Series, parallel, or 1 large battery?

[EricG1793]

We have a John Deere 310 that currently has a pair of 12-year-old John Deere TY21737 batteries (Interstate equivalent 3EH-VHD). Each battery is 6v, 850cca, reserve of 270 mins. They are in series for 12v. My dad never maintained the batteries and it started cranking weakly in the last couple years, then not at all. He refilled the cells earlier this year and charged the batteries, but they didn't come back.

I tried charging them in series with a 12v Battery Minder 1500 (1.5 amps) but it kept saying the batteries timed out -- probably too much battery for it. I figured the desulfation would be a benefit. Then I took the weaker battery (6.15v; stronger one was 6.25v) and put it on the big charger, which only has a 40 amp setting for 6v. I charged it for 45 minutes or so and it didn't seem to hold a charge. I might have done it for another half hour at some point, still no more charge. So I charged it for 2 hours this morning. Now, it's measuring 4.1 volts... I think I fried a cell, unless I was hallucinating and it was saying 4.1 volts all along. Could the 40 amps at 6v have killed it? That seems like a reasonable current to me, since it's 6v and they're such large batteries, but some of you would probably know better!

Assuming I'll have to replace them (they're definitely old enough), what's the best way to do so? Same setup, about $270? Or perhaps similarly-sized dual 12v batteries such as Interstate 3ET-VHD in parallel, about the same price? Or, one large 12v battery, such as a 4DLT-VHD ($180)?

I'm leaning towards one large battery. Much cheaper, and simpler less terminals to corrode and connect. Just even bigger of a pain to drop way down in that little battery box.... Either that or two 12v in parallel, which would be easier to handle and maintain, since each battery could be charged individually. My understanding is that it would be less stress (amperage) on individual batteries in parallel rather than in series which would theoretically give them an easier life. I know that equalization is an issue with series, perhaps not with parallel? I can't see the benefit in another 6v series set up. Perhaps, in the 70's, that was the most economical setup for the machine?

Thanks for your words of wisdom!

 

[Gale Hawkins]

Ours came with just on big (not large like to the 265 MF) so I just bought another the same size but not JD brand like the old one. There is room for another 12v but we do not use it below freezing and it starts in a flash at 40F and above. It sometimes sets for a few months but still starts fine.

 

[aczlan]

All other things being equal, one large battery will last longer than two smaller ones... The weaker battery in a series or parallel will always make the stronger one work harder.

Aaron Z

 

[SPYDERLK]

One big battery. Cheaper than the series setup and less connections as you say. Avoid a parallel setup because when 1 battery weakens the strong battery will charge it while parked and the pair will slowly go dead.
larry

 

[Bigfoot62]

Just make sure that you have ENOUGH battery, if you're only going to use one.
I know several people that have burned up a starter on older Ford tractors that were supposed to have a 4DLT, but were replaced with a smaller capacity "car" battery to save money. A new 4DLT is less than $200, a rebuilt starter is over $300. Do the math.

 

[EricG1793]

Thanks for the info, guys!

Bigfoot, that's something I've been briefly tempted by -- getting a high-amperage battery with less reserve. But that's a good point about starters. An extra $50 once every decade (as in our case) isn't much of a sacrifice to have something perform well. The 4DLT I'm talking about is 850cca with a 250 min reserve. Originals are 850cca and 270 min reserve. It always starts in just a couple seconds of cranking, but God forbid something happens to the fuel system and it needs to be primed.

My dad said we'd be stupid to get the big one, since we struggled so much just to get the small ones out (he's 60 and I'm scrawny LOL). I'd like to figure out a way, devise some sort of crane or pulley system.... At least wrap a pair of straps or something around it so we could each grab an end and be able to stand up while lowering it down into the box. It's awkward getting the batteries up in to the cab, then down where they are over a foot below the floor. Too bad we don't have an engine lift. But now I'm convinced that it's worth the initial hassle.

 

[aczlan]

I HIGHLY recommend a battery handle for setting batteries. I have one like this: Amazon.com: K-D Tools 205 Battery Carrying Strap: Home Improvement and its great for moving golf cart batteries.

Aaron Z

 

[Big Barn]

I HIGHLY recommend a battery handle for setting batteries. I have one like this: Amazon.com: K-D Tools 205 Battery Carrying Strap: Home Improvement and its great for moving golf cart batteries. Aaron Z

I don't think that handle would work for lifting the 4 DLT

Terry

 

[orezok]

All other things being equal, one large battery will last longer than two smaller ones... The weaker battery in a series or parallel will always make the stronger one work harder.

Aaron Z

This is true for parallel connections but not series. After all, a 12v battery is six 2v batteries in series. Thats how it works.

 

[Gary Fowler]

This is true for parallel connections but not series. After all, a 12v battery is six 2v batteries in series. Thats how it works.

And that is why when one cell goes bad, the battery is dead.

 

[aczlan]

And that is why when one cell goes bad, the battery is dead.

Also, if you have a weak cell, the good cells get overcharged to compensate for the bad one (as happens frequently with the banks of series 6v golf cart batteries, one weak battery will drag the whole pack down).

Aaron Z

 

[Tx Jim]

One important thing you can do to help starting is relocate the tractor negative battery cable from battery box to engine block or better yet starter mounting bolt.

 

[Texasmark]

I didn't read any of the replys but here's how it works. It takes about 10v at a 12v starter, while cranking, to get any kind of cranking performance. Depending upon the application, aka engine HP, that could mean anywhere from 100 to 200 amperes.

If you have a 12v worth of voltage pressure, let's use the more normal term for a fully charged battery at standard temperature and pressure, aka 12.75v.
If you need 10v at the starter you only have 2.75v worth of loss you can tolerate during cranking.

Taking the least case, 2.75 volts at 100 amperes equals a max of .0275 Ohms (electrical unit of resistance) in the starting circuit between the battery pos and neg terminals, including the batteries internal resistance, and the starter hot terminal and case which is where the battery - is connected. For the heavy duty application it's half that much resistance that's tolerable. In short, this means that you essentially can have no resistance in the circuit, aka battery internal resistance, small hookup wire, corroded crimp connections at the ends of the cables, corroded terminals, nuts, and washers at the termination points.....etc.

Having had experienced several of Mother Deere's engineering !@#$%^ (4010, 4020, and 4230C) where they put a 6v battery on one side of the tractor and another on the other side, connecting them in series, you were shot in the foot before you started with circuit resistance.

The internal resistance of two 12v batteries is half due to being in parallel where the seriesed 6 volt adds the internal resistance at 2x. Right off the bat parallel gives you a 400% advantage. Having adequate wiring in parallel, like a pair of 00 wires helps too.

My 4230 was a dog to start in the winter without ether which was a pain to introduce plus I didn't think it did the engine any good. I replaced the 6v on either side with the ground going through the engine block and a single 0 gauge wire under the cab, with a pair of HD 12v batteries (31 series OTR HD truck batteries) wired in parallel, one on each side where the OEM batteries were located with a pair of 00 wires across the tractor under the cab.

Ha! The sucker would start before you could realize it and get your fingers off the key.

HTH,
Mark

 

[SPYDERLK]

I didn't read any of the replys but here's how it works. It takes about 10v at a 12v starter, while cranking, to get any kind of cranking performance. Depending upon the application, aka engine HP, that could mean anywhere from 100 to 200 amperes.

If you have a 12v worth of voltage pressure, let's use the more normal term for a fully charged battery at standard temperature and pressure, aka 12.75v.
If you need 10v at the starter you only have 2.75v worth of loss you can tolerate during cranking.

Taking the least case, 2.75 volts at 100 amperes equals a max of .0275 Ohms (electrical unit of resistance) in the starting circuit between the battery pos and neg terminals, including the batteries internal resistance, and the starter hot terminal and case which is where the battery - is connected. For the heavy duty application it's half that much resistance that's tolerable. In short, this means that you essentially can have no resistance in the circuit, aka battery internal resistance, small hookup wire, corroded crimp connections at the ends of the cables, corroded terminals, nuts, and washers at the termination points.....etc.

Having had experienced several of Mother Deere's engineering !@#$%^ (4010, 4020, and 4230C) where they put a 6v battery on one side of the tractor and another on the other side, connecting them in series, you were shot in the foot before you started with circuit resistance.

The internal resistance of two 12v batteries is half due to being in parallel where the seriesed 6 volt adds the internal resistance at 2x. Right off the bat parallel gives you a 400% advantage. Having adequate wiring in parallel, like a pair of 00 wires helps too.

My 4230 was a dog to start in the winter without ether which was a pain to introduce plus I didn't think it did the engine any good. I replaced the 6v on either side with the ground going through the engine block and a single 0 gauge wire under the cab, with a pair of HD 12v batteries (31 series OTR HD truck batteries) wired in parallel, one on each side where the OEM batteries were located with a pair of 00 wires across the tractor under the cab.

Ha! The sucker would start before you could realize it and get your fingers off the key.

HTH,
Mark

Connections and wire size is very important as you say.

... But the internal resistance of a 6V battery that is the same size as a 12V is only 1/4 that of the 12V because theres twice the plate area per cell and only half as many cells. The // 12V pair would present no current sourcing advantage and has the inherent disadvantage of the weaker batt discharging the pair when the tractor is parked.
larry

 

[nc redneck]

I made the mistake of not buying Interstate batteries 2 years ago. Heard they had been bought out by Chinese company no longer any difference. Instead I bought the best " gold " ones at big brand parts stores. I ended up replacing most of them in 2 to 3 years. Biggest difference I had was with my Duramax. Last fall with 2 year old " Gold " batteries it was slow on spinning starter, knew in cold weather it would be a problem. I replaced Gold with Interstate and so far it still spins it over like a sewing machine. I will know for sure in a year or 2.
I doubt I saved $ 10.00 per battery buy buying " Gold "
Hope this helps.
Scott

 

[EricG1793]

I HIGHLY recommend a battery handle for setting batteries. I have one like this: Amazon.com: K-D Tools 205 Battery Carrying Strap: Home Improvement and its great for moving golf cart batteries.

Aaron Z

Interesting product, thanks for sharing. My only problem with it would be damaging the posts from using them to lift all that weight. Plus, the 4DLT has both posts on the same side as the battery, so it'd be useless anyway.

 

[aczlan]

Interesting product, thanks for sharing. My only problem with it would be damaging the posts from using them to lift all that weight. Plus, the 4DLT has both posts on the same side as the battery, so it'd be useless anyway.

True. They also make a clamp on version that clamps onto the top of the battery:
Amazon.com: EZ RED S520 Side Lifter: Home Improvement
Battery Carrier - Drill Bits - Amazon.com

Aaron Z

 

[Texasmark]

Connections and wire size is very important as you say.

... But the internal resistance of a 6V battery that is the same size as a 12V is only 1/4 that of the 12V because theres twice the plate area per cell and only half as many cells. The // 12V pair would present no current sourcing advantage and has the inherent disadvantage of the weaker batt discharging the pair when the tractor is parked.
larry

Good point on your resistance assessment and I don't disagree. My point was given as a matter of circuit connection of a series resistive circuit vs a parallel. I do have a battery load tester and can determine the internal resistance but currently have no usable 6v batteries for a comparison.

However, whatever the internal resistance, having one battery adjacent to the starter with 12" 00 wire hot and cold tied directly to the starter with the backup essentially sitting next to it certainly made a difference for me.

On the discharge comment, can't dis agree with that either, but there are other variables to consider in my opinion before this would be an issue.
-----------------
On one large battery, for reference the 31 is roughly a 27, like trolling motor batteries usually used but with 3/8" stud terminals centered at the ends. The batteries I bought were HD for high vibration environments and at $57 each, nobody in town could touch the deal; the OTR truck dealer bought them by the skid and apparently got a great price.

Now here is the kicker; was for me anyway. I bought a 4010D (roughly 70 or so hp, 6 cyl) once that had been thoroughly gone through in the not too distant past, so the guy said. You could see his red RTV sealing remnants in numerous places on the machine and it worked just fine. Don't know/remember if an engine OH was part of it. He had one battery and it was a size 27 trolling motor battery, not combo but straight TM. It was apparent that he had used it for several years. I continued to use it for a couple more although winter starting was sluggish.

We're told that TM batteries have too much internal resistance, too few fat plates with insufficient surface area (as you mentioned) to tolerate multiple deep cycles, to be effective at high current levels like are required to start a 4010D in the winter. Well it was an Excide, if that makes any difference and it did. So much for that hearsay.

Mark

 

[SPYDERLK]

Now here is the kicker; was for me anyway. I bought a 4010D (roughly 70 or so hp, 6 cyl) once that had been thoroughly gone through in the not too distant past, so the guy said. You could see his red RTV sealing remnants in numerous places on the machine and it worked just fine. Don't know/remember if an engine OH was part of it. He had one battery and it was a size 27 trolling motor battery, not combo but straight TM. It was apparent that he had used it for several years. I continued to use it for a couple more although winter starting was sluggish.

We're told that TM batteries have too much internal resistance, too few fat plates with insufficient surface area (as you mentioned) to tolerate multiple deep cycles, to be effective at high current levels like are required to start a 4010D in the winter. Well it was an Excide, if that makes any difference and it did. So much for that hearsay.

Mark

Yeah, Iv gone away from deep cycle batts. Their cranking amps and CCA are both down from hi performance shallower cycle batt. An engine in good shape should start quick. A good hard electrical kick of several hundred amps is what you need for the cold starts. Needing more than 5 seconds is excessive. but easily supportable by a 800CCA batt.
larry

 

[EricG1793]

Sorry for the extremely overdue follow-up guys, but here it is, at least for the sake of anyone else trying to get info from this in the future. And thank you again to everyone who gave their $0.02!

We ended up getting one large 12V battery, a 4D type, Napa Commercial. My dad and I each looped a ratchet strap around one side of the battery and lowered it in by hand. I've been happy with it.

I started the tractor yesterday when it was 33*F with no block heater or starting fluid and it did fine. Normally we always plug it in when it's below 40 or so, but I wanted to see what it could do. Here's a video. Skip to 3:33 for the actual start.

https://www.youtube.com/watch?v=zOUcdV_glkM