locked Re: Batteries starting to get weak - MMM - What to do -

Scott SV Tengah

I used to own and race BMWs and was a big fan of them.

Previously, they recommended oil changes every 3,000 miles. When they started including free oil changes, suddenly their recommendation was that you could go 20,000 miles or more between oil changes. Nothing changed in the engine nor the oil they used.

From a business perspective, it makes complete sense. Since BMW started including the oil changes, they rationally, as a business, determined that they could save money by only giving you 2 oil changes before your warranty ran out. Any damage due to extended oil change intervals would probably occur after that. When the customer was paying for oil changes and they wanted to protect their reputation, you were supposed to change the oil 6-7 times as often.

If I was a profit maximizing business, I would want my batteries to last the warranty period + 1 day. Or for you to get enough loss of capacity that you buy new ones. They go out of business if their customers only buy once every 10-15 years.

For this reason, I rely on statistically valid research from people who are not conflicted to make my decisions. When I leave the boat, I setup a simple programmable relay that drives a load will keep the SOC between 40-70%. Sure, there's one guy who seemed to do ok (in 1 out of 2 tests) when he goes against the non-conflicted researchers' advice...but he also sells lithium related products. It's not much effort and there's very little known downside to doing what the research says.

Or you can trust the guys trying to sell you stuff and who have a strong incentive for you to buy from them again once the warranty period ends.

2007 A54 #69
SV Tengah

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