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| What is the motivation of intel to want PSUs that are 12V only? |
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| ajb:
A big factor in car battery size is also going to be the shift towards smaller and lighter engines. Most of what a battery is there to do is crank the engine, smaller engine, less cranking power required, can use a smaller battery. Also, I would be surprised if car batteries had NOT improved their capacity to size ratio in the last 30yrs simply due to the advances in fundamental manufacturing technology, like plastic molding and metal forming. I don't expect those changes to be massive, but certainly observable. You can still get older batteries probably just due to the increasing lifespan of cars leading to older cars still being around and worth making parts for. Also if you've built up a supply chain around a specific battery design, it could be attractive to stick with older, established designs just to milk the investment a bit longer. |
| David Hess:
--- Quote from: Red Squirrel on March 07, 2020, 12:43:33 am ---The thing with lead acid though is you can float it and don't need to balance charge it. --- End quote --- Lead acid batteries are still balanced but using a different method. Since they are tolerant of overcharging, a slightly higher voltage "equalization charge" is applied for a brief time before the float voltage is applied. |
| Red Squirrel:
--- Quote from: David Hess on March 08, 2020, 06:03:24 pm --- --- Quote from: Red Squirrel on March 07, 2020, 12:43:33 am ---The thing with lead acid though is you can float it and don't need to balance charge it. --- End quote --- Lead acid batteries are still balanced but using a different method. Since they are tolerant of overcharging, a slightly higher voltage "equalization charge" is applied for a brief time before the float voltage is applied. --- End quote --- Yeah but since that is still a voltage driven process and also does not require special monitoring of each cell it's fairly trivial to do. Typically it will be done after an extended power outage, or on a schedule. The load will see the increased voltage too, but it will normally be designed to handle it. |
| David Hess:
--- Quote from: Red Squirrel on March 09, 2020, 01:59:33 am --- --- Quote from: David Hess on March 08, 2020, 06:03:24 pm --- --- Quote from: Red Squirrel on March 07, 2020, 12:43:33 am ---The thing with lead acid though is you can float it and don't need to balance charge it. --- End quote --- Lead acid batteries are still balanced but using a different method. Since they are tolerant of overcharging, a slightly higher voltage "equalization charge" is applied for a brief time before the float voltage is applied. --- End quote --- Yeah but since that is still a voltage driven process and also does not require special monitoring of each cell it's fairly trivial to do. Typically it will be done after an extended power outage, or on a schedule. The load will see the increased voltage too, but it will normally be designed to handle it. --- End quote --- I have always wondered if cell balancing a lead acid battery by forcing identical cell voltages like with a lithium battery would improve operating life. |
| DBecker:
--- Quote from: Circlotron on March 07, 2020, 10:26:01 pm ---I got my first car 43 years ago. I remember the battery very clearly. Probably the only thing that has changed is the car manufacturer specifying a smaller battery to save weight and cost. Depends on whether it is covered by the vehicle warranty whether it lasts long enough. The only real change afaik was going from the black hard rubber cases with external cell links on the top in the mid 60s to the more compact and space efficient plastic cases used nowadays. And going to the low maintenance type that had more calcium in the lead to eliminate the weekly checking of battery acid level. --- End quote --- Modern engines have lower internal friction from better machining and lighter oil. They have geared starter motors which can turn over the engine even with sagging voltage. And a modern ECU is vastly better at starting an engine within one or two compression strokes. Crank position used to be measured from VR sensor (pick up coil) measuring a "missing tooth" reluctor wheel in the crank with evenly spaced teeth with a gap, and perhaps a camshaft sensor. That required a minimum speed to generate a usable signal and perhaps two full turns of the crank to know the position. Today Hall sensors allows a usable signal down to 0 RPM. That allows the ECU record the crank position during engine shutdown, and accurately detect a slowly moving crank. Some engines (e.g. GM) use an irregular tooth pattern on the reluctor wheel, which lets the crank position be quickly confirmed. Fuel injectors form an ignitable mixture with minimal airflow, and multiple sparks ignite an unevenly mixed intake charge. As for technology improvements in the battery itself... I haven't seen an increase in power density, energy density or longevity since the 1980s. I have a sealed AGM that is nearly unusable just a few months after its 3 year warranty expired, and just replaced the battery in another car after 4.5 years. That's from a small sample size, but it points out that the automotive batteries haven't really improved. |
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