NC TRACKRAT

CTEK MUS 4.3 on Winter setting puts out the required voltage for AGM's. I have my ODYSSEY and, occasionally, the MACAN Turbo on the CTEK's and they do a great job. Reminder: Even though the current offering of lead-acid batteries proclaim to be "maintenance free", it's a good idea to pry off their tops or unscrew the cell plugs to check electrolyte levels every 6 months or so. Use distilled water only. The biggest factor in lead-acid battery life beside parasitic drain is sulfating due to electrolyte level going below the plates.

bjornebo

I have an AGM battery (Optima Red Top). It is 12 years old and I have had no issues with it. I have a CTEK MUS 7002 charger/tender and iI use it on the AGM setting.

Edward

I've read this (and heard this echoed) for a loooong time, but for all of our personal cars, and my parents' of whom I've maintained for decades now, I've never once checked/filled the cells; never. And yet I can only recall ever replacing a conventional lead battery once inside its 5-yr warranty; just once; and this over decades. All of them last well past their warranty, and I just replaced one that is probably over 10 years old ...I say "propably" because I can't remember it's been soooo long (and that's the one batt that I oddly don't have a receipt on! ...stranger, still, is this 10+ yo batt was in my Trackmeister which sees only occasional street driving and so rarely a battery tender!). Contrast my having to replace two Odyssey batts within only a few years; and both times on DD cars!

I'm glad these pricey batteries and their special chargers work for you folks. But as for me, the decision to stick with conventional lead acid was and remains, plainly, an easy one. YMMV

Edward

HalfGerman

Edward, see if you sing the same tune when your voltage regulator "cooks" your battery with acid cleanup required in the frunk. ( my experience) The AGM was only $30 more than the "regular" battery. They even had it in stock at my local O'Reillys, made by DEKA ( East Penn). So if I only get 3 yrs, it wasn't an expensive lesson.

NC TRACKRAT

I, too, echo HalfGerman's comment. I had a lead-acid battery explode in a beautiful BMW 3.0CS. Fortunately caught it before significant damage was done. Manufacturer replaced the battery but no remuneration for the "pain & suffering". Edward, I'm glad you've had such good luck. You must be living right. OTOH, for us mere mortals, I still recommend checking the electrolyte level in conventional batteries with removable cell covers. If they don't need additional distilled water, you're good to go.

IainM

Edward

Yessir, I've heard that one too ...often. Sorry that anyone's battery barfed in one's trunk/engine compartment; that stinks, to be sure. On that vein, I've never --not ever even once!!!-- had a conventional battery do likewise in any of my cars, wife's cars, kids' cars, both parents' cars, and this over several decades. And if I add that none of my motorcycle and car geek buddies have ever shared such a battery malady either --again, in what, 40+ years that I've been backyard wrenching-- then perhaps that further helps shape my opinion. So I think I'll continue to live on the wild and scary side

Oh, but if I factor my two, in addition to how many I know and have heard of, whose Odyssey batt (or the like) have had ridiculously short lives (short by any battery standard), well, that just cements it. Just as you all are sharing data points, so will I. Could be my just dumb luck, right?! Or maybe there's a correlation between battery type and longevity. Or not. Just tossin in here.

Edward

HalfGerman

Edward, guess I'm just that lucky. The kind of luck you don't want. Honestly, it might never happen again. If the AGM battery only lasts a couple of years who knows, might switch back. Personally think if you get more than 5 yrs on a battery you are doing good (especially in snow states).

Harold

Edward

Yeah, I hear you about the snow states. Extreme temp swings are tough on a battery, to be sure. I have relatives in Phoenix and they face their car issues there, to be sure. The "luck" I have may very well be the SoCal climate. But don't worry, we pay for that luck in astronomical taxes and asinine activism. ...said with "LOL" in half tears

Be well, sir!!!

Edward

IXLR8

That works both ways. Winter does put an extra load on a battery, but so does high heat. Every 8C over the standard temperature cuts battery life in half.


Plus having a voltage regulator that does not temperature compensate properly may overcharge the battery. You do know that voltage cutoff drops as the temperature increases and that applies to all lead acid batteries including VRLA.

IainM

IXLR8

Yes, battery temperature. Ideally, a temperature probe connected to the VR would be great which is what they are doing these days on some vehicles.


My Acura and 991 have a module on the negative battery post with a wire going to the ECU. Honda has been doing that for years. You can Google Honda's Dual Mode Charging System (something like that). It's why I'll see voltages like 12.8V while driving and the next minute 15.0V on the 991 (it has an AGM battery factory fitted). The manufacturers are making charging smarter and trying to cut down on loads.

IainM

IXLR8

There are pics of the Acura and 991 modules on my web site. I remember one of them having a Bosch PN. Tried looking up some tech info, but came up empty.

The 15.0V on the 991 had me concerned at first (too high for a flooded lead acid battery). I later found out it was an AGM battery, plus it was 4C outside, so it made sense.

AX993

I also have an Optima red top AGM battery in my 993. I also keep it hooked up to a CTEC 3300 battery maintainer/tender when in the garage, which is most of the week as it's not my daily driver. Early on in my 993 ownership I noticed that after hooking the battery up to the battery maintainer after a long drive, the maintainer/tender would immediately go into charge mode. Seems like the maintainer should have just gone into maintenance mode. My alternator was a new remanufactured Bosch unit. That Optima stayed in the car around 7 years, replaced only because it was getting up in years. FWIW, I keep the CTEC on the motorcycle setting which I think is somewhere around 1amp.

After talking with someone who knows much more about 993s than most will ever know, it looks like 993 alternators sometimes (often?) do not put out enough voltage to properly keep a car battery charged. I have a mini obd2 reader mounted in my car to give readouts of voltage and other stuff, and it showed about 12.5-12.7 volts at the DME while driving. I looked at the voltage at the battery with rpms around 2000, with accessories on, and voltmeter said about 12.7-12.8 volts IIRC. I didn't think this was enough to keep any car battery properly charged. I then put a new Bosch voltage regulator on the alternator which didn't really change the voltage output.

After some internet research I found an adjustable voltage regulator for a similar Bosch Alternator (for a Volvo!) sold by someone on the internet. He also offered a remote adjustable voltage regulator (remotely wired to the brush assembly on the alternator). So took a chance and installed it, mounting the adjustable voltage regulator to a vacuum bracket to the left of the engine fan shroud. I then set the voltage regulator to see 13.5-14 volts at the battery terminals with accessories turned on. Been on the car for several years now. After a long drive and putting the car on the CTEC it now goes straight to maintenance mode. Problem solved (I hope).

As Always, YMMV, Just my experience.