[Nita Nupress]

Hey, backhoe. Good morning! I'm sitting here running the laptop off the new marine battery we bought. I have a question that maybe you or anyone reading can help me with.

We found our battery charger but I can't remember how to operate it. The owner's manual is long gone and it's one of those big ones on wheels (a Schumacher SE-2158). I'm afraid if I hook it up wrong, it'll explode the battery or something. Anyway, which one of these settings do I use to try and recharge one of those old marine batteries? Here's the info for the marine battery:

Brandname - "Stowaway Tournament" (Bill Dance)
900 Marine Cranking amps
205 Reserve Capacity minutes
Part No. 31DP-6

Here are the possible dial selections for the battery charger, a Schumacher SE-2158:

1.
12 Volt/10 amp
6 Volt/125 amp start

2.
12 Volt, 50 amp

3.
12 Volt, 225 amp start

4.
6 Volt, 50 amp

5.
12 volt, 2 amp

Any help would be appreciated! I hate messing with electricity, and I want some knowledgeable info before my spousal unit wakes up and starts messing with it. (Bless his heart; he's a wonderful husband but he's mechanically-challenged. :-)

[Nita Nupress]

...I want some knowledgeable info before my spousal unit wakes up and starts messing with it.

Never mind on that. He woke up but he's off doing something else. I convinced him to wait until tonight or tomorrow to work on that marine battery, so I have more time to dig up some info.

[backhoe]

Here are the possible dial selections for the battery charger, a Schumacher SE-2158:

1.
12 Volt/10 amp
6 Volt/125 amp start
2.
12 Volt, 50 amp
3.
12 Volt, 225 amp start
4.
6 Volt, 50 amp
5.
12 volt, 2 amp

Nita!

We were wondering how you were faring.

I bolded the correct setting-- when you have the option of allowing more time to charge, the lowest "amps" setting is better- it's what's called "trickle" charging, for a day or two, and will bring the battery up to full charge.

The 10 amp option charges faster, but it is a less thorough charge.

The even higher amp settings are for emergency starting of a gas engine- they aren't really for charging the battery, but rather for supplying starting power for the starter motor on an engine.

Let me review charger & battery basics:

Always, plus ( positive + ) to plus... minus ( negative - ) to minus. Use a crayon or china marker to make the symbols on the battery easier to see.

On the charger, plus is red ( the hot lead ) minus is black ( ground, or Earth as the Brits call it ).

It is good practice to connect the battery leads first, then plug the charger into AC power-- minimizes sparking.

Clean the battery terminals ( lead posts ) with a wire brush 'till they are shiny. Smear with vaselene ( or spray with WD-40 ) to slow corrosion.

Check electrolyte levels- charging heats, and can evaporate the water-- the acid does not evaporate, which is why you add only distilled water.

How do you tell the battery's voltage?

This is easy-- count the cells ( holes )-- three is a six volt, six is a twelve volt. The charger voltage setting must match the battery's voltage.

Each lead-acid cell produces 2.1 volts at full charge ( that is why vacuum tubes were listed with 6.3 or 12.6 volt heaters-- the oldtimers were very literal and precise ) so you count cells, and multiply.

When you can, get a hydrometer-- a specific gravity reader-- you use a squeeze-bulb to draw the electrolyte into the instrument, and read the density of the electrolyte-- a scale is provided on it which will tell you how much the cell you are reading is charged.