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Electrical: Engine Starting, Charging
Disconnecting both cables and keeping them clear of the battery
Mixing a baking soda solution in water
Wiping that on the surface of the battery and on the connectors, then rinsing
(this removes acid). Rinse the tray as well.
Cleaning grease off with rubbing alcohol and a rag
Polishing up the posts with either fine sandpaper or a metal brush
Cleaning the terminals with a metal brush and fine sandpaper
Inspecting them and the cables for damage, broken strands, etc. Replace if
needed.
Reassembling with the little red and green battery anti-corrosion washers
(they really work!) under the terminals and then, once the cables are secured,
spray the post, connector and exposed part of the cable with anti-corrosion
spray (a red lacquer you can buy in the battery section at KMart, Walmart,
etc.)
Your biggest problem will be corrosion damage inside the cable, which is tough to
fix. See
battery cable connector repair
Connector Under Battery Tray?
[Inquiry] Whilst cleaning up (minor) corrosion under the battery tray on my '85
765T I found a rubber device (inserted into the tray) with a cable which leads off to
a (disconnected) 2-wire plug. Where does it go? What does it do?
[Response: Abe Crombie] It is a temperature sensor that affects the voltage
regulator activity. The idea was to alter the voltage as battery temp changed. The
voltage needed to charge battery without overdoing it and risking electrolyte
evaporation varies with the temp of battery. This noble engineering feat was
fraught with troubles though as the sensor could (and most times did) get attacked
by acid and the temp value would be wrong. The result was exactly the thing the
sensor was there for, i.e., it would overcharge. There was a service bulletin 13
years ago saying to disconnect the sensor plug on back of alternator. The voltage
regulator would revert to internal temp regulation when the sensor resistance went
infinite.
Unexplained Drivability Problems: Failing Battery Wiring Harness
Rotting Battery Wiring Harness or Insulation.
Rotten Harness. Last weekend, I uncovered the 1989 780T to show a friend. The
car ran well, but seemed a little ''late''. After glancing at the gauges, I noticed the
volt meter reading low. I don't trust the volt meters in Volvos, but felt the need to
check alt. output anyway. At the battery (new OE), the output (input, actually) was
12.9V. No good. I could hear the alternator charging, but checked the
regulator/brushes anyway. No problem. I checked the output at the alt. and the
output was 14.1V Good. This car has a battery cable ''Harness''. After cutting it
open, I found the insulation to be gooey and loose. Current was flowing between +
and -- through the insulation. After replacing the harness, everything came back to
''like new!'' The car's acceleration was impressive, not just ''good''. The ECU said
thanks, and the slight drop in fuel economy went away. The problem was wiring
this time, but sometimes just changing the battery returns life to a Volvo. Check
your electrical system thoroughly.
file:///C|/Users/Steve/Documents/Volvo%20FAQ%20Updated/ElectricalStarting.html[01/13/14 10:02:47 PM]
for procedures.
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