Battery Charger - Fiberglass RV


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Old 08-12-2008, 09:37 PM   #1
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I'm really thinking that the battery charging function on my onboard converter/inverter/battery charger thingy is not working. It's a magnatek with the battery charging option.

I had the trailer plugged in over the weekend and the monitor panel in the trailer said the battery was 'Good' (as opposed to the other options of 'Fair' and 'Poor'), but as soon as the trailer was unplugged the panel then read 'Poor' and poor it is - not enough juice for one light even.

My main question for now is: How do I test the battery charging function specifically to see if it is working at all?

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This is the multimeter I have, but to be honest - no laughing - I'm afraid of it. Electrical work is not my forte.
Ya, silly, I know, but I have this fear that I'm going to put something in the wrong place and blow something up - so, it's over a year old and never been out of the package



On a side note, I do already have a great three stage charger: This One, but the problem with using it is that I have to pull the battery every time as I don't want to leave the charger out in the back alley as I'm sure it would grow legs and walk away. So, it would be nice to have a more permanent solution. (Although if I ever get that garage built, then it would be a non-issue.)

Thanks
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Old 08-12-2008, 10:33 PM   #2
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I bet the reason your monitor is showing as 'good' is because it's 'inline' with the charger / converter - thus when it's charging it's getting 13-14+ volts of juice and showing as full. When you unplug the shore power that load is gone and what you are seeing is the dead battery.

Take that multimeter of yours and turn the knob to 20 under DCV (I don't have the 12v battery feature on mine so that might work for you). Put the Postive probe on your postive battery terminal and put the negative probe on your negative terminal (if you get 'em switched it will show a negative number). A 100% charged battery should show around 12.6v. Anything less then 12v means you are less then 1/2 charged. I am guessing that you will show less then 11.5 if lights won't work.

So two things - a.) your converter isn't charging the battery or b.) your battery is no longer taking a charge. You can check the first by plugging in your shore power and doing the above test. If the battery is reading 13+ then the converter is sending a charge to the battery. If it is sending a charge then your battery needs to be replaced. If it is not then it's between the converter and battery.

I bought and had a WFCO 8725 (3 stage converter installed while getting my wiring tidied up. I was originally going to go with one of those Crappy 3 stage charges but I didn't want to messing with connecting it up all the time.

EDIT: Whoops - anyways, so on the 3 stage charger I show 14+ when its bulk loading, 13,6 when it's topping up and around 13 when it's in monitor mode. It is a cheaper converter but for my minimal needs it works great.

EDIT2: Here is an article that I have read and reread - it's an awesome overview of RV 12v

EDIT3: and for our non-canadian members ... by Crappy 3 stage charger I mean Canadian Tire 3 stage charger, not Crappy as in quality
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Old 08-12-2008, 11:34 PM   #3
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The previous comment is good, you can do a specific gravity test on the battery itself, testers are available at auto supply centers and they are cheap, this will tell you the actual chemical condition of the battery...The other simple solution is take the battery to a battery seller who will test it under load...bet you it fails...cheap under load testers are available too, but do not discern if its "bad" or just in need of a charge...The new electronic analyzers do specific tests and do reliably discern under charged batteries from a just plain shot ones, these testers are in the to "expensive for us catagory"...that tester is one to find at a reputable seller.

Harry



Quote:
I'm really thinking that the battery charging function on my onboard converter/inverter/battery charger thingy is not working. It's a magnatek with the battery charging option.

I had the trailer plugged in over the weekend and the monitor panel in the trailer said the battery was 'Good' (as opposed to the other options of 'Fair' and 'Poor'), but as soon as the trailer was unplugged the panel then read 'Poor' and poor it is - not enough juice for one light even.

My main question for now is: How do I test the battery charging function specifically to see if it is working at all?

Attachment 15143
This is the multimeter I have, but to be honest - no laughing - I'm afraid of it. Electrical work is not my forte.
Ya, silly, I know, but I have this fear that I'm going to put something in the wrong place and blow something up - so, it's over a year old and never been out of the package



On a side note, I do already have a great three stage charger: This One, but the problem with using it is that I have to pull the battery every time as I don't want to leave the charger out in the back alley as I'm sure it would grow legs and walk away. So, it would be nice to have a more permanent solution. (Although if I ever get that garage built, then it would be a non-issue.)

Thanks
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Old 08-13-2008, 01:21 AM   #4
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Some of the large auto parts chains have free testing of battery and charging system.

About your real battery charger, just connect it to the 12VDC fuse block inside the trailer and that will get it to the battery without it being in view. The 'smart' maintenance chargers come with a wiring kit to hardwire them to the battery and plug into the 120VAC system so when ever the egg is plugged into shore power, small charging is occurring.
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Old 08-13-2008, 09:21 AM   #5
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Thanks, some good information everyone.

Quote:
Take that multimeter of yours and turn the knob to 20 under DCV (I don't have the 12v battery feature on mine so that might work for you). Put the Postive probe on your postive battery terminal and put the negative probe on your negative terminal (if you get 'em switched it will show a negative number). A 100% charged battery should show around 12.6v. Anything less then 12v means you are less then 1/2 charged. I am guessing that you will show less then 11.5 if lights won't work.

So two things - a.) your converter isn't charging the battery or b.) your battery is no longer taking a charge. You can check the first by plugging in your shore power and doing the above test. If the battery is reading 13+ then the converter is sending a charge to the battery. If it is sending a charge then your battery needs to be replaced. If it is not then it's between the converter and battery.
That was what I needed to know for starters.

I'll check things out tonight and figure out what's happening.
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Old 08-13-2008, 09:17 PM   #6
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Okay - I used my multimeter (and nothing blew up )

The battery is measuring 11.64 - both as stand alone and when the trailer is plugged into shore power.
Battery is currently hooked up to the smart charger and taking a charge just fine. So, it looks like the charger function on the converter is toast.

Is there anything maintenance wise with the converter that maybe I'm forgetting to check?

Quote:
EDIT3: and for our non-canadian members ... by Crappy 3 stage charger I mean Canadian Tire 3 stage charger, not Crappy as in quality
- I knew what you meant
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Old 08-13-2008, 09:32 PM   #7
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On my old converter I have a breaker on it that I could reset if it had popped. Otherwise I dont have any other suggestions.
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Old 08-15-2008, 02:38 AM   #8
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Quote:
The battery is measuring 11.64 - both as stand alone and when the trailer is plugged into shore power.
Battery is currently hooked up to the smart charger and taking a charge just fine. So, it looks like the charger function on the converter is toast.

Is there anything maintenance wise with the converter that maybe I'm forgetting to check?
Hi Lainey,

A converter should put out 13.5-14.5 volts when your battery is low. You might check to see whether your converter has a fuse and whether that fuse is blown. Our converter has two fuses: one in the 12v fuse panel, the other (a glass fuse) under the converter cover.

If worst comes to worst you might consider buying a cheap battery charger to boost your battery up to 13+ volts before any trip you go on.

--Peter
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Old 08-15-2008, 11:47 PM   #9
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The other alternative is to forget the converter and just use a good three-stage battery charger like a Vector for good battery charging when connected to shore power. The modern electronic ones are manual start, so you have to remember to push the button.

Ideally, what I would use is something like a Vector, plus a small, smart maintenance charger (auto-start), both hard-wired to battery. The large charger would be used after boondocking to restore a depleted battery and the smaller one used as a float charger to maintain charge.

The converter's role in life is as a 12VDC power supply to run all the DC stuf when connected to shore power. Up until recently, its role as a battery charger has been a distant second.

You can buy a lot of serious battery charger for the money it takes for the upgrade options on converters (or replacements) and the charger would be good for charging other batteries, including your neighbors. If a large charger with the engine-cranking option is bought, it can also be used to start vehicles.
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