Installed Mains Battery Charger overheating (1 Viewer)

R

ronrumbol

Deleted User
I have an Elnagh Marlin 59 motorhome on a Fiat Ducato chassis registered in 2000.
I have had some problems with the charging of my leisure battery and have just replaced the battery and had to replace a 50amp strip fuse. It now appears to be charging from the alternator ok but on connecting the van to a mains hookup, the built in mains charger seems to get very hot and now smells hot if you know what I mean. It never used to get hot or smell.
Any ideas anyone?
 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
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5,089
MH
Zilch Mk1
Exp
From Aug 2007
the built in mains charger seems to get very hot and now smells hot if you know what I mean. It never used to get hot or smell.
Any ideas anyone?

What make is it ?

Has it got a cooling fan that has stopped working ?
 

pappajohn

LIFE MEMBER
Aug 26, 2007
43,207
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Has it got a cooling fan that has stopped working ?

thinking just the same thing Brian....

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Wildman

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May 30, 2008
0
8,470
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have just replaced the battery and had to replace a 50amp strip fuse.

for the 50 amp strip to blow a serious overload has occurred, possible short in the charging transformer changing the charge rate, that would account for all of the symptoms. Until sorted do NOT try to charge whilst on hookup or you will burn out the 50amp strip and maybe bugger the new battery as well. If it is something as simple as a fan it could be a cheap fix. Seriously needs looking at by someone who can check the charge rate and charging voltage from the zig unit. smells hot, then insulation on transformer is melting, good way to start a fire. Make sure insurance is up to date.
Good luck
 
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ronrumbol

Deleted User
Thanks for all your replies.
The charger is made by cbe and has no fan.
Please see the attached photos.Link Removed

Link Removed
 
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ronrumbol

Deleted User
Have just made the following measurements:
Voltage across battery with terminals connected 12.70v.
Voltage across battery with terminals disconnected 12.69v.
No current with everything switched off.
Across terminals with mains charger switched on but not connected to battery 0.12V.
When connected to battery started at 12.97v and gradually increased to 14.08v.
I also checked the A/C voltage across the terminals which was 30.00v and the current was measured at 7.75amps.
I was surprised at the A/C current.
Any thoughts please?
I have switched it all off as I have to go out but I will resume tomorrow and will see how hot it gets but won't leave it for obvious reasons.
 

scotjimland

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Jul 25, 2007
2,084
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I have switched it all off as I have to go out but I will resume tomorrow and will see how hot it gets but won't leave it for obvious reasons.

Hi

The AC readings I presume were on terminals inside the charger ?

The other readings look typical .. nothing untoward, do as you suggest and monitor for a couple of days ..

Just a thought, if your old battery was knackered it's possible the charger hasn't been working hard for a while .. it may just have been dust burning off .. ?

jim
 
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ronrumbol

Deleted User
Hi Jim,
No the readings were at the terminals that connect to the leisure battery.

Ron.

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pappajohn

LIFE MEMBER
Aug 26, 2007
43,207
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Hi

The AC readings I presume were on terminals inside the charger ?

The other readings look typical .. nothing untoward, do as you suggest and monitor for a couple of days ..

Just a thought, if your old battery was knackered it's possible the charger hasn't been working hard for a while .. it may just have been dust burning off .. ?

jim

more likely working too hard pushing volts/amps into a very high resistance....
 
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ronrumbol

Deleted User
Sorry a slight misunderstanding. The current measured was DC not AC.

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Andy - V8 Diesel

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Sep 3, 2008
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0
Manchester
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30ft 5th wheel
Maybe charging all the time and not cutting out when the battery is fully charged.

over charging the battery ?

Battery cells damaged and creating problem for the charger?

Teat your battery and also the charge output of the charger.


love nad light Andy
..
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..
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.
 
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ronrumbol

Deleted User
Thank you all for your advice and thoughts on the matter.
While I have a little knowledge of electrics, I am by no means an expert and what concerns me is the fact that I measured 14volts dc and 30volts ac across the battery terminals with the mains charger switched on.
Firstly, does anyone know if there should be ac voltage across the terminals?
Secondly, since the battery condition on the motorhome main control panel shows it as fully charged, I was surprised to measure a dc voltage of 14volts and a dc current of 7.75amps flowing. Shouldn't the charger's voltage and current reduce as the battery becomes fully charged?
Any thoughts anyone please?

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camper69

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Nov 22, 2007
107
0
North Bucks
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Thank you all for your advice and thoughts on the matter.
While I have a little knowledge of electrics, I am by no means an expert and what concerns me is the fact that I measured 14volts dc and 30volts ac across the battery terminals with the mains charger switched on.
Firstly, does anyone know if there should be ac voltage across the terminals?
Secondly, since the battery condition on the motorhome main control panel shows it as fully charged, I was surprised to measure a dc voltage of 14volts and a dc current of 7.75amps flowing. Shouldn't the charger's voltage and current reduce as the battery becomes fully charged?
Any thoughts anyone please?

ronrumbol

How good is your meter. The charger should maintain a charge of 13.8 volts when the battery is fully charged. Not a million miles from 14v

Derek
 

scotjimland

LIFE MEMBER
Jul 25, 2007
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Suffolk Coastal District, UK
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A good point from Derek

If you don't already have, buy a hydrometer, it is the only way to really know the state of charge .. panel meters and measuring voltages are only a guide .. take SG readings after the battery is off charge and has rested for a few hours, otherwise you will get false 'high' readings.


100% Charged = 1.277
90% Charged = 1.258
80% Charged = 1.238
70% Charged = 1.217
60% Charged = 1.195
50% Charged = 1.172


NOTE: Use your battery manufacturer's specific gravity chart. If your manufacturer does not have one, use the above chart as an approximation.

If only one cell gives you a low reading, while the other cells in the same battery give you normal readings, this is an indication of a bad cell in your battery




Jim
 
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ronrumbol

Deleted User
Thanks Jim.
Unfortunately my battery, which is brand new, is sealed so I can't measure the specific gravity.
Ron.

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hilldweller

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Dec 5, 2008
605
36,108
Macclesfield
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Zilch Mk1
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From Aug 2007
Thank you all for your advice and thoughts on the matter.
While I have a little knowledge of electrics, I am by no means an expert and what concerns me is the fact that I measured 14volts dc and 30volts ac across the battery terminals with the mains charger switched on.
Firstly, does anyone know if there should be ac voltage across the terminals?
Secondly, since the battery condition on the motorhome main control panel shows it as fully charged, I was surprised to measure a dc voltage of 14volts and a dc current of 7.75amps flowing. Shouldn't the charger's voltage and current reduce as the battery becomes fully charged?
Any thoughts anyone please?

Red herring time -- some meters will read a voltage on the AC range even if it's DC. Also the voltage will be wrong.

7.75 amps is good, 17 would be better but maybe it's just a low current charger.
14V fine - it should go as high as 14.6V then drop back to 13+.

I'd power up and keep watching very carefully and see what happens - don't leave it just in case. At 7.5A it will take ages to charge a flat battery - 12 hours sort of time.

If the voltage goes to 15V ( how accurate is your meter ? ) then you have a problem.
 
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ronrumbol

Deleted User
Thanks Brian.
I will take your advice and just leave it on all today but keep monitoring it.
My meter is a digital one which I think is accurate.
Regarding the ac voltage, I have thought about it and remember in the past if I select ac voltage range by mistake it does show roughly twice the dc voltage. As you say that was a red herring.

Ron.
 

scotjimland

LIFE MEMBER
Jul 25, 2007
2,084
9,007
Suffolk Coastal District, UK
Funster No
15
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Regarding the ac voltage, I have thought about it and remember in the past if I select ac voltage range by mistake it does show roughly twice the dc voltage. As you say that was a red herring.

Ron.

Hi Ron

Yes, indeed, but even the DC output of the charger isn't a true DC ..

A cheap charger using Half wave rectifier looks like this

Link Removed

Full wave rectifier with capacitor, your output will probably look much like ths..

Link Removed


So, the point is that even measuring with a good DMM there will be inaccuracies .. not that it matters much.. really just for info..

Keep us posted with your results ...


Jim

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ronrumbol

Deleted User
Well I have had the hook-up connected for a few hours now and while the charger is warm it is no longer getting very hot (don't ask me why) and the voltage across the terminals has been fairly constant at about 14.6volts. So it looks as though all is ok.
Many thanks to you all for your advice.

Best regards,

Ron.
 

pappajohn

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Aug 26, 2007
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looking at the photo of your charger it looks like a 2 stage jobby.

it should charge at 14.4v for a short period until the battery is showing a good charge state then revert to 13.8v to maintain the battery.

on my 3 stage charger it shows 14.4v if the charge rate is above 2amps.....once the charge amps drop below 2amps, indicating an almost full battery, it reverts to 13.8v then 12.6v to float charge
 
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ronrumbol

Deleted User
Ok. Thanks for the info. I will still keep an eye on it when I take the van out again next weekend,

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