was reading the other day about the jap batteries on here, i think it was on the thread battery box, someone said how poor the jap batterys were. well today i left me car for ten minutes while i poped into to see the vicar, left the light on as it was raining hard to let people know the car was there, ten minutes later the battery was totaly dead. Ten Minutes, just warning really
car battery
- Thread starter nimhbk
- Start date
O
owens
Guest
the best thing to do especially after driving the car with a lot of electrical equipment on ie; lights, heater, is to leave the car running for about 5 mins with no electrical items switched on to re-charge your battery before you switch the car off, this will help the elongate the life of your battery
Fusion Ed
Active Member
"the best thing to do especially after driving the car with a lot of electrical equipment on ie; lights, heater, is to leave the car running for about 5 mins with no electrical items switched on to re-charge your battery before you switch the car off, this will help the elongate the life of your battery"
Not so, Once the car has started ALL power is supplied by the alternator, which will also recharge what was taken to start. There should be no conditions at all upon which the battery will need to supply power once the engine is running. To prove this point, the alternator voltage when running should be around 14v. This is above the rest voltage of the battery (fully charged about 12.8-13.1 after sitting for 24 hours) Since this would be the case if the alternator is working, its not possible for the battery to supply any current.
What would have happened in the case of Nimhbk is that the battery would have been a few years old and the reserve capacity would have decreased. It would have had enough power to start the car, (which can be surprisingly little in some cases) but little reserve capacity to run the lights for any length of time on its own. A new battery would have been fine.
Ed
Not so, Once the car has started ALL power is supplied by the alternator, which will also recharge what was taken to start. There should be no conditions at all upon which the battery will need to supply power once the engine is running. To prove this point, the alternator voltage when running should be around 14v. This is above the rest voltage of the battery (fully charged about 12.8-13.1 after sitting for 24 hours) Since this would be the case if the alternator is working, its not possible for the battery to supply any current.
What would have happened in the case of Nimhbk is that the battery would have been a few years old and the reserve capacity would have decreased. It would have had enough power to start the car, (which can be surprisingly little in some cases) but little reserve capacity to run the lights for any length of time on its own. A new battery would have been fine.
Ed
O
owens
Guest
at 12.6v a battery is fully charged, at 12.3v the battery is half charged, when a car is driven with excessive load on it it will only recive 12-13v max and when the car is switched off this voltage dissapears, try testing a battery after this scenareo and see the results for yourself
if you leave the car running with the altenator producing 13-14v for 5 minutes this WILL recharge the battery and the battery should return to 12-12.6v after resting for 10-20mins unless the battery has problems like a faulty cell which will not hold a charge or your altenator has a charging fault
if you leave the car running with the altenator producing 13-14v for 5 minutes this WILL recharge the battery and the battery should return to 12-12.6v after resting for 10-20mins unless the battery has problems like a faulty cell which will not hold a charge or your altenator has a charging fault
Fusion Ed
Active Member
12-13v is the difference between a completely flat battery and an full one (most be tested with surface charge removed/sat for 24 hours)
If during ANY operating condition the system voltage drops as low as even mid 13's the alternator is not large enough/is failing to produce the current needed/has bad wiring, and should be inspected. At ALL times if the system voltage is 13v or above the is NO load being placed on the battery, (but at 13 there is not enough to charge it either)
Turning off all load may increase this further (max allowed is 14.4) but it wont add to the charge on the battery since it should already be fully charged if everything is operating correctly, again demonstrated by nimhbk since he never had a problem until he left the car sitting for a few minutes with the engine off.
12.6v is not a fully charged voltage for a lead acid battery. Its nearer 60%, 12.1v is around 25% and 13v is around 100%.
If during ANY operating condition the system voltage drops as low as even mid 13's the alternator is not large enough/is failing to produce the current needed/has bad wiring, and should be inspected. At ALL times if the system voltage is 13v or above the is NO load being placed on the battery, (but at 13 there is not enough to charge it either)
Turning off all load may increase this further (max allowed is 14.4) but it wont add to the charge on the battery since it should already be fully charged if everything is operating correctly, again demonstrated by nimhbk since he never had a problem until he left the car sitting for a few minutes with the engine off.
12.6v is not a fully charged voltage for a lead acid battery. Its nearer 60%, 12.1v is around 25% and 13v is around 100%.
have to say was amazed at how little juice was need to jump start the little car had the jump leeds on for about 10 seconds and it stated no problems.... the car before hand did not have enough to try to turn over, it just made a clicking sound. funnt these little cars my old golf rally was beast to jump start on a dead bat