Alternator issue ?? and Leisure Battery question

[jo10000_6]

Hi All,

ALTERNATOR
I've had my Hymer B544 (1993) for approx. 10 months.
Over the last few outings the battery light on the dash has come on red. I know this covers battery and alternator and the cab battery is new and I've tested it and all seems ok with it.
I went to get the alternator tested but it needed to go on a ramp and they couldn't do so I'm having it tested when it goes for a service later this week.
I cant see the alternator not having the capacity for what its clearly been doing for the last 10 months (And longer) so I'm guessing its on its way out if its not a capacity issue ? I switched off the fridge when travelling home from a weekend away yesterday as this is connected to the 12V system when driving to see if this relieved the alternator of some work but the light remained although periodically it goes off but on more than off.
Would my assumption be fair or should I check anything else ?

LEISURE BATTERY QUESTION
Is it a given that my leisure battery will charge when Im driving or is this just an option for set up when the battery is installed - is there an easy way to check ? The only tool I have is a multimeter but I'm a complete amateur with using it other than checking the battery charge levels which is why I bought it.

Thanks,
Jo

 

[tacr2man]

Re the alt light forget about the battery, other than telling you that there is a voltage in the system . The light tells you if the alternator is supplying a charge , if its on then you have alternator fault . If its intermittent , it could be something as simple as brushes , or more complicated like a regulator . Do you have a voltmeter in the system , or even a handheld one as this will give you a lot more info , your multimeter should have the capability of checking volts

 

[PhilandMena]

Start your engine, let it tick over and set your multi-meter to 20 Volts and put it on the cab battery terminal. You should be getting around 14. 4 Volts. You could do the same with your leisure battery if your sure it's also charged by the Alternator. You might want to consider a battery to battery charger if your relying solely on your Alternator and you may need an alternator with a bigger output too depending on what yours is pumping out. Look at solar, it's what many motorhomes have.

 

[pappajohn]

Alternator

Sounds to me like the alternator brushes are worn out causing an Intermittent non charge.
The alternator can be checked as it is with a multimeter so I don't understand why the garage needs to physically access it.


Leisure battery
.
I doubt very much your leisure battery WONT be charged when the engine is running via a split charge relay... Its too old for any electronic trickery
To check it connect the multi meter across the battery and note the voltage.
Start the engine and note the voltage.
It should be considerably higher with the engine running.
If its the same the split charge relay or fuse may have failed.
Of course, this test can only be done if the alternator is proved to be working which is done in the same way but connect across the engine battery instead of the hab battery
IE... If the engine battery voltage stays the same with the engine running or not the alternators knackered .

 

[Minxy]

I suppose the question is, is the alternator putting in a charge and if so at what level, if it's okay then it could simply be a fault relating to the light itself.

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[jockaneezer]

As Phil says, check the voltage at tickover. Apart from a loose D+ wire or a slipping belt, the only thing likely to be wrong will be internal to the alternator (like the brushes and diodes) and as it's 25 years old, I don't think fitting a reconditioned alternator would be a bad move.

 

[chesterfield hooligan]

I would check if the alternator belt is tight first, before doing anything.

 

[jo10000_6]

Thanks all. I will get the garage to check the alternator belt as above.

Readings suggest leisure battery isn't being charged with engine running - readings were both 13.12

Cab battery measured 12.93/94 when off and 14.60 when running.

 

[PhilandMena]

Thanks all. I will get the garage to check the alternator belt as above.

Readings suggest leisure battery isn't being charged with engine running - readings were both 13.12

Cab battery measured 12.93/94 when off and 14.60 when running.

Perfect! Your alternator is charging correctly. What other charging source do you have for your leisure battery as they are receiving power from somewhere. I suspect it is from your alternator but perhaps just a trickle feed?

 

[eddie]

D+ is designed to extinguish the Alternator warning light, we use it to energise the relay that is optimistically called the split charge relay

If the engine battery is reading 14.6 VDC when the engine is running and the leisure battery voltage doesn't increase when the engine is running, identify the split charge relay.

The Supply/load will be on numbers 30 and 87 and the D+ will be on number 85 or 86 and the negative will be on the other one.

Disconnect the D+ connection and start the engine and see if the alternator warning light is extinguished. If it is, replace the relay and it should solve both problems