is my battery on its way out?

Burnham Bob

Burnham Bob

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I have a leisure battery that runs things like the water pump on the pressurised system so the pump needs to have some oomph to pressurise the system. When the pump kicks in, the voltmeter dips from 12.5 - ish volts to maybe just 12 volts - you can see the needle swing down. So under load it's not delivering the same voltage as at rest. The battery was charged before going back into service. If the voltage is falling when a load is applied is the battery on the way out?
 
At 12.5 volts your battery is low. But it could be your meter is not acurate. a Fully charged battery should be well over 13 volts. Test with a hand held meter after charging.
The biggest draw is generaly your starter.But a pump will be pretty close. The meter will dip when pump or starter engages but should return after starter has stopped.
Before you run out and get a new battery, Check each cell for water level and top up any which are low. Charge and test see if it will come up to 13.5 or more.
A good auto parts shop will test and give you report. my local one tested mine for no charge and asured me it was ok.
 
Burnham Bob said:
I have a leisure battery that runs things like the water pump on the pressurised system so the pump needs to have some oomph to pressurise the system. When the pump kicks in, the voltmeter dips from 12.5 - ish volts to maybe just 12 volts - you can see the needle swing down. So under load it's not delivering the same voltage as at rest. The battery was charged before going back into service. If the voltage is falling when a load is applied is the battery on the way out?
Click to expand...

how old is it
 
Have you checked whether the battery terminals are clean and getting a good metal - metal contact with the clamps. Just re-installed mine, and needed to give them a good clean up. Worth checking before moving on to the next stages recommended in the other replies.
 
yes all cells topped up and the terminals were greased with vaseline. hand held meter as opposed to built in one read 12.7 volts. its over five years old. will try with another battery tomorrow to see if the pump runs better
 
Burnham Bob said:
I have a leisure battery .......................is the battery on the way out?
Click to expand...

As suggested above check all the connections are clean and secure.

If possible test the electrolyte with a hydrometer but if levels are low top up with distilled water and charge before testing. If the cells do not all read the same it is suspect.

Recharge it until you can get an open circuit voltage after it has stood for 12 hours or so of 12.7 ish or higher. If you cannot get it up to 12.7 ish its suspect.

Then monitor the volts over several days and preferably weeks without further charge or discharge. It'll fall quickly at first but it should take several days to fall below 12.6ish and several weeks weeks to fall below 12.5 ish.

If it does not hold its charge its suspect.

If it passes all the above it might be Ok but if in doubt get it properly tested.
 
12.7V is fully charged for a wet battery (maybe as much as 12.9 for an AGM). Forget the 13+V referred to earlier: this is just a transient effect after charging, and will decay to a 'true' reading over the next few hours. Voltage dropping to 12.5 under load is quite normal (obviously depends on how big a load: it would be helpful to know the pump rating); if the load is brief and the battery healthy, the voltage should soon recover.
 
You are worrying too much. A pump will draw a lot of current on start up. Just ignore the voltages until you get more definite signs of old age battery. Like going flat too soon. olewill
 
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