Sears DieHard 10/2/50 Amp Automatic Battery Charger Review

Michael Posner
by Michael Posner

Like most middle aged men, I had a car crisis. So, after convincing my wife that an Imola Red BMW M Roadster isn’t “chick magnet red,” I bought my dream car. Of course, the dream is never the reality. I rarely drove the M. Summers were too wet and hot (real men don’t drive a convertible with the top up and the a/c on). Fall was too wet. Ah, winter in Florida! It’s the best ‘vert weather but… I just got a new daily driver. So Emily became a garage queen. And died.

Yesterday, I went out to drive her for the first time in two weeks. Unlike The Grand National, she’s never failed to start. But this time, key in, quick turn and nada. The dash lights were on but she didn’t even bother emitting the dreaded click click click sound. A dead battery was the blindingly obvious call. So I rolled her out of the garage, grabbed the jumper cables, opened the trunk, removed the battery cover and– remembered that jump starting a car is generally a bad idea.

Jump starting a modern car is two kinds of dumb. First, we’re talking dumb and dumberer, or, if you prefer, the Darwin factor. That’s when you accidentally reverse the cables and/or cause so much sparking that the battery blows. Second, there’s the small matter of an overly sensitive $1k electronic control unit that can up and die from a spike in the voltage transmitted from the running car to the dead car via Old Sparky– I mean jumper cables.

Some jumper cables now include a special resistor to reduce voltage spike. Some manufacturers also include a jumping block off the battery, which should help prevent battery explosions. But, as you’ve read here, no one reads the owner’s manual anymore. And I’m a lawyer; I don’t trust anyone, with anything, ever.

As an alternative, Sears sells several battery chargers. I reckon they’re a must for any vehicle driven less than once a week. So I tested the Sears DieHard 10/2/50 amp Automatic Battery Charger. The unit MSRPs at $64.99, but way-hey! As of December 23, 2007, it was on sale for a bargain price of only $39.99.

The Diehard charger is your basic, garden variety metal box with one analog battery charging gauge, two leads (for power on and full charge) and a three-way switch. It has two plugs, a 110 amp wall plug (not grounded) and two small jumper cable style wires with a red and black clamp. The Diehard does so with a vengeance; the heavy and sturdy block weighs in at eleven pounds.

So, connect the Diehard to your Diehard battery (or similar), red to red, black to black (or brown, as apparently some car companies didn’t get that memo regarding the international colors for positive and negative). Select the style of charge, plug in the device and wait. The Diehard offers spark proof protection in automatic mode, and even includes a Darwin feature for fashion victims who insist on hooking up red to black and black to red because it’s more aesthetically pleasing.

The Diehard Charger offers three settings depending on your needs. The 50 amp setting is similar to a jump from another car and should allow most cars to start up right away (though I would still give it a minute or two, and keep in mind the warning above, though the voltage from the Diehard is delivered spike free according to Sears).

If you’re not planning on driving the vehicle straight away, set the Diehard in the ten amp mode and wait about two hours. A blinking light will advise you when the battery is fully charged. WARNING: the Diehard doesn’t have an automatic shutoff; leaving the charger in ten amp mode for extended periods can damage your car’s battery. How lame is that?

I used ten amp mode for my M. A couple of hours later the car started like a dream, and ran the rest of the day without battery troubles.

There’s also a two amp trickle charger mode. This is the mode I SHOULD have been using for my M before I let her die. A trickle charge feeds just enough juice to keep the battery charged and the electrical system refreshed without overcharging the battery. Since most cars continue to draw power when off, a trickle charger also prevents damage to electrical components that seem to freak at low voltage.

I recently sampled a rarely driven loaner 2006 M5. When I picked her up after a short lay-up, the dash was lit up like a Christmas tree with dreaded engine damage warnings. A flat bed to the dealer later, I learned that the low voltage had falsely triggered the warnings. If only I’d learned to live free and Diehard.

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Michael Posner
Michael Posner

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  • Confused1096 Confused1096 on Jan 11, 2008

    Sorry, gotta say it. It's a battery charger. Who cares how it looks as long as it works?

  • Rfurnival Rfurnival on Jan 27, 2008

    I bought one of these last summer at Sears and when I unpacked the box, the mode switch was snapped off and rattling around inside the old-school style case. I quickly ran back to town and swapped it for another one. When I got back to my shop -- yessir that one was broken as well. Back to Sears and having opened the last of the three the had on the shelf; yep -- that one was broken too. Fool me twice... I went to Tractor Supply and picked up a Schumacher multi-mode unit for about the same money. For my coin, I got a modern heavy duty case and "smart" mode-switching built it. I have since bought two additional Schumacher trickle units, as well. These are first class chargers that should be in everyone's shop.

  • 3-On-The-Tree I don’t think Toyotas going down.
  • ToolGuy Random thoughts (bulleted list because it should work on this page):• Carlos Tavares is a very smart individual.• I get the sense that the western hemisphere portion of Stellantis was even more messed up than he originally believed (I have no data), which is why the plan (old plan, original plan) has taken longer than expected (longer than I expected).• All the OEMs who have taken a serious look at what is happening with EVs in China have had to take a step back and reassess (oversimplification: they were thinking mostly business-as-usual with some tweaks here and there, and now realize they have bigger issues, much bigger, really big).• You (dear TTAC reader) aren't ready to hear this yet, but the EV thing is a tsunami (the thing has already done the thing, just hasn't reached you yet). I hesitate to even tell you, but it is the truth.
  • ToolGuy ¶ I have kicked around doing an engine rebuild at some point (I never have on an automobile); right now my interest level in that is pretty low, say 2/5.¶ It could be interesting to do an engine swap at some point (also haven't done that), call that 2/5 as well.¶ Building a kit car would be interesting but a big commitment, let's say 1/5 realistically.¶ Frame-up restoration, very little interest, 1/5.¶ I have repainted a vehicle (down to bare metal) and that was interesting/engaging (didn't have the right facilities, but made it work, sort of lol).¶ Taking a vehicle which I like where the ICE has given out and converting it to EV sounds engaging and appealing. Would not do it anytime soon, maybe 3 to 5 years out. Current interest level 4/5.¶ Building my own car (from scratch) would have some significant hurdles. Unless I started my own car company, which might involve other hurdles. 😉
  • Rover Sig "Value" is what people perceive as its worth. What is the worth or value of an EV somebody creates out of a used car? People value different things, but for a vehicle, people generally ascribe worth in terms of reliability, maintainability, safety, appearance and style, utility (payload, range, etc.), convenience, operating cost, projected life, support network, etc. "Value for money" means how much worth would people think it had compared to competing vehicles on the market, in other words, would it be a good deal to buy one, compared to other vehicles one could get? Consider what price you would have to ask for it, including the parts and labor you put into it, because that would affect the “for the money” part of the “value for money” calculation. An indicator of whether people think an EV-built-in-a-used-car would provide "value for money" is the current level of demand for used cars turned into EVs. Are there a lot of people looking for these on the market? Or would building one just be a hobby? Repairing an existing EV, bringing it back into spec, might create better value for the money. Although demand for EVs is reportedly down recently.
  • ToolGuy Those of you who aren't listening to the TTAC Podcast, you really don't know what you are missing.
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