Electrical problems

[bertvb]

Hi everyone,

I've noticed some strange behavior on my 126.
When I drive during the day, everything runs just fine. However, when I turn on the lights, I sometimes notice a small loss of power.
When I let the car idle, with the lights on for longer than 1 minute, the engine stalls when I push on the gas pedal. Idling seems ok.
The problem gets worse when I turn on the indicator lights. And sometimes, not always, when I'm just driving with the lights on and turn on my indicator, the engine stalls for half a second.

I've checked the battery voltage. With the lights off it stays in between 13.2V and 14V (depending on the engine rpm). With the lights on it goes to 12,1V - 12,5V.

Does anyone have an idea what might be the problem? Or what I can do to analyse the problem further.

Regards,
Bert

Picture of my car  :

[ChrisRLewis]

Possible battery failure putting extra load on the alternator? You may need to get the battery load tested.

[bertvb]

Hi Chris,

Thanks for the reply.
The battery is only 3 months old. But to make sure, I will check it.

Maybe it is a grounding issue, not sure yet. I've cleaned all the grounding points to the chassis. Small improvement but the problem still exists.

The electrical aspect of my car is really a mess. Unfortunately I'm not the first one to fix something on it.
Maybe it's better to re-do some parts of wiring? But a voice inside of me tells me that this is a bad idea...

[ronb1967]

sounds like the load on the alternator causing the poor idling as it tries to keep the battery topped up ,what amperage is your alternator, maybe look at youtube for "alternator load test" battery should stay over 13v with load .

[bertvb]

[SOLVED]

I've tested the battery, it was fine (good because it was new).

I've then proceeded with measuring the voltage at different points. With the lights on, the voltage at the ignition coil was only 10v, with lights and indicator it dipped to 9,3v~9,5v!
Working may way back, I saw that there was a 1v~2v voltage drop over the ignition switch.

To solve it, I've connected this switch to a relay (40A). The power side of the relay now replaces the ignition switch.

Additionally I've added a volt meter on the car. Voltage stay's above 13V at all times now. Indicator lights still give the largest voltage drop (0,7V). Later I will check if there are some additional losses, but for now everything works fine.

Thanks everybody for your help.