Humidity problem with inverter

[zuluphil]

I have a 600w Pure Sine 24v to 220v Inverter with has worked fine for nine months, however it failed on me last week with a blown 35 amp fuse. I sent pictures to the manufacturer who thinks that the dust and humidity has caused it to 'blow'. On checking the specs. it has a max working R.H. of 90%,on checking the R.H. of the air last week it sometimes hit the 90% mark(usually after sundown when my lights are needed!)
It looks like the manufacturer could be right. To prevent this happening every summer, could I put the inverter into a wooden box with a fan and filter and connect it directly to my batteries? Any thoughts or ideas ?

[Sunking]

That will not remove any humidity. Only way to do that is by installing dehumidifiers which consume a lot of power. Basically a air conditioner which removes humidity and heat.

What is happening between dust, heat, and humidity is causing the inverter to over heat. Dust is an insulator, and high humidity negates evaporative cooling. That is why 90 degree dry heat is much more comfortable than 90 degree humid heat. 90 degrees in Maimi is unbearable and 90 degree heat in Las Vegas is long sleeve shirt weather.

[inetdog]

That will not remove any humidity. Only way to do that is by installing dehumidifiers which consume a lot of power. Basically a air conditioner which removes humidity and heat.

What is happening between dust, heat, and humidity is causing the inverter to over heat. Dust is an insulator, and high humidity negates evaporative cooling. That is why 90 degree dry heat is much more comfortable than 90 degree humid heat. 90 degrees in Maimi is unbearable and 90 degree heat in Las Vegas is long sleeve shirt weather.

I doubt that the inverter is relying on evaporative cooling to reject heat. People sweat, equipment does not generally. And overheating by itself should not blow a fuse. Damage to internal components as a result of overheating could blow a fuse, but in that case a replacement fuse should blow immediately too.

If the dust was marginally conductive (organic dust for example) then a dust layer deposited inside the unit could be non-conductive at low humidity but collect moisture hygroscopically at high relative humidity and become conductive enough to disrupt the inverter electronics.

If there is a visible layer of dust inside the unit, then you probably would benefit from a filter of some sort on the air entering the unit.
And if cleaning out the dust restores the unit to proper operation (fuse does not blow) then I would take a chance that keeping dust out will also prevent the humidity from being a problem.
If the dust is contributing to an overheating problem, then cleaning the unit and filtering the air (without restricting the air flow too much) should help you.

If the inverter body cools off during the night and then you pump humid warm air into it when the fans first turn on, you could end up condensing moisture even with low RH, but it does not sound like that is your problem.

In short, I think that you do have a dust problem, that it may have caused internal damage from overheating, and that the humidity was a red herring cited by the manufacturer.

[Mike90250]

Look towards the Morningstar sure sine 300 for a rugged, fanless inverter

[zuluphil]

I doubt that the inverter is relying on evaporative cooling to reject heat. People sweat, equipment does not generally. And overheating by itself should not blow a fuse. Damage to internal components as a result of overheating could blow a fuse, but in that case a replacement fuse should blow immediately too.

If the dust was marginally conductive (organic dust for example) then a dust layer deposited inside the unit could be non-conductive at low humidity but collect moisture hygroscopically at high relative humidity and become conductive enough to disrupt the inverter electronics.

If there is a visible layer of dust inside the unit, then you probably would benefit from a filter of some sort on the air entering the unit.
And if cleaning out the dust restores the unit to proper operation (fuse does not blow) then I would take a chance that keeping dust out will also prevent the humidity from being a problem.
If the dust is contributing to an overheating problem, then cleaning the unit and filtering the air (without restricting the air flow too much) should help you.

If the inverter body cools off during the night and then you pump humid warm air into it when the fans first turn on, you could end up condensing moisture even with low RH, but it does not sound like that is your problem.

In short, I think that you do have a dust problem, that it may have caused internal damage from overheating, and that the humidity was a red herring cited by the manufacturer.

Hi Inetdog,
I understand R.H. and why the dewpoint is happening just when I need to put my security lights on, My set-up is housed outside inside a large open garage unit, We are at the end of the summer now and had had exceptional rains and high temps. I have used compressed air to clean out the unit although except for some very small spidery bits it was not "dusty".The new fuse blew immediately I connected the power on two occaisons ( although I only had 30 amp fuses not the 35 amp original) so I think the unit has failed. the manufacturer is willing to replace the unit although I don't want the same problem next summer. It is only a small 200w security light system so I don't want to go down an expensive de-humidifying route. Surely there must be someone in similar humid conditions as Me with an outside Inverter that does not blow every summer. Do most inverters have a max R.H. of 90% which is my specification? Or maybe it is just the unit that I have installed which is poor quality ! It is a Maili Ce&Rohs approved 24v to 220v Thermostatic fan 600w pure sine inverter costing approx. $130 .

[zuluphil]

Look towards the Morningstar sure sine 300 for a rugged, fanless inverter

Hi Mike,
Thanks for the suggestion, I have looked at the specs of the Morningstar and it is made for the tropics and does not have the power consuming fan either, it also can handle 100% R.H. the operating temp. is 45 degrees and my outside shaded temp. can go over 40 sometimes, before I call any salesmen , do you think that the unit itself would increase the temp. at all.

[Mike90250]

I don't know. It depends on what your load is, 100, 200w not much problem. 300w, you may want to mount it on a big aluminum plate as a heat sink. Be sure you order the right voltage model for your area.

[Sunking]

At 90% humidity I bet he is very near salt water.

[zuluphil]

At 90% humidity I bet he is very near salt water.

The nearest saltwater to me is my mouthwash, the next nearest is 65 metres below me and 25 kilometres away, if you are referring to the salt corrosion potential then I think that either the tropic models or possibly a marine version is probably the answer. In the meantime, I will place the new (same as previous)inverter inside an old metal computer case with cooling fan and mozzie netting . Are there any type of anti-moisture spray or maybe silca type moisture absorbers that would help prevent high R.H. shorts maybe that wouldn't damage the circuitry :