
drdavidzhang
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https://www.youtube.com/user/corgLLC
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san jose, ca
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2015 forester
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I think the idea of "the confidence that my vehicle wont leave me stranded" is very compelling, that most people would not want to be stranded. So the question is how do you decide if it needs replacement. If you replace it every 2 years, may be you can cancel your AAA membership, may not be too bad. Or you could lease a new car every 6 months. If I just had jump-cable started and go to autozone, he may tell me to replace it because the battery was not recharged and he does not check with Hydrometer first. The purpose of my experiment is to find a way for those people who don't have a load tester. I am pretty happy with the result, it only involves to take a 10-second video to get a characteristics of the battery, combined with a cheap Hydrometer, I should be able to easily determine if I should replace it. Another advantage is the load used in my method is the real load, not the fixed 100A current, different car should affect battery differently. My 16 sets of sampling data come from different cars/batteries, so it is not just Subaru specific. I am happy to learn that a battery may damage an alternator. Although I think alternators are running all the time (because alternators supply 100% of the electricity needed while running), so it is not alternators running longer time, but rather it could be running harder. During the 300RPM to 500RPM, the alternator can not be damaged because the current generated from alternators is too low. When you have higher RPM, suppose the circuit was designed in such a way to charge a battery quickly, then you will have larger load and potential damage specially at larger RPM. If the circuit is designed to have alternators slowly charge a battery, then it may have little damage.
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To me, I will re-charge it and then from my experiments, based on the Fall Rate and Rise/Fall Ratio, with just a 10-second video I can objectively decide whether it should go. I understand other people would have different ways to make decision. Steve Jobs leased a car every six months he traded it in for a new one. People say time is money, my problem is that if I saved time, I can't use the saved hours to make money. This is a different subject: When I showed my friends my time saving and money saving youtube videos, they shrugged "time is money!" How do you respond if you were me? It is obvious if I have choice of either spending an hour saving $20 or spending an hour making $100, I would choose making $100-$20=$80. However since most people don't have a way to use that hour to make $100, then this "time is money!" is not valid to them. So I think my response should be: unless you can figure out a way to use your extra hours to make money, you should not abandon saving/being frugal.
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I agree a not fully charged battery would have lower resistance than fully charged, thus the BIG WARNING TAG would make sense. But am I correct that a weaker battery would have higher resistance? See my video, I made a point on the specific weight (Hydrometer) as defined whether fully charged or not fully charged. An old battery can be weak(smaller capacity) but fully charged.
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good discussion and interesting theory about the life span of alternators, I would be curious to see more data. I only had alternators problem 35 years ago. I have not had any alternators break-down in recent 35 years even though all my batteries lasted more than 6 years, this Subaru is the shortest because I repeated many experiments (re-charging, overcharging, re-conditioning, Epsom salt see many of my videos). I agree the load could be larger with a weaker battery, but I don't know how significant this increase is. There are a few things I can speculate: 1. the alternators work on fixed RPM, thus fixed RPM should produce the same constant power regardless of the load, not working harder. So once the RPM changed from 500 RPM to 1200 RPM, it has little load (I assume the battery does not supply power at 1200 RPM). 2. a weaker battery would have higher resistance, thus less load with respect to the alternator, so if the alternator is charging the battery at 1200 RPM, then alternator is working lighter. At the startup, the starter motor with lower impedance would draw more current because the voltage is fixed. So I assume it is not " It's job is NOT to charge a dead battery", but rather it will need to share more load because the weaker battery does not contribute more than it should. 3. the initial power at 0RPM should be provided by the battery only. Between it is >0 but less than 500RPM, does an alternator provide any power? If it does, an alternator need to work the hardest is only at the very start up ignition when we have max current to raise the voltage. So the start up would require the alternator to generate larger current for 1 seconds. In another word, the alternator "abuse" may happen only 1-second "occasionally". BTW, I let the battery die too many times to perform my experiments. My wife would not have such patience, she did not argue alternators, she made me to stop the experiment +:)
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I took my 4 years old battery to autozone, and I did get the free test. He said: you definitely need to replace your battery. Other than replacing the battery, he did not say any reason. So I did not replace my battery. Now my battery lasted 6 years, I still can re-charge it, but because of the pandemic, no longer driving frequently, from these 16 data point, so I decide replacing it. Another issue of not charging frequently, the sulfation will cause problem:
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My Subaru Forester battery 6 years old (14D) with a small CCA=390A lasted 6 years. I noticed the battery problem last year (when it was a 5-year battery). I monitored the engine's start up for a year. With a set of 16 cars/batteries, I now know the characteristics of an old battery. I can analyze more data if other people contribute their data. How To Load Test A Car Battery Without Buying A Load Tester. can we do load test without buying a load tester?
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2. When I buy filters made by others, I could not find the PSI number. 3. If I added less oil, then temps would explain it, but the opposite is true, I had to add more oil. It's possible it wasn't level. I parked with the front of the car being higher than rear, do you this would show more oil? This could be a good research top. haha. I am able to change oil for regular sedan cars. As long as your arm is long enough. In case it is too hard, I use this trick: without jackstand
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subaru oil change a few questions: 1. a non-dealer garage installed a Metrostreet filter. How bad is this? 2. The owner's manual calls for filter number 15208AA160, when I called the Subaru dealership they said the correct number is now 15208AA15A what is the reason Subaru changed their part number? What exact the difference in turns of spec between 160 and 15A? 3. The manual says 5.1 quarts oil, I did not measure more precisely in the past, but this time it looks like I have to add more more than 5.1 quarts, I don't know why. Does anyone else have similar experience? 4. When I watch other people's video, they all jack up their car first. Do most people jack up their car when changing oil? Even if it were not SUV, I found that I can change the oil without a jackstand.
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Thank you for the tip on the discount code, people who could not start their cars are so worried that they usually don't think about this kind of coupon in that kind of state of mind. Are you saying that there's free windshield wiper fluid at gas station? My original post about wiper fluid was meant to say that I can check the battery fluid when I check and add wiper fluid, so there is no waste of time checking battery.
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One question is where to buy your $74 battery. My thinking is since big stores such as costco, walmart, homedepot have high volume, they can sell the same quality at lower price. The smaller stores auto specialty stores such as autozone, oreilly, pepboy may give you better service, but higher price for commodity products.
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Where did you get your 72 month battery? FYI, Walmart: $50 ValuePower: 12V car battery with 1-year free replacement warranty. $94 EverStart Maxx: An included five-year warranty (three years free replacement and two years prorated) provides peace of mind. homedepot: $89 SPRINTER 12 volts Lead Acid 6-Cell 35 Group Size 550 Cold Cranking Amps (BCI) Auto Battery 2-year free replacement $99 SPRINTER MAX 12 volts Lead Acid 6-Cell 35 Group Size 650 Cold Cranking Amps (BCI) Auto Battery 3-year free replacement Costco: $79 interstate: three years free replacement.