Blast Your Battery’s Sulphates, Is It Worth It?

When a friend finds her caravan’s deep-cycle battery manager has expired over the summer, and her holiday home on wheels is without its lighting and water pump, what can you do? Faced with a dead battery with a low terminal voltage in your workshop, check its electrolyte level, hook it up to a constant current supply set at a few hundred mA, and leave it for a few days to slowly bring it up before giving it a proper charge. It probably won’t help her much beyond the outing immediately in hand, but it’s better than nothing.

A lot of us will own a lead-acid battery in our cars without ever giving it much thought. The alternator keeps it topped up, and every few years it needs replacing. Just another consumable, like tyres or brake pads. But there’s a bit more to these cells than that, and a bit of care and reading around the subject can both extend their lives in use and help bring back some of them after they have to all intents and purposes expired.

One problem in particular is sulphation of the lead plates, the build-up of insoluble lead sulphate on them which increases the internal resistance and efficiency of the cell to the point at which it becomes unusable. The sulphate can be removed with a high voltage, but at the expense of a dangerous time with a boiling battery spewing sulphuric acid and lead salts. The solution therefore proposed is to pulse it with higher voltage spikes over and above charging at its healthy voltage, thus providing the extra kick required to shift the sulphation build up without boiling the electrolyte.

If you read around the web, there are numerous miracle cures for lead-acid batteries to be found. Some suggest adding epsom salts, others alum, and there are even people who talk about reversing the charge polarity for a while (but not in a Star Trek sense, sadly). You can even buy commercial products, little tablets that you drop in the top of each cell. The problem is, they all have the air of those YouTube videos promising miracle free energy from magnets about them, long on promise and short on credible demonstrations. Our skeptic radar pings when people bring resonances into discussions like these.

So so these pulse desulphators work? Have you built one, and did it bring back your battery from the dead? Or are they snake oil? We’ve featured one before here, but sadly the web link it points to is now only available via the Wayback Machine.

Cheap Electric Car Drives Again with Charger Repair

If someone sent you an advert for an electric car with a price too low to pass up, what would you do? [Leadacid44] was in that lucky situation, and since it was crazy cheap, bought the car.

Of course, there’s always a problem of some kind with any cheap car, and this one was no exception. In this case, making it ‘go’ for any reasonable distance was the problem. Eventually a faulty battery charging system was diagnosed and fixed, but not before chasing down a few other possibilities. While the eventual solution was a relatively simple one the write-up of the car and the process of finding it makes for an interesting read.

The car in question is a ZENN, a Canadian-made and electric-powered licensed version of the French Microcar MC2 low-speed city car with a 72 volt lead-acid battery pack that gives a range of about 40 miles and a limited top speed of 25 miles per hour. Not a vehicle that is an uncommon sight in European cities, but very rare indeed in North America. Through the write-up we are introduced to this unusual vehicle, the choice of battery packs, and to the charger that turned out to be defective. We’re then shown the common fault with these units, a familiar dry joint issue from poor quality lead-free solder, and taken through the repair.

We are so used to lithium-ion batteries in electric cars that it’s easy to forget there is still a small niche for lead-acid in transportation. Short-range vehicles like this one or many of the current crop of electric UTVs can do without the capacity and weight savings, and reap the benefit of the older technology being significantly cheaper. It would however be fascinating to see what the ZENN could achieve with a lithium-ion pack and the removal of that speed limiter.

If your curiosity is whetted by European electric microcars, take a look at our previous feature n the futuristic Hotzenblitz, from Germany.

Save a Couple Thousand Dollars with a DIY Remote Lighting System

When you don’t need the durability of a professional system, this DIY remote lighting system will do.

Pelican makes a great remote lighting system. Unfortunately, it’s the kind of great that comes with a “Request Quote” button instead of “Add to Cart”. It’s designed to be thrown in the back of a tank and guaranteed to work at the end of the day. [mep1811]’s system is not that system. It’s the store-in-a-Rubbermaid-tote and throw in the back of the family Honda kind of great, but it’s made from stuff you can buy anywhere.

The build is contained by a water resistant plastic box. Two sealed lead acids and a battery charger sit inside. The system is hooked together with simple car outlets — also known as the worst accidental electrical connector standard of all time. For the lights, [mep1811] simply made mounts for chinese LED spots and bought some inexpensive camera tripods. With a full charge, he says it runs for forty hours.

In the end it’s not a complicated hack, but its simplicity adds a certain amount of ruggedness, and it will definitely do the trick in a power outage.

Hacklet 39: Battery Power

3296371398740598106[robin] has a Red Camera (lucky!), an absurdly expensive digital video camera. As you would expect the batteries are also absurdly expensive. What’s the solution? Battery packs from cordless drills.

Cordless drills are interesting pieces of tech that can be easily repurposed; there are huge battery packs in them, big, beefy motors, and enough hardware to build an Automatic Cat Feeder or a motorized bicycle.

What if those old Makita batteries don’t charge? That usually means only one or two cells are dead, not the whole pack. Free LiIon cells, but you need to charge them. Here’s a single cell charger/boost converter that will do the trick.


A problem faced by amateur radio operators around the world is the lack of commercial power. Plugging a portable shack into a wall will work, but for uninterrupted power car batteries are everywhere. How do you combine wall power and car batteries for the best of both worlds? With an In-line battery backup module.

9k=All of the projects above rely on charging a battery through wall power, and sometimes even that is impossible. Solar is where we’re headed, with solar LiPo chargers, and solar LiFe chargers. That’s more than enough to keep a smartphone charged, but if you want to go completely off the grid, you’re going to need something bigger.

[Michel] has been off the power grid 80% of the time since he installed his home PV system a few years ago. How’s he doing it? A literal ton of batteries, huge chargers, and a 5kW inverter.


An Interview with Tesla Battery Hacker [wk057]

We covered [wk057] and his Tesla Model S battery teardown back in September. Since then we had some time to catch up with him, and ask a few questions.

You’ve mentioned that you have a (non hacked) Tesla Model S. What do you think of the car?

It’s the best car I’ve ever driven or owned, period. Not to get too into it, but, I love it. I’ve put almost 20,000 miles on it already in under a year and I have no real complaints. Software feature requests… but no complaints. After almost a year, multiple 1700-miles-in-a-weekend trips, and an overall great experience… I can never go back to a gas vehicle after this. It would be like going back to horses and buggies.

A salvage Tesla Lithium battery had to be expensive compared to a Lead Acid setup. What made you go with the Tesla?

Actually, if you consider that the Model S battery is already pre-setup as a high-capacity pack, contains the wiring to do so, and the modules are much more energy and power dense than any lead acid battery bank, it’s actually almost cheaper than a comparable lead acid bank and all the trimmings.

I haven’t officially weighed them, but the modules from the Model S battery are roughly 80 lbs. 80 lbs for a 5.3 kWh battery is around 15 lbs per kWh, which is impressive. For comparison, a decent lead acid battery will have a little over 1 kWh (of low-rate discharge capacity) and weigh almost the same.

Also, the Tesla pack is much more powerful than a lead acid bank of the same capacity.
Generally a lead acid battery bank would have a capacity that would only be realized with slow discharges, so, 1/20C. Much over that and you sacrifice capacity for power. 1/20C for an 85kWh pack is only 4.25kW, barely enough for a central air unit and some lights without losing capacity.

Now the Tesla pack can be discharged (based on how it does so in the vehicle) at up to 3.75C for short periods, and at 1/2C continuously without really affecting the overall capacity of the pack. That means I can run 10x more power than lead acid without a loss in overall charge capacity. Leads to a much more flexible battery solution since the loads will, in reality, always be so low that this will not even come into play with the Tesla pack, but would almost always be a factor with lead acid.

Charging is also somewhat better with the Tesla battery. Charge a lead acid battery at a 1/2C and it will boil. Charge the Tesla pack at 1/2C (42kW) and it might warm up a few degrees. Oh, and the charging losses at high rates are much less than lead acid also.
Overall, without continuing to yack about the technical aspects, it’s just a much better battery, takes up less space, weighs less, and has more power available.

There are likely decent arguments for other solutions, but the rest aside, this one won out because it was definitely more interesting.

Click past the break to read the rest of our interview with [wk057]!

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Electric BMX Has Pedals That Can’t Be Pedalled


We don’t mind it that there’s no chain connected to these pedals. At least there’s still somewhere to put your feet and our legs are too long to comfortably pedal this size of bike anyway. As you can tell, the added hardware takes care of locomotion using an electric motor.

The first step in this project was to find a steel bike frame to make welding a bit easier than it would be for aluminum. From there the paint was sanded at the attachment points and mounting brackets were fabricated from some angle iron. The rear mount houses a 500W 30A AC motor which uses a chain to drive the rear wheel. A specialty hub was found which allows the added sprocket to be installed on the left side of the rear wheel. Some threading issues prompted [Michael Monaghan] to come up with a method of adding a slot to lock the part in place.

Near the front fork the second mounting bracket holds the batteries; a pair of sealed lead-acid units. The speed control mounts on the top where the rider has easy access to it. The finished bike can get up to thirty miles per hour with a range of up to twenty miles between charges.

If you want your own electric bike on the cheap you can try building one from a salvaged washing machine motor.

555-timer charges lead acid batteries


[Kenneth Finnegan] took the focus of a great design and redirected it to solve his own problem. What results is this lead acid battery charger based on the 555 timer. It’s not a top-of-the-line, all the bells and whistles type of charger. But it gets the job done with a readily available IC and no need to code for a microcontroller.

The original idea came from a solar battery charger entered in the 555 timer contest. The main difference in application between that and [Kenneth’s] application is the source. A solar array or wind turbine is limited on how much juice it can produce. But mains power can push a shocking (har-har) amount of current if you’re not paying attention. Herein lies the alterations to the circuit design. To control this he’s using a Laptop power supply as an intermediary and only implementing the constant current portion of the tradition 3-stage lead acid charging profile (those stages are explained in his write up).

He did a talk on the charger at his local radio club. You can see the 90-minute video after the break.

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