Batteries! How weird they are...

[Grumpycat]

sounds like the larger is sulfated. you would need a load test, your testing shows the smaller battery trying harder, but may be able to release more amperage.

Voltage while starting would be sucked lower if the battery is limiting current. That is why the starting voltage is lower on the smaller battery.

The large battery is not fully charged, that is why after 10 minutes running it is not up to 14.2. Is possible 5 of 6 cells are fully charged (or overcharged) and one is shorted. But that doesn't explain the higher starting voltage.

 

[Fuddy1952]

Post #13 "I replaced that with a known good car battery." meaning a completely different car battery, one that starts a 4 cylinder car just fine. It also started this single cylinder motor fine, until I was back to square one after a few start/stop cycles.
What I realize now is I should never have posted this to begin with since it starts arguements. I know what works and it worked for me, just trying to help others was a big mistake.

 

[K5lwq]

Fuddy, I am glad you did post. It is interesting for sure and am confident it will be helpful in the future. I think everyone is trying to understand what you are experiencing and trying to relate it to what is understood about batteries.

 

[stevem5215]

Test the battery properly with a real CCA / AH tester. This measures IR in the battery and will go a long way to telling you the status of the battery. The days of just checking the voltage are long gone.

 

[rScotty]

Fuddy, I am glad you did post. It is interesting for sure and am confident it will be helpful in the future. I think everyone is trying to understand what you are experiencing and trying to relate it to what is understood about batteries.

I am too. Fuddy has the courage to have a good idea, and got a lot of discussion started.

 

[Fuddy1952]

Test the battery properly with a real CCA / AH tester. This measures IR in the battery and will go a long way to telling you the status of the battery. The days of just checking the voltage are long gone.

Post #1 "Although battery was new, I had it professionally checked, it was good and actually measured 717CCA"

 

[grsthegreat]

I too think the tractors charg system will not charge the larger battery properly. I had a friend that had this issue with his dump trailer. After a bunch of trial and error results, he purchased a NOCO Genius prom50 battery charger. Expensive little bugger. But instead of only getting 2-3 lifts per battery charge (off truck alternator) hes getting about 15+ cycles.

 

[Fuddy1952]

Well...the proof is in the pudding they say.
Remember me saying no matter what car battery I used, a new 700CCA or one out of a running car I could run tractor for hours and never get over about 13V.
Today I bought a 300 Everstart Walmart $39.95 mower battery. Tractor fired right up and running 14.54 volts. Headlights, tail spotlight on it drops to about 13v...but still bright. I shut it off, restarted several times it's like night & day. I even started with lights on...fired right up.
No it may not make sense, all I know is I'm happy and it works great. I just need to fabricate a holder for the smaller battery.

 

[WranglerX]

Well...the proof is in the pudding they say.
Remember me saying no matter what car battery I used, a new 700CCA or one out of a running car I could run tractor for hours and never get over about 13V.
Today I bought a 300 Everstart Walmart $39.95 mower battery. Tractor fired right up and running 14.54 volts. Headlights, tail spotlight on it drops to about 13v...but still bright. I shut it off, restarted several times it's like night & day. I even started with lights on...fired right up.
No it may not make sense, all I know is I'm happy and it works great. I just need to fabricate a holder for the smaller battery.View attachment 708120

New hot charged battery with plenty of capacity vs used battery pretty tired and weak on capacity.... I have very old (maybe 15 year old) AGM battery in VW dune buggy... Funny it only gets stated and run for maybe 30-45 minutes once every 3-4 months, this battery contradicts all you science....

 

[Fuddy1952]

Post #1 "I installed a new 700CCA battery. I had it professionally checked, it was good and actually measured 717CCA".
The End (hopefully).

 

[Handloader109]

No, no matter, the larger auto battery was never charging properly. That is the science. Just because it was tested good means nothing. Your just hadn't damaged the battery. Your system charges the lower capacity battery way better than the larger battery hence better performance. The larger battery would ultimately die if it wasn't charged long enough.
Amp hour means nothing if you crank and engine starts quickly. If it takes 10 tries, and the engine uses up what power is stored, it ain't cranking. Yes you have to match the battery to the charging system for best performance.

 

[Williy]

Just get a block of wood to fill th;e gap no need to
build something

willy

 

[Fuddy1952]

No, no matter, the larger auto battery was never charging properly. That is the science. Just because it was tested good means nothing. Your just hadn't damaged the battery. Your system charges the lower capacity battery way better than the larger battery hence better performance. The larger battery would ultimately die if it wasn't charged long enough.
Amp hour means nothing if you crank and engine starts quickly. If it takes 10 tries, and the engine uses up what power is stored, it ain't cranking. Yes you have to match the battery to the charging system for best performance.

Yes you have to match the battery to the charging system for best performance.
That sums it all up. Hope this helps someone else. I used the tractor yesterday and wow! it fired right up and ran fantastically. I stopped and restarted several times, great each time.

 

[oosik]

I put a large Group 31 Odyssey AGM battery in my Kubota last year. The charging system is compatible with this larger battery.

I saw the local BMW motorcycle shop was selling lithium ion batteries. No joy. My new BMW R1200 GSA motorcycle charging system is NOT compatible.

There must be some type of vehicle that they sell that IS compatible.

 

[JWR]

By match I mean it should be as original for application as possible. I'm finding out a 20 amp charging system isn't a match for a high CCA battery.
No different than putting a 1/2 hp pump in a 500 ft deep well.
Again...only trying to help others by my many hours trial & error. I know what works.

Oh BS. There is no such thing as a battery being matched to a charging system.

 

[CoyPatton]

"Matching" is not the answer to charging a battery.
I'm sorry. It's an innovative idea, but probably incorrect.

There is a minimum size (ampacity) battery required to turn the starter and start the engine. Any larger capacity battery will simply do the same thing for a longer time. "Matching" the charging system to the battery capacity is not real.

Everything you are seeing and measuring could also be due to a large battery that is able to develop cell voltage, but is not able to store much of a charge (amperage) in those cells. A possible cause for that is something in one or more cells is not allowing the plates to use their full area to store charge. The plates may not be properly isolated, there could be uneven sulphation due to how it was stored, or it may simply be one or more cells have a low amount or acidity of electrolyte.

Science starts with the simplest theory that explains the facts. A poorly built battery makes more physical sense than the electrical matching idea.

rScotty

I agree and disagree with rScottty on this one!
Charging a battery in it simplest terms is a combination of amps and voltage. Voltage needs to match the battety (in this case 12 volts), amps determines how quickly the battery will be charged. This is where matching does come into play and my disagreement with rScotty.
If you are relying on solely on the charging system of the motor, the battery and charging system need to be matched.
Frequent undercharged could lead to a state where the battery is consistently not getting a full charge and develops weak cells thus not being able to accept or hold a full charge.
so again unless regularly connecting an external battery charge to an oversized CcA battery, you are probably better off match the CCA’s to the motor requirements to start it (via mfg recommendations) which will result it it matching the charging system installed on the machine.
If a charging system is rated at 10 amps. It puts out approximately 10 amps for every operating hour at the rated voltage. If the 300CCA battery is totally depleted, it needs 30 hours of run time to charge as an example.

 

[Fuddy1952]

I'm sorry those thinking this is BS.
At times I wish I hadn't posted, made my discovery and moved on.
Today I put the 700 CCA battery in a '74 Chevy Nova. I had to use top to side post adapters. Car had been sitting 10 years.
After all the prep (tires, fluids, ign.,etc) it fired right up. 14.3 volts fast idle (before choke kickdown).
Again used tractor...started and ran perfectly.
There are people who go through life knowing all the answers, right or wrong.
There are people (like me) the older I get the less I know or I should say discover new things every day. Things I thought were true didn't exactly work or act the way I thought it would. That to me is what makes life interesting, making new discoveries.

 

[Grumpycat]

There is some need to match charger to battery. A wet cell lead-acid needs to be cared for a bit different than an AGM. And lithium chemistries are even more different. However there is a lot of overlap.

All have a different maximum charging voltage. And a different maintenance long term voltage. All have maximum current limits for safe charging. The lithium does not like to be held on perpetual maintenance charge.

A 10A “automatic” charger will hold 10A until the battery reaches 14.2-14.4V then taper off the current to prevent voltage from going higher.

 

[JWR]

There is some need to match charger to battery. A wet cell lead-acid needs to be cared for a bit different than an AGM. And lithium chemistries are even more different. However there is a lot of overlap.

All have a different maximum charging voltage. And a different maintenance long term voltage. All have maximum current limits for safe charging. The lithium does not like to be held on perpetual maintenance charge.

A 10A “automatic” charger will hold 10A until the battery reaches 14.2-14.4V then taper off the current to prevent voltage from going higher.

This discussion has all been in the context of ordinary automotive type lead acid batteries. Lithium Ion batteries are totally different in many respects and not involved here. Lead acid batteries of 12v variety in normal tractor and auto context need around 13.8 volts for charging. Above 12 obviously. Alternators and older generators do that just fine. We are all aware of the numerous battery chargers for shop use. Aside from irrelevant cases (like lithium ion) alternators, generators and 20 brands of battery chargers all work to charge 12v batteries having no clue what the battery is other than it is lead-acid and 12v nominal . While this dissertation goes on (sorry but may as well get it over with) the CCA has utterly nothing to do with getting a battery charged except that a big capacity battery with large CCA rating will take longer for a given charger in order to get fully charged. So what ?
Mr. Grumpycat, I respectfully disagree about automatic battery chargers tapering off to prevent voltage from going higher. Battery chargers (in general) apply something higher than 12v to get current flowing into the battery rather than out of it. This stores energy in the battery... and when the current flow gradually goes down to near nothing the automatic chargers declare victory and shut of the charging process. Nothing to do with voltage going higher. And no, they do not hold 10A at all. They will supply UP TO 10A during the initial charging process which then tails off as the battery becomes charged.
We can all go off and study lead acid battery tutorials (which is a good easy study using the web or various books) rather than preaching at each other. Sorry if I am preaching at anyone. I do believe you will find my comments in this post #39 accurate. If not, as an electrical engineer long retired, I need a serious remedial class.

 

[stevem5215]

The truth is in Ohms law. Some charging systems on smaller mowers are really only a trickle charger with a half wave rectification circuit. As a result it only puts a trickle amount into the battery system. If you look at most schematics for lawn and smaller tractors you will see this as a single diode on one part of the generating circuit. The other generating circuit usually is AC and not rectified and powers the lights only. So, that said if you put a "too large" battery on that circuit it will not charge up a battery that is higher CCA. And the reason is that there isn't enough power being generated to do so. But, a smaller battery can be charged up. It doesn't take as much current to over come a smaller IR (Internal Resistance) within the battery and fully charge it. Same would hold true if you were to use a low current trickle charger to charge a large CCA battery. It has to overcome that high IR in a bigger battery and charge it up. That's why you want to match a bigger CCA battery with a larger current charger. Make sense now ?