The insidious problem with 6v batteries

[Stan Disbrow]

Hi,

....is they deteriorate so very gradually.

Which, I was just reminded of over the past two weeks. The solution, of course, is to stick in a brand new one. Preferably, an actual JD Strongbox brand one. If your local dealer parts guys actually know what a 6v battery still is.

The background is I last put new ones in my 420c and M (standard, wheel tractor) ten years ago. I keep them maintained at least on a yearly basis, usually working them over in the Spring. By that, I mean pulling them out and watering them, cleaning or renewing all the connections, and giving them at least an overnight charge with a small 2 amp charger.

This, because in Winter here in NC it is too wet to doze anything and we rarely get enough snow which would require a dozer to plow. The M is used with a fertilizer spreader and a set of disc hillers and a cultivator rig. Hardly things used in Winter.

My main machine I would use in Winter is my 2008 5103 with loader and back blade. But, that isn't 6 volts, so it really doesn't fit this topic. I mention it because it helps illustrate why the two older machines sit unused for three months.

But, come Spring there are plenty of jobs for both antique machines to do. So, I wish to service them both so I can simply jump on and go. The usual oil and lube jobs must be done, and service the electrical systems as well. Because with only 6 volts, there are no electrons we can lose and get them to start properly.

Now, to the insidious part. A 12 volt battery tends to work OK, and then one day just give up the ghost. As in it fired up yesterday, and won't even turn over today. A 6 volt battery, however, slowly loses the important Cold Cranking Amps. But, it will still turn over the engine. Ever more slowly. This is the very definition of the word insidious!

Electrically, what happens is a 6 volt battery is nominally 6.5-6.3 volts with no load. When cranking one of our vertical 2 cyl engines it drops a volt or a tad more to 5.4-5.2 volts. This leaves enough for the coil to spark well. With decent compression (I know this varies quite a bit from one to the other), it ought to pop off in a couple revs of the crank.

But, an older battery, while still able to crank over, will drop below 4 volts. This is no longer enough to fire the plugs properly. So, no fire. Or, worse, it fires the plug weakly, and the fuel charge fires just before TDC and the thing tries to start backwards.

This is what I was getting last fall on both machines. Having to crank several revs for only a backwards fire. I knew the batteries were insidiously about done. Now, I could fire either up using my (also antique) 6/8/12 volt charger with a Start Boost for 6 volt. This is a big shop charger from back in The Day. A leftover from when my family had dealerships.

But, I knew I needed to replace both batteries come Spring. Last week, I put a new one in the 420c. One such battery is all the local JD dealer stocks. I had to order the second one, so that came in this week.

Why spend extra for a JD brand battery? They have their own battery plant. Their Group One has 200 more CCAs than the next best one, Interstate. Which, BTW, is better than any other brand of 6v G1 out there (various auto parts stores or even Batteries Plus).

So, now both machines pop off on the first full rev, and I ought to be good for another 10 years.

I brought this up because of a couple other recent electrical problem threads and the thought that lots of us are likely firing up our Old Iron after a long Winter's Nap.

Stan

[Stan Disbrow]

Hi,

I should add something about battery ratings and actual performance. All three brands of 6v batteries I have tried in the past 20 years are rated at 625 CCA. Note that I have a load tester for batteries (of course I do! Don't we all? Ha!) which I can see how much peak current a battery can actually supply. Something else I inherited.

Interstate meets this and continued to meet this for several years before falling off. Mind y'all, the last one of these I had was 20 years ago. Ten years ago, I bought a couple Werker brand (Batteries Plus). They also met 625 right off, but had fallen off about 50 CCA per year for three years before stabilizing. These are what were just pulled out.

Lavoy likes the JD batts, so I went that route this time. 800 CCA measured on both. Nice. We shall see how they hold up these days. Way back when Dad bought the 420c (1966 IIRC) the then-new JD batt went 15-16 years.

Stan

[Tigerhaze]

Do you know how makes the JD brand batteries? I've been told batteries are like tires in that there are only a couple of major manufacturers.

[hydrogeo]

I had a 6v Interstate in my 40c that lasted just long enough for the warranty to be over. I will not go that route again.

I now have a Deka 6V that is two years old, so far so good. Started it several times in below zero temps this winter without issue.

I believe Deka also makes a bunch of private label-branded batteries, wonder if they make them for Deere?

[Stan Disbrow]

Hi,

Deere created their own battery plant long ago. Looking online, it appears they sold it to what was known as Gould and now is known as GNB. They, in turn sold to Exide.

Or, maybe the Deere battery factory was a dedicated-to-one-customer Gould plant all along. That part, I can't seem to find a reference for.

Deka is from East Penn, who also makes CarQuest, Douglas, NAPA and Oreilley.

All these makers have long lists of brand names they make for.

Stan

[hydrogeo]

Learn something every day. I have had pretty good luck with Deka 12v batteries, we'll see how the 6v holds up. I have not had good luck with Interstate, and most certainly not Exide. I will never buy another battery from Tractor Supply again. They seem to last just long enough to not make it worth trying to get them to honor the warranty.

[RacinJason]

Hi guys. I've read, in previous posts, that the Deere battery is probably the beat. I've also read mention of using an eight volt battery. I've seen one at a cool store called Klem's, in Spencer, MA. Off the top of my head, right now, I don't know who makes it. I don't think it had a high CCA rating. Perhaps someone in Central MA can expound on it. My biggest question is, does the generator put out enough volts to keep it charged?
I had considered buying one for my 420C, but am running the 12 volt, Group 78 out of my '06 Silverado. It is still going strong, for going on 10 years old, but needs an occasional recharge. Some day I'll mount a 12 volt alternator. Groups 75 and 78 have only side terminals, which I like because there's almost no chance of shorting on the fuel tank which is directly above the battery compartment. Probably being a little paranoid, but ... you never know.

[Lavoy]

Generator will not charge at 8 volt unless regulator is adjusted. Even then, the extra voltage is pretty much offset by the reduced CCA of the 8 volt battery. Best bet is still a good 6 volt, heavy cables, and a rebuilt starter.
Lavoy

[Stan Disbrow]

Hi,

An 8v battery really doesn't help a whole lot. That was something IH used to help cold weather starting. The problem is the extra plate section cuts the amperage down. If you figure what is really needed are watts, and multiply the amps and the volts, the watts come out essentially equal.

I did try it anyway, long ago. The end result for me was the starter spun a little faster but not for long before it slowed back down. Better to use a charger for 10 minutes to build surface charge on a 6v battery prior to starting. Also, the 8v battery only lasted two years.

The 8v battery would charge since my generator would rise to 9 volts. Or, I should say sort-of charge. It really ought to have 10-11 volts and I suspect the slightly low charge voltage led to a faster rate of plate sulfation. Which, would actually explain the battery lasting only two years.

I am not a fan of using a 12v battery unless one switches out both the 6v starter and generator at the same time.

The best solution I have found for the top post battery under the gas tank is to cut a trapazoidial piece of 1/4 inch plywood so it conforms to the hood taper and have that slipped on top of the battery and under the tank. Nothing is better than a layer of insulation to keep electrons where they need to be and not let them run amok.

Stan

[RacinJason]

Thanks, to Lavoy and Stan. A lot of good info there. I had already decided to stick with the 6 or 12 volt rather than go to 8. Good idea about making an insulator atop the battery, also. I hope to be installing a 12 v alternator this year, when I get a couple other projects taken care of. (Get my winch going and changing the final gear ratio on one side. I'll be commenting on that, soon)
Not to worry about changing the starter to 12 volt, I've been told.

[Stan Disbrow]

Hi,

The resistance of the windings in a 6v starter is too low for 12v. This leads to a fast rise in temperature at the commutator. This, in turn, leads to crystallization of the solder where the winding wire attach. That leads to the starter failing.

That all boils down to how long one holds the starter engaged. If it starts right up, the starter will last a while. If it doesn't, well...... So, don't hold the rod out for more than a second. Don't get into one of those long grinds.

Also, the starter rotation is too fast and will put a lot of extra wear on the ring and pinion gears.

I would change the starter myself.

Stan

[hydrogeo]

Just out of curiosity, would there be a way to use a 12v battery but drop the voltage to 6v using a small transformer? I suppose a second transformer would be needed in the opposite direction to jump the voltage up from the charging system, and maybe it doesn't push enough amps. P=IV, right?

The only reason I'd ever consider converting over to 12V is to get some decent lights. The 6v lights aren't much better than duct taping a couple candles to the hood. Do they make 6v LEDs?

[Stan Disbrow]

Hi,

Transformers do not work on DC. It has to be interrupted, as in pulsed, at the minimum. Which is what the points do for the step-up autotransformer we call a coil.

Power inverters use transistors to 'chop' up the DC and feed a transformer. The output is usually 120 vac, but can really be anything. Such as the higher voltage used by HID lights they actually make AC, step it up, and then rectify it to DC. They call those DC-to-DC converters, but there is AC inside.

The 120 vac ones are 60 cycles per second (aka Hertz) but that, too can be anything. A common frequency is around 18 kilohertz, as in those HID lights. And, camera flash unit. It is where the whine comes from.

Now, there used to be DC-DC step up units that went from 6v to 12v. JC Whitney was one source. They were thinking Volkswagens, but would work on a Deere as well. ;)

One way to easily do this on a crawler would be to use the Group 1 battery as usual, then use another battery on the fender. Tie the main battery to the secondary one in series. Then hook the lights and alternator across both batteries.

You could leave the ignition at 6v or opt to hook it up 12v using a ballast resistor. Or, change to a 12v coil. Or, even a 12v CDI. :)

Of course, you have to hook it up Negative ground to please the alternator. The starter won't care.

The secondary battery ought to be the same CCA as the primary for balance. But, it could be smaller, since it will never see starting current. If it is smaller, then expect it to lose water faster than the primary.

Stan