flat battery?

the dodge · Post by **the dodge** » Sun Sep 23, 07 4:23 pm

at long last ive been able to drive the dodge again, i drove to work on friday night it started up fine as it usually does, drove at a nice steady 55/60 most of the way but got up to 70 all running nice and smoothly, left work at 12 and nothing - barely a glimmer on the dash, called out the AA who diagnosed a knackered battery, not holding enough amps but the alternator is fine, the AA did a few other checks but didnt have a suitable battery on board for me to buy, by this time the dodge had been running for about 5 mins & i was ready to drive off home i pulled out the light switch and the engine died again, the AA man restarted the engine and this time i raised the revs up and turned on the lights, just to be sure the AA man followed me for about 5 miles but i got home ok, next morning obviously nothing but managed to jump start it off my other car, i took the battery off and went in search of a new one - 60 quid later i was in possession of a new battery, fitted it to the dodge and it started excellently first time just as it used to, went out for a 20 mile drive stopped and started the dodge 2/3 times all ok, went out to see my dad today started ok, when i came to leave my dads same problem barely a glimmer on the dash no amount of jump starting from my dads cars would start just not enough amps i suppose, called my wife who came to collect me, i took the new battery off and have put it on charge, so what my dear friends is or could be my problems, over the last few weeks i have been starting the dodge once or twice a week and have not had any problems starting it up at all always started first time

any help or advice would be most welcome

Dave-R · Post by **Dave-R** » Sun Sep 23, 07 5:04 pm

Charge the battery up and measure the voltage across the battery. First. Make a note for later.

Now put the battery in the car and connect the negative side of the battery to ground and put an ammeter in series with the positive cable and the positive terminal of the battery.

If the meter measures current (make sure no electrical equipment, fans, or interior lights etc are on) you have a short circuit somewhere. You need to find where.

If not move on to the next test.

Connect the positive cable to the battery now. Start the car. After a couple of mins measure the voltage between the +ve and -ve terminals of the battery when the engine is at idle. Is it more than you noted when you measured the battery out of the car? It should be around 14 - 14.5 volts which is what the battery needs to charge up.

If lower than that take your rpms up to over 1000 and see if the voltage is high enough then. That will tell you if the charging system is working or not.

the dodge · Post by **the dodge** » Tue Sep 25, 07 11:00 am

cheers for the tips, here's what has happened since, charged the battery for 24 hours +, tested voltage showing 28.1? connected to the car checked amps between battery and + connector none showing, swapped over terminals and still none showing, connected both terminals to the battery and switched on the ignition nice bright dash lights, tried to start the car up nothing, tried jumping it from my car still wouldn't have it, for some reason i decided to take the earth strap off (the one that goes from the - terminal on the battery to the engine block) and clean the connectors, put it back on voila it started up ok with a jump from my other car, left the car running for a few minutes to warm up but forgot to check the battery voltage (duh!!) so cant tell if the charging system is good, drove the car home at a steady 55/60 no problem, parked the car turned off ignition and............ nothing no dash lights no nothing, I've taken the earth strap off the battery and am going to source a new one today as this could be the cause of the problems it certainly has a few nicks & cuts on it so i will try that next and see what happens

Anonymous · Post by **Anonymous** » Tue Sep 25, 07 11:04 am

28.1 volts at the battery????????

WAAAAAAAYYYY too high.

latil · Post by **latil** » Tue Sep 25, 07 11:11 am

If the battery volts are that high,check it hasn't boiled a cell,wheres the electrolyte level? Check the output of your battery charger too.

the dodge · Post by **the dodge** » Tue Sep 25, 07 11:12 am

yeah thats what i thought to, but its a brand new battery, could be my cheap volt meter thou, gonna borrow another one from a mate tonight to double check

Dave-R · Post by **Dave-R** » Tue Sep 25, 07 11:13 am

Man. It is a 12 volt battery. I doubt very much it has 28 volts across it.

You do know the difference between volts and amps and how to measure them yes?

the dodge · Post by **the dodge** » Tue Sep 25, 07 11:15 am

how do you check for boiled cells? ive taken out the caps and checked the level of the fluid all are a nice clear colour and above the plates

AllKiller · Post by **AllKiller** » Tue Sep 25, 07 11:25 am

Thought you said New Battery ?
if its going flat you cant have damaged the Plates in a day or 2 ?
Unless your chargers Kaput and outputting some higher voltage

Also if the battery is flat the alternator will NEVER charge it sufficiently even on a long run...the battery must be fully charged before hand.

Jeff · Post by **Jeff** » Tue Sep 25, 07 11:27 am

28.1! Should be bout 13.8 right? Kaput meter?

the dodge · Post by **the dodge** » Tue Sep 25, 07 11:33 am

yep, on my meter you can read volts in either 3 digits i.e up to 999 or in a decimal i.e 99.9, amps is read either as a whole or as milliamps

the dodge · Post by **the dodge** » Tue Sep 25, 07 11:37 am

the meter could be nackered, its a few years old, i put a new battery in it and tested it by measuring a 1.5v battery and it gave a satisfactory result 1.6v

Dave999 · Post by **Dave999** » Tue Sep 25, 07 11:40 am

measure resistance of earth straps

continuity test ignition lock switch power in on 1 wire power out on 2 in run position 3 in start position. if the plates in it come loose or the springs in it fall out they can short out across the swicthes in there leaving a circuit powerd up

ammeter connections in dash loose?

interior dome light connections shorting out to the rusty inside of your roof. does the dome light work?

does the number plate light work

any alarm or imobiliser?

is it automatic? does it have a start inhibit switch

actually does everything electrical work correctly??

the dodge · Post by **the dodge** » Tue Sep 25, 07 11:50 am

to be honest i dont think its a flat battery, the original one my have been duff (who knows as its long gone now) but the only useful info i could get from a mate at short notice was that the new battery is discharging itself somehow, he didnt elaborate as to how it could be discharging, i have taken out the stereo and the wires are still in the stereo slot the stereo didnt work unless the ignition was on, but seeing as it was pretty Bananarama! it out,
the battery charger has 3 charge options 6v, 12v trickle or 12v fast charge, i put it on 12v trickle for 24 hours and the needle was at 100% anyway,
i didnt have a battery for the meter to check the voltage of the battery before charging it up, the manual with the charger says it cant overcharge the battery,

the dodge · Post by **the dodge** » Tue Sep 25, 07 12:01 pm

dave 999, the interior light does not work havnt been able to get the lens off to look at it properly, number plate light works, all other light work ok although the side lights are a bit iffy i.e if you move them in their holders they can stop working, no alarm & no imobiliser fitted,
i will see if my mate can help tonight to check the ignition switch electrics, although when trying to get a jump from another car the dash lights up ok and all the lights work

where are the earth straps located and how do you measure their resitance do you take them off to measure them?

edit: its manual