Author Topic: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.  (Read 615 times)

Offline gary griffin

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I have read in many posts that some of us are using 8 volt batteries for faster and more reliable  cranking and starting in our older cars.  I am thinking about trying that also.  I was perusing 8volt batteries on the internet and found them for golf carts. Where are the better 8 volt batteries found??  I have had multiple battery equipment before such as fork lifts and man lifts and it was nice to just change a few cells once in a while instead of the whole bank of them.  They put them in series to get higher voltage for equipment golf carts??  Does anybody have a developed wiring diagram for this conversion for our older Cadillacs? I think I can figure it out but why reinvent the wheel so to speak??  How will it affect the starters and generators? What are the pitfalls and the benefits??
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1942 Cadillac 6719 (parts car) (Gone)
1957 Cadillac 60-special (Needs a little TLC)

Offline TJ Hopland

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #1 on: October 31, 2017, 09:13:09 PM »
Golf carts usually use 6 batteries in series so you end up with 48v in the case of 8v.    When ever you hook batteries together you ideally want them to be as identical as possible.   Same model and even batch code is ideal.    Yes you can replace one but that will tend to shorten the life of the whole set.  If you are going cheap what you do is get a bunch of batteries and load test them to try and find the closest match but even then you are back to having issues sooner than later so if you really want something that works you end up buying a new matched set.     Diesels often have 2 batteries and I played that game with just two many times and just like the golf carts it ended up being more hassle than it was worth.

My 2 cent on the 6 vs 8 is if you are not staying original why not just go to 12?   The 8 volt just seems like a band aid like dual 6's to cover up bad / undersized cables and tired starters.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline Caddyholic

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #2 on: October 31, 2017, 09:22:06 PM »
look at the tractor supply store for 8v batterys
I got myself a Cadillac but I can't afford the gasoline (AC/DC Down Payment Blues)

1961 Series 62 Convertible Coupe http://bit.ly/1RCYsVZ
1962 Coupe Deville

Offline TMoore - NTCLC

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #3 on: November 01, 2017, 10:42:00 AM »
Gary -

Before you take the 8 volt route, you should really consider giving the 6 volt battery a chance.  I honestly believe that if you follow all the tips in the (multiple) hard starting threads, you should have no problems using 6 volt batteries with the flathead.  It will save you a lot of grief (gauges, fan motors, radio, generator, regulator) and keep your car original.

My engine has been rebuilt, and so far, the only thing that I have done is to make sure the starter mating surface to the block was cleaned up before mounting, and I have had no issues with the 6 volt battery.  When the time comes, I will swap out the cables for properly sized 00 wire, and perhaps move or add a ground to the starter, but for now, there have been no real issues - this is using an 8 year old Optima 6 volt (I know, not original, but good enough for a restoration project).

I am assuming that your LaSalle is still on six volts, so you have a battery nearby that you can test with - give those old threads a good read and some consideration.

Tod

Offline bcroe

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Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #4 on: November 01, 2017, 09:32:16 PM »
The 8V battery sounds like a kluge somebody tried without very much
thought or planning.  It might have gotten past some flaws in the starter
system, replacing them with a whole new set of problems.  Going
straight to 12V makes a lot more sense, but that wouldn't be needed
to solve starter issues.  Going to a 12V ALTERNATOR could be justified
by a need for more operational power, or a need to use 12V negative
ground equipment. 

Bruce Roe

Offline Janousek

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #5 on: November 02, 2017, 04:50:49 PM »
6volt systems are all about the battery cables.  The heavier the better and ditch the braided ground if you want a really good system.   The ground should run right to one of the starter bolts.   The starter snout and bellhousing should be clean without any paint where the starter mounts.  I wipe silicone past on the clean snout and bellhousing before I install the starter. 

I run 1-0 or 2-0 welding cable for my cables.  These will carry the current on a hot engine where small diameter stuff will drop the current.  I like to use Napa's big 6volt batteries.  I have an optima in our Auburn but it's not any better than the Napa it replaced.   Some guys run dual 6 volt optimas for more cranking  power but I think that is trying to overcome an underlying problem.   I probably average 6 cars a year that I replace the battery cables where some yahoo puts 12 volt cables or runs 10' of battery cable to a battery disconnect.  They all wonder why the car won't crank when it's hot. 

Just run the cables and a 6 volt battery and you'll be fine.   Your also pushing extra volts to your fuel and temp gages that can cause problems along with light bulbs having a shorter life span. 

Offline TJ Hopland

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #6 on: November 02, 2017, 04:57:04 PM »
Battery disconnect is a good point.   Even the good ones which are old now often are not quite up to the current draw of a 6v.  Newer ones seem to be just about worthless and cause way more issues than they could ever solve.   

Not too long ago I was helping a friend with a 29 Chev that would barely crank.  We went to tractor supply for some heavy cables which didn't make much difference then we got rid of the battery mounted disconnect and the thing started cranking like it should.  I'm sure the new cables helped but most of the problem was the disconnect.     This car had the battery under the front seat with the floor switch so fair amount of cable compared to later cars where the battery was under the hood. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline gary griffin

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #7 on: November 02, 2017, 06:48:06 PM »
The disconnect switches that go directly on the battery are not rated high enough and in the wrong place. If you have a fire you will probably not be able to get to the switch on the battery. I purchased a high amp switch that will mount on the firewall and be available from the front seat.
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1942 Cadillac 6719 (parts car) (Gone)
1957 Cadillac 60-special (Needs a little TLC)

Offline Bill Ingler #7799

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #8 on: November 02, 2017, 07:37:17 PM »
This might be the switch that Gary has mounted in his car.   Bill


Offline gary griffin

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #9 on: November 02, 2017, 08:31:14 PM »
Thats it  Bill but is is staying in the tool box until I get the last of the bugs worked out.
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1942 Cadillac 6719 (parts car) (Gone)
1957 Cadillac 60-special (Needs a little TLC)

Offline Jay Friedman

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #10 on: November 02, 2017, 09:51:58 PM »
I agree with Janousek.  An 8 battery can be hard on 6 volt sealed beam headlights, which was my experience with a '51 Olds I owned many years ago which was used frequently at night.  They'd only last a few months. 
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
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Offline TonyZappone #2624

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #11 on: November 03, 2017, 05:08:32 AM »
I removed the 8 volt battery from my '47 convertible.  It is nothing but a cheaters shortcut, that I would not tolerate.  Do all the battery cable, proper kill switch things that people advise here, problems for starting etc. go away.
Tony Zappone, #2624
1936 Pierce-Arrow conv sed
1947 Cadillac Conv cpe
1958 Cadillac conv cpe
2002 Thunderbird
2002 Cadillac DTS
2016 Cadillac CT6 Platinum

Offline gary griffin

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #12 on: November 03, 2017, 11:50:09 AM »
I have heard of using 8 volts for starting only and separate circuit for the 6Volt items like lights and radios.
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1942 Cadillac 6719 (parts car) (Gone)
1957 Cadillac 60-special (Needs a little TLC)

Offline bcroe

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Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #13 on: November 03, 2017, 03:53:41 PM »
Generally incandescent bulbs have a life dramatically affected by
operating voltage.  I would expect a 6V bulb to lose 90% of its life
operating at 8V.  Bruce Roe

Offline TJ Hopland

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #14 on: November 03, 2017, 10:50:50 PM »
I have heard of using 8 volts for starting only and separate circuit for the 6Volt items like lights and radios.

How would you go about doing that?  2 batteries and 2 generators?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline gary griffin

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #15 on: November 04, 2017, 02:38:57 PM »
T D H I would adjust generator regulator to 8 volts, and run 8 volts to starter only and have a branch off of the 8 volt to a 6 volt regulator which would supply the rest of the car.
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1942 Cadillac 6719 (parts car) (Gone)
1957 Cadillac 60-special (Needs a little TLC)

Offline bcroe

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Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #16 on: November 04, 2017, 08:34:18 PM »
T D H I would adjust generator regulator to 8 volts, and run 8 volts to starter only and have a branch off of the 8 volt to a 6 volt regulator which would supply the rest of the car.

Might be more complicated than that.  Things like heater and gauges need
6V from a reg that comes on when the engine is running.  But headlights,
horn, etc that stay on would need a reg that stays on.  Another problem
with that, is that reg would be running the battery down even though the
lights, etc are all turned off.  I wonder what is available in regulators of
capable rating?  Bruce Roe

Offline C Gorgas

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #17 on: November 05, 2017, 08:05:38 AM »
I have to add my thoughts as this article has gone back and forth as how to solve the problem. Studebaker Club had an article that explained the 6V problem and it was that between the starter and coil there was an internal argument as to which received the electricity thus a slow turning of the starter. The problem was solved by adding an additional ground to the starter using standard battery strap. The strap was added at the face plate of the starter then grounded on the block. I had the same problem as originally discussed and solved it by adding the ground strap. I do not know why it worked but it did. Chet 25441

Offline Bill Ingler #7799

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #18 on: November 05, 2017, 09:14:30 AM »
The younger generation, and that I am not, are accustomed to jumping into today`s modern car, turning the key and instant engine start. That is not how a 40s Cadillac started even when it was new. There is not a 346 Cadillac engine out there today that cannot be made to start as it did when it rolled off the assembly line. Even with all the previous postings on proper cables, correct grounding, rebuilt starters and a good cranking amp battery, we still have those wanting to use a 8 volt battery with all it`s associated problems when with a little more effort on their part, the 6 volt starter system on a 346 will work as it did when new.    Bill 

Offline TonyZappone #2624

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Re: Lets talk about batteries and cranking power 6V vs 8V for 346 flathead.
« Reply #19 on: November 05, 2017, 11:53:41 AM »
We have talked about this so many times.  My car was delivered back to me by a prominent shop in Florida with an 8V battery.  I discarded it, did all the grounding tips, large cables, starts like a 12V
Tony Zappone, #2624
1936 Pierce-Arrow conv sed
1947 Cadillac Conv cpe
1958 Cadillac conv cpe
2002 Thunderbird
2002 Cadillac DTS
2016 Cadillac CT6 Platinum