Sine Wave Generator blowing chargers - help!

[Hydra]

Hi all, I am totally new here and have posted this because I'm at my wits' end. I have blown 3 battery chargers in a row (1 Absaar 16000, 2 x CTEK MSX10s!) and can't get to the bottom of the problem.

My motorhome is often parked on a rural site with no electric hookup and for 18 months my charging system worked fine. I have been using a Wolf Power Genie 1200 sine wave inverter generator from which I run an extension cable to the vehicle hookup. Inside the vehicle I was charging the battery with an Absaar 16000 charger directly attached to the battery. There are no problems or faults with the hookup. In November last year I replaced my old leisure battery with a Leoch SFL 120 leisure battery, which charged fine on my system for about 6 months, then the charger suddenly died, showing no lights or activity when plugged in. I purchased a new CTEK MSX10 charger, which worked fine about 4 times, then died in the same way. A second CTEK MSX10 charger subsequently died after just 2 charges. All the chargers appear to have blown fuses - though I haven't looked inside them, but there is simply nothing, no sound, no lights, nothing coming from them. Since then I have been charging the Leoch battery directly from the generator which has a 4 amp DC battery charging socket and the battery has charged fine, though slowly!

The generator output was checked at a service centre who said it was stable.
I took the battery to the battery centre to check for faults/internal short circuits - they say there is nothing faulty, although they can't get the battery up to more than 40% capacity so it is essentially knackered after just 10 months use, which I can't understand (I have never let it go below 11.5V and always top it up fully, it may have been left standing at half capacity for a week or so occasionally, but that is all)
I have sent the CTEK chargers to CTEK for repair and am awaiting their response.

So my question is, If the battery is not the problem and the generator is stable, what could have blown the chargers? Could a dodgy extension cable be at fault? If my generator is pure sine wave, surely it can't be the generator? Something I have been guilty of is occasionally firing up the generator (after it has run out of fuel usually) with the battery charger still plugged in - could this have caused the problem? But if so, why did it take over 18 months to start causing the problem? I am also not sure if it is OK to use the 'eco' setting on the generator while charging the battery, something else I have been doing.

Anythoughts/info on this would be greatly appreciated.

 

[Guzzilazz]

As these are available for around £350, I'd be very surprised if they are PURE sine wave... In my quick internet search they only claim voltage and frequency stability.... You really need to see an oscilloscope on the output, but I would have thought it would be closer to a square wave, and that would upset devices with sensitive electronics....

 

[ProfJohnL]

I'm inclined to suspect the generator, and like Guzzilaz, I have looked for the information about the Wolf Power Genie 1200, and no where have I found Wolf claiming the output to be a sine wave, though they do claim its suitable for sensitive electronics.

Pure "sine wave output" is one of the holy grails of generation, and I'd be pretty certain a manufacturer would have it plastered all over their products to highlight it as a feature, so its absence is concerning.

Whilst a small generator that produces pure sine wave, will almost certainly use inverter technology to achieve it, simply using inverter technology does not mean the output will be a sine wave. Inverters are controlled by an frequency synthesisers which will keep a very stable output frequency independent of the engine speed. They will also be good at controlling the peak output voltage, but neither of these characteristics mean the output has to be a sine wave.

I do note that one magazine claims the unit has a sine wave output, but that cold be journalistic licence rather than fact based evidence.

https://www.outandaboutlive.co.uk/motorhomes/news/new-range-of-inverter-generators-are-out-of-the-bottle

 

[JTQ]

Surely even a rudimentary alternator generates a pure sine wave?
That is what spinning a coil within a magnetic field naturally generates, one locked in frequency to the speed of rotation.
Where it gets messy is in synthetically generating a sine wave, done so the generator can operate at lower speeds on light loads to reduce the noise. These units rectify the various frequencies being generated, then have a frequency controlled inverter to develop, in our case a 50 Hz wave, it is the quality of that inverter that decides the purity of the waveform.
A low cost unit will be some modified sine wave.

 

[ProfJohnL]

Surely even a rudimentary alternator generates a pure sine wave?
That is what spinning a coil within a magnetic field naturally generates, one locked in frequency to the speed of rotation.
Where it gets messy is in synthetically generating a sine wave, done so the generator can operate at lower speeds on light loads to reduce the noise. These units rectify the various frequencies being generated, then have a frequency controlled inverter to develop, in our case a 50 Hz wave, it is the quality of that inverter that decides the purity of the waveform.
A low cost unit will be some modified sine wave.

I totally agree, and the reason these small generators don't just use an alternator is three fold, firstly as the applied load changes suddenly the mechanical speed governor is not fast enough to adjust the RPM, so both frequency and voltage can change quite dramatically as the engine catches up.

Also being a very small generator (compared to the CEGB ones) the windings in an alternator can't absorb transient spikes of interference anywhere as effectively, so the generator can produce some quite nasty spikes which can radically exceed safe working voltages of connected equipment.

Inverter technology can cope far more effectively with such events, provided the inverter is well designed. And that is what is being questioned in this thread.

 

[JezzerB]

I too would suspect the generator; the less you pay the less 'pure ' the generation and sadly the ctek charger is a VERY sophisticated bit of kit that monitors battery/ can recover and maintain it etc-too much of a coincidence I feel.

 

[Dustydog]

I have a wolf 900 watt output Jenny. Cost £28.00 ten years ago. Never never have I plugged into the caravan as the voltage and power output appear to be solely rpm governed.
It is a crude device for us3 in the “outback” for basic lighting.
Otherwise as frequently stated on here Jennies are not for the caravanner :woohoo:

 

[Hydra]

Many thanks all. I have to suspect the generator - I am wondering why it gave me no problems for the first 18 months, (It was brand new at the beginning of that period)

I have looked at the manual and info on this genny and I can't find anything about the sine wave technology either - not sure why I have even made the assumption that it did have pure sine wave!

Two more questions arise from this:

Is it common for generators to blow chargers etc if they are not pure sine wave?

Does anyone have any thoughts as to whether using the ECO setting may have caused the problem? The ECO setting uses a 'smart throttle' which adjusts engine speed according to the load, to save fuel.

Thanks again everyone.

 

[Damian]

Quote " Is it common for generators to blow chargers etc if they are not pure sine wave?"

The simple answer is yes , especially if they are allowed to run out of fuel,or on initial start up.
A generator must be allowed to warm up and settle before connecting anything to it.
It is worse with 2 stroke units, but it has been known for a genny to push out 480v in a spike !!!!

Quote " Does anyone have any thoughts as to whether using the ECO setting may have caused the problem? The ECO setting uses a 'smart throttle' which adjusts engine speed according to the load, to save fuel."

The ECO setting is normally quite good, but there will be a delay in demand and supply.
However it all comes down to how good the components are inside the genny, and as is the usual case, you get what you pay for.
Buy cheap and get cheap bits and the associated problems.

 

[ProfJohnL]

There has been an increase in the number of mains powered appliances used in caravans, and for people without a mains hook up that can be a problem. This has started to be addressed with the advent of modern electronics allowing for example 12Vdc from a battery to be converted to 230V ac. This uses an inverter module, and it's very likely a similar circuit module will be used in inverter generators.

Historically some caravanners have had problems with cheap two stroke non inverter generators, mainly with inconsistent speed regulation, particularly noticeable when removing an electrical load where the generator can over speed producing over voltage and higher frequency output, until the auto throttle has had time to adjust and bring the RPM back to the rated speed.

This was one reason why inverter output generators became popular, because the output frequency and voltage is electronically controlled and is independent of the engines RPM.

Most touring caravanners do not use generators because they are perceived as antisocial, and some sites ban them or limit the times when they can be used.

They're heavy and have to accounted for in the vehicle loading . They are also very inefficient at converting fuel to electricity and the fuel is usually road pump priced which is inflated due to traction fuel taxes. There also servicing costs for the generator. Most off grid caravanners explore other solutions such as solar panels to replenish battery charge. and the use of LPG for fridge, water and space heating as well as cooking etc.,

But despite these drawbacks for some people there is no alternative to a generator, and the advice is to go for a good quality (and probably more expensive) 4 stroke petrol generator with a sine wave inverter output.

I don’t think we have enough data from other users to be able to say that generators will blow chargers, there is a distinct possibility that non sinusoidal outputs may damage some appliances but its not certain.

And for similar reasons I don’t think we can offer any insight into the dangers of ECO settings on generators.

There is of course the possibility the problem is unique to you particular generator and a replacement might be perfectly satisfactory, but it's my professional advice that you should be looking for a pure sine wave output unit.

 

[JTQ]

As others have said our chargers can be damaged by the characteristics of some generators and the careless use of them. The running out of fuel is a prime example. As also said the inherent "quality" of the generator plays a part and it is unrealistic to expect a budget generator to offer the same performance as for example a brand leader like the expensive Hondas.
One leading charger maker offers and add on device to limit the voltage range, both high and low hitting its charger. It affords an added level of protection.
This unit is the Schaudt OVP1
http://shop.apuljackengineering.co.uk/index.php?route=product/product&product_id=115
It is packaged to suit their units and simply goes between the kettle plug mains supply feeding the controller and the controller.

 

[Anseo]

On the subject of low costbuget generators damaging battery chargers.

If a pure sine wave inverter was plugged into a low costbuget generator and the inverter then switched on to supply electricity via the EHU plug to the caravan; would this reduceeliminate the possibility of damage to the battery charger.

 

[Guzzilazz]

You'll probably blow up the inverter... The whole issue is the "dirty" output of the generator...

 

[Gafferbill]

On the subject of low costbuget generators damaging battery chargers.

If a pure sine wave inverter was plugged into a low costbuget generator and the inverter then switched on to supply electricity via the EHU plug to the caravan; would this reduceeliminate the possibility of damage to the battery charger.

Hi John..........Inverters use a DC supply (usually 12 volts) and covert it to around 230 volts AC.
Cheap low cost generators produce not very stable 230 volts AC and can't be used with an inverter.
More expensive inverter generators produce a low voltage DC output and covert this to 230 volts AC with the addition of an inverter all contained within the generator casing.

The most proficient and fastest charging generator for 12 volt batteries when off grid is a vehicle alternator.

An alternative is one of these which uses the same technology..... Click here