Voltage regulator for 12 volt system

[Chateau_Nomad]

I recently installed two MaxxAir fans. From what I read, the two biggest failures of them are overvoltage to the motors, and moisture shorting an unprotected main circuit board.

The moisture problem seems to be an easy fix... a few coats of conformal coating.

The overvoltage could be solved using a 5 amp 12 volt regulator for each fan.

Then I got to thinking... why not just regulate the 12 volts being supplied to the entire fuse panel? Then any voltage sensitive device would never get the potential 13 - 14 volts in the system?

Any suggestions welcome... how many amps need to be accounted for in regulating the entire 12 volt house panel... and is this really worth the effort? Next is cost. ???

[Geterdun]

Originally Posted by Chateau_Nomad

I recently installed two MaxxAir fans. From what I read, the two biggest failures of them are overvoltage to the motors, and moisture shorting an unprotected main circuit board.

The moisture problem seems to be an easy fix... a few coats of conformal coating.

The overvoltage could be solved using a 5 amp 12 volt regulator for each fan.

Then I got to thinking... why not just regulate the 12 volts being supplied to the entire fuse panel? Then any voltage sensitive device would never get the potential 13 - 14 volts in the system?

Any suggestions welcome... how many amps need to be accounted for in regulating the entire 12 volt house panel... and is this really worth the effort? Next is cost. ???

I believe you were previously told all 12 volt items are normally rated to 20 volts, and normal FLA charging voltage can easily be 14.5 to 15 volts. It's a non-problem. Not sure where you heard those "old wives tales".

[Chateau_Nomad]

Originally Posted by Geterdun

I believe you were previously told all 12 volt items are normally rated to 20 volts, and normal FLA charging voltage can easily be 14.5 to 15 volts. It's a non-problem. Not sure where you heard those "old wives tales".

Documented and known problem from many owners... MaxxAir fan main boards historically go bonkers and usually fry at voltages as low as 13.5 volts. Allegedly this issue has been fixed on newer fans... but who knows for sure? All I know is for the price, these fans should have a built in regulator AND conformal coated electronics... I mean seriously... it's in an RV!

That's my motivation to address both issues... even before the warranty expires.

[Beau388]

Originally Posted by Chateau_Nomad

Documented and known problem from many owners... MaxxAir fan main boards historically go bonkers and usually fry at voltages as low as 13.5 volts. Allegedly this issue has been fixed on newer fans... but who knows for sure? All I know is for the price, these fans should have a built in regulator AND conformal coated electronics... I mean seriously... it's in an RV!

That's my motivation to address both issues... even before the warranty expires.

The alternator probably is voltage regulated to 14.2-14.3 volts with no load. Generally the engine will draw 5-9 amps allowing the alternator output to 13.9 volts or so. Even lower voltage if the batteries need charging. Typically Thor MC use a 50 amp CB in the house battery system to protect the AWG #6 wire. Your converter can ramp up to 14.2 volts in charging well discharged batteries. Typically it puts out 13.1 - 13.5 volts depending on the converter's temperature unless you have a remote battery temperature probe. You can buy a 12 volt to 12 volt converter in many watts sizes to provide a stable voltage.

[Chateau_Nomad]

In my lithium upgrade I ran 6AWG from a busbar to the 12 volt house fuse panel. I usually don't leave the inverter/charger on since the solar charge controller is also feeding the batteries through that busbar.

The Li-BIM will also dump alternator power into that busbar... occasionally.

So the battery voltage seems like it's always going to be 13+ volts to the fans... likely more. Does that seem like a plausible assumption??

I'm wondering if I could install a regulator in the 6AWG cable between the busbar and fuse panel. I realize even 14 volts won't cause any issues with anything else... it's JUST the fans. Or is this overkill??

The other option is to install relatively cheap 12v 5amp regulators directly in the fan circuits.

[16ACE27]

I have 3 MaxxAir fans in my RV and lithium batteries. No issues with "overvoltage" causing problems on anything.

[Chateau_Nomad]

Originally Posted by 16ACE27

I have 3 MaxxAir fans in my RV and lithium batteries. No issues with "overvoltage" causing problems on anything.

Thanks! That's reassuring to hear. I just happened to run across a few videos detailing those two "problems". I'm just trying to be proactive. Which ones do you have? I got the ones with all the bells & whistles - remote, thermostat, etc. Maybe it's those that are prone? I don't think motors are the problem... it's the circuits that handle all the other stuff.

[lwmcguire]

Tuscany has 3 MaxAir 10 speed, power lift fans.

When the alternator voltage regulator failed several years ago we experienced high voltage several times before a replacement arrived.

Luckily, there are no issues with any 12v equipment

[16ACE27]

Originally Posted by Chateau_Nomad

Thanks! That's reassuring to hear. I just happened to run across a few videos detailing those two "problems". I'm just trying to be proactive. Which ones do you have? I got the ones with all the bells & whistles - remote, thermostat, etc. Maybe it's those that are prone? I don't think motors are the problem... it's the circuits that handle all the other stuff.

Low end 3/4 speed, manual crank, no thermostat fans.

[blw2]

all my maxxair fan failures...three I think... were the gearbox and motor related...not circuit board

(this was written while knocking on wood...)