Battery theory....

Why couldn't I take a good 12v battery, discharge it to 6v, then used it on my stock 6v tractor. It would stay charged at 6v-7v which is all the tractor needs and have more cells to work more efficiently.

Will a 12v battery discharge to 6v or will the number of cells prevent it from discharging that low.

Just thinkin'.

Dell

The amount of energy stored in a battery is not linear with respect to voltage.

Below 11 Volts, there is almost no energy stored in a 12V battery. Maybe enough to light a flashlight bulb, but nowhere near enough to start a tractor.

At 10 Volts, the battery is essentially dead, and quite possibly fatally damaged.

I just started my 2010 Chevy 1500 on 9 volts the other day. Started many a tractor with only 11 volts in the battery.

Dell, no harm in thinkin, I been guilty of that myself lol

NO it wont work, a 12 volt battery is sort of like two sixes (or 6 2.1's) in series, inside that case are 6 cells of 2.1 volts each all in series. Trouble is when you discharge that 12 volt battery ALLLLLLLLL its cells, including three that make up 6 volts, become depleted.

When a 12 volt gets anywhere near that voltage ITS DEADER N A DOORNAIL and sure wont crank a starter.

HOWEVER way back when I was a kid some old crusty mechanics would screw a brass screw down inside a 12 volt battery in the mid point AND IT WAS 6.3 VOLTS ACROSS.

So the short answer is NO to discharging a regular 12 volt battery and get work and use out of it as a 6 volt unless you could get a real high current efficient POST in the mid point and NOT have it discharged.

NOTE years back I bought a 6/12 battery that indeed had a center post and a solenoid all built in. It was used to start the vehicle on 12 then run on 6 by the solenoid on top.

All are entitled to their own opinions and Id bet most (likely alllllll) who answer this share my opinion and that below, we will see.

Still a legitimate question Dell, gotaa like your curiosity

John T

John T. I have forgotten about running a screw in a 12v battery and getting 6 volts. Back in the 1950-60's, dad would do that on a 6v electric fence charger using a 12 volt battery to get just 6 volts out of it.

The brass screw idea in essence makes the battery into two 6V batteries. You just gotta know where to drive the screw to hit between the 3rd and 4th cells.

Same here, in fact it was one of my Uncles, long since passed.

John T

I ran a screw into the middle of a 12 volt battery, and must have hit the right spot to get 6 volts, to run a fencer as late as 1989. It worked well, and I could recharge it too. Dave K.

How long of a screw all we talking about?

John,

Soooooo, would the center screw be pos or neg?

There I go thinkin' again.

Dell

Just get a good 6v battery before you mess around and blow yourself up. Ya donts use a 12v half charged for 6v.

A 12 volt battery is functionally stone-dead at 11.6 volts - that's why it won't work.

Battery discharge is not linear.

I have taken a 12 volt with a bad cell and cut it in two & used it as a 6. Cut the case & then use a sharp small chisel to remove the plates from the lug coming out of the cell. I drilled a hole in the lug to bolt a cable on. I put plastic caps on the good cells to keep the acid in & drain the rest before cutting. I had one that lasted longer as a 6 than at 12.

DELL; LOT OF GOOD INFO BELOW. HOWEVER AS DANGEROUS AS SOME THINGS ARE. MONEY IS NO OBJECT TO YOUR HEALTH, AND RUINING YOUR TRACTOR. IN CASE YOU IF DIDN"T KNOW,[AND WHY SOMEONE DIDN"T MENTION IT]YOU CAN GET A 8V BATTERY ;[WHICH I HAVE DONE], FOR A LITTLE EXTRA PUNCH FOR STARTING.

(quoted from post at 12:03:41 01/30/11) John,

Soooooo, would the center screw be pos or neg?

There I go thinkin' again.

Dell

Click to expand...

Depends on which end of the battery you are using... the original + and - would still be the same, and the middle screw would be the opposite according to the post you use. From the positive post to the middle screw, the screw would be negative and visa-versa. Each cell is individually positive and negative 2 volts (or slightly over) and all are tied in series.