Hi,

I keep coming back to a dead battery for months now. I has a new alternator put in about 2 years ago, a new battery last month and had my car checked for a parasitic drain. The auto electrician found one in my glove box and fixed it but told me he didn't think the vehicle had been charging as I drove to meet him. He said this might be a mistake and to replace the sensor on my negative terminal so I did. Nothing works. My car keeps dieing. I charged it up fully the other day and parked it for three hours at most. When I went to restart it, it struggled for a second- did the clicking thing but then got going. I left it parked overnight and its dead again. Losing my mind with this car. What could go from making a car fully charged to struggling to start in 3 hours? Any ideas before I drive it off a cliff for the insurance money?

Have you checked the voltage on the battery..

Also maybe the terminals on the starter motor (corroded) mine was but clicked like a flat battery 

 

33 minutes ago, Danny cj said:

Have you checked the voltage on the battery..

Also maybe the terminals on the starter motor (corroded) mine was but clicked like a flat battery 

 

Hi

I have a device which measures the output as I drive  I plug it into the cigarette lighter. When the fully charged battery is put in the voltage is above 14.

when I went to restart it the other day the voltage had dropped to 11 causing the car to struggle to restart for a second but it did ultimately get going. It went from above 14 to just above 11 in 3 hours. The voltage did increase after the engine started and with a 20 min drive but dead the next day.

I'd go back to a parasitic drain.

If you have access to a DVM, with nothing witched on, see if you can measure anything between the -ve terminal on the battery, to the chassis earth.  It should only be mV if anything.  If you can switch on a single interior light, do that and see if the voltage between the -ve terminal and the chassis earth increases by a significant amount compared to the previous measurement.  If significant, probably no parasitic drain.  If negligible then you have a problem.

Another trick is to measure battery o/c voltage, then stick a known load on the battery, and see how much the voltage drops.  

18 minutes ago, Paulkp said:

I'd go back to a parasitic drain.

If you have access to a DVM, with nothing witched on, see if you can measure anything between the -ve terminal on the battery, to the chassis earth.  It should only be mV if anything.  If you can switch on a single interior light, do that and see if the voltage between the -ve terminal and the chassis earth increases by a significant amount compared to the previous measurement.  If significant, probably no parasitic drain.  If negligible then you have a problem.

Another trick is to measure battery o/c voltage, then stick a known load on the battery, and see how much the voltage drops.  

Thanks definitely willing to give that a go but I'm just wondering if you think a parasitic drain could have affected the car like that in 3 hours? I thought it would take most of the night that's why I'm so confused. A mechanic passing by helped me remove my car battery as he had tried to help me jump it but no luck. He suggested it might be a bad earth but it was just a suggestion he didn't inspect the car in a garage or anything.

Our fiesta's original battery started to go dead after about 2 years, ford replaced it for free, nearly 3 years on and it was going dead again, was sick & tired of taking the battery off/on and charging it overnight, so went to our local car parts shop and got the best battery available, they looked at my battery and said the cells was splitting, so on with the new it went, that battery has been on ever since and hasn't gave a hinkling it's going dead, its been on now for over 8 years and still spins the engine over super fast.

Maybe a really high quality battery is needed instead of something cheap.

On 11/25/2023 at 7:30 PM, Ian Lanc said:

Our fiesta's original battery started to go dead after about 2 years, ford replaced it for free, nearly 3 years on and it was going dead again, was sick & tired of taking the battery off/on and charging it overnight, so went to our local car parts shop and got the best battery available, they looked at my battery and said the cells was splitting, so on with the new it went, that battery has been on ever since and hasn't gave a hinkling it's going dead, its been on now for over 8 years and still spins the engine over super fast.

Maybe a really high quality battery is needed instead of something cheap.

Thanks,  it's the same type of battery I've always used on this car and its only started dieing this year, the first two years were fine so I don't think that's what's causing it

Excerpt from a spreadsheet using an H11 55W lamp as a load.

Ca1 has since been replaced

 

H11 Load 55W Bulb	Battery Capacity	No Load V1	Load Current A	On Load V2	Voltage Drop V3 (V1-V2)	Battery Internal Resistance m Ohm (=V3x1000/A)
Solar/Ca	390/43Ah	12.44	4.27	11.58	0.86	201.41
Pb	590/60Ah	12.28	4.25	11.93	0.35	82.35
Ca 1	590/60Ah	12.43	4.29	11.91	0.52	121.21
Ca 2	500/52Ah	12.47	4.31	12.29	0.18	41.76
Ca 3	500/52Ah	12.40	4.30	12.20	0.20	46.51