Must move the battery cut off switch

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I just replaced two optima batteries with a big NAPA 6 volt battery .  And now find that there is not  enough room for the battery cut off switch which hangs down from the floor board .  My question is where do most folks put a cut off switch.  my car is a 1933 1247.  I am thinking on the fire wall just under the startex.  Thanks agin Doug Vogel

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Doug,

I am just curious, why did you replace the two Optima batteries?

Did they discharge beyond their ability to recharge?

Are they ancient?

I ask because an Optima 6V Red Top should be good for between 8 & 10-years.

I did the same a few years back, but that was for a weekend when I needed to run he car.

I had left the ignition ON!    EESCH!

My two charged up within a few days and the standard NAPA wet-cell 6V battery is now on the shelf awaiting my next screw-up.

I now have two Optima batteries in my battery box, but only one is hooked up and the other sits idle as a backup.

You might want to put them on a serious charger (NOCO Genius-10 – https://no.co/genius10)

Again, I am just curious.

Good luck!

Peter

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I screw mine into the floorboard below the front edge of the seat with the switch handle poking out just ahead or behind the seat bottom. It is hidden depending on seat position but easy to get to.

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The optima batteries are 6 years old and just could not crank the v12 over fast enough to start the engine. This is the second set of optima batteries I have had in my pierce, and the last ones I will buy.  They seem to go down fast and then take two days to recharge.  One day to get to 75 percent and then cool then the next day to get up to 100 percent charge. I had them hooked up to add more CCA . In the years I have gone through 4 optima batteries my son in law has the same Napa 6 volt in his series 80 that is totally reliable. Just time to try a different approach..

 

 

 

 

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Doug —

Could you let me haved the part number for your big NAPA bat teery.  I am restroing a 1930 PA and was / am planning to put in two Optima batteries.  I’ve had good expereiences with the Optimas.

Thanks,

Arnold Romberg

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Arnold,

Below are a couple of tables on 6 volt batteries. The first is a size table vs. Group number for 6 volt batteries. The second is out of PASB 2019-2 which is a comparison of AGM (Optima) batteries vs. regular flooded lead/acid batteries. The full article includes the pro and cons of AGM batteries vs. lead acid.

I use a Group 4 in my Series 36 cars, although this may be too large for your 1930.  Part number is Carquest 4-30. Check the table and see what size fits your battery box correctly.  My group 4 is slightly smaller than the dimensions in the first table, so it is probably worthwhile to confirm the dimensions of any battery you are going to buy. I think there is probably some difference in size and capacity between different manufacturers.

I have not put an Optima in my cars, mainly because my batteries always seem to fail when the sale is 6 months away.  The flooded lead-acid battery in my touring car is 7 years old and still working fine.  I do occasionally charge it with a desulfation battery maintainer.

Dave

 

 

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Arnold ,  The battery I got from Napa is a 7212 commercial 975 A group 4 .  It fits great in the 1933 1247 battery space, and cranks the engine over well. hope this helps.

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Hi Doug and others,

1.  I have a battery cutout switch on the floor under the driver’s seat in my ’34 convertible coupe  (ok because it’s easy to lift the small seat); and on the short vertical riser board under the front of the front seat in my ’33 convertible sedan, nearly out of sight because the board is recessed.

2. Regarding batteries -The most important spec to me is Ampere-Hours (A-H).  It is directly related to the size of the battery, and how LONG it will crank. (Almost any battery will start a car several times.)  Example: a 50 A-H battery will supply 200 amps (typical starting current) for 15 minutes, 50 amps for one hour, or 1 amp for 50 hours.  The more modern spec of “Reserve Capacity” (RC) is related to A-H by specifying the number of minutes a battery will last when supplying 25 amps.  So a 50 A-H battery will have a RC of about 2 hours, or 120 minutes.

Single Optimas have a rating of 50 A-H, and a RC of 100 minutes (=42 A-H, due to different levels of discharge involved in the specs).

Double Optimas thus have a 100 A-H and 200 minute RC rating.

I use an Interstate group 4xhd commercial battery (about $140) in my V12, which has an RC rating of 295 minutes.

So, I can crank the engine about 3 times as long as a single Optima, and about 50% longer than a double Optima.   If my generator stops charging while I’m driving on a mountain road at night (25-30 amps draw including brake lights) I have almost 5 hours, vs. 3.3 with double Optimas, or 1.6 hours with a single Optima.  Of course, I have to check water level every 6 months. (I do use single Optima batteries on other cars  because of their low current draw.)

The 4xhd A-H rating is not listed, but is estimated to be 150 A-H.  The 1933 P-A salesmen’s “Green Book” lists the battery for the 1933 V12 as “…Willard 160-165 ampere-hour battery”.

Cheers.

 

 

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