Early 911 - Sonnenschein Batteries

[dwood]

Well, this is the year to get my '73 back on the road.

First things first, new batteries are in order. After reading all of the posts here about early 911 battery options, I thought the Sonnenschein A212/36A's (081-90640) were a good choice.

I contacted a local dealer about pricing/availability of the A212, only to find out that Sonnenschein discontinued that battery about 3 years ago.

The 'recommended' replacement is the A512/40A - same size, A-terminal, but slightly more capacity (40Ah vs 36Ah), and slightly heavier (14.8kg vs 13.4kg, about 32.5lb vs. 29.5lb). BUT (there's always a but, isn't there?) the A512 apparently requires a higher charging voltage than the A212 did - I'm waiting for further info on this detail.

So, does anyone here have any experience with the A512/40A? The Sonnenschein link is here. Take a look near the bottm of the list at #895630.

Thanks,
Dave...

[Wil Ferch]

Why not a small, sealed recombinant-gas gell -cell...like an Optima?

Do a search...many pics and options fopr a single or dual battery early 911 application

Wil

[pwd72s]

As long as the size is the same, I guess these will be my replacement sonnenscheins. Wil...some of us are kooks...we actually perfer to retain the original battery set-up. Dave, thanks for the heads up. I'm no electrics guhru, but I'd think the original voltage output of our early alternators should be fine with these. A few more amps output sounds a-ok to me.

[304065]

Paul, you might want to verify that you have the correct charging output from your alternator. The charging voltage of those cells is 14.1v with a "float" voltage of 13.8v.

According to LorenFB, who, despite his public relations issues WRT the whole chip thing, was an excellent source of information, the early Motorola/Marchal external VR and alternator could handle a max of 13.7v charging voltage-- any higher and the alternator would be overdriven.

If you are going to give the gel cells a try, I would recommend a thorough cleaning of the B+ terminals, starting with the back of the alternator, the starter terminal, the battery clamp and the ground terminal on the body, to minimze any voltage drop caused by corrosion.

For comparison purposes the Optimas use a charging voltage of 13.3-15.0v and a float charge of 13.2-13.8v. The Hawker/Odyssey, 14.4-14.7, 13.6-13.8.

The internally regulated Carrera alternator in my '71 (a misguided upgrade on my part, BTW, which has resulted in unscheduled pit stops due to an overheated VR that looks like a broken fan belt) has no problem with 14+ volts measured at the battery terminals. The later alternators have higher output voltages. No less a personality than Early_S_Man said,

A very probable reason for the higher output Voltage on 1982 and later alternators was the adoption by the lead-acid battery industry of the so-called 'low-maintenance' battery technology about 25 years ago ... switching from lead-antimony plates to lead-calcium alloys. The lead-calcium batteries actually require a higher 'float' Voltage ... by approximately 0.12 Volts to 0.16 Volts per cell. The change to lead-calcium by the battery industry was done for simple economic reasons ... but it had major implications for industry, including revisions of maintenance procedures & practices, and publications in the stationary power plants, such as telephone switching offices, and standby emergency generator batteries for hospitals, etc. All such installations had to have their battery chargers readjusted for the lead-calcium cells.

The other alternative would be to use an adjustable external VR, like the ones made by Transpo, and adjust the setpoint with a screwdriver. The Lamar VR in my airplane has such a screw. If you were truly going to concours the silver Bosch or Motorola can could be swapped back, along with the original batteries!

[dwood]

Thanks for the feedback.

I've considered many of the alternatives (Optima, Stinger, Exide, etc. etc. etc.), but like the 'stock' size of the Sonnenscheins, and have decided I want to stay with the dual battery setup. Relocating the battery isn't something I want to do, and I'd prefer batteries that fit the stock boxes.

I got some more info from my local Sonnenschein distributor. They say they've sold these batteries for early 911's and everything should work fine with the new A512/40.

His only warning was charging. He said "Your alternator should charge the battery just fine if it is functioning correctly", but did also say "A standard automotive charger will probably NOT
charge the A512/40A properly and may also damage it, because they are designed to charge standard wet-cell starting batteries."

So, my follow-up question to current Sonnenschein users is, how do you charge your Sonnenscheins - regular automotive charger, or something else?

I don't mind paying the price premium for the Sonnenscheins, as long as I won't also have to invest in a special dedicated charger for them.

[dwood]

Originally posted by dwood
So, my follow-up question to current Sonnenschein users is, how do you charge your Sonnenscheins - regular automotive charger, or something else?

Anyone??? Any Sonnenschein owners/users out there? Did you acquire an expensive dedicated charger for your Sonnenscheins, or is anyone using a good old run-of-the-mill automotive charger?

After comparing prices with the Interstate 911 batteries, the Sonnenschein's are looking more attractive than ever! (+$10 over the Interstate).

[pwd72s]

Glad you bumped this...I charge my sonnenscheins with a Sears auto shut-off charger...It will charge at 2 amps, 12 amps or 75 for a starter charge. I only use the 2 amp "slow" charge with my sonnenscheins, and it seems to work fine. It takes time at this low setting, but it works well. OPTIMA doesn't want you to charge at high amps, so I'm assuming the same with sonnenschein? My sonnenscheins are about 5 years old now, no problems with my alternator or V regulator. Another charger option would be one of the mini auto shut off "battery maintainer" chargers. Most of them seem to charge in the 1.5 amp range.

[Phoenix]

dwood:

I installed 2 Sonnenscheins in my '73 late last year and used 2 Griots "Battery Manager Junior II"'s throughout the winter to keep them from fading. When I pulled her out a few weeks ago I had full juice.

I permanently attached the Jr. II's to the batteries with the kit that they come with. It's a neat solution as when I know I won't be driving it for a few weeks, I just plug in the Jr's and I'm sure I'll have a full charge when I need it.

[zzwhm]

I just pulled the Optima from my 87 and it won't fit my 72 battery boxes. From published dimensions it seems that an Odyssey 925 will fit nicely.
Bill

[911pcars]

"
I just pulled the Optima from my 87 and it won't fit my 72 battery boxes."

Bill,
You have to be creative with the early battery boxes. The Optima fits, but not right side up.




Another option. Some install their battery in the smuggler's box.

Hope this helps,
Sherwood

[Brt911]

I know this is an old thread but I hope someone has updated information and/or experience on installing Sonnensheim batteries in an early 911. I just acquired a 1973 911E and would like to replace the batteries with gel's. Which one are a good (no mod) fit.

BTW, I used a CTEK designed to charge gel batteries (instructions say to use their winter "snowflake icon" on the charger for optima batteries.

[manxter26]

I put them in my 1972 911T last fall. They fit perfect with all of the factory hardware in place. Seems like I paid about $200.00 each plus shipping, but it was well worth it to me to have all fit like it should. I am a big fan of optima and oddessey batteries but wanted the original fit. My car has the wingnut on the ground strap at the body and when I leave the car sitting for a while, I just disconnect that ground and hook up my Battery Tender one battery at a time. I was told that if all was connected together I wouldn't get a proper charge. I'm very happy with my choice of batteries and would recommend.