battery chargers

[stuart147]

I have been using a Halfords Battery charger/conditioner for 2 years with no problems until now. Noticed last week that even after a really good run, when connecting battery charger up to car, the Red light on unit would come on that indicates charging. Red light would still be on after 2 hours so suspected something wrong with unit . Switched it off and straight on again, and green light illuninated, indicating, battery charged. Unit was very hot, so I thought time for a new one. Ordered a new CTEK one and connected it up today after good run and exactly the same symptoms. What could be wrong with the battery?

[Gordon C]

Have you checked the fluid level in the battery ?

 

_________________________

Gordon.

 

 

[stuart147]

Whoosh, I make certain that the level is correct fairly regularly. Checked today and they are fine. The car also starts O.K.

[John Vine]

It may not be the battery. Have you checked the alternator charging voltage? It should be around 13.6v.

 

JV

[stuart147]

I don't believe that the alternator is the problem, the charge light on dash always goes out after starting. Even when I take the battery off the car the chargers still dont operate correctly. The car always starts O.K and the lights are really bright without the car running, so I presume that in that sense ,the battery must be good, but having tried 2 different charger/conditioners, I cannot be sure. I have connected a very old trickle charger to the battery and after a couple of hours the charger is reading that battery is full. My comment about the lights being ok would confirm that. What would stop 2 conditioner/chargers switching between charge and condition?

[Colin Mill]

Its well worth having a poke about with a DVM to see what the charger is doing. In general the conditioner chargers do an initial charge up to about 14.4v, maintaining this voltage until the charge current drops low enough (should be set to match the battery capacity but is usually some compromise to cover a range of typical car batteries). Once this happens the voltage of the charger should drop to about 13.8v as a 'float' charge.

 

If the battery is sulphated the internal resistance causes the charge current to drop off very quickly and the charger drops back to the float charge even though the battery is a long way from fully charged. Conversely, a duff cell can mean the charger stays in the bulk charge (14.4v) mode and overcharging the remaining cells and endlessly failing to reach a low charge current to transition to the float stage.

 

Edited by - Colin Mill on 24 Aug 2009 21:31:18

[patneale]

2003 Caterham SV 140bhp Xpower K series 40,000 miles. Now on 3rd Banner battery (only paid for one replacement as 2nd failed within guarantee period)...... So from my experience 3 years is about the most you will get from the battery. NB I use same Halfords conditioner which works perfectly on other cars. Think your battery is on the way out.

Hugh Robinson

Chelmsford

[stuart147]

Checked voltage of battery last night and got 13.2 volts showing. Borrowed an optimate charger/conditioner and exactly the same. Unit had charging light on all night (well at least when I left it and then again this morning). If I switch off at mains and flick back on again unit light goes to green .This happens on all 3 units that I have tried. The battery does not seem to be telling the charger/conditioners that it is full. Where does the problem lie?

[Colin Mill]

Well that is most odd! 13.2v is slightly low even for a float charge so if the charger is in 'bulk' charge mode at 13.2v it should be chucking in a serious current (trying to charge the battery to over 14v) - be hitting the current limiter I would think. That does not fit the picture of a sulphated battery which would allow the charger voltage to rise too readily.

 

Why the chargers are tripping into float mode when the battery is only getting to 13.2v is very strange.

[MickP]

Sorry if this is completely daft, but couldn't this be explained by a short circuit somewhere and the charge in the battery constantly leaking?

[Colin Mill]

I don't see how it would account for the chargers going to the 'green' state when flicked off and on again.

 

Good puzzle!

[Stationary M25 Traveller]

Perhaps try disconnecting the earth lead from the battery and then connecting the charger, to prove/disprove the theory above ?

 

 

[stuart147]

Took battery off car today and connected ctek charger. Light went to green, as you would expect. Connected a 12 volt inspection lamp for 5 mins, and then reconnected ctek charger. After about 10 minutes, green light again. Put battery back on car, connected inspection lamp again for 5 mins, re-connected ctek charger, and would not go from Red to Green. Disconnected the earth, and after about 5 mins, green light. So, the explanation of a leaking earth seems to be correct. Problem for a numpty like me, where the hell do I start? Could someone list the earth points if thats possible?. Would an auto electrician have a way of finding it?

[CageyH]

Do you have a battery master switch? (The red key doobry?)

 

Only dead fish go with the flow....!

[stuart147]

no

[tbird]

Knowing where the earth points are may not be that useful, the drain from battery is current flowing so a possible strategy would be to connect battery as normal, pop out half the fuses, (make sure you record which go where 😬

try battery charger, if battery charges ok then you know that it is a circuit you have disabled, if it does not charge then you know the circuit still has a fuse fitted.

if first case replace fuses one or two at a time until fault occurs, carry on until down to 1 fuse, then at least you know where to look on circuit diag

if second case then remove other half of fuses one or two at a time until problem circuit is identified

think that makes sense

 

Having said that I would have thought that realisticaly about the only thing that could drain current with ignition off would be immobiliser circuits . or a real long shot, if 1 diode in the alternator pack has gone short the alternator would work just about ok but would allow current flow to earth with ignition off, you could check by removing battery to alternator lead (at the alternator) and doing your charger test, removing fuses would not pick this up, however I would have thought it would drain your battery within a couple of days at best

 

good luck

Tim

 

 

Edited by - tbird on 27 Aug 2009 01:21:19

 

Edited by - tbird on 27 Aug 2009 01:25:59

[stuart147]

Put battery on car last night and checked the voltage, 12.87 volts. Checked again this morning and onlt lost 0.2 of a volt. Surely, the immobiliser would account for that? Took off the earth today and left battery charging. When I check later today, what voltage should I see?. I believe it should be around 13.2 volts. If it is not, could I suspect that it is the batery after all?

[Bob_Rich]

 

I am not certain of the full workings of the halfords charger but it may be judging the state of the battery by viewing the terminal voltage. It is possible that your battery has a weak/faulty cell. this would take the total voltage down to a lower value and the halfords charger would see an overall low voltage and switch the trickle ( or maybe even full charger) on.

 

If you have a DVM after a run let the whole car cool down and make sure U do not have too much of a load on the car electrics. Under no load conditions and normal temperature around 25C you should get around 12.6V bit more OK 12.3V or less could be one or maybe more weak cells.

 

I have know batteries to battle on for quite a time with slightly weak cells as detected by voltage sensing based battery conditioners-- but it does depend on how hard the batteries are used.

 

hope this helps

 

Bob

[tbird]

Stuart, Hi,

IMHO trying to gauge battery health with a DVM (probably not a hugely expensive one ie less than a couple of hundred quid) is very diffcult, DVMs have very hi internal resistance and unless a cell has pretty much shorted out you will see around 12/13 v depending on meter, even on a pretty flat battery, its the ability to deliver/accept current that causes problems, a good battery place will have an instrument for checking battery condition, ON NO ACCOUNT TRY TO MEASURE CURRENT ACCROSS THE BATTERY WITH A DVM IT WILL AT BEST DESTROY YOUR METER,

in previous posts you have said that the problem exhibits with battery off car, then you said later that the problem had gone if you disconnected the battery, first you need to decide if this is the case, so are you sure that with the battery off the car the chargers work ok, if so then you are almost definately looking for a current drain with ignition turned off, if this is the case you will need to do some logical fault finding, one way would be to follow procedure in my previous post. If you do not feel happy doing this a good electrician/auto electrition should be able to identify if there is any current drain within about 5 minutes and a couple of hours to find which circuit, fix may take a little longer

Just a thought, when you disconnected/connected battery earth did you notice any sparking as you disconnected/connected the lead.

If you want to dive straight in to look for a current drain,

with battery on car +v terminal connected, turn OFF ignition disconnect earth at battery, set DVM to measure DC current, set to measure 2amps or more, connect DVM leads so red lead is on negative terminal of battery and black lead is on earth lead so you are putting dvm in series with battery circuit. if v low reading reduce range until you get a reading, if you get one let us know wha it is

 

keep at it and I am sure BC can help find the root of the problem

 

 

 

Edited by - tbird on 27 Aug 2009 10:18:33

 

Edited by - tbird on 27 Aug 2009 11:36:23

[Colin Mill]

The way I check the current leak take a bit of juggling but gets around any problem of the immobiliser/ECU pulling a large current on power up.

 

I set the DVM on the 2 amp range. Take the nut off the ground terminal but leave the ring terminal(s) on the bolt so the system is still powered. Then, while holding one prod ofthe DVM against the ring terminal(s) and one agains the battery negative terminal I pull the ring terminals off the bolt so the earth current to the battery is flowing through the DVM.

 

On a standard Rover MEMs and immobiliser mine pulls a steady 0.014A (14mA). Much more than this is likely to be a leakage fault.

[Roger Ford]

Colin - this is with the ignition switched off, I presume?

 

Based on that current, it's going to use about 10AH per month, so with a 28AH battery it's clear why you need a battery conditioner if the car is infrequently used.

[Colin Mill]

Yes, sorry to forget that detail. This is also the current after the immobiliser has armed itself and the inverter in the ECU has stopped whistling.

[stuart147]

Thanks for all of the advice. I took the battery to an Auto Electrician and he has declared the battery kn*****ed.The date stamp on the battery is 11/04, so 5 years old . Ordered a new one from him and I am keeping my fingers crossed.