Volvo: Problem Starting in 96 850 Volvo Wagon (90k miles), volvo wagon, alternator performance

Question
After sitting in traffic for 1 hour in 104 degree temp. (outside temp indicator read 120 degree), my wife drove an additional 10 miles and stopped for gas. Car would not restart. Breakdown service suggested that battery was old and may be a problem with alternator. My wife continued with trip and drove 300 more miles before stopping and replacing battery. Upon returning from trip (another 400 miles) we noticed difficulty starting. Radio codes would reset and the key would have to be held in the forward ignition position before the starter would turn and after about 5 seconds the engine would catch. Took the vehicle to my volvo service shop, they could find no problem with the alternator ( although they did mention that they had heard of high temps. degrading Volvo alternator performance). They performed a 90,000 mile service replacing plugs, leads & distributor cap.

We are still having the problem. When turning the key in the ignition to start, there is either no response or a very weak starter, continuing to crank the starter will eventually start the engine after a couple of seconds. After the engine has turned off, the battery warning light stays on for 2-3 seconds. After the engine has fired, the ABS, overdrive TRAC and SRS lights stay on for about 10 seconds before going out. I have cleaned all battery connectors including ground to chassis. After the engine has been running, it is slightly easier to start again.

Since we have a small child, I don't want my wife to be stranded with a dead car. Any ideas what could be causing this problem and what steps we can take to correct it

Answer
Martin,
Have the shop test the ignition switch, there is a high failure rate with them. If the battery is good there should be enough power to activate the starter. Have the battery tested to see that it is good. I would check to see if there is at least 10.5 volts going to the starter when the key is turned. That is to the small wire at the starter. They maybe a voltage drop due to to much resistance in that wire.