problem with 12V system

[GordonLynn]

2022 Bambi

First time on forum so I hope this is an OK place to post this.

Problem: low DC power; around 9.3 causing CO2/propane sensor alarm to beep even after 5 hour drive and with shore power plugged in. Internal lights are barely lit. Shouldn’t inverter convert shore power to run internal lights? Checked battery connections and the plug into vehicle. Oddly, with the Curt Echo Wireless Brake Control in place the external trailer tail-lights do not work. They do with it removed. Either way, still low charge on the 12-V system even with vehicle running. Also checked all fuses; pulled out and re-inserted. Earlier this morning at 6 am the CO2 sensor began beeping due to low DC, also, but went off at some point. But when parked for night and pulling on the DC power it went off again. I eventually pulled the 1 amp fuse so as not to listen to the alarm tonight while sleeping. I don't think the furnace fan can operate without DC. Any suggestions? Thanks.

[ROBERT CROSS]

Has it ever worked properly?

Start with the shore power pedestal, has it's breaker tripped?
Then go the the AS's circuit breaker, has it tripped?

Don't expect the tow vehicle to charge much at anything shorter than a continuous 6hr trip.
Once repaired, plan to replace the battery.

Good Luck

Bob
🇺🇸

[GordonLynn]

Yes, I checked the shore power pedestal breakers and confirmed we had 110 (120?) inside for microwave, etc.

Also checked the breakers in the converter/inverter; pulled out and replaced fuses.

I now see the manual says: "When the (battery disconnect) switch is turned off and the trailer is plugged into an external AC power source, the 12-volt distribution panel will still receive power from the converter."

I have done that but still do not have sufficient DC power. So, does that mean the converter is faulty?

I camped 3 night before tonight so have probably been pulling down DC since I began trip without charging it. Only took one 2-night trip before but ran the furnace. So I am not sure it ever worked properly since I bought it.

Now that I think about it, I don't think I had the battery disconnect switch turned on when I pulled out before my 5-hour drive today. So, batteries did not get charged durning the day, but should have been getting charge from shore power last night when switch was turned on. I am confused...

[field & stream]

I am not an expert, but for what it is worth I suspect the inverter.

From my experience I think you should expect very little charging from the vehicle while driving, and full charging of the battery(s) from being plugged in overnight. The facts that it did not recharge, and that even while on shore power your lights are dim, suggest to me that the converter function of your inverter (i.e. 120v ac to 12v dc) is not functioning. While plugged in a volt meter will read the charging voltage, not the stored power, and 9.3v is what you get from a seriously depleted battery not what you get from a functioning converter.

[richard5933]

Couple of things first...

An inverter takes in 12v DC power from the batteries and outputs 120v AC power to use for household electrical devices.

A converter takes in 120v AC shore power and outputs 12v DC power for the trailer to use to recharge the batteries, run the internal 12v DC devices like the furnace and light.

Unless someone has made alterations to your trailer, the manual shows that you should have a converter which is responsible for charging your batteries, and it shows that the batteries will not charge from the converter if the battery switch is not in the 'on' position.

It should still charge from the 7-pin cable connected to the tow vehicle, but that provides only a minimal power flow to the batteries. When the 7-wire harness is connected and the tow vehicle is running you should see an increase in the trailer's voltage reading.

[ROBERT CROSS]

Have you checked the converter output with a meter at the battery & converter terminals?
Both converters we have used has had a light when they are powered up.
Ck yours.
Last resort call your dealer.

Bob
🇺🇸

This was our first up-grade 6mos after purchase, an Iota IQ4 55a.

[Kemmy]

Hi Gordon, I’ve been through this. Search for my post under Kemmy. I had to replace the replace the converter. It’s a pretty easy job. I did use an OEM replacement but there are other options. I also carry a 50 amp battery charger with me now. Extra weight but batteries are expensive. Check my thread for some good user replies and good luck to you. I do agree that your batteries are probably gonna need replacement.

[vanderwielen]

When on shore power, the converter will provide 12V to both the batteries and the house. therefore, if you plug in and verify the pedestal is good (and perhaps checking a non-inverter receptacle for power), i would agree with others that if you have low voltage, look at the converter (or the breaker feeding the converter).

[TitusNW]

Gordon,

I've also had some questions about the charging of our batteries. I received the attached drawing from WFCO to help me visualize where I should test the converter output voltage. If you study the drawing you'll see the positive connections (and dotted lines behind the main board) between the converter and the batteries.

The converter output voltage can be checked at the terminal above the two 40A reverse polarity fuses. The house battery voltage can be tested at the terminal below the 40A fuses.

WFCO support was very helpful, give them a call to help you troubleshoot.

Steve

[OrangeCrush]

Just to clarify, you DO NOT need the battery disconnect/kill switch to be on in order for the TV charge line to be working (weak as it is), but you DO need the battery disconnect/kill switch to be on in order for the converter to charge the batteries.

I agree with TitusNW on your next step to see if the converter is bad but will add to it. I suggest you leave the disconnect/kill switch off and remove the reverse polarity fuses and check the voltage at one of the fuse terminals. Reason I suggest this is to make sure nothing down stream is dragging down the converter which is not likely, but. If you don't get 13+ volts at one of the reverse polarity fuse pins then you definitely have a bad converter. Continuity check the fuses while you are at it as those blown fuse LED indicators don't always work. Good luck!

[GordonLynn]

I thank everyone so much for their input. And, thankfully, another Airstream owner at the campground has bent over backward to help me work through this. So much help from "strangers" is encouraging to an aging cynic!

So, my plan for the present is to hook-up the powerful battery charger I just bought and use that to keep the two 12V batteries fully charged (they had been taking a slow charge from a trickle charger so we think they are good). And then have a qualified repairman check the converter and replace if necessary when I can.

Can I run my trailer as normal, plugged in to off shore power, while simultaneously keeping the charge up in my batteries with the new charger plugged in to 110 power at the same pedestal? In other words, the charger being hooked up will not "confuse" or damage anything?

[OrangeCrush]

Originally Posted by GordonLynn

Can I run my trailer as normal, plugged in to off shore power, while simultaneously keeping the charge up in my batteries with the new charger plugged in to 110 power at the same pedestal? In other words, the charger being hooked up will not "confuse" or damage anything?

Absolutely do NOT connect the internal converter on shore power and the external converter to the batteries at the same time. Make sure the battery disconnect/kill is OFF when you connect the external charger to the batteries. You should be able to turn it back on when you disconnect the external charger. Be careful here and there may be other gotchas I am not seeing that others will.

[Wazbro]

Originally Posted by OrangeCrush

Absolutely do NOT connect the internal converter on shore power and the external converter to the batteries at the same time. Make sure the battery disconnect/kill is OFF when you connect the external charger to the batteries. You should be able to turn it back on when you disconnect the external charger. Be careful here and there may be other gotchas I am not seeing that others will.

I doubt this warning is needed if the onboard converter is working with an external charger it should react the same as the converter working with a solar charger.

[OrangeCrush]

Originally Posted by Wazbro

I doubt this warning is needed if the onboard converter is working with an external charger it should react the same as the converter working with a solar charger.

You are probably correct and apologies for such a stern warning but here is my concern. All data so far indicates there is a good chance the converter is bad. The OP said he plans to hook up a "powerful" battery charger which we don't know anything about or how it behaves. Connecting this charger to a converter with a blown output stage could result in a short which even then would probably only blow the reverse polarity fuses in the converter. Since we don't know what is wrong with the converter I suggest playing it safe and not letting the external charger have any opportunity to sink current through the internal converter.

[ROBERT CROSS]

How bout>>> remove the batt's, hook up powerfully to the charger and load test when/if they reach fully charged.

POI... the AS can be plugged into shore power while all this in going on.

No warnings needed.

Bob
🇺🇸

[OrangeCrush]

That is what I would do Bob. Safest but requires turning a wrench.