Question on Univolt

[Ag'71]

Will my original 1971 Overlander Univolt be sufficient if: I am always hooked up to shore power AND I use my electric fridge, a small old style tv (not an HD), a computer, some lamps and maybe a hair dryer on occasion?
If I can do without buying one right now, that would be good!
Thanks for your help.

[HowieE]

The univolt is a 12 power supply to charge the battery. It has nothing to do with the 120 volts outlets that you will be using for your computer, TV, hair dryer, and the refig if it is operating on 120 volts.

The 12 volt system is mainly for the 12 volt lights. You may also have 120 volt lights in an older trailer.

[azflycaster]

The univolt converter powers the 12 volt systems in the trailer and charges the battery. The items that run on shore power (120 volts) would operate even if you did not have a converter.

Old univolts are not 3 stage devices and they will overcharge and boil the battery if you are on shore power for a long time.

[Mikethefixit]

The tv unless its 12 volt and hair dryers and any extra lamps plugged into any standard outlet in your trailer are 110 volt. The rest of your lites and fridge and mounted fans (unless its been changed to a 110) are all 12 volt and operate from your Univolt.
I personally would like to rebuild mine because it hums (to Loud) (it dont know the words,lol) and has begun to cause static in the radio.
I have had my trailer almost 3 yrs mine has yet to boil the batterys. I do check them for water( distilled) Once a month.
I dont want to hi-jack this thread but if anyone has the diagram for the Univolt. I'd sure appreciate a copy. I know I can rebuild it.
Roger

[Dave Park]

If you wish, you can buy a charge controller for solar panels, and have the Univolt feed the charge controller inputs, and have those feed the battery outputs, when on AC power. When on battery power, you would need to reconnect the battery to the 12v system by unclipping the charge controller and remounting the positive clamp - no biggie.

[Ag'71]

Thanks for all your input! I know, at some point, I will need to update the Univolt. We do want to use the interior lights and I plan to put in a new car radio/speakers that will run on 12v. I have noticed a little hum from the Univolt and it's right under my head on the curb side bed. I guess I'll just have to monitor the battery to see if it is charging at all when hooked up to shore power, and certainly if it gets over charged. Any recommendations on which new unit to get?

[azflycaster]

I installed a Intelli-Power 9245 in my 75 TW. It does an great job and makes no noise.

[Lumatic]

Originally Posted by Ag'71

Thanks for all your input! I know, at some point, I will need to update the Univolt. We do want to use the interior lights and I plan to put in a new car radio/speakers that will run on 12v. I have noticed a little hum from the Univolt and it's right under my head on the curb side bed. I guess I'll just have to monitor the battery to see if it is charging at all when hooked up to shore power, and certainly if it gets over charged. Any recommendations on which new unit to get?

Univolt hum is normal. I also put in an Intellipower 9245

[Ben4762]

Originally Posted by azflycaster

I installed a Intelli-Power 9245 in my 75 TW. It does an great job and makes no noise.

I installed the same converter about 2 years. I have been very pleased. The old univolt was cooking my batteries.

[BobbyD]

I just found this forum tonight and it has been a great help.
A friend of mine has an older AS and it is connected to shore power all season long. I believe in the short time I had to check it out today that the batteries are disconnected . Her main issue was that the radio had a hum problem. This sounds like a filter or rectifier issue .I would like to help diagnose the problem and find a repair solution.
Because the unit is stationary and the shore power is reliable , back up power isn't required . Would it be wise to try to test the 12 vdc for ripple and or ac leakage through the rectifier?
Sorry if this is off topic at all as this thread appears to leading towards finding more info about the univolt and possible wiring diagram.
Thanks for all the help ...I have learned a great deal tonight already!
BobbyD

[Dave Park]

It could be a rectifier issue, but it's more likely the smoothing capacitors in the 12v output stage have gone bad. Also, it could potentially be a ground fault, where the 12v DC ground and AC ground or neutral are connected, causing and earth loop.

[BobbyD]

Thanks for the pointers! I will take the voltage readings this weekend and report back. Is there an actual "internal connection" schematic with component values available ? I know that I could get the capacitors together , just need to know the values and the rectifier specs.
BobbyD

[BobbyD]

Back again with a follow up. I temporarily added a 120VAC to 12 VDC @ 5 amp power supply to power the radio. This will work for now , but I would like to speak with the owner about how she would like to proceed next.
Has anyone out there found the actual schematic for the univolt so I can know what size filter caps and rectifier ratings I may need?
BobbyD