Weird Battery Charger Problem

[Sailor-man]

I'm having an electrical problem with my charging system. Just replaced the 7-year old CRISTEC charger on my Dufour sailboat with a Xantrex TrueCharge2 40A battery charger.

It works fine except when we run the refrigerator on shore power. After about 30 mins the charger shows a temperature warning. (According to the manual this indicates the charger itself is overheating). Suggested solution is to confirm fan is working. make sure the unit is in a suitable open area, etc.

The charger fan is working properly and the unit is in a good location. I have tried running the charger under load with all halogen lights and accessaries on except the refrigerator and it works fine. But if I turn on the fridge with or without light or accessories on, within 20-30 mins it shows the temp warning.

Thought this might be a faulty charger, but the replacement one does exactly the same.

The refrigerator seems to work ok on battery and the 3 Odessey batteries in both the house and engine bank are new.

The refrigerator is a factory installed 12v Frigoboat "Frigomatic Madrid 35F" wired to the panel. As far as I can see, it's not wired directly to the charger and is drawing power through the batteries as per factory specs. Haven't changed any wiring from the factory other than connecting the new charger.

Any suggestions would be most appreciated.

 

[kloudie1]

Is the charger in a location (compartment) where the hot air rejected from the fridge goes?? Put a thermometer a few inches away from the Xantrex when you start the fridge.. leave the compartment as normal.. and when the charger gives the alarm, read the temperature of that compartment.. A 40 ampere rated charger should have no problem with the fridge load..

 

[Don S/V ILLusion]

This is a good mystery. My guess is that there is some internal resistance in the refrig wiring such that the charger is being loaded too much.

If I understand correctly, the refrig works okay directly off batteries;
You have observed same problem with two different chargers;
Refrig places greater demand on the charger than your other electronics;
ventilation is not the issue.

If it were me, I'd substitute the refrig with an equivalent resistive load and observe what happens, e.g., radar, small A/C, inverter load.

 

[Benny17441]

How far is the charger from the batteries? Check for proper wire gauge being used for the distance. Also make sure all connections are clean and tight. See attached installation manual. If everything checks out you may check the refrigerator connections to the panel. Just because its run OK on batteries does not mean there is not a problem; the batteries do not have a warning light to warn of excessive loads due to increased resistance. That refrigerator shoiuld draw less than 5 amps/hour. Also do not forget the 120V source. Good hunting.

 

[Steve Dion]

charger, batteries & compressor all in the same compartment?

 

[Stu Jackson]

The OP said everything was installed correctly, so same compartment, wrong location, etc., seem not to be an issue.

I think Don's & Benny's suggestions about wiring connections for the fridge are the best place to start, then check the battery connections to the main DC panel. What may "look" OK ought to be verified by taking them apart and redoing them all.

I know he has a different fridge than the Adler Barbour we have, but I have found the connections at the fridge to be problematic over the years and have redone them many times.

Also, if the fridge has a fan on the condenser coil, assure the fan is working. If not, it drives the compressor load up through the roof.

And do BOTH ends of the wires, as in: behind the electrical panel, too.

The OP should also confirm for us that he's done the setup routines in the manual.

Only other thing I can think of is how many output wires for his two banks are being used.

Other than that, could it be that he got two lemons? In a row?

 

[Sailor-man]

All good suggestions. Don't think connections at the battery or charger are a problem as we just redid these. Batteries, monitor and charger are all in close proximity so I've ruled out an issue there.

I've tried loading up every accessory including all the lights, navigation instruments, etc taking power consumption up to 40% for an hour and had no problems or warnings on the charger.

Someone on one of the other groups suggested the problem is likely on the AC side: the source AC outlet on the dock, faulty power cord or a bad connection inside the boat between shore power outlet and charger. The thinking is a connection problem anywhere along the way could cause the fault when the fridge cycles on.

Next time I'm down to the boat will try a new SP Cord and checking all the connections again.

Any other suggestions would be appreciated.

 

[Bill Roosa]

Are all the charger wires being used. Most have 2 or 3 positive to charge separate battery banks. If you have 2 then a 40 amp charger would have 20 on each circuit. If only one is connected it will limit the current to 20 amps.

 

[Don S/V ILLusion]

These chargers have used-provided posts to which wires are connected at installation for each bank such that no extra charger wires should exist Bill.

The manual for the charger lists some likely causes of a temp fault at 50 deg C or greater but there is nothing related to input current I could find so I doubt it is related to shore power.

As you indicated you just redid all cables, I would verify the work if the chronology works, i.e., no problem before re-wire, problem after??

 

[Witzend]

Measure the current draw and stop guessing.

 

[SEMIJim]

All good suggestions. Don't think connections at the battery or charger are a problem as we just redid these.

Besides which a poor connection would increase resistance, decreasing current flow, placing less demand on the charger, not more. The refrigerator would run harder, possibly not reach temperature, and likely die an early death, not the charger.

Someone on one of the other groups suggested the problem is likely on the AC side: ...

Possible, but unlikely.

Here's how it's possible: Poor AC delivery would make the charger's electronics work harder to supply the output demanded. Here's why it's unlikely: Assuming the charger is putting out at its full rating: 40A * 12VDC = 480W. 480W / 120VAC = 4A. If we assume even only 50% efficiency on the charger, that's still only 8A. A 30A shore power cord would have to be in pretty sorry condition not to be able to handle a piddling 8A.

I'd check it by measuring AC volts on one of our boat's AC outlets with the refrigerator both on and off. That would tell the story on the AC side right off.

Then I'd go and tell The Admiral our shore power provisioning is lacking and insist I have to upgrade it to SmartPlugs

Jim

 

[Ron20324]

S-M, this is such a wierd problem so far that I've gotta ask: This isn't one of those Rube Golberg arrangements where someone wired a charger output directly to power the fridge, is it ( not working off the batteries)? I mean, the fridge IS still drawing on the batteries at the same time as the charger is running, right?

 

[Sailor-man]

S-M, this is such a wierd problem so far that I've gotta ask: This isn't one of those Rube Golberg arrangements where someone wired a charger output directly to power the fridge, is it ( not working off the batteries)? I mean, the fridge IS still drawing on the batteries at the same time as the charger is running, right?

The refrigerator is definitiely not wired direct to the charger. It's wired to the panel and the panel is wired back to the batteries.

 

[Maine Sail]

You really need to know the output of the charger. If it is only putting out half of its rated current and going into over temp then it may likely be a charger issue. The Xantrex chargers have been known to have some fan issues but that is usually an inoperable fan not one that can't keep up. Beg borrow or steal a DC clamp meter and find out just how many charging amps she is putting out. A battery monitor will tell you exactly what you need to know also. While you're in there clean and check all connections in the charging circuit, AC & DC.

Those Odyssey batteries can take a TON of current and may not be a s fully charged as you think hence the temp shutdown? Also the position of the charger makes a difference in the way air moves through it and it may not be getting enough air.

 

[Benny17441]

I thought about voltage fluctuations in your 120V input but you had said it all worked well without the refigerator so I take it you were plugged to shorepower then so that should not be the problem. You have installed two chargers so that greatly diminishes the chances of a charger failure. Did you do a new install or just plugged in the new charger into your existing prior charger wiring? I still think you have a wiring issue and more than likely it is in the refrigerator.

 

[John T1594]

Charger operating mode

I have a Xantrex 20A charger and it functions OK with my fridge running.

This may be a long shot but you should check that your charger is not operating in the fix voltage mode. In this mode, the charger acts as a DC power supply. I quote from the Xantrex manual:

"The fixed voltage mode setting is meant to be used as a power supply or
battery eliminator. It is not meant for charging batteries. The battery type,
battery temperature, and equalize switches are all ignored in fixed voltage
mode. The remote battery temperature sensor does not compensate the
voltage, but the battery over-temperature shutdown is still active."

 

[Sailor-man]

I will check but the lights on the remote indicator indicate what stage of charging is going on, so it must be set for charging.

 

[simplicity]

I agree with SEMIJim. Turn on the refrigerator and while it is running before it overheats , take a voltmeter and check the high voltage side of your charger. It should be around 115 to 125 volts.If it is anywhere below 110V I would think you found your problem to be a somewhere in the shore power wiring between your boat and the meter can.

 

[Sailor-man]

Took a series of voltage and amp tests at the batteries and refrigerator with the charger on and off. Nothing untoward found. All readings to me appeared normal. The refrigerator draws 3.5A at startup at both the batteries and at the refrigerator. It drops to 2.6A or so when it's running. Voltage with the charger on was 13.3v at the batteries and 13.2 at the refrigerator. With the charger off amps were the same and voltage was 12.9 at the batteries and 12.6v at the refrigerator. With the refrigerator off voltage was 13.1v at the batteries and 12.7v at the refrigerator. HAven't checked anything on the AC side yet but tried a new power cord and a different power source without any difference. If anyone has any other suggestions on the power side let me know.

My focus is shifting back to the charger itself. It's mounted on the hull near the transom. See the pic attached. It is an enclosed area at the back of the boat and there's lots of clearance above and under the charger. While there is a lot of volume in the area, it isn't ventilated per se and I'm wondering if that is the problem. It takes 30-60 mins for the unit to overheat with the area enclosed so I'm wondering if the the warm air exiting the charger has no where to escape and eventually builds in the area and causes the unit to overheat.

The fan on the charger does come on when the unit is outputting >30% however one thing that is odd is that when the warning light comes on indicating the unit is overheating, the fan shuts off. Unfortunately Xantrex Support didn't know if this was normal. Hard to imagine it is, but that's a mystery.

If anyone has any experience with this type of problem, let me know including ideas on adding ventilation to the area; what would be the best way to do that without compromising waterproof integrity of the cockpit; adding a fan, etc. Hard to believe that in an area this large the charger would throw off that much heat; and it's not even that warm here yet.

 

[SEMIJim]

My focus is shifting back to the charger itself. It's mounted on the hull near the transom. See the pic attached. It is an enclosed area at the back of the boat and there's lots of clearance above and under the charger. While there is a lot of volume in the area, it isn't ventilated per se and I'm wondering if that is the problem. It takes 30-60 mins for the unit to overheat with the area enclosed so I'm wondering if the the warm air exiting the charger has no where to escape and eventually builds in the area and causes the unit to overheat.

It's possible. The rather large-ish server sitting next to, here, that serves as our home server, our Internet server (web, mail, etc.) and my workstation is often running it's fans at high speed if we've left the house and had the room's door closed. (Otherwise the cats may set off the motion sensor in the room.)

If that was my suspicion, I'd purchase an inexpensive indoor/outdoor wireless digital thermometer from Radio Shack or the like, and put the outdoor unit in that space, near the charger.

The fan on the charger does come on when the unit is outputting >30% however one thing that is odd is that when the warning light comes on indicating the unit is overheating, the fan shuts off. Unfortunately Xantrex Support didn't know if this was normal. Hard to imagine it is, but that's a mystery.

Ah, the world-renowned Xantrex customer and technical support. They make good stuff... well, mostly good stuff, but their customer and technical support often isn't the greatest, from what I've read and been told .

If anyone has any experience with this type of problem, let me know including ideas on adding ventilation to the area; ...

If that's the problem, you might be able to get away with just putting a small, low-power fan in there to simply circulate the air. If that area is completely closed-off, as you say, odds are the air stagnates. Just moving the air around will expose the warm air to more cooler surfaces. Also: If you can put the charger down as low as possible, w/o compromising wiring routing or creating a potential for it become immersed in water, that might help.

Jim