Bill, 
I personally don't have one but a guy in my local chapter had (and may still have)  one in his 37 Terraplane. I remember asking him about it and he did like it. I have not been able to find one at my local auto part stores. But  i did ask about them on the  Open forum sometime back. got a lot of info as I recall. . 

I have one in my 51 Commodore 8 that came with it when I bought it from Roy Marks about 5 years ago. It’s still going strong, and I have know idea how old it is. I hated the look of it so I bought a case off eBay that is an empty 6 volt battery with caps on top and the Optima fits inside. The lead acid batteries make an awful mess if they leak or explode from a spark .

I have been using both the Optima 6v and 12v for years and really like them. On any type battery that sets for long periods you should
always have a trickle charger running, it is not good for any battery to set while it is not fully charged. Even new batteries should be fully charged before installation. 
Here is some info on the trickle charger-
https://zenaracing.com/car-battery-trickle-chargers-what-are-they-how-do-they-work/
 

Kerry,
The Optima battery cost more but seems I have been buying the lead acid battery every year so if the Optima will last three years it will cost less in the long run.
Thanks again
 

I will be shocked if you only get 3 years. Just remember the trickle charger!

[b][size=150]I've had 3 Optima 6v batteries over the years. The first (date coded 1999) lasted 12 years. The second (2003) lasted 3 years. The third (2011) is still going strong. These were all used to occasionally start cars, not for drivers. I also have 2 Bosch (2018) and they are like new. All batteries get charged every few months, and are not left connected to the cars. 

You regular batteries should last more than a year. What brand are they?[/size][/b]

I too have heard that Optimas have a long life, though of course they're much more expensive than lead-acid batteries.

It's a trade-off.  I end up buying lead-acid batteries every 5 years on average, and pay a bit less than $100 for them.  (The ones I have nowadays are made by DEKA and are sold by Batteries Plus Bulbs, under the "Duracell" name, part #902.)  

If you got a short life out of your lead-acid battery, you may have an inexpensive one.  You need a quality one with a lot of Cold Cranking Amps to have sufficient power to get you started.

[quote="Bill Johnson post=27726"]Has anyone used the Optima 6 volt battery ?. It seems like the old 6 volt lead-acid batteries do not last very long and don't have enough power to start the car like  they should.
Any thoughts or suggestions ?
Thanks,
Bill

Bill:  You can purchase the 6 volt batteries from NAPA that have high CCA they are around a 100 bucks for the battery.  BUT, these batteries like most other lead acid batteries will be sourced from non US manufacturers.  The result of the EPA and other agencies who have decided that the manufacture of essential pieces and parts are not in the best interest of the ..... OH,  I guess that is not helpful.  YES... I am an OPTIMA user.. I have both the 6 and 12 volt versions in use.  I have a 6 volt that I have had for over 16 years that is no longer in a HUDSON ( worked its magic for 10 years in my 1953) it is now used as a chain load battery when I deep discharge and recharge my 6 volt optima batteries.    My experience with Optima has been pretty consistent... most will last about 8-10 years. There was a time when one of the CHEAPER battery assembly plants in Mexico had the contract to assemble these batteries... I rotated 4 each 6 volts during that trying time.  Recently have purchased 3 each 12 volts which are giving great service as well as 2 each 6 volt which likewise are working well in my Hudsons.       I am no longer a lead acid battery user... Ken 

Ed,
I don't know what brand but was bought from Orileys parts store. I'm sure they do 't sell many and may have been sitting for years.
 

Ken,
I have bought several 6V for my Model T bust still have to hand crank it, so no big deal. When I got the Terraplane I want it to start if I drive somewhere. I have carried a 12v jumper just in case. I see that Jay Leno has them in his cars. With his money I guess he can afford the best. 
Thanks for you comments.
Bill

Be aware that if you jumper 12 volts to your Terraplane you are likley to blow the oil and Amp indicator bulbs. Don't ask me how I found out!

Bill
Most batteries have a date code stamped into them on the side. They are pretty easy to decode. Some batteries also have a round label stuck on when they are supposed to be shipped from the factory.(occasionally these get put on a month early)

When I bought my 625 CCA Bosch 2 COM batteries in 7/18 the both had 6/18 labels on them

Another advantage is the Optima battery is much lighter and therefore easier to man handle. 

Robert,
You are correct. Unless I have a strap, the battery which is under the driver's feet in the '35 Terraplane can be difficult to remove. Just received the Optima which is not as wide as the old battery and is much easier to install. Now to make some kind of holding straps to keep the battery in place. Just hope this battery is as good as advertised.
Thanks,
Bill