3 year old "yard tractor" battery is probably no good. Rules for connecting battery charger: Red clip of charger connects to the + post (positive post) of battery, Black clip connects to the - post (negative post).
***"I borrowed a neighbors trickle charger it but smelled like something was burning so I stopped. Is that normal?"***
Well, I can't smell it through the internet so I really don't know if you smell "something burning" or if you just smell the usual fumes that come from charging a battery.
You need to buy your own battery charger, batteries don't charge up in just a few minutes if they are really dead. Most of the time, if a battery is "really dead" and has been for a while, you can't bring them back to service. You can usually buy a replacement battery for lawn tractors just about everywhere. "Wally world", Sam's, Costco, Lowes, Sears, and auto parts stores by any brand, to mention a few.
***"Where can I get a manual or charging instructions for this battery?"***
Google (or other search) "DIY auto battery charging" and begin reading, it might take you a while to wade through it all.

Walmart 19.00

take your old one for a core

Start by removing the cell caps and looking inside. Can you see liquid that is above the plates in all six cells? If five cells have liquid above the plates and one cell appears dry, then you have a bad cell and the battery is toast. If all the cells have liquid above the plates, the someone needs to at least try and recharge your battery.

I've had batteries last much longer than three years so no one can say for sure that this battery is no good until an attempt has been made to recharge it so it can be tested.

Once the charging has taken place, then the cell caps can be removed and a hydrometer can be used to suck the battery fluid (electrolyte) into to so that you can get a reading on the specific gravity (state of charge) in each cell. All cells should test equal or very close to equal. A wide difference in one or more cells will indicate weak or shorted cells and the battery is toast.

Even if all the cells test evenly and very high, a "load test" using a special load testing instrument should be used to determine the amount of reserve power the battery has available for cranking a stubborn engine. These are the tests that need to be performed because maybe....just maybe.... the real problem is with the charging system on your Honda rider. Batteries that don't get recharged, eventually go flat and everyone just assumes that the battery is at fault.

Bottom line..... you could go buy a new battery and a week from now, it will be dead as a doornail too. Then what????

Thanks for the quick replies,

All six cell have water and the plates are covered. I used my volt meter and the battery is reading 10.70. If a battery is only $20 at Walmart it's worth it to try and trouble shoot. The honda dealer charges a fortune just to pick up the machine.

If I use the borrowed charger:
A. Do I need to remove the caps?
B. How long does it take to charge using the 12 volt 2amp setting?

If you read less than 12 volts on a "charged"
battery it is gone...
Don't think the "water" is harmless IT IS ACID.

Ay 10 volts, I would reborrow the charger hook up
like Mownie said and give it a few hours.
You can measure volts while charging it should be more than 13 volts. ACID SHOULD BE BUBBLING.
after charging. Meter should read 12 VDC for a long
time.

I would just remove it take it to autozone and have it tested. I dought the battery is any good. three years is about the life of them. course some will say I get 6 years out of them, but IMO that's is not norm.

The Wal Mart $19 battery is worth about $2. Get a good battery with more cranking power or you will be looking for a battery again soon. Yea, I know some of you guys will come on here and say that a Wal Mart garden tractor battery will start your Kenworth 18 wheeler after sitting in a mower for 12 years. Whatever. They are just junk. Buy a good battery...

The lawn mower and battery were sitting outside of my neighbors house for almost two years. I turned the key and it started up.

I charged the battery and it has 12.28 volts. I will try it on the machine over the weekend.

I'm like rcmoser. I take mine to Advance Auto, have them test it, then buy a new tractor battery ($20) if bad.

Get a new battery and keep a battery tender on it when you are out of season. In 5 years, proactively replace it. Do the same with your cars and you will always have a battery. Even if a battery tests good, extreme cold will kill it in minutes. It can still test good with no load and not be able to support load. You will need a load tester to test it the right way. Like I said, throw it out every 5 years . Name one other thing you bought for $30 and it lasted 5 years.