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Yesterday I picked up a 64AH Fiaam ( Pug and Cit OEM )_battery at a trade motor Factors as one of my cars battery is giving notice after 5 ½ years. I dropped it off in the garage and hooked it up for a gentle charge and left it. 1 hour later I checked the voltage with 1 amp trickle charge and it read 16.2 volts. What !! 16.2 volts. I changed meter and sure enough 16.2ish volts ( Analogue meter ). I took it off charge and it dropped to 15.5 and slowly, 10 mins, it dropped to 13.4 where it wanted to stay. So surface charge I thought, or may be over zealous electrolyte so I put a 5 amp load across it and left it for 1 hour. Measured voltage 12.65 volts. Another hour 12.58 volts. Disconnected the load 12.8 volts after 10 mins. Put it back on a very low charge and slowly it crept up to 15.5 volts and still rising. Now I’ve fitted, tested, built charges, and used lead acids for 40 years and I can honestly say that I have never seen a normal battery go to that voltage unless it has been faulty or old, both implying a high internal resistance. This battery is not typical of a high internal resistance as disconnecting it only allows it to fall to 15.5 then it very slowly falls to 13.4. It does appear that this may be a rather generous SG but I can not find my SG bulb to test it. Clearly taking the battery back is an option but if it is a SG thing then the whole patch will be like it. Has anyone else come across this new initial high voltage or is it really a duff battery. I purchased smaller Fiaam battery for another car 4 months ago and did exactly the same with that but it topped out at 14.6 volts and quickly fell to 12.8 volts. Regards Peter
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This is a very long winded way of saying the battery's cream crackered.
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Not necessarily. You havent mentioned the charger. If its a basic constant current charger then the voltage could easily rise to 16v or more. If its an electronic three of four stage charger then either the electronics have failed or the battery is suspect.
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No its my old faithfull charger that I also tested on another battery last night and it is fine the battery floated up to 14.6 volts and the current rolled off to a few hundred milliamps and was stable. The new new battery charges the current rolls of to 10 of milliamps when the abnormally reached 16.2 volts. Strange but true. I have contacted Fiamm but had no reply. Rgerads Peter
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But will it behave this way when attached to a vehicle, for which it's intended?
Surely, the voltage regulator will come into play, protecting your various electrical bits - or will it?
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Who am I? Where am I going? Will I be able to park when I get there?
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Quote reply form Fiamm. I have spoken to our Charging manager, he tells me that the likely cause is that this battery was not charged properly in the first place, possibly the battery was in a bank of 18 batteries on charge in the factory and the circuit was broken, so the charge was not completed. The battery was then charged before we shipped it to our customer. The time period where the battery was sitting flat will have caused the problem you are referring to.
Can I suggest you return the battery to the supplier and we will honour the warranty with them.
Glad I did not fit it. Regards Peter
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Excanged battery last night and returned home and charged new battery. Completely different characteristics. However the factors tested the return and it held up well under discharge and the SG /cell was OK but they excepted the return with the cover letter from Fiamm. The replacement soon settled at 14.9 on charge ( 2 Amps )so fitted to car and all is well. Regards Peter
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Very interesting answer. A three or four stage electronic charger would have overcome that problem because the first stage is a constant current stage (therefore the battery voltage rises steadily to overcome the increased resistance of the partly charged battery but is limited to around 14.3v) followed by a voltage controlled stage in which the current gradually falls as the battery reaches 100 pct charge.
The electronic circuitry for the first stage is quite complicated but is very simple for the second stage. Because of this the basic or common trickle charger is effectively just the second stage. The disadvantage is that a basic charger can seldom get a battery to more than about 85 pct charge without the voltage rising to unacceptable levels and for this reason the voltage in some chargers is generally limited to say max 15-17 volts. An exception is the mini Draper or Clarke chargers which, though they are voltage controlled, have such a low current output (couple of hundred mA) that the voltage never rises beyond about 13.7v
After a week those little chargers will have a battery up to about 95-100 pct charge but, of course, they arent much use in getting an initial charge into a flat battery.
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Yes I know all that but it really was not my problem. If a battery that started the charge with only a couple of amps rises to 16.4 volts and a few milliamps then it ain't normal and I was not going to get into a massive discharge cycle. The stange thing was that is discharged well within spec in terms of current and voltage but rapidy turns itself into a resistor when recharged. However the new one passes all tests and if fine. Now I know why I always charge a new battery for a couple of hours prior to fitting. If I had not tested it I am not sure what would have been the result. ! Regards Peter
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