Batt charging?

[solar]

Hi,
When I'm on shore power my batt's show 14V+ BUT after 3-4 hours of motoring they only show around 12.2V ???
Batt's are ONE year old.
Is it normal?
Do I have a charging/alternator problem?
Please advise.

 

[Billjratt]

If they measure 12.2 with the engine running, the answer is "yes" you have a charging problem

 

[VicS]

[ QUOTE ]
Do I have a charging/alternator problem?


[/ QUOTE ] Yes most probably. A battery rested for say 12 hours with no charging or discharging will read something like 12.7 volts if fully charged and around 11.7 if effectively flat . 12.2 volts (when rested) is approx half charged.

While actually motoring you would expect the volts to rise to between 13.8 to 14.2 even 14.4 with a conventional alternator regulator (ie no fancy stuff).

If you dont get in this range something is wrong, faulty alternator or regulator, duff batteries perhaps, although a diode splitter wired to an alternator that is not battery sensed would knock 0.6, 0.7 volts of the reading at the battery.

How confident are you though of your readings. Decent meter known to be reasonably accurate?

 

[Anonymous]

It sounds as though you have a charging problem but are you measuring the batteries with the same instrument in the same way? By 12V you are nearing the end of the normal discharge limit for lead acids and you best advised not to discharge below 11.5V or irreversible damage can start to occur.

 

[Refueler]

[ QUOTE ]
Hi,
When I'm on shore power my batt's show 14V+ BUT after 3-4 hours of motoring they only show around 12.2V ???
Batt's are ONE year old.
Is it normal?
Do I have a charging/alternator problem?
Please advise.

[/ QUOTE ]

The V shown on shore power is your charger probably. What is the reading if you disconnect shore power and check after say 1 hour ? 12.2+ ? If so batts are shagged. If batts show 13V or more then not.

If you are getting V figure of 12.2 when engine running - this indicates to me that alternator is not charging batts at all. Do you have an alternator switch (my boat had one !!). This should be put to ON before starting engine and left on untill all stopped. (I took my switch of and wired up with ignition ...).

Simple way to check alternator ... get into Halfords or similar Car Acc's shop and buy a simple Battery / Alternator LED checker. About 5 - 10 pounds. I use one and it's very good - it diagnosed shagged regulator on my alternator. 20 quid with local car alternator guy and all fine.

 

[VicS]

[ QUOTE ]
Simple way to check alternator ... get into Halfords or similar Car Acc's shop and buy a simple Battery / Alternator LED checker. About 5 - 10 pounds. I use one and it's very good - it diagnosed shagged regulator on my alternator. 20 quid with local car alternator guy and all fine.


[/ QUOTE ] I dont think you'll find them in Halfords these days. Suspect you may have had yours a wee while. Lidl or Aldi had something similar not a million years ago though. Looked quite nice but won't do anything that a £6 multimeter from Maplin will do, in fact a lot less.

I reckon you'd be pushed to find anyone to repair a faulty alterrnator for £20 as well. About £80 for the last one I had fixed!
Prices have escalated since you absconded to Siberia.

 

[Bilgediver]

If you dont get in this range something is wrong, faulty alternator or regulator, duff batteries perhaps, although a diode splitter wired to an alternator that is not battery sensed would knock 0.6, 0.7 volts of the reading at the battery.

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or a broken filament in the charging lamp on the dash!!!! Does the ALT light come on???

 

[William_H]

Yes exactly the charging circuit needs to be checked out before you pull the alternator for an overhaul. Look for loose wires. Check the alt light glows before the engine starts then goes out when engine is running.
Battery is not being charged by the alternator.
You may be able to remove the regulator from the end plate of the alternator and inspect the brushes and slip rings for condition.
good luck olewill