.2 A up to temporary max of 5.6 A (average approx 1.3A)

Rated thermal output in mixed operation – max 5800 W

Rated thermal output in electrical operation – 1800 W

[lennyhb]

In normal mode will take around 6 amps for the first 15 - 20 mins until van is up to temperature then the fan speed reduces to lower speed and current drops to about 3.5 amps and when fully up to temperature speed will reduce even further and current down to about 1 amp. Obviously if very cold it will run for longer at the high setting, generally they are economical on electrical usage.

If you have a CP-Plus controller, you can set the fan to ECO or HIGH, on high it runs constantly at the higher speed.

 

If you ran it at max for 3 hours it would take about 18 a/h but normal use is more like I've described above and 3 hours use more likely to be between 6 -10 a/h depending how cold & how warm you like the van, gas consumption is usually more of a problem.

[Tracker]

If you are worried about 12 volt consumption why not do as many of us have done and either get a larger capacity battery if it will fit or add a second leisure battery?

 

[Solomongrundy]

Thanks lennyhb – a very clear and concise explanation and it's appreciated.

We have a Gaslow system and filling up at home or abroad has never been a problem – a bit of extra gas consumed isn't going to break the bank.

 

Tracker – an extra battery, or not, is what I'm working towards.

We use the Aires in France and rarely use EHU but last week in France the battery control panel showed the leisure battery dropping close to the 'naughty' step despite there being wall-to-wall sunshine most days, we have an 80W solar panel, and not having to use the heating at night.

The only electrical appliances working on a regular basis after dark are the fridge/freezer and about 6 or 8 LED lights.

Appliances used occasionally are the water heater for about an hour a day; water pump for the washing up water; shower each night; electric toilet flush and electric ignition for the gas cooker - I can't think of anything else.

The leisure battery is the Manufacturers own brand 105Ah, about two years old, and I had a 'capacity' test done by Manbat and they said earlier this year it was excellent.

But I don't want the worry of not having enough power during the back end of this year and into next year before the weather improves.

We are away over New Year in France when the weather may be at its worst and we want a reliable source of power in that period.

I'm considering getting a second battery, replacing the 'old' battery with two new ones, but after reading forum posts on here and other forums it's a devils own job deciding which brand or type to buy.

I've considered Varta, Banner and Numax (any other suggestions?) but there seems so many different opinions of each make that I finish up sighing, banging my head on the table and pouring a drink (and now it's time the bar opened!).

Back tommorow.

[lennyhb]

A lack of battery power and charging appears to be the problem.

An 80 watt panel is not going to do much at this time of year, the suns angle declines rapidly after September.

 

For example, I live on the south coast near Brighton, a couple of weeks ago I ran my batteries down a bit to check the output from my panels (2 x 100 watt) late October day clear sky bright sun, midday, I got 3.5 amps.

Under the same conditions an 80 watt panel would only give 1.5 amps. Also you will only get that output for a couple of hours either side of midday and will fall of rapidly outside of that. Obviously you will fair better in the south of France as the sun will be higher.

 

I would think you need to double your battery capacity and add one or preferably two 100 watt solar panels.

 

Have a look on This Thread a lot of useful information from Jon(Brambles) our resident battery expert.

[Brian Kirby]

Or drive for longer between stops! Off EHU the alternator is your most powerful and reliable battery charger. The solar panel will put some back, but if your consumption exceeds what the solar can supply you will be progressively exhausting the battery. Then, unless you drive for long enough to fully re-charge it before you next stop, the downward cycle will continue.

 

If the battery is sound, I think I'd be a bit inclined to fit more solar before fitting larger batteries. If the ratio of solar input to battery capacity remains more or less the same, so will the problem. The larger the battery bank, the longer it will take to charge. If you don't get the solar input right, you risk merely kicking the can down the street a bit.

[Billggski]

Just don't mention generators.......

[lennyhb]

I would disagree with you on this one Brian, as the OP need is for winter power which is the time of year where there is not much to be gained from solar. I believe it would be better to increase the battery bank size first and possibly making sure the batteries chosen as have good deep cycle characteristics.

 

Gel & AGM both give good deep cycling, both have their own drawbacks. Gel are very good for deep cycle use have a long life but take considerably longer to fully charge, AGM are a good alternative to Gel but at the moment there are no Motorhome chargers or Solar regulators that are capable of fully charging an AGM battery so you will not get the full performance out of them. The newer calcium technology batteries like the Bosch S5 appear to be a good alternative, good deep cycling, quick to charge and fairly cheap.

 

Driving not really an option (I did notice your exclamation mark) as to fully recharge a battery it would take a few hundred miles unless a Battery to Battery charger is fitted, link to the Serling one there are cheaper altenatives.

[Tracker]

A lot depends on how long the van is standing without the engine running.

 

If the OP moves every other day or two one decent leisure battery should suffice even in winter but just running the engine for a few minutes will not be enough. That said, being a dedicated non ehu user, I would always opt for two batteries and have one thing less to be concerned about!

 

Let's say that a 110 ah battery is part depleted and needs say 40 ah to top it up. The alternator charge rate is usually limited to around 10 amps for a leisure battery so in basic terms that will need at least 4 hours running as the charge rate tails off as the battery fills.

 

You can get a battery to battery charge/regulator that overcomes that low charge rate but they are not cheap and do need specialist wiring in view of the high currents involved.

[lennyhb]

Tracker - 2014-11-07 10:25 AM

 

 

Let's say that a 110 ah battery is part depleted and needs say 40 ah to top it up. The alternator charge rate is usually limited to around 10 amps for a leisure battery so in basic terms that will need at least 4 hours running as the charge rate tails off as the battery fills.

 

On a standard split charge relay installation once the battery voltage starts to rise the charge will drop considerably depending on size of wiring could be as low as a couple of amps after half an hours running.

 

Would help if we knew what the van is an the make & model of charger fitted as some like the Elektroblock can get a lot more charge into the battery.

[Brian Kirby]

lennyhb - 2014-11-07 11:46 AM

 

Tracker - 2014-11-07 10:25 AM

 

 

Let's say that a 110 ah battery is part depleted and needs say 40 ah to top it up. The alternator charge rate is usually limited to around 10 amps for a leisure battery so in basic terms that will need at least 4 hours running as the charge rate tails off as the battery fills.

 

On a standard split charge relay installation once the battery voltage starts to rise the charge will drop considerably depending on size of wiring could be as low as a couple of amps after half an hours running.

 

Would help if we knew what the van is an the make & model of charger fitted as some like the Elektroblock can get a lot more charge into the battery.

I take your point about low solar inputs in winter. TBH, I think the pattern of use might be more revealing than knowing the type of charger. The use of the battery seems quite light. Just heater, water heater, LED lights and pump.

 

The lights will be on for long periods at this time of year, ditto the heater. Even so, 105Ah (assuming it is a genuine 105Ah!) is a reasonable sized OEM battery, and should easily cope with those loads for 3/4 days.

 

But, as I was trying to say, and Rich said rather clearer, if the van is not driven for long enough before it is next stopped, it will not be fully charged before it begins its next discharge cycle. So, at the end of the next stop it will be further discharged and so on, until it becomes flat.

 

If the OP will only be away for a relatively short time, is likely to stay put for several days, and will drive several hundred miles to and from his eventual destination, the battery should be fine, and will arrive at each end fully charged.

 

OTOH, if the trip will be of several weeks duration, will involve a series of stops with only 50 or so miles between them, and will not stray far south of the Channel ports, the battery will be liable to become progressively exhausted.

 

Ultimately, what is taken out has to be put back. Doubling battery capacity gives longer before re-charging becomes critical, but it also doubles (approximately) the time it will take to re-charge. Of course, all this assumes there is not a defect in the battery. Probably the most cost efficient solution in the short term would be periodically to find an aire with a mains socket, and plug in to re-charge, or spend to odd night on a campsite, and use hook-up to let it charge there.

[Guest Joe90]

I read somewhere that you should isolate the output from the solar panel when driving, the logic being that if the alternator "see's " the appropriate voltage outputted from the solar reg to the leisure battery, it will not give the full rate of charge, which could well be far more than the panels amperage output.

 

It's something I have done with no ill effect. ;-) might be worth looking into as I don't know the exact science despite doing it, but it does seem to make sense.

[lennyhb]

Should not be necessary, chargers such as Elektroblock & CBE are intelligent enough to give the alternator priority, in other cases where the solar regulator is connected direct to the battery, the regulator will see the increased voltage from the alternator and turn off the solar charge.