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The '41 180 that I bought in the spring failed to start last month. It was just before I went on vacation so I didn't bother to mess with it until now. It came with two 6v Optima batteries as pictured. If I am reading things right, it looks like one is circa 2010 and one is 2015, so I don't mind replacing them. I disconnected the jumpers and put a load tester on each one. The older one tested WEAK and the newer one tested BAD.

My question is, since the car is 6 volt, why would there be a pair of banked 6 volt batteries rather than one? Is it overkill? They do fit well in the battery box in this configuration, so that is a plus. Not being a mechanic and trying to do things on my own as best I can (often a steep learning curve), my thoughts are always to not reinvent the wheel and go with what had worked.

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Pairing them in parallel gives more available amperage. Not essential but a single Optima-type battery may have less amperage capacity than the heavy duty commercial lead/acid batteries so pairing them gives a comfort factor - more reserve capacity.

I think you are better off with a single lead acid battery-than 2 optima in parallel-Also if you insist on using the 2 batteries in parallel-they need to be purchased together to try and get internal resistance as close as possible to each other . Reason is in recharging if not equal one battery will get more charge than the other.

One of the issues with parallel batteries hooked to a single charging source is they should be a selected pair so they can be fairly closely matched as to internal resistance. 6v Optimas are not really sold in pairs and without special test equipment it is rather hard to match them in the field. If you have a pair of mismatched batteries the one with the lower internal resistance will tend to get the majority of the charge current to the point it can be in a continually overcharged state and damaged while the one with higher resistance may not get enough to keep it fully charged so is never up to voltage and develops a "memory" that the lower capacity is a normal state.

The 6v red top Optima's have a fairly high CCA rating of 800 amps which is a bit less than the 3 largest Napa wet batteries available. I don't remember the number of the Napa battery some use that will fit in the space under the seat but many have found that a single Optima is capable of doing the job even on the 356 engine. John Ulrich sells a new under seat carrier tray with a section sized for a single Optima battery.

Optima batteries today aren't what they use to. A good (Interstate e.g.) 6 volt lead acid battery will provide you with plenty of cranking power. If you aren't going to drive it on a regular basis (weekly)I would recommend keeping a quality battery tender hooked up to.

Don't forget that cars are best maintained by driving them on a regular basis and that they are to be enjoyed,

My thanks to all. Lots of good information.