The Official 356Talk Forum

I'm not real happy with the last two six volt batteries I've bought - a lead acid group 1 from a local battery warehouse that failed within a few weeks and two red top Optimas that haven't lived up to their previous reputations.
I've run 12V Optimas in my Land Rovers and we have noticed that the quality has declined over the last few years as well.

Exide apparently doesn't make the 6 volt batteries they sell with their labels on them - and Odyssey doesn't show a 6 volt in their line up. Apparently Odyssey bought Extreme batteries some time back (a friend recommended Extreme but they aren't an independent manufacturer any more).

NAPA, Tractor Supply, Autozone all have 6V batteries of dubious provenance - I'm looking for something that will just plain work and has enough CCA to crank over a high compression 4-cam motor.

So who's using what and which ones are the good ones? It seems that there are only a couple of actual manufacturers of 6 volt batteries but a whole lot of labels out there. Deka, NAPA, Optima - what do you guys recommend?
The way the larger manufacturers are buying up all the independent battery makers its hard to tell without a score card what you're buying.

Jack Walter wrote:I'm not real happy with the last two six volt batteries I've bought - a lead acid group 1 from a local battery warehouse that failed within a few weeks and two red top Optimas that haven't lived up to their previous reputations.
I've run 12V Optimas in my Land Rovers and we have noticed that the quality has declined over the last few years as well.

Exide apparently doesn't make the 6 volt batteries they sell with their labels on them - and Odyssey doesn't show a 6 volt in their line up. Apparently Odyssey bought Extreme batteries some time back (a friend recommended Extreme but they aren't an independent manufacturer any more).

NAPA, Tractor Supply, Autozone all have 6V batteries of dubious provenance - I'm looking for something that will just plain work and has enough CCA to crank over a high compression 4-cam motor.

So who's using what and which ones are the good ones? It seems that there are only a couple of actual manufacturers of 6 volt batteries but a whole lot of labels out there. Deka, NAPA, Optima - what do you guys recommend?
The way the larger manufacturers are buying up all the independent battery makers its hard to tell without a score card what you're buying.

I haven't used one in years but the Sears Diehard 6V used to be good, of course with Sears on it's last legs the warranty may be questionable.

Jack: Yes, the problem that does not go away, the hard starting 6V. I have had good luck with the Optima 6 volts. I have on in my 356-B and one in a '56 VW beetle with a high performance engine. As long as they are maintained on the trickle charger, they start fine. In a 1940 Mercedes 170-V, I have two Optima 6 volts, wired with a series parallel switch. When I depress the starter button, it switches to 12 volts direct to the starter. When the starter is not being used, it returns to 6 V for charging purposes. I have ordered one of those fancy 700 dollar 6 volt modern starters from the UK, I will advise how that works out once I try it. Some say that the DEKA group 1 battery is the best available currently.

6V Optima's in my 59 and 64. The 59......6 years and still going strong. 64, two years so far so good. I keep them on battery tenders.

One of my issues may be the charger I'm using - I've got a NOCO Genius G3500 which has a setting for 6 volt batteries but I'm not sure it plays well with a six volt AGM battery like an Optima.
I've read that the Granite Digital 2365-LCD charger works well on AGM batteries, since I have Optima batteries in several cars I'm wondering if that might help.

It doesn't look like Sears even has a six volt battery any more.
I saw a Duesenberg at Amelia last year that had two 6 volt Optimas wired in parallel - he said it worked really well but it might be a problem to fit two Optimas in a 356A.

An Optima on a tender cranks over a 10:1CR engine with a short cam, probably a higher effective CR than any 4-cam. And does so after long delays.

I buy stock 6 volt lead acid batteries from Tractor Supply. I buy the ones on the shelf with the most recent dates on them then I always fully charge them then load test them before fitting in the car. If I have any problems I take it back and exchange it for another. I have only had to do this once. No hassle and no questions. Over the years I have bought many batteries and in general I buy the cheapest one I can find and some have lasted 7 years but all have lasted at least 5. I have had some go completely flat when I have left an interior light on but have had them recover after charging.
As mentioned there are fewer independent manufacturers than in years past but as most all batteries are made by the same process and to the same standards so I doubt there is a great deal of difference in life expectancy. If you shop around you will find prices starting around $75 and upwards which is not unreasonable considering that is about the price of three gas fill ups. If it lasts three years that is about $25 a year which again is not unreasonable. I bought one Optima some years ago when the price was reasonable. Now they are not a good buy as they are seem to be no more reliable than a stock lead acid battery in a 356 and it does not fit very well.
If you are having problems with what appears to be a weak battery even after a full charge then I would suggest you do a load test on the battery then a complete R&R of the starter system before blaming the battery. Make certain you have a good starter bushing and a Porsche starter motor. Many cars have been retrofitted with cheap exchange starters and they will likely not be as powerful as the original spec starter.

You must use a battery tender on all vehicles that are stored and not driven at least weekly. If you look at the output of your generator 6 or 12 volts you will find that the 6 volt generator makes 50 amps of electricity and the correctly labeled 12 volt small generators make25 amps. The 12 volt generators will begin to disintegrate when they have to pump out more than 22 amps. NO 12 VOLT REGULATOR IS AVAILABLE IN A 20 AMP CONFIGURATION. Early 12 volt American Regulators do not seem to work properly! RESTORATION OF ELECTRICAL SYSTEMS IN YOUR VEHICLE: Just like rebuilding the engine, painting the car or repairing the seats the electrical system needs attention. Check for resistance from the battery to the ground by placing one lead from the ohm meter to the negative post of the battery and the other to the lip above the battery at the front tend of the trunk floor and on the positive in the first 12 inches of the positive cable of the battery to the battery post. The results will probably surprise you.
Optimas are now made in Mexico and according to our supplier instead of scrapping the batteries that do not function properly they are returned to the manufacturer. The advantage of the optima is that there is no sulphuric acid fumes when charging an older battery. This keeps rust out of the trunk. As I have posted earlier, at some point in the not too distant future, some 6 volt part will no longer become available and that will spell the end of reasonably priced 6 volt products. Two weeks ago I looked at a 356 that had a conversion to start on 12 and run on 6 with a rotary switch to change parallel to series. Fortunately for the owner the fire confined itself to the battery compartment and did not burn the paint or the wiring. al zim

My last couple have been Interstate I-17FF They have 75mo warranty and that's about max for them. Nothing really outstanding about this battery other than they are in stock and at 12v price. One sales guy commented that we are lucky RV's used banks of 6V battery or we would be SOL. Keep on Deltron trickle charger and if I want extra piece of mind I will give it a shot of 10amps from larger duel range automatic charger for a hour or so the night before day trip. Need to get one before trip to Phoenix Club.
Enjoy Daryl 63 super 90

Jack Walter wrote:One of my issues may be the charger I'm using - I've got a NOCO Genius G3500 which has a setting for 6 volt batteries but I'm not sure it plays well with a six volt AGM battery like an Optima.
I've read that the Granite Digital 2365-LCD charger works well on AGM batteries, since I have Optima batteries in several cars I'm wondering if that might help.

It doesn't look like Sears even has a six volt battery any more.
I saw a Duesenberg at Amelia last year that had two 6 volt Optimas wired in parallel - he said it worked really well but it might be a problem to fit two Optimas in a 356A.

I use the NOCO Genius G3500 on the Optima 6 volt and have had no issues, Jack.

Chuck

It does seem odd that so many batteries seem to have 'gone south' on Jack's car. It would lead me to believe the problem is not with the batteries but further up-stream.
My first approach would be to check for a constant power drain somewhere. One friend always had a dead or weak battery in his C coupe and could not figure out the cause. One afternoon, I happened to be in the garage where his car was parked and noticed a faint glow of an instrument light. Seems when the ignition was on the light went out...when the ignition was off and the key removed, the light came on. After days of remaining on, the battery would be drained. It was a simple matter to correct the wiring.
I have used various batteries on my 356s and all seem to be more than adequate. On my factory 12v '63, I eventually used an Optima and used that battery for about ten years without a problem...even later used the same battery in a Mercedes diesel sedan. It was one of the earlier Optimas, so perhaps it was better than the newer ones. In my '64 coupe, I have been using a plain old acid battery for at least eight years or so and have had no problems.
My advice would be to diagnose the entire charging system, clean every connection, ensure the regulator is delivering the right voltage, etc. It just doesn't seem likely that three different batteries would show the same weakness.

I agree with Geoff. I have had a generic tractor battery in my C for the past 5 years, always keeping it on a Genius 6V when parked. So far it has survived 4 long winters in unheated storage, often down to minus 30, and still cranks fine.

I have been using what have now become Interstate 19L batteries in both my 356's for years. I'm able to get about 7 or so years out of each one, although I do live in an area that does not see great temperature extremes. I have not had any that failed early.

I've had a 6v yellow top optima in mine for 12 years and it is still fine. it's on a 6v CTEK when not in use. I did hear the quality and durability of the optimas suffered a lot when they relocated production to Mexico.

I had a 6v/12v Genius charger almost burn down my house so i will never buy one again, it fried my 6v battery.

Porsche is now supplying Moll 6-volt batteries. Interestingly enough, they are the 77-ah version, not the 84-ah original specification. There are dealers in Europe which sell the Moll 84-ah version. Why Porsche doesn't sell the correct one is a mystery.