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At the beginning of this season, I couldn't find bolts that hold the cables to the battery posts, so I used random bolts and nuts that I found.
At the end of this season one of the nuts looked burned and that battery post was darker then the other one.

Does it matter what kind of metal the bolts that hold the cables to the post are?

I've always used Grade 5 or 8 hardware, just whatever the hardware store has in the correct size. and haven't had an issue like you describe.

Proper battery bolts are lead plated
Whenever any 2 metals are touching and they get expose to an electrolyte ( water ) you have a galvanic cell
This is why people will paint or grease battery terminals
If you have a plain copper battery terminal then you have a whole series of cells, lead-steel , lead - copper , copper - steel .
The very best thing you can do is polish then all nice & shinny, bolt them tight together then paint them over with liquid electrical tape.

To further confuse people the + & - terminals on you battery are different alloys of lead.
One is lead-antimony and the other is lead-silver or lead-cadmium
So even is just sitting on the shelf, one will go sort of black & the other sort of silver grey

FWIW I buy brass coach bolts and wing nuts
Do them up tight so the square section cuts into the terminals then undo and fit the wires then paint over all but the end of the bolt.
Being there all by itself it will not corrode and provide a point to read voltages or connect a jumper lead or battery charger.
Do not go overboard you really only need to cover anywhere that water can get to two parts or seep in between them .
If you want to be Safety Sam, it comes in both red & black

Zinc-aluminum-coated steel screws are about five times as corrosion resistant as zinc yellow-chromate plated screws and have good resistance to salt water and acids. Also known as ultra coat and armor coat. To maintain corrosion resistance, use these screws with zinc-aluminum-coated nuts and washers

Thank you

I got a not so related follow up question.

the battery in my mower sat for a month and wouldn't start the mower.
I have a boat battery on a maintainer so I brought that battery to the mower and started it.
I then put the original battery back in the mower while the mower was running.
I was scared that the battery was going to shock me while I tightened down the nuts,
but there was no shock at all.
how come the battery didn't shock me?

2ball said:

Thank you

I got a not so related follow up question.

the battery in my mower sat for a month and wouldn't start the mower.
I have a boat battery on a maintainer so I brought that battery to the mower and started it.
I then put the original battery back in the mower while the mower was running.
I was scared that the battery was going to shock me while I tightened down the nuts,
but there was no shock at all.
how come the battery didn't shock me?

Click to expand...

You can be shocked by 12VDC, or even less. Grab a new 9V battery and touch it to your tongue. Now touch it to your hand. Tongue = low enough resistance that OUCH!
Hand = high enough resistance that no perceptible shock takes place.

This is also why birds and squirrels can sit on power lines without being shocked. They are exposed to voltages from 7.2kV to 33kV without any issues, because they are isolated from ground and all other phases. Occasionally, a squirrel will step from the line to the pole rather than jumping, at which time we have to take a moment of silence and hope that particular tree rat made his peace with Jesus.
I did get a tingle from a truck 12v battery one time, i was soaked with sweat (water) and i was leaning over the engine bay, and touched my forearm to + and - and it tingled me enough to where i wondered "What the heck was that!?"

Scrubcadet10 said:

You can be shocked by 12VDC, or even less. Grab a new 9V battery and touch it to your tongue. Now touch it to your hand. Tongue = low enough resistance that OUCH!
Hand = high enough resistance that no perceptible shock takes place.

This is also why birds and squirrels can sit on power lines without being shocked. They are exposed to voltages from 7.2kV to 33kV without any issues, because they are isolated from ground and all other phases. Occasionally, a squirrel will step from the line to the pole rather than jumping, at which time we have to take a moment of silence and hope that particular tree rat made his peace with Jesus.
I did get a tingle from a truck 12v battery one time, i was soaked with sweat (water) and i was leaning over the engine bay, and touched my forearm to + and - and it tingled me enough to where i wondered "What the heck was that!?"

Click to expand...

Remember in the movies the bad guy always takes fat cables attached to a car battery and touches them to someones bare chest after throwing a bucket of water on them.

Only works when wet. Its all about resistance.

Ever wondered why the battery is 12 V and not 6 or 18 or 24 like some trucks ?
Well it just happens that 12 V is ON AVERAGE the resistance of dry skin
Remember those old square 9V batteries that were popular in transistor radios & still used in a not of multimeters ?
remember how you used to test them ?
Yep the tip of your tounge would tingle as the power passed across it .

I abandoned lawn tractor battery bolts about 20 years ago. Heavy duty C-Clamps are convenient, quick and provide 2 handles to carry the battery when necessary.

Scrubcadet10 said:

You can be shocked by 12VDC, or even less. Grab a new 9V battery and touch it to your tongue. Now touch it to your hand. Tongue = low enough resistance that OUCH!
Hand = high enough resistance that no perceptible shock takes place.

This is also why birds and squirrels can sit on power lines without being shocked. They are exposed to voltages from 7.2kV to 33kV without any issues, because they are isolated from ground and all other phases. Occasionally, a squirrel will step from the line to the pole rather than jumping, at which time we have to take a moment of silence and hope that particular tree rat made his peace with Jesus.
I did get a tingle from a truck 12v battery one time, i was soaked with sweat (water) and i was leaning over the engine bay, and touched my forearm to + and - and it tingled me enough to where i wondered "What the heck was that!?"

Click to expand...

Small tid bit-- I hear you can connect a 9v battery to land line phone to ring it. Don't know anything else about it, just saying

Normally telephone are operated at -48 VDC with the phone sending a 20Hz 105 VAC signal along the line to ring the phones The negative voltage use to prevent the phone wires from corroding.

Fiber optics is changing this.

StarTech said:

Normally telephone are operated at -48 VDC with the phone sending a 20Hz 105 VAC signal along the line to ring the phones The negative voltage use to prevent the phone wires from corroding.

Fiber optics is changing this.

Click to expand...

Yeah, POTS lines use 75 vac minimum for the ringer.

in my area 40 years ago ringing current 110 volts pulsating DC. Old phone man

Being we've wandered way off topic from BOLTS to VOLTS, what volts did the telephone we had generate? We could answer it or take it fishing.

The post WWII system used in OZ was 50 V DC
Dad finished his working life as an exchange cleaner for the GPO.
One of his jobs was to top up the batteries in the battery room and wax the walls & floor to protect them from the excessive humidity
These were open toped glass battery cases in lines of 25 single 60 plate 2 volt cells so when they were getting old the battery technician could simply pull the busbar up & replace the worn out plates .
During the 90's they were all replaced with sealed maintenance free cells and the old glass battery cases ended up in antique & decorator shops labled as "antique acid storage jars " because the glass battery case had the words "acid level " on all 4 sides and a pouring lip on both short side so the old acid could be poured out cleanly before the cases were washed & returned to the racks .