Battery indicators in Trailer

[turonueve]

Hi,

Another battery question. I know I ask a lot but I’m learning.

In our 2021 Classic, there are three different battery voltage indicators.

1. One is under the sink (Garnet See Level)
When I’m plugged into shore power and press the battery button, it indicates 13.5 volts.
2. One is above the stove (victron energy MPPT control)
It indicates battery voltage 13.5 volts on shore power.
3. The other is on the C-ZONE panel
It indicates battery voltage is 13.5 volts on shore power.

Turning overhead lights on raises it to 13.6.

Three out of three indicates that 13.5 volts is at the battery. Since I’m getting that voltage at the battery, doesn’t that mean my converter is working to charge the battery? Isn’t 13.5 the converter output voltage? It is dark outside right now so there is no solar input.

Interested to know. Thank you.

arthur

[tbrowne]

You're correct - the converter is charging the battery. You appear to have a new unit so the converter should be good for some years to come. You can test solar power by disconnecting shore power during daylight hours, turning on a couple of vent fans and some lights then make the same check for battery charging on the solar panel.

[turonueve]

Originally Posted by tbrowne

You're correct - the converter is charging the battery. You appear to have a new unit so the converter should be good for some years to come. You can test solar power by disconnecting shore power during daylight hours, turning on a couple of vent fans and some lights then make the same check for battery charging on the solar panel.

Thank you. Great to hear. My lifeline AGMs are dead sometimes when unplugging from shore power. But the indicators always show >13v on the indicators. People keep saying it is a converter problem but it seems to be working. Must be weak batteries.

[richard5933]

Originally Posted by turonueve

Thank you. Great to hear. My lifeline AGMs are dead sometimes when unplugging from shore power. But the indicators always show >13v on the indicators. People keep saying it is a converter problem but it seems to be working. Must be weak batteries.

If this is a 2021 trailer, then I'd look for things other than the batteries unless you've done things which can harm them, like run them way down multiple times.

First thing I'd be checking is to be sure that the battery cables and the connections between them and the charging circuit are all wired correctly. Obviously your charger is putting out enough voltage to charge, but you don't know if that voltage is actually getting to the batteries.

I'd also be checking for things like a damaged or otherwise compromised battery cable. Are all the connectors and terminals firmly attached? Are they tight to the battery? I just had a problem with my Suburban failing to start. It happened suddenly, after months of ownership with no problems. When I got under the hood, I found that one of the cables could be moved on the battery terminal, and just enough corrosion had formed under it to keep the electrons from freely flowing. A few turns of a wrench got me moving, and when I got home I was able to properly clean things and make sure that all connections were correct.

If you have an intermittent problem, then connection weakness is quite possible. Don't forget to double check all the ground connections as well, as without good grounds your batteries won't charge.

[uncle_bob]

Hi

No, it does not mean you are charging the battery.

It does mean that the converter is wired to the DC bus and that the converter is supplying power to the trailer. None of the gizmos you are looking at read the battery posts. They all are looking at the DC bus one way or another.

Simple way to demonstrate this: Pull the negative lead off the batteries. Those voltages don't change. Same thing using a full disconnect switch. DC bus in the trailer is fine, batteries are getting nothing. Depending on how your use / store switch actually is wired it may get into the act as well. Yes the manual shows it wired a certain way. That does not seem to happen on all trailers. Do dealers have their own ideas about this? Who knows ....

Grab your multimeter and take a look at the battery posts. If they also read 13.x volts then yes, your batteries are charging.

Bob

[uncle_bob]

Originally Posted by richard5933

If this is a 2021 trailer, then I'd look for things other than the batteries unless you've done things which can harm them, like run them way down multiple times.

First thing I'd be checking is to be sure that the battery cables and the connections between them and the charging circuit are all wired correctly. Obviously your charger is putting out enough voltage to charge, but you don't know if that voltage is actually getting to the batteries.

I'd also be checking for things like a damaged or otherwise compromised battery cable. Are all the connectors and terminals firmly attached? Are they tight to the battery? I just had a problem with my Suburban failing to start. It happened suddenly, after months of ownership with no problems. When I got under the hood, I found that one of the cables could be moved on the battery terminal, and just enough corrosion had formed under it to keep the electrons from freely flowing. A few turns of a wrench got me moving, and when I got home I was able to properly clean things and make sure that all connections were correct.

If you have an intermittent problem, then connection weakness is quite possible. Don't forget to double check all the ground connections as well, as without good grounds your batteries won't charge.

Hi

This is one of *many* threads all talking about the same issues in the same trailer. Diagnosing the root cause is going on in a different thread at the moment as is another separate thread on replacing the batteries.

Bob

[turonueve]

Originally Posted by uncle_bob

Hi

No, it does not mean you are charging the battery.

It does mean that the converter is wired to the DC bus and that the converter is supplying power to the trailer. None of the gizmos you are looking at read the battery posts. They all are looking at the DC bus one way or another.

Simple way to demonstrate this: Pull the negative lead off the batteries. Those voltages don't change. Same thing using a full disconnect switch. DC bus in the trailer is fine, batteries are getting nothing. Depending on how your use / store switch actually is wired it may get into the act as well. Yes the manual shows it wired a certain way. That does not seem to happen on all trailers. Do dealers have their own ideas about this? Who knows ....

Grab your multimeter and take a look at the battery posts. If they also read 13.x volts then yes, your batteries are charging.

Bob

Do I need to disconnect anything at the battery posts when checking?

[uncle_bob]

Originally Posted by turonueve

Do I need to disconnect anything at the battery posts when checking?

Hi

Nope, just put the DVM probes on the posts.

There are "direct to the battery" voltage monitors out there. They don't cost a fortune. Even so, I'd spend the money on a SmartShunt and do the job right before I'd fiddle with a voltage only monitor.

Bob

[turonueve]

Originally Posted by uncle_bob

Hi

Nope, just put the DVM probes on the posts.

There are "direct to the battery" voltage monitors out there. They don't cost a fortune. Even so, I'd spend the money on a SmartShunt and do the job right before I'd fiddle with a voltage only monitor.

Bob

All the meters in the trailer indicate 13.58v. Each battery (while connected to shore power) measured with a digital multimeter indicates 6.44.

Does this mean that there is a wiring issue and the converter output is not reaching the batteries?

[richard5933]

Originally Posted by turonueve

All the meters in the trailer indicate 13.58v. Each battery (while connected to shore power) measured with a digital multimeter indicates 6.44.

Does this mean that there is a wiring issue and the converter output is not reaching the batteries?

Do you have 12v batteries or 6v batteries? If you have 6v, then all is good. My guess is you have two 6v batteries wired in series to make a 12v battery bank. If correct then your voltage readings are correct. If not, then you are losing half your voltage somewhere. That's a lot to lose, so if you have 12v batteries reading 6.44v than you are obviously not charging them and they are seriously discharged.

[turonueve]

Originally Posted by richard5933

Do you have 12v batteries or 6v batteries? If you have 6v, then all is good. My guess is you have two 6v batteries wired in series to make a 12v battery bank. If correct then your voltage readings are correct. If not, then you are losing half your voltage somewhere. That's a lot to lose, so if you have 12v batteries reading 6.44v than you are obviously not charging them and they are seriously discharged.

They are 12V AGMs.

I just discovered that the 50A bus terminal fuse is blown. That must be why it is not charging. Why is that fuse there and what does it do?

[richard5933]

Originally Posted by turonueve

They are 12V AGMs.

I just discovered that the 50A bus terminal fuse is blown. That must be why it is not charging. Why is that fuse there and what does it do?

That answers a lot. Good find.

Fuses are used to protect the wiring downstream. Something must have attempted to pull more than 50 amps, and the fuse did it's job by blowing. Possibly you had/have a short, or possibly something like the inverter tried to do more than it's supposed to do and blew the fuse trying to do it.

Is that fuse protecting the converter/charger on the charger itself? On my Progressive Dynamics charger there are fuses designed to protect the converter against being connected with reverse polarity.

Or, are they further downstream?

Maybe a photo of your setup?

[turonueve]

Originally Posted by richard5933

That answers a lot. Good find.

Fuses are used to protect the wiring downstream. Something must have attempted to pull more than 50 amps, and the fuse did it's job by blowing. Possibly you had/have a short, or possibly something like the inverter tried to do more than it's supposed to do and blew the fuse trying to do it.

Is that fuse protecting the converter/charger on the charger itself? On my Progressive Dynamics charger there are fuses designed to protect the converter against being connected with reverse polarity.

Or, are they further downstream?

Maybe a photo of your setup?

The fuse is on the battery terminal where the main red power wire connects to the battery. The voltage (when plugged in) is 13.6 in the multimeter if tested on the main red wire before the fuse and the neg battery terminal. If on the +battery terminal after the fuse it is 6.4.

Still trying to figure out how to post pic here. -arthur

[richard5933]

Originally Posted by turonueve

The fuse is on the battery terminal where the main red power wire connects to the battery. The voltage (when plugged in) is 13.6 in the multimeter if tested on the main red wire before the fuse and the neg battery terminal. If on the +battery terminal after the fuse it is 6.4.

Still trying to figure out how to post pic here. -arthur

How many amps output does your converter make?

[turonueve]

Originally Posted by richard5933

How many amps output does your converter make?

According to the specs sheet, the rated DC current is 50A as it is currently set. It is a WFCO WF-9855LiS. If it were set to Lithium mode it would be 55A (but it is not on that setting now).

[richard5933]

So you've got a converter which can output 50a, and a fuse rated at 50a.

Strange that they didn't provide any head room. Do you see any marking on the wiring going to/from the fuse to indicate the gauge?

Any indication in the Airstream manual or the converter manual if that fuse is the correct rating?

If this were mine and I saw no indication of a short circuit (discolored/burned insulation, etc) I might just try replacing the fuse and seeing what happens. Not there to see, so I am hesitant to make the suggestion.

[uncle_bob]

Hi

I don't think you will find that 50A fuse in the Airstream manuals. This is not how they typically do a trailer. Their normal approach is to put a thermal breaker at the DC bus inside the trailer. My guess is that somebody decided to "improve" things by adding that fuse.

Why does AS use thermal breakers? They self reset. You have a temporary short ( = you bump a wire doing some work) and they protect the wires. Once you move your screwdriver, they put power back on the circuit.

If the batteries are at 6.4V then *something* is still wired to them when the fuse is blown.There has to be another wire going to the battery positive side. The batteries didn't just dump 200AH of energy all on their own.

Bob

[turonueve]

Originally Posted by uncle_bob

Hi

I don't think you will find that 50A fuse in the Airstream manuals. This is not how they typically do a trailer. Their normal approach is to put a thermal breaker at the DC bus inside the trailer. My guess is that somebody decided to "improve" things by adding that fuse.

Why does AS use thermal breakers? They self reset. You have a temporary short ( = you bump a wire doing some work) and they protect the wires. Once you move your screwdriver, they put power back on the circuit.

If the batteries are at 6.4V then *something* is still wired to them when the fuse is blown.There has to be another wire going to the battery positive side. The batteries didn't just dump 200AH of energy all on their own.

Bob

That particular terminal has 2 wires going to it. One is a red 4 gauge (from the inverter) that goes to a 100A buss fuse. That fuse isn’t blown. The other is a red 6 gauge (from the main distribution point). This is the one with the 50A that is blown.

The replacement for this fuse is expensive (>$15) and hard to find. Is it even necessary? Are there alternatives?

[uncle_bob]

Originally Posted by turonueve

That particular terminal has 2 wires going to it. One is a red 4 gauge (from the inverter) that goes to a 100A buss fuse. That fuse isn’t blown. The other is a red 6 gauge (from the main distribution point). This is the one with the 50A that is blown.

The replacement for this fuse is expensive (>$15) and hard to find. Is it even necessary? Are there alternatives?

Hi

The wires in the distribution system do need to be protected. That's what fuses and breakers are for. In order to do this they *should* be as close as possible to the power source. AS has been a bit iffy on this over the years. It may be that they now have decided to do it right.

Looking at the electrical diagram in the manual for your trailer from:

https://www.airstream.com/owners/man.../tt/year/2021/

on page 8-16

.... yup, they improved things.

$15 is pretty cheap for the sort of fuses you often find doing this stuff. The fuse they typically run going to the inverter was $70 at the big box store when I went looking for one. Much cheaper on Amazon.

So simple answer: yes you need them, yes you should replace them.

The same manual page shows that the big red battery disconnect switch does not disconnect the inverter ... that's not a great thing.

Bob