Saturday, January 29, 2011

Lately I've been considering the inclusion of pending automotive exploits on these pages, technically speaking an automobile is more of a machine than an oscillator. Of course, some of the prohibitive elements is that working on a car is a messy business that's been covered in great detail elsewhere. I probably will pollute this place with some chatter about the type 3s, but I'll endeavor to keep it appropriate.

Nudging closer to this eventuality, I'm up against some sort of electrical goblin in the truck that drains the battery. Attending to the flat battery ushered in the realization that my Century 8710SC battery charger (known in the vernacular as a cheap piece of shit) is hosed.

To illustrate how much of a cheap piece of shit this is, let's disassemble it to have a look at the guts.

Right out of the gate, an indicator of quality. There is no hardware used in assembly outside of the occasional rivet securing interior components. Bent metal construction has one method of disassembly, it involves bending metal (again) which is obviously not a path to longevity.

My first approach was direct, utilizing the screw driver oriented as pictured I attempted to pry the tab out. Sadly, due to constraints established by tool depth and hole size I couldn't exert more upward force than face loading and the tab simply popped into the position shown.

Next angle proved effective, and limited unnecessary disfigurement of the metal to the tab itself (which could technically be bent back into shape should I lose my mind and decide to employ the same method of assembly the original designers opted for).

Naturally, the tabs (yes, plural) that had been pushed in farther than original were considerably less pristine when finished. I had to alternate sides and disfigure the tab prior to establishing clearance enough to pry it out. The enclosure is, however, in much better shape than it would be had I employed a BFH to expedite disassembly, which was plan B.

I may have found the problem.

Primary wiring to the right ties hot AC mains to the transformer, and switches neutral to various legs in order to determine operating voltage and "output current range", which, must be tied to the thermal switch to interrupt the cycle once the transformer begins to overheat.

From the top:
Blue: 6V @ 10 amps
White: 12v @ 2 amps (my preferred setting)
Black: mains hot
Black: 12V @ 10 amps
Yellow: 12V @ 55 amps for starting

I don't think I would use this to start a car on a bet. Especially since this particular unit shows a shorted diode on the rectifier at one side of the center tapped secondary. Leading me to believe that there may have been an AC component to the battery feed side of the leads.

Here's the offending part. I'm considering replacing this with a high current diode pair, fixing the range switch so only one range is available and the other ranges are "off". In the meantime it looks like I should go get this battery checked to make sure it wasn't destroyed by my failing charger.


pearshapedhuman said...

You know, I think the battery was holding fine until you replaced that fuse during the bad weather. Ha, I guess you don't need me telling you that that area of the system was wonky!

crochambeau said...

I'm hoping it is that circuit, and I suspect you're right. Probably just jam a switch to pull out the wipers when not in use.

I dug up some DO-5 stud diodes good for 40 amps that I'll jam into place on the old rectifier plate once my drill battery charges up.