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Tuesday, April 23, 2024

Doug's Domain

Doug Vetter, ATP/CFI

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Saturday, April 8, 2017

BatteryMINDer Research

As regular readers of my E36 and E46 blogs know I have previously recommended the use of a multi-stage battery charger for any and all vehicles that sit for extended periods of time or that are used for short trips. For reference, you can check out an entry I wrote for my E46 a few years back.

Until recently I used my E36 daily and drove for an extended period (30+ minutes) for each turn of the key, and for this reason I have enjoyed relatively long battery life over the life of the vehicle. As I no longer commute on a daily basis and my trips have become shorter (the "price" of living where everything including post office, food shopping, bank, drug store, etc. is literally around the corner), over the last year I've made a point to put a spare BatteryMINDer on the E36's battery for a short time after returning from my errands, the intent being to ensure that the battery does not spend the days between errands significantly discharged, as I know that will lead to sulfation and premature failure.

I have found that I typically have to charge the battery for 3-5 hours on the Battery Minder's 8 AMP setting, depending mostly on how many times I turned the key and what accessories I was running during my errands. For example, heated seats appear to require the longest charging cycle. In the grand scheme 30-40Ah might not seem like much, but it represents enough of a discharge to cause sulfation, so I think the extra effort I take now will keep the battery alive for as long as possible.

Incidentally, I was investigating the purchase of another BatteryMINDer and I noticed that the 12248 units I have are no longer in production. While browsing for a replacement I discovered the 128CEC1 but found it less than favorable initially for two reasons:

  1. While the 12248 had a different mode for gel, wet, and agm battery types, the new 128CEC1 had combined the wet and agm battery modes -- something I believed to be impossible given the different charging profiles for these battery types.
  2. Like later versions of the 12248, there is no reset button. On the newer 12248 models this forces disconnection of the battery and/or A/C power to manually reset the unit. In short, it's annoying.

I brought both issues to the attention of BatteryMINDer support and this was their response:

The only AGM battery that requires a 14.75V charge rate until the battery reaches capacity is Odyssey battery company. A lot of other AGM's, (Optima) or small AGM's (like motorcycles) were being overcharged in AGM mode. All BatteryMINDers are temperature compensated and help to alleviate this problem of overcharging in hot weather. If you have an AGM battery that is similar to Odyssey specs, then you have the option to use the Odyssey setting. You are right all batteries are not the same, better to undercharge them slightly than overcharge.

The new 128CEC1 will allow you to make full changes to current and battery types while in any charging position. No need to unplug it.

So it appears that the 128CEC1 is the replacement for the 12248, but I still question the decision to combine the wet and agm modes. AGM batteries of which I am aware require a higher charge voltage than a wet cell so lacking any additional technical information I can only conclude that the combined mode is a compromise created by the company to avoid liability for damaging AGM batteries...at the expense of both wet cells, which will be potentially overcharged, and most AGMs, which will be undercharged to some extent.

My take is that the company should have left well enough alone, retained the separate gel/wet/agm modes and simply changed the temperature compensation algorithm to be more aggressive in AGM mode to protect those battery types from overcharging in hot weather. But I would still purchase a BatteryMINDer over a Battery Tender -- as the latter are clearly garbage. I tolerated four Battery Tender failures before I woke up and replaced them with BatteryMINDers -- all of which are still going strong after 4+ years in service.

More Engine Overhaul Research

As I wanted to avoid traveling an hour or more to get to the machine shop I discovered last year I called a few shops closer to me. Fortunately I found one that had some BMW engine experience and had worked with my local indy Mr. M Car. who, as you may recall, provided assistance with my suspension overhaul projects.

I discussed the project with the shop owner and he seemed interested, despite the summer being his busy season (racing engines are a staple of auto machine shops, after all). Not all machine shops do full engine assembly, however, so I first asked if he would be willing to tackle the assembly for me and he agreed provided I gave him a bit of lead time. So I know I have that option if needed.

I then asked if he had a diamond hone, and he admitted he did not, but retorted that the same finish can be achieved with traditional stones, and with a lot less heat introduced into the block. I confirmed independently that this is true -- the diamond cutters require (somewhat counter-intuitively) a higher force to do their job and this additional force creates more heat. As any heat introduced into the block can and will affect the size of the bores during the various operations, the less heat the better. Regardless of the abrasive type used, the shop owner acknowledged the importance of letting the block cool down between operations to ensure the end result is as expected and I emphasized that I was willing to accommodate any schedule that achieved the desired results.

This lead to a discussion of the piston to cylinder clearances required in my application (0.0015" ± 0.0002) assuming I use the MaxSil pistons. He said he could achieve those specs. Incidentally, I'm still on the fence whether to use MaxSil. I tried calling them several times this week to confirm whether the pistons for my application are in stock and no one answered. When I tried to use their contact form I got a 404 on submission, meaning their site is borked. I'll try again next week and if that doesn't work out I'll seek other solutions, which could include punting and buying the BMW (Mahle) original parts.

What I neglected to ask the shop owner is whether he could provide a plateau finish on the cylinders, which can significantly reduce the time required for the rings to seat. This process is achieved by one final honing cycle with abrasive brushes in place of the stone or diamond abrasives. From what I've read this is recommended on all engines except where the cylinders may deform as the head is torqued on the block (which is to say, all engines that have not been bored and honed with a torque plate installed). I interpret this to mean that if I want a plateau finish then I have to use a torque plate, but as that was the plan all along this is no inconvience.

Speaking of torque plates, I asked the shop if they had a torque plate for this engine and the answer was, predictably, "no" but fortunately I learned recently that VAC Motorsports rents torque plates for $150. That's great news, since they sell outright for $350 (I found another company selling them for $600) and I have no interest in owning a one-time-use tool like that or renting it out on my own afterward.

The news of the week was the discovery of a series of great videos on YT channel 50sKid, that nicely document the process of a M54B30 rebuild. These well-produced videos and the supporting documentation were a gold mine. While I don't necessarily agree with all of the decisions he made during his project, overall I think he achieved his aims, which are similar to mine. These videos have inspired me to consider doing the bottom end rebuild myself. I can safely say, however, that I still have no interest in doing the R&R as that is simply too much work for me, and I have no interest in tackling the head as that requires too many specialized operations and tools that are best left to pros that know the heads well.

If I can manage to negotiate some access to my brother's garage I will probably just have my tech give me the engine fully assembled so I can do the disassembly myself. This will allow me to box up the head and then inspect and blueprint the bottom end. With that data I can then make intelligent and focused decisions about what parts to buy and what to have machined. As usual, I'm concerned with the time this will take, but I may relieve some of the scheduling pressure by having the car flatbedded back to my garage so it doesn't sit outside at the dealer during the process. Then when I'm ready I'll just bring everything back to the shop and have my tech tackle the installation and initial start.

Mileage: 265400