Electrical issues 850 T-5R

[MrTomLegit]

13.4v at battery terminals when engine is idling with headlights is too low.

It should be 13.8-14.2v with headlights,heater blower on(but not max) and radio...at idle.

B+ cable is the main culprit...but you will need to perform a voltage drop test when everything under the hood is warm....after 30min of driving and without turning the engine off prior testing.

Is it possible that the short I am having with the radio is drawing that power? I did the B+ cable before winter, granted it was from oreily and not an OEM cable. I will attempt the drop test today or tomorrow depending on how the rest of the day goes.

[misha]

I was talking about positive battery cable which goes from positive battery terminal to starter and from starter to alternator.

It's called b+ cable because it goes to b+ terminal on alternator....some calls is just positive cable.

It MUST be the same thickness like original cable ..if i recall correctly...it is 2awg wire for your standard
25mm2 is EU spec.
It can be thicker,but MUST NOT be thinner than original.

Main negative battery cable and other grounds can also make high voltage drop.
In your case it's 0.4-0.6v which is HUGE voltage drop...since the spec is 0.2v MAX.

Perform voltage drop test on both...positive and negative side.

The fastest test is to check the alt.output on battery terminals with digital multimeter and engine idling,heater blower and radio ON...but after 30 min of driving and without turning the engine off...and to check it directly on alternator on b+ and alternator's casing(which will be the ground).

If alternator output is higher than on battery terminals...you have a voltage drop in positive or negative side.

If you get the same readings...below 13.5v on both alt & battery....alternator output is low.

Healthy charging system on these cars have 13.8-14.2v on battery terminals.

Everything below 13.5v at idle with headlights,heater blower radio and rear defroster ON....is not enough to keep the battery fully charged.