Batteriehülle: Kosten vs. Nutzen? | Posts 32+

Mephisto wrote:

It's possible that something in Ulf's regulator is temperature compensated. But whether it actually involves adjusting the battery charging voltage to account for the temperature-dependent charging cutoff voltage?

What else could the intention be?
"The direction seems right, at least: when it's hot in the engine compartment, my voltmeter shows a lower reading than after a cold start in winter."

ulf wrote:

What else could the intention be? The direction is definitely right: if it's hot in the engine compartment, my voltmeter shows a lower reading than after a cold start in winter.

The question is also how quickly the battery reaches that temperature. When driving for less than an hour, measuring the cooling air temperature may not be a reliable indicator of the battery's condition.

It should also be noted that a lead-acid battery would require a charging voltage of 15.5V at -20°C and only 13.5V at 60°C if charged at the gassing threshold.

How would a temperature-dependent charge regulator fare with this insulating cap in the winter? The battery will never really charge because it remains ice cold. If the charge regulator is actually temperature compensated, it would be beneficial to remove all coverings from the battery so that it can reach the temperature level of the engine compartment as quickly as possible (but you shouldn't drive uphill or downhill then).

Aron wrote:

The question is also how quickly the battery reaches that temperature. For driving times under 1 hour, measuring the cooling air temperature may not be a reliable indicator of the battery's condition. How would a temperature-dependent charge controller perform with this insulating cap in the winter? The battery will never really charge because it remains ice cold.

And what about its internal losses, which cause it to heat up from the inside?
Does a battery have an efficiency of approximately 100% when it is discharged (during starting) and then recharged?

The temperature reference in the air intake of the battery management system (BMS) is not ideal, but it appears to be such a good compromise that many batteries exceed their "programmed" lifespan of 3-5 years .

ulf wrote:

And what about their internal losses, the things that burn them from within? Does a battery have an efficiency of approximately 100% when it is discharged (during starting) and then recharged?

"You're right, the efficiency isn't 100%, but the internal resistances are usually quite low, so not much power is lost as heat. It's only when a battery is fully charged that it converts a significant amount of energy into heat. You also have to consider the weight of such a battery and how slow its thermal capacity is given its mass."

In my opinion, the battery cover only makes sense in summer, during longer journeys, such as on the highway, with a driving style that results in a coolant return temperature of 60-70°C. In winter, it's much more beneficial to get the battery up to temperature as quickly as possible, or to use a charging voltage of 15.5V, but what impact this has on the electronic consumers in the vehicle's electrical system remains questionable.

Mephisto wrote:

It's possible that something in Ulf's regulator is temperature compensated. But whether it actually involves adjusting the battery charging voltage to account for the temperature-dependent charging cutoff voltage?

Okay, I found the note again.
Bosch regulator type F00M 145 261, temperature coefficient = -10 mV/K.

It's probably a bit too lenient regarding the battery's voltage requirements. Perhaps this is intended to mitigate the voltage-related effects of greater temperature fluctuations in the regulator on the battery?