Jason's "built" D24T engine build

[casioqv]

Originally Posted by ngoma

I'm hoping it charges fine without this circuit active.

With the plug disconnected from the back of the alternator, they work just like a normal alternator.

It's an interesting idea that theoretically would both shorten charge times and improve battery longevity by charging at a higher voltage while the battery is cool, but in practice battery acid destroys the sensor and causes it to over-charge when the battery is hot. Volvo later released a FSB that they should all be left disconnected, to revert to normal (non battery temp sensing) operation.

A lead acid battery can be safely (and more quickly) charged at higher voltages at low temperatures, which also helps to avoid sulfation BUT it's absolutely critical to drop this voltage lower at high temperatures to prevent battery damage. A charging system without a temp sensor must assume high temp at all times, and charge the battery with a lower voltage which results in slower charging, and more sulfation (which can shorten battery life).

In theory it's a cost-saving feature that improves battery longevity, but in practice it's an overly complex unreliable system which reduces battery longevity.