I keep an old Merc in a garage and take it out on occasion. This year , it's not been out at all, on account of poor weather ( it's a drop top ) and , annoyingly, when it was due for a run, it wouldn't start
Now , I bought an ' Accumate ' type slow trickle charger about 2 years ago that I keep plugged in, meaning the battery ( about 3 years old ) is always topped up. Lately though, the charger doesn't go into the ' charge complete ' cycle showing a green light, whenever I check, it's always ' on charge ' and not enough juice is stored to crank the engine. On the contrary, the alarm starts wailing which is a huge din . There is always enough power to bring on the interior lights , but the dash lights are much weaker than usual .
Is the battery faulty ? is there a drain ? ( all doors are kept locked ) am desperate to take it out before something seizes ..
Edited by Dynamic Dave on 28/10/2008 at 00:34
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Try charging the battery disconnected from the car.
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And once it's mobile again, do try to use it every week, whatever the weather. Don't just drive it around the block; go for trips of at least ten miles. If it gets wet, leave it out and then have another drive to dry it off when the weather allows. You will otherwise experience more and more problems arising from under-use.
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You need to get the battery fully charged and then do a discharge test to prove if it is ok or requires replacing.
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Discharge test , how does that go ?? with the battery wired back into the car, or freestanding ?
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It does not matter really take it to any reputable garage and they will do it for you free(should) of charge.
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managed to start car with mobile battery pack, fired Ist time. Drove to petrol station about 2 miles away, as expected would not re-start ( you'd think it would be grateful for 70 litres of Premium unleaded.. ) , used the battery pack, drove home , it cut out as I reversed - parked, same method to re-start . Any clues there ?
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is the battery a sealed for life, has it got removeble caps ,is the battery acid visable
it may have boiled dry , if you can top up the battery use distiled water
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3 things come to mind.
1. the battery is not holding a charge and needs replacing.2. this could be down to your alarm going off without you knowing, which kills all remaining power in the battery once it gets below a certain level.3.the alternator is defective-if you drive a short while it makes the battery worse as it drains it completely. I long term store cars this way and these are the commonest reasons. Best is to store with 1 battery terminal disonnected.
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mercnut, thought I was bypassing these storage issues by using an advanced trickle charger ?? alarm would not be going off whilst parked , nothing to trigger it in the garage , but will ensure it's not activated in future just in case .
Edited by motorprop on 29/10/2008 at 06:04
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I think you are going to have to get a new battery!
I understand where you are coming from, been there, etc, but when I reached the stage of having to crank the P4 on the handle in petrol stations, as well as first thing, I reluctantly bought one and problem sorted.
Can you 'borrow' a battery from another vehicle just to double check?
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The only way to test a battery is to do a discharge test on a fully charged unit until you do this then there no point in doing anything else.
Edited by Andy Bairsto on 29/10/2008 at 07:17
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battery has 6 access chambers, they were low but not bone dry, so topped up on distilled water. Car is back in garage with all terminals disconnected and linked to the trickle charger. Let's see what happens .
Borrowing not avail option to me , batteries come in all sizes and terminal layouts , and with all the consequences of disconnecting from modern cars ( the donor car, not the SL ) , radio / alarm codes , it just isn't worth it .
Edited by motorprop on 29/10/2008 at 11:15
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What type of trickle charger are you using? Some won't work if the battery voltage has dropped too low. eg if it's an Airflow battery Condition/Charger:
"It will charge a battery from a minimum of 9 volts to 13.8 volts and then turn off."
www.airflow-uk.com/shop_accessories_battery-condit...l
Maybe other trickle chargers are the same?
Also see other posts in the thread:
www.honestjohn.co.uk/forum/post/index.htm?t=54431
I suspect though that the battery is well past its sell by date. As you've had to top it up (quite substantially by the sounds of it) then it's probably got more distilled water than sulphuric acid in the cells.
Edited by Dynamic Dave on 29/10/2008 at 12:51
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