Brakes/Univolt

[Rob]

I removed the Univolt and plan to replace it. There is no battery in the unit.
Are the brakes and that system tied together in any way? Or can I have full use of the braking system until the univolt is replaced?

Rob

[smily]

The emergency brakes are fed from 12 volt Battery via the Univolt.

If there is no battery, there is no emergency brake.

The break way switch is located at the tongue of the coach.

Smily

[Rob]

How about regular brake function? Are the univolt and brake function tied together or wil the brakes work without the univolt present?
I guess I could just hook up the trailer and test it but I thought it would be safer to ask first.

Rob

[FrankR]

The trailer brakes and the univolt are not connected in any way. Power for the trailer brakes is from tow vehicle. The breakaway brake system is connected to the trailer battery. There is a cable operated switch at the front of the trailer tongue that will energise the brakes if the tow vehicle and trailer are seperated while being towed. Well yes the univoolt is connected to the battery but only if connected to shorepower. The univolt is a battery charger and or substitute for a battery while connected to shore power.
The breakaway switch is either ON or OFF.
The trailer brake system is NOT dependent on the univolt in any way.

[Rob]

Thanks guys. I've learned through mistakes to ask first. Even if it seems like stupid question.
Rob

[FrankR]

There are NO stupid questions.........only not asked questions....

Wisdom is the results of lots of failures.....

[smily]

with all due respect Frank,

I keep hearing and reading that there are direct connections to the trailer battery other than the leads to the Univolt........

I can assure you that on my 1971 Overlander, There are no connections to the Trailer battery other than the positive and negative lead that both go to the UNIVOLT!!!!!!!

All roads lead to the Univolt. whether connected to shore power and or the tow vehicle or none, all voltages traverse the Univolt.

The supply power may or may not be provided by the Univolt but the voltage WILL pass through the Univolt.

Is it possible that my trailer is wired incorrectly? I do not believe that this is the case.

Smily

[FrankR]

Smiley, I guess I have not spoken clearly. The trailer BRAKES are not connected to any electrical part of the system. The breakaway switch , on the trailer tongue, is connected to the battery system. The concept being, when the trailer is seperated from the tow truck suddenly, a pin is pulled from switch and trailer brakes are applied. The trailer brakes , in normal conditions, become powered ONLY by the tow vehicle electrical power.
The univolt is connected to the batteries. The batteries are connected to the fuses. No dc voltage can go into a univolt as there are diodes that are a one way electrical check valve, that prevent any dc voltage to enter unit. On most Airstreams, the blue wire in the trailer connector is the wire that conducts power to the trailer brakes. When the univolt is NOT connected to shore power, and the battery is NOT connected, the brakes will work properly.

[FrankR]

This drawing from the Airstream manual 1979 31 ft...
The drawing indicates wiring connections..

[smily]

I believe our debate is a matter of context.

When you refer to Univolt, I believe that you are referring to the "section" of the Univolt that actually converts AC to DC.

When I refer to the Univolt, I am referring to the whole unit including the Busses and the fuse panel.

It is apparent from your diagram that all wires and or conductors traverse the Univolt as I had pointed out.

I understand that the Univolt may or may not be the source but it does provide protection for all voltages applied within the trailer. Whether the source is from Univolt, trailer battery, and or the tow vehicle.

Respectfully,
Smily