Paralax fan runs constantly

[Bilo Hak]

I have a paralax converter in an 2005 30amp airstream. The fan runs almost constantly.

I believe it is a model 7355 but there is no tag indicating such.

Anyone know what I must do to fix? Stop the fan. Could it be a thermostat?

[Al and Missy]

When mine did that I had a bad battery that was sucking up all the current. The fan was on because the converter was working hard trying to charge a bad battery. Check your batteries and see if one is hot.

Also, the 30 amp is your AC input and doesn't have anything to do with the converter, FYI.

Al

[gypsydad]

That is a single stage converter, that came stock on most all AS's until they went to a 3 stage converter in 2018 models. Sounds like something is drawing current, like your batteries perhaps causing the converter to stay on? Many threads on the Forum about switching out the stock converter to a new multi-stage (4 stage) unit to protect your batteries. If your interested, research the Forum on this or I would suggest you call Randy at Bestconverters.com; he can recommend a replacment converter which will service your batteries while providing worry free service once installed. Good luck!

[ROBERT CROSS]

Your AS is only 2yrs younger than ours...I swapped batteries and converter at 2yrs old, batteries tested shot👎 IOTA 55a IQ4.

Went to Lithiums last Season and replaced again.

IIWY...I'd swap, upgrade both the batteries,(if tested & not 100%), and converter.

Bob
🇺🇸

[garry]

If not the batteries the converter may be full of dust clogging the air flow.

[Kamiak]

Originally Posted by Al and Missy

When mine did that I had a bad battery that was sucking up all the current. The fan was on because the converter was working hard trying to charge a bad battery. Check your batteries and see if one is hot.

Also, the 30 amp is your AC input and doesn't have anything to do with the converter, FYI.

Al

Same experience for me. It was very hot. I should have known better because it showed symptoms of sulfation when I bench-charged it prior to the trip. I removed the bad battery, cleaned out the case and surrounding metal (though no evidence of boil-over, covered the connectors, and ran on one battery for several months until I bought replacements.

[thewarden]

Originally Posted by gypsydad

That is a single stage converter, that came stock on most all AS's until they went to a 3 stage converter in 2018 models.

My 2017 has a Parallax 8355 3 stage 55 amp converter.

[Antique Pedaler]

When the fan on mine ran all the time I did everything as above, talked with the factory tech.....then replaced it.

[gypsydad]

Originally Posted by thewarden

My 2017 has a Parallax 8355 3 stage 55 amp converter.

Not sure, but your post signature says it's a 2016 model?? I know my 2017 was a single stage...if your AS is indeed a 2017 model, perhaps you got yours after they started upgrading to the newer 3 stage models before the 2018's were released??...happens like that sometimes. I got my 2017 28' in May of 2017... My converter was working fine but it fried 2 sets of batteries before I replaced it; the original Interstates and the replacement Interstates...New converter and new 6V Trojan batteries; no problems since.

[thewarden]

Arrrgg!! Typo. Mine is a 2016 and it does have the 8355 3 stage converter.

[68 Overlander]

Originally Posted by thewarden

Arrrgg!! Typo. Mine is a 2016 and it does have the 8355 3 stage converter.

That is a single stage converter. Changing current is totally different than changing voltage when it comes to multi stage charging. The battery internal resistance changes the current (tapers) with its internal resistance anyway so changing the current inside the converter has little effect. This is why you don't hear about over charging with a multi stage that drops the voltage when the batteries are fully charged.
Voltage is the key. It's the force that pushes the current. If you have a 55 amp converter for instance, all 55 amps are available at any time if the battery "wants" it or will let it in. As the resistance builds, the voltage increase will help push more amps faster but it's important that it is limited in time. Otherwise the batteries gas off too much resulting in over charge and that rotten egg smell, or worse.
Since AGMs don't gas per se, there is nowhere for it to go until it trips the pressure relief valve when the pressure gets too high (The reason AGMs need venting to the outside if used inside) Next problem, there is no way to replace the electrolyte in VRLA type batteries. AGM, SLA and Gel.

[68 Overlander]

I agree with others above that a bum cell in the battery could create a low voltage condition and cause it to run full output to compensate. The fan control logic is different on various converters. Some are temperature controlled like the PD and Boondocker, some are load controlled like the WFCO and others are a combination. Some are constant speed fans and others are variable speed. I will say this, predicting your fan is less accurate than choosing lottery tickets. It's going to run when it thinks it needs to and it might be dead of winter!

[gypsydad]

Originally Posted by thewarden

Arrrgg!! Typo. Mine is a 2016 and it does have the 8355 3 stage converter.

That is not a 4 stage converter. Check out the factory specs on the Boondocker or Progressive Dynamics to better understand the difference the 4 stage gives you. You can leave plugged in and it will not fry your batteries; in fact, it will condition your batteries...Here is a short description:
Built-in features such as electronic current limiting, reverse battery protection, high voltage protection, low voltage operation, and over temperature shut down ensure long-term reliability. The built-in Charge Wizard is a microprocessor-controlled system that constantly monitors the battery voltage and ensures a rapid; yet, safe, recharge. The Charge Wizard can select one of three charging voltages and one of four operating modes depending on the condition and use of the battery.