I am done with Flooded Lead Acid Batteries – an AGM battery is it! –
 

A while back I was redoing the A/C and installed a wagon sway bar on my 1983 w123 300D. While I was at it, I had the opportunity to fix the rust under the battery tray and the tray itself as shown in this thread.
http://www.peachparts.com/shopforum/body-repair/344019-ketchup-vinegar-wire-brush-3-days-%3Dalmost-no-rust.html#post3210214

I had since reinstalled the Autozone battery and operating it ever since but was noticing more acid causing corrosion on the tray. This has made me very unhappy.
http://www.peachparts.com/shopforum/...1&d=1477844839


I finally decided a Flooded Lead Acid battery will never be installed in this car ever again and will replace it with an AGM (Absorbent Glass Mat) Battery.
These batteries are typically installed in the trunks or in the cabin of newer cars. It's a sealed battery, doesn't leak and doesn't emit any gasses. Some even say you can mount an AGM battery on it's side. :eek:

I purchased a Deka Ultimate AGM - part number 9AGM49 - from my local parts supplier for around $220.

New leak free Deka AGM vs the leaky Autozone Duralast Flooded Lead Acid.
http://www.peachparts.com/shopforum/...1&d=1477844871

Fixed the corrosion on the battery tray and was very glad under the tray was clean.
http://www.peachparts.com/shopforum/...1&d=1477844871

As installed...
http://www.peachparts.com/shopforum/...1&d=1477844871

Comparison of battery stickers.
http://www.peachparts.com/shopforum/...1&d=1477844871



AGM Battery

• Excellent value - Product life lasts up to two times longer
• Reliable - Extremely heat and cold tolerant
• Robust - Ideal for vehicles equipped with lots of electronics
• Worry free - Slower discharge in storage
• Durable - outstanding vibration resistance
• Safer - No free-flowing electrolyte or spill hazard
• Powerful - A high performance alternative
• Resilient - Excellent ability to tolerate deep cycling

Flooded Lead Acid Battery
• Shorter battery life
• Less tolerant of heat, cold and vibration
• Faster discharge
• Contains free-flowing electrolyte
• Poses a spill hazard



I really do think this is the way to go with our vehicles like the w123 and w126 to keep them safe in the battery area from corrosion. So I urge you all to dump your flooded lead acid batteries and install an AGM. It's well worth it.


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Another option is the original MB battery from the dealer, if you tell them you want the one for a W210, it's an AGM, it will fit the 123/124 holder, and the +/- is oriented the right way. It's sub $200. Tell the parts guy to plug the model type 210.025 into the EPC, if he needs a car to go off of to get the battery P/N, that is the 98-99 E300 Turbo Diesel model.

Be sure to rig a vent hose from the vent port on the battery down to clear space under the car (like they do on the cars with internal batteries). The AGM do vent if overcharged, and you don't want it just going off the side of the battery and into the tray. You can buy the W210 vent hose, it has a piece of clear tubing and the right elbow fitting to plug into the side of the battery, and let it either hang down or join it to a longer piece of tubing.

Great tip. ^^^ That's a group 49 battery?

Check your voltage under charging conditions. Too high and you can see actual acid residue out of the battery.. Basically they are boiling out some of the electrolyte in those situations. The normal out gassing when charging does not seem to be too bad in comparison under the hood usually.

Also I have forgotten where copper is in relation to steel. I used to place a few real copper pennies on top of my battery to sacrifice themselves over the terminals and their cable connections being attacked.

If the copper or whatever you can find to use as a sacrificial anode perhaps zinc. Is placed on the battery tray it might aid in protecting it.

The last I checked year or so, within the last the chain store wanted twice as much for an AGM for my Cummins for similar CCA. The warranty was much less than the old regular acid battery. I decided to keep my money. I don't really need pay money to change what's worked for the last 30 years and still is working.

Some Autozone Duralast batteries are AGM, I recall "Platinum". I have their "H8" in both my 300D's, since less cost and 10 lb less weight for similar spec's than the "correct" size ("Frame 74", I recall). The Optima batteries that custom cars have long used are AGM, mostly to avoid acid damage but also the unique look. You can find reliability complaints about AGM, especially Optima.

Since using lead-acid batteries in my vehicles, I put a "Battery Mat" (ebay) under them to neutralize the inevitable leaks. My 1984 300D had rust on the battery tray and underneath, so much I had to cut off one bolt to remove the tray. My 1985 had a white powdery spot on the firewall behind the battery. Fortunately, I caught it before it ate all the way thru. Both were before the battery mat. Due to its thickness, plus the H8 difference, I had to form a special nut to from a long hex nut to get down to the clamping stud on the tray.

AGM batteries require a slightly different charging profile, if you charge them like a flooded-cell you will not get the full life out of them.
I ran an Optima red-top in the TD without changing regulater however, still cranked great this fall, 8 years old.

Are you saying the regulator has to be changed when switching from a lead acid to an AGM? What is the p/n of a H8 AGM regulator ?

I have a blue top Optima that was around $84 from Costco, that was a long time ago for that price.... my guess 15 to 20 years (today they are around $200). It is still working fine in my 92 VW diesel with the stock alternator/ regulator.

No idea.
On a coach with $4,500 in batteries, i select AGM on the inverters, in the car I dont believe it's an option unless you go custom.
If what was posted above about the W210 is correct, that car should have a VR optomized for AGM.

Firstly, AGM batteries are still Lead-Acid. Same lead, same acid. They are sealed and can be installed on there side but don't. The acid is immobilized like water in a sponge. If the case cracks you will still have acid in the tray. A properly vented free flooded battery is no more likely to spill or damage your tray than an AGM. Contrary to popular opinion AGMs do not need a different charging regimen than the conventional free flooded type you have. They are very tolerant of voltage differentials from 13 to 15.5. They have lower internal resistance because the lead plates are compressed closer together. This yields more cranking energy and faster recharge rates. Typically they cost about twice as much. They will recharge even faster and fuller with multi-stage charging but so do free flooded batteries. One potential drawback is overloading your alternator because they will take its full output. This is mostly a concern for much larger battery banks. Not a concern for your car. that your alternator may be Nobody wants to pay more for a battery and not get what they pay for. If you got time and money to change to AGM and upgrade to a an expensive regulator, alternator modifications, or an alternator built for external regulation go for it. Hell, slap some Li-ions in there. But, know that the marketing claims with AGM batteries e.g. "Lasts up to 2 times longer..." are largely based upon the typical neglect and abuse most batteries receive from the end user. You should make sure the top of your battery is kept clean no matter the type. Keep the terminals and posts clean and use a very light coat of silicone grease on the posts and terminals to prevent corrosion. Don't overtighten the clamps. If you have a free flooded battery and you are willing to remove the caps once or twice a year and add some distilled water as needed they are the best bang for the buck. East Penn MFG's retail name is Deka. I highly recommend them or one manufactured by them with a different label. I think they make Duralast for carquest, NAPA, and many others. The free flooded battery is the DEKA Gold Exact Fit #649MF. I bought a new one last month for $125 and it fits like a glove in the w123 tray. It comes with a plastic tube elbow that you can plug into the vent on either side. Plug or cap off the hole that's unused. Connect a piec of 3/16" PVC tubing and route the vent line down and away from the engine compartment. You can have it hang a few inches off the deck if you wish. The only thing that should ever go through this tube is hydrogen gas. If you don't vent a free flooded battery in a like manner gassing will lead to corrosion primarily under your hood. If you've never changed the insulating pad you are likely in for a rude surprise. Hydrogen gases rise and circulate in the engine compartment. As for spillage, if your caps are sealed, your battery vent discharged, the only reason you should have acid on or near the battery is if there is damage to the case. AGM's are no more immune to this. Before you install the battery be absolutely sure there is nothing on top of your tray like fasteners, pebbles, or coins. Do not put anything but a slim pad and the battery in the tray. Don't use pennies. Anything between the battery and tray that doesn't fit or shouldn't be there will damage the case and result in leakage. Periodically clean the tray especially around the edges. A slim pad may be installed under the battery but if you get the recommended battery, it will need to be very thin. The most important thing you can do to prevent damage to the case is to use the OEM lock plate(s) and secure the battery. It shouldn't move at all once secured. The 'Exact Fit' series has a lip front and back. The back edge fits into the tray and the lock plates over the lip in front. Because it's a glove like fit, installing it is not easy. The back of the battery needs to slip under the trays edge. If you think it's not quite level you are right. You will know with certainty when it's in. The Exact Fit series have a couple holes <1/8" near both positive and negative posts. These are for a snap in cover plate to protect both your terminals and accidental arc from dropping a wrench. They don't come with the battery. I found the Red Positive cover at ECStuning for a few bucks... worth it. I'm sure you can find the black negative one if you try but you can provide arc/terminal protection with boots, racquet balls, and all sorts of creative ways. Cover both. The negative isn't an arc threat but still deserves terminal protection.

For something completely different to replace a conventional battery (can't be bothered typing it all out again sorry):

Anyone else got these? Ultracapacitors for car starting


I am since running all 18 at the moment, not that the car is used yet alone road legal.

Technically gel batteries are lead-acid, as are AGM, but each has a different optimum charging profile for long life and a different tolerance to heat and overcharging.

An AGM battery is less tolerant to overcharging, should float charge no higher than 13.8vdc, lower if in a hot location. Most older cars like ours will float over 14v.

The AGM will fully charge at this voltage but since this thread is about battery life, this will shorten its life.

Also note that AGM only means that the acid is absorbed in a glass sponge. The normal flat-plate battery is modified by many with this AGM holding the acid, where others like Optima are significantly different and more expensive to produce with their spiral wound cells.

I appreciate all the comments on this thread to give a different perspective on this subject.

I've own this car a long time and had a variety of flooded lead acid batteries. When I first recieved the car, it had a pretty new Mercedes Battery. By the time I removed it, it was leaking and the tray was starting to deteriorate. I didn't do anything to it, installed an Interstate and off I went. When I replaced that battery, it had been leaking also. Now the tray was in even worse condition. I bought the Autozone battery and used that until this replacement of the AGM.

I've been visiting the local wrecking yards for a number of years, and I have never come across a perfect battery tray. All of these trays, whether it be a w115, w116, w123, w126 and etc., all have a ton of corrosion on them. And most of these are rust free "California Grade" vehicles.

So I just wanted a maintenance free, forget about it battery. I believe the AGM, with it's aforementioned quarks, fits the bill.

As far as voltage, this is what I am pulling...

Engine off...
http://www.peachparts.com/shopforum/...1&d=1477929265

Engine at idle...
http://www.peachparts.com/shopforum/...1&d=1477929265

Engine at 3,300 rpms....
http://www.peachparts.com/shopforum/...1&d=1477929265


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12.33V is awfully low for a new AGM battery—ought to be 12.6V or more unless there's a load on the battery or it's been sitting a long time.

Jeremy

Is the DVM accurate? Engine off voltage is low, should be around 12.6 to 12.7 V for a fully charged battery.

I also have an AGM H8 battery from Interstate for a little more than a year now, no signs of any leakage or corrosion on the tray.