Battery Replacement -- 1999 Ford Ranger

The original battery in my '99 Ranger finally died on me. That's extraordinary battery life -- I've never seen a battery last twelve years.

Anyway, replacing a battery is a pretty straightforward job, but there is a crucial safety consideration that one is wise to bear in mind.

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Safe Battery Handling

A charged battery, if inadvertently short-circuited by a wrench falling across its terminals, say, will deliver a massive amount of electrical energy to the short-circuit. Such an occurrence can have consequences ranging from merely inconvenient to downright tragic; it must not be allowed to happen.

A battery out of a vehicle presents only the span across its two terminals as a possible short-circuit path. Taping over either of its terminals will preclude the possibility of a short-circuit. (New batteries come with little plastic caps on the terminals.) A battery installed in a vehicle is another matter. When connected in a vehicle, every exposed bit of metal -- body, chassis, engine, everything -- is electrically equivalent to the battery's negative terminal. There are lots and lots of possible short-circuit paths.

That's why, when removing a battery, one always disconnects the negative terminal first. With that terminal disconnected, you're back to having only one possible short-circuit path. Conversely, when installing a battery, one always connects the negative terminal last.^[1]

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Replacing the Battery

Here's a view of the battery at the left front corner of the engine compartment.


And here's a view of the single clamp-block that secures a ledge at the inboard-bottom of the battery.

The fasteners are all 8mm A/F hex head. Use only a six-point socket; those fasteners have had a long time to seize, and you'll need all the hex engagement you can get to get them out. Expect snags on an installation this old.

And sure enough, the round, swaged-in-place M6 nut at the negative terminal broke loose.

I managed to get it apart by clamping Vise-Grips on the nut to hold it from turning. Then, I had to bend up two little retaining 'ears' trapping the washerhead screw, so I could get the screw out for a proper wire-brushing.

Holding the terminal with Vise-Grips made it possible to straighten the ears (it's a poorly lit photograph).

The fastening at the positive terminal was uncorroded and loosened easily.^[2] With both cables off their terminals, the battery blanket^[3] can be slipped off. Here's a view of that.



The M6 screw holding the clamp-block in place was a bit of a struggle. The screw is much longer than it needs to be, which leaves plenty of exposed screw-end to rust. With wire-brushing and WD-40 and much 'toing-and-froing', I got it out. (By 'toing-and-froing' I mean unscrewing until excessive resistance is met, screwing it back in a ways, wire-brushing some more and reapplying WD-40, then unscrewing again until excessive resistance is met. Repeat as needed until the screw comes out. It's tedious, but if you just go straight at it with a big wrench, you're much more likely to break the screw.)

That's all the difficult stuff dealt with. Clean the muck and grime out of the battery pan and off the blanket, wire brush the screws and terminals and the new battery can go in. Here it is with everything buttoned up and ready to go.

That purpose-made wire brush works nicely for scouring battery terminals and connectors. I reassembled all the threaded fasteners using anti-seize compound. Down in front is the round nut that broke loose. I replaced that with an M6 hex nut, lock washer and flat washer.

So there we are. It was a breeze, just like everything in the Haynes manuals always is.

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Notes

[1] What I've been on about here assumes a negative ground vehicle; i.e. battery negative connected to body/chassis/engine. As far as I know, modern vehicles are all negative ground. In early days in the auto industry, Ford and the Brits employed positive ground -- battery positive was connected to body/chassis/engine. I seem to recall that my first car, a 1961 Austin-Healey Sprite, was positive ground. For a positive ground vehicle, all negative/positive terms in the preceding two paragraphs would have to be transposed.

[2] I wish I understood the chemistry/physics/whatever of this. The positive terminal was clean as a whistle; the negative terminal was quite corroded. What's with that?

[3] This is so neat. The battery has a 47 watt electric blankie to keep it cozy on chilly nights in the north. Ford really pulled out all the stops to make this vehicle startable in extreme cold. It came with both a block heater and a battery blanket.

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