I've used an H4155 on and off for about a decade now and every two years or so the backup battery begins to increase in standby voltage and fail. I prefer to replace it just for the sake of it running optimally (though it is not required for normal operation; just battery swaps) but over the last few years trying to source both the battery (Varta V20HR) and premade replacements has been difficult. I'm tempted to forgo it completely since I rarely use WiFi on it.
I can't tell if this is a sort of Molex connector or something proprietary as I've not seen anything like it and only have seen it in my iPAQs. It is also the same type of plug used for the microphone and the H4355's speaker. What makes it different is that the plug is perfectly rectangular. The underside (not pictured) is simply the two wires as it doesn't have the protrusion I've seen in CMOS/RTC batteries for my ThinkPads.
As most of the batteries have corroded I want to either source new connectors or replace the wiring as the negative wire I believe is the one the corrosion travels through and onto the connector. Curious as to which is easier or where to look for wire that thin.