Overvoltage on 12 volt circuits

[Samboney]

I've been burning out 12v LED bulbs alot. So I started checking socket volts and I'm frequently finding 24 volts. I've made no electrical mods to our filth wheel (2005 Cardinal).
Converter is a WFCO 9855. I'm thinking that's a good place to start. Is there a better brand I should consider? We winter in our RV 6 months.

[NavyLCDR]

Do you have two 12 volt batteries that are connected in series rather than parallel?

I like Progressive Dynamics converters. You would be looking at the PD9260CV for a replacement.

[Samboney]

I only have a single battery and haven't made any changes to it since I replaced it 2 years ago when I changed out all the 12v lights to LED bulbs.
Also, the overvoltage isn't continous. It is episodic and only began recently

[NavyLCDR]

I would recommend the Progressive Dynamics converters. I upgraded my last 2 TTs from WFCO to PD just because I got much better charging performance for my 2 6-volt golf cart batteries when boondocking.

Also, the PD converter is better for deep cycle batteries because it automatically does the periodic equalizing charging that helps extend the life of a deep cycle battery.

[Samboney]

Thanks for the input

[llr]

Do you have your battery connected?

It does sound like a converter issue but the battery should help stabilize the voltage. If the battery is connected I suspect it is bad too

[Samboney]

Tested the battery. It's toast. Checked converter with battery disconnected and getting 25.7 volts. Confirms converter is toast as well.
Ordered a PD9260CV as LCDR recommended. Will replace the battery when it arrives next week. Thanks everyone

[DougW]

Originally Posted by Samboney

Tested the battery. It's toast. Checked converter with battery disconnected and getting 25.7 volts. Confirms converter is toast as well.
Ordered a PD9260CV as LCDR recommended. Will replace the battery when it arrives next week. Thanks everyone

Open circuit voltage will be higher than when a battery is connected. First replace the battery then keep an eye on the voltage readings, it could be the converter is OK, although it also could be the converter is putting out too much voltage even when load and it damaged the battery. Just monitor it closely to see.

[Samboney]

Thanks Doug. I've already dropped the trolling battery from my boat in when I check the RV battery & converter. No change to the overvoltage. I put the boat battery back.

I'm a belt & suspenders guy. Even a cheap battery isn't really cheap. A good deep cycle AGM is about the same price as the PD converter. Rather than risking a battery investment, I'm more comfortable replacing both at the same time.

[boondocking]

I would say the converter is toast.
A bit higher voltage is expected when no battery is connected, but not anywhere close to 25.7 volts.

[TitanMike]

Originally Posted by DougW

Open circuit voltage will be higher than when a battery is connected. First replace the battery then keep an eye on the voltage readings, it could be the converter is OK, although it also could be the converter is putting out too much voltage even when load and it damaged the battery. Just monitor it closely to see.

This is often the case with some power sources but modern RV Converters are designed now to be used without a battery.

If more than 15 volts is measured at converter output with no battery, the converter is bad and needs to be replaced.

Way back in the 90's, before multi-stage converters, the battery was pretty much required to both stabilize output voltage as well as act as a noise filter. I used to have a Magnatec converter that was a single voltage converter and this was what they recommended. Things changed and in the new millennium the battery is essentially optional unless you are towing.

[Hclarkx]

Originally Posted by Samboney

Thanks Doug. I've already dropped the trolling battery from my boat in when I check the RV battery & converter. No change to the overvoltage. I put the boat battery back.

I'm a belt & suspenders guy. Even a cheap battery isn't really cheap. A good deep cycle AGM is about the same price as the PD converter. Rather than risking a battery investment, I'm more comfortable replacing both at the same time.

I think replacing both is wise. However, getting such a high voltage from the converter when the battery is connected suggests some problem beyond the converter and battery. The converter can't possibly deliver enough current to push the voltage that high with the battery connected .... unless the battery is going open-circuit internally. This is possible but unlikely. More likely a flakey connection between the converter and battery is disconnecting the battery and letting the converter voltage rise. Such a flakey connection could as well have been the cause of the converter failure. Arcing (not necessarily visible) in a flakey connection may have generated enough voltage transients to damage the converter. It seems giving all 12V connections between the converter and the battery a good cleaning and tightening would be a good move as you install the new converter and battery to maybe prevent a repeat of this experience.

[NavyLCDR]

Originally Posted by TitanMike

This is often the case with some power sources but modern RV Converters are designed now to be used without a battery.

If more than 15 volts is measured at converter output with no battery, the converter is bad and needs to be replaced.

Way back in the 90's, before multi-stage converters, the battery was pretty much required to both stabilize output voltage as well as act as a noise filter. I used to have a Magnatec converter that was a single voltage converter and this was what they recommended. Things changed and in the new millennium the battery is essentially optional unless you are towing.

I completely agree. I specifically asked Progressive Dynamics if their converters could be used without a battery and they replied yes, no problem at all.

[Samboney]

Checking all connections is part & parcel of major co.ponent replacement.

Haven't put a whole lot of effort into finding one, but I'd like to find a circuit schematic for toasted converter. Not to try & repair but to use for an autopsy.

[U.S.ArmyVeteran]

24 volts DC?
Must be a military grade trailer :-)

[Herk7769]

Originally Posted by Samboney

Thanks Doug. I've already dropped the trolling battery from my boat in when I check the RV battery & converter. No change to the overvoltage. I put the boat battery back.

I'm a belt & suspenders guy. Even a cheap battery isn't really cheap. A good deep cycle AGM is about the same price as the PD converter. Rather than risking a battery investment, I'm more comfortable replacing both at the same time.

I am with you.

No sense blowing up a new battery even if they might replace under warranty.

I only want to do that job once.

[TGR]

I wonder if the reverse polarity fuses are blown in your converter, the battery disconnect switch is in the "Off" position or an inline circuit breaker from the battery is open. As Hclarkx wrote, it is unlikely that a converter is able to reach the voltage levels you read when connected to a good battery, i.e., your trolling motor battery. I assume you were reading the high voltages at the converter, bulb socket, etc., and not at the battery.

A converter should be able to operate without a battery, so your converter likely needs replacing.