Marine Battery 6V 12V Combination Type ...

I was reading a 40 year-old magazine (Cars & Parts) and one fellow wrote a letter to the editor telling of how he had his electric system on his old truck set up. He installed a 12 volt marine battery that had a 6 volt tap on it somehow (no further explanation). He had the 12 volt side of the battery power hooked up to his generator (12V) and starter (he didn't mention the starter voltage). The rest of the vehicle (lights, gauges, wipers, etc) received 6 volts from the battery tap feed. I did some Googling just now and couldn't find anything on such a battery. Anybody here ever hear of that kind of battery or maybe even have seen one in use?

Just a guess, but that recently there might have been a few tar-top batteries around yet, where the cell connecting straps were external. I can see how you could tap any voltage you wanted up to 12 volts, by attaching to the appropriate strap. I still have this obsolete cell tester that measured the voltage of the individual straps. It is just a wooden handle with two points and a 3 volt gauge that swung in both directions. You just poked the straps and read the voltage.

Never heard of such a battery, but it would be easy to do with the old style batteries with the external connecting straps, just drill and tap into the strap at the correct spot.

I saw one in a customers T Bird once .
It was a 12 v battery hooked to the starter circuit and a lug halfway down for the 6 v accessories.
I don't know the brand and I gave a quick look but didn't find anything , but there is something out there.

I remember old 12 volt batteries, the kind with the lead bridges on top that would sometimes have a stud sticking out of the link between the 3rd & 4th cell (2 volts each) that would give you 6 volts. My dad had plenty of old construction equipment that had 2 or 4 six volt batteries wired in series to give you 12 or 24 volts and depending on where you placed your tap wire between batteries, it would give you 6, 12,or 18 volts on the 24 volt system.

We also had two 12 volt parallel-wired batteries hooked up to an aftermarket dual solenoid starter system in a Westinghouse/Le Tourneau scraper that, when you hit the starter button, disconnected the 12 volt electrical system from the scraper, re-connected the batteries in series to give you 24 volts to the starter and once it started and you released the starter button, it switched back to 12 volts and re-connected to the rest of the electrical system- whew!

If you tapped into any of the bridges between the 2 volt individual cells on the 12 V battery below, youd get ever increasing voltage, 2 volts at a time. Thats probably how he was doing it.

(quoted from post at 07:41:13 06/04/23) I saw one in a customers T Bird once .
It was a 12 v battery hooked to the starter circuit and a lug halfway down for the 6 v accessories.
I don't know the brand and I gave a quick look but didn't find anything , but there is something out there.

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I thought most cars converted to 12 volt in 55.

Marine aka Deep Cycle batteries are not recommended in truck, car, tractors.


TPD

.[/quote]

I think GM did in 55
Ford and most others were 56

For what it's worth. Retired volunteer fireman. We used some military surplus trucks on loan which are 24 volt (2 12s). We were told that if we tapped for 12 volts for radios, emergency lights ect. that the equipment would be pulled from us as this upset the balance (equalization) of the batteries resulting in battery and charging system damage.

I used a couple of those combination 6 12 volt batteries back in the day on old 6 volt cars n trucks enabling them to start (ONLY affected starter when cranking) on 12 and run on 6 WORKED GREAT....They were a 12 volt batteries with a built in series/parallel relay mounted onboard. HOWEVER I have not seen them in years. Best I recall some semi trucks did the same but they started on 24 ran on 12

John T

On this subject, what were the battery manufacturers doing about 30 years ago when they had a reserve/emergency switch on the battery? The idea didn’t last long but there were a few around. 8v with a 4v backup ?

Crazy Horse said:

I was reading a 40 year-old magazine (Cars & Parts) and one fellow wrote a letter to the editor telling of how he had his electric system on his old truck set up. He installed a 12 volt marine battery that had a 6 volt tap on it somehow (no further explanation). He had the 12 volt side of the battery power hooked up to his generator (12V) and starter (he didn't mention the starter voltage). The rest of the vehicle (lights, gauges, wipers, etc) received 6 volts from the battery tap feed. I did some Googling just now and couldn't find anything on such a battery. Anybody here ever hear of that kind of battery or maybe even have seen one in use?

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My 56 CJ3B Willis Jeep is converted to a 95amp alternator and all lights are 12v. The gauges and heater blower are at 6v using resistors to lower the voltage. Jim

Russ from MN said:

Never heard of such a battery, but it would be easy to do with the old style batteries with the external connecting straps, just drill and tap into the strap at the correct spot.

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I have done exactly that!

Crazy Horse said:

I was reading a 40 year-old magazine (Cars & Parts) and one fellow wrote a letter to the editor telling of how he had his electric system on his old truck set up. He installed a 12 volt marine battery that had a 6 volt tap on it somehow (no further explanation). He had the 12 volt side of the battery power hooked up to his generator (12V) and starter (he didn't mention the starter voltage). The rest of the vehicle (lights, gauges, wipers, etc) received 6 volts from the battery tap feed. I did some Googling just now and couldn't find anything on such a battery. Anybody here ever hear of that kind of battery or maybe even have seen one in use?

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All you need is two modern 6 volt batteries connected in series to choose between 6 or 12 volts. Duh.

An easy way to get a 6 volt tap is to use two 6 volt batteries in series. If you take the time to draw the circuit it should be apparent that any current pulled from the one 6 volt battery is not available to charge that battery. Therefore, this battery tends to run in a low charge condition, resulting in shortened life. A better solution would be to use the series/parallel relay, see "John T" post. These relays are still available, simply do a google search. Years ago, a neighbor had a tractor with two 12 volt batteries (from the factory) wired in series. He wanted to run a monitor on his planter which required 12 volts. The neighbor simply connected one wire of the monitor to the center junction of the two batteries; for the required 12 volts, see "leroy in ne" post. As the planting season continued the tractor developed charging issues. Finally, the neighbor took the tractor to the dealer. The mechanic installed a "selector switch" and instructed the farmer to change the switch position once every hour of planter monitor use. Again, better to use a series parallel relay.

tomtinker said:

All you need is two modern 6 volt batteries connected in series to choose between 6 or 12 volts. Duh.

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Wow, this dude must have quite an IQ.

Indiana Ken said:

An easy way to get a 6 volt tap is to use two 6 volt batteries in series. If you take the time to draw the circuit it should be apparent that any current pulled from the one 6 volt battery is not available to charge that battery. Therefore, this battery tends to run in a low charge condition, resulting in shortened life. A better solution would be to use the series/parallel relay, see "John T" post. These relays are still available, simply do a google search. Years ago, a neighbor had a tractor with two 12 volt batteries (from the factory) wired in series. He wanted to run a monitor on his planter which required 12 volts. The neighbor simply connected one wire of the monitor to the center junction of the two batteries; for the required 12 volts, see "leroy in ne" post. As the planting season continued the tractor developed charging issues. Finally, the neighbor took the tractor to the dealer. The mechanic installed a "selector switch" and instructed the farmer to change the switch position once every hour of planter monitor use. Again, better to use a series parallel relay.

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I guess we've wandered off a bit but that's OK, lots of interesting stuff. Thirty years ago my son had a '79 Toyota Land Cruiser (Jeep type) that almost everything was 24 volts (it had two 12V batteries) but two things were still 12 volts for sure. The radio and the sealed beam headlights. But all the light "bulbs" (turn signals, etc) were 24 volt.

Crazy Horse said:

I was reading a 40 year-old magazine (Cars & Parts) and one fellow wrote a letter to the editor telling of how he had his electric system on his old truck set up. He installed a 12 volt marine battery that had a 6 volt tap on it somehow (no further explanation). He had the 12 volt side of the battery power hooked up to his generator (12V) and starter (he didn't mention the starter voltage). The rest of the vehicle (lights, gauges, wipers, etc) received 6 volts from the battery tap feed. I did some Googling just now and couldn't find anything on such a battery. Anybody here ever hear of that kind of battery or maybe even have seen one in use?

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You should never use a DEEP CYCLE (MARINE) battery (GOLF CART battery too) for anything other than your boat, RV/3-wheeler, or golf cart. That is a an old myth perpetuated by many old wives. Does NOT make your system any better or stronger. On your car, truck, or tractor use: 6-VOLT = GRP 1 Type; 12-VOLT = GRP 25 or GRP 35 type. Invest in a good FLOAT charger (NOT a trickle charger) like the DELTRAN units. When vehicle is idle in garage or barn, a FLOAT CHARGER keeps your battery maintained at optimum efficiency so it is ready to go when you are. Specific Gravity. Hydrometer. Electrolyte. Lead Plates - familiar terms? A battery begins to lose effectiveness after setting idle for a week or longer. A standard car garage/shop trickle charger is NOT and will not the same. Many assume you can just connect one when your car won't start to quick-charge the battery. Worse is some battery leave connected overnight. Some trickle chargers do not have an automatic shut-off feature and if left unattended can over charge the battery, boil it out, and do permanent damage to the battery. Once you boil out the electrolyte in a battery it is junk. You can't just add more, it doesn't work that way. The constant discharging and recharging depletes battery life fast and each time loses efficiency. Invest in good brand battery like DEKA, INTERSTATE, DURACELL, EXIDE, EAST-PENN as all are good brands. Bargain House brands sold at your local auto parts store,TSC, Wally World, and other retail outlets tend have poor lifespans - 2 years on average. . Heck some can be junk out the door. Check date codes when buying. FWIW & FYI: The 2nd popular myth is to get an 8N-VOLT battery for your 6-V vehicle. It won't do anything more and charging one can be a problem. Do you have an 8-V Charger??? DELTRAN FLOAT CHARGER, about $30. JR version is 6V.

Tim Daley (MI)

Crazy Horse said:

I was reading a 40 year-old magazine (Cars & Parts) and one fellow wrote a letter to the editor telling of how he had his electric system on his old truck set up. He installed a 12 volt marine battery that had a 6 volt tap on it somehow (no further explanation). He had the 12 volt side of the battery power hooked up to his generator (12V) and starter (he didn't mention the starter voltage). The rest of the vehicle (lights, gauges, wipers, etc) received 6 volts from the battery tap feed. I did some Googling just now and couldn't find anything on such a battery. Anybody here ever hear of that kind of battery or maybe even have seen one in use?

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Not smart or efficient . Half of the 6V supply will always be discharged . The other half of the 6V supply will be over charged .
Much smarter methods out there .

buickanddeere said:

Not smart or efficient . Half of the 6V supply will always be discharged . The other half of the 6V supply will be over charged .
Much smarter methods out there .

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Have you ever really done this/? Experience or just talking?