car battery dead

Almost every technical device has such failure modes. But in most cases people just don't monitor the telltale signs. A lot of times you hear a car in the neigborhood doing that tired ahhh-choo ... ahhh-choo ... vroom. Then one morning it's a bit more chilly and ahhh-choo ... ahhh-phhhht. That's preventable. My battery slowed a wee bit last fall so I replaced it. That sped up the starter to where it used to be. No more worries on that late night flight back home as to whether it'll start. The old one can still do it's job as a back-up power source. I know, I know, it ain't a deep cycle battery but it's essentially free.

in

In my roughly 30 years of driving I never had a truly sudden failure. But that could be just coincidence or luck.

in

I've always seen telltale signs with a battery failure. Phoenix is a little problematical in that hot cars don't need a ton of current to start. In a cold climate, you'd have the symptom of slow cranking. In phoenix, what usually occurs is intermittant starting. Turn the key to start and nothing happens. Turn the key off, turn it to start again and it starts normally. Then it's time to drive to get a battery replacement.

That won't work. You need about 14V to charge and the charger should be current controlled.

Use a higher voltage, say an 18V laptop supply. Then calculate a series resistor for a desired charging current on a 0V load (18V difference). Recalculate the current for a 12V load (6V difference) and insure that it won't overcharge the battery after it is charged.

weather in

Barring a catastrophic cell short or open, I note about a day's worth of warning... slight hesitation at beginning of crank.

AZ Nomad, Are you in the Phoenix area? If so, drop by some time. (I'm in Ahwatukee Foothills, just west of Desert Foothills Park.)

...Jim Thompson

Yuk. You don't need the power efficiency, nor the regulation, nor even ripple filtering. You DO need current, and the surface-mount PS parts won't like that.

If you have any kind of old power transformer, put a high current rectifier on the output, and limit the input current (like, connect the primary winding in series with a 100W incandescent light). For a car battery, anything in the

Heatsinking the rectifier might be a good idea, though.

The ones I disected were current-limited and did 14-15V even though it said 12V nominal on them. Newer ones are mostly 18-19V.

Yes, if you don't mind the dissipation. A fat headlight bulb might do.

In the past decade they've made the transition to switchers and some blinky LED's.

Low end of the couple-amp switcher chargers seems to be $30 (e.g. B&D VEC1086). $100 for the 40 Amp sizes (e.g. B&D VEC1093).

You ought to be able to pick up a big klunky older one for a couple bucks, used, at a yard sale etc. I personally prefer the old clunkers with low-precision ammeters etc. Beside, when they hum and buzz, that's how you know they're actually doing something!

Tim.

tery

As time went on, the emissions on my wife's car (17 years old - the car, not the wife - when we got rid of it last month) seemed to be getting cleaner and cleaner and cleaner on the state dynanometer testing. According the paperwork it was passing with only 3% of the allowable emissions, and I remember it being much closer to 50% when the car was new. I became convinced that there must've been some massive emissions system leak, or maybe the guy running the test just couldn't find the tailpipe.

Tim.

I never had any problems starting in the desert. Either in the battery or in the radiator hard water is very very bad. Almost everything inside the engine compartment gets cooked, wiring, water hoses, etc. Hoses age about 10 times faster, outside paint, tires, etc. And you get sand in all spots.

greg

With my '61 Renault Dauphine (aluminum block) I got into the habit of using distilled water in my radiators. But I still, as a matter of course, replace all hoses at around 5-7 years of age.

...Jim Thompson

I had the same problem last winter. The terminal got loose due to the cold. That was easy to fix.

It seems 50/50 mix is sold more often now. I assume its been distiled or something ?

grge

That's probably an anti-freeze. I was talking of add-water.

...Jim Thompson

Someone once told me that deionized (DI) water, aka soft water, is OK for flooded lead-acid batteries, that it doesn't have to be distilled. I've still got a little bit of qualms about that, but my RV battery is still working after about five years, and I have no idea how old it was when I got the RV.

I would certainly have no qualms about using DI water in the radiator,

Any opinions about DI water in a battery?

Thanks, Rich

When I first got out of the USAF (1976) I bought a used Ford Econoline van, because vans were cool back then. ;-) I was living in Minnesota at the time, and from time to time it wouldn't start. I got ahold of one of those battery post cleaning tools - inward pointing brush for the posts, and a stiff bottle-brush type thing to clean the inner surface of the terminals. Then, whenever it was balky starting, I'd take my post tool and my wrench, take the terminals off and scratch them and the posts up real good, put the terminals back on, and it started right up!

I got laid a lot in that van. ;-)

Cheers! Rich

It was Sunday, I needed one "now" and had a large hunk of iron, a 25 amp bridge rectifier and some other stuph. Epoxyed bridge to side. Open circuit was +20V; hook up and even charged battery draws WAY too much current; transformer too hot to touch in only a few minutes.

Have some ~40 watt metal case resistor to put in series, but they are wrong values; too much drop by a long shot. WaitaSec - 10ohm/40 watts in the primary side....just right! Epoxied it on other side, tape over the connections, and away she goes.

You own[?ed] one? That car was infamous for decades; in the same family as the Borgward and Fiat and Yugos became...

Yep. Bought it in 1961, from Luby Chevrolet (Boston), when I was a junior at MIT. Sold it to a friend (in Arizona) in 1968. He drove it for many years. I had virtually no trouble with it. On the other hand I had modded it... oil filter assembly from a Caravelle, Ford alternator with one of my own-design regulators, BNC connector thru roof for 2-meter antenna ;-)

But no A/C plus two young children... bought a Dodge Dart (slant-6) in '64, then a Mercury Cougar (V8 ;-) in '67.

...Jim Thompson