Any thoughts on this USB-powered RCR123/RCR2 charger?

fyrstormer

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orbtronic com/batteries-chargers/cr2-ultra-compact-usb-battery-charger-2-li-ion-rechargeable-cr2-batteries-kit

I came across this while looking for a RCR123 charger that I could plug into a solar-charged battery pack with USB charging ports built-in. This was the only charger of the sort I could find. The picture shows it holding a pair of CR2s, but there are apparently screw-on size adapters that attach to the positive terminals in the charger, and those can be removed to allow it to charge RCR123s as well.

On the one hand, it looks like typical off-brand Chinese electronics. On the other hand, just the fact that some company thought to make this impresses me. Has anyone else ever seen it, or had the chance to use one? Any reason to think it might turn my batteries into blasting caps?
 
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Joe Talmadge

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The charger smarts are in the part that holds the bays, and the wall/car warts are just for power, right? So theoretically you could run it off any compatible USB power source?
 

space-cowboy

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The charger smarts are in the part that holds the bays, and the wall/car warts are just for power, right? So theoretically you could run it off any compatible USB power source?

You are right.

I think Xtar is trying to target people with laptops, PCs, power boxes....go mobile. You do not depend on power grid at all.
 

space-cowboy

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Excellent. I don't feel so nervous about buying two kits then. :D This should go nicely with my solar-charged battery pack.

Living in SUNSHINE state, and not being into solar is pretty embarrassing for me :)

A few companies are going bankrupt, maybe it will be something for me.
 

walterr839

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I have seen a small single cell changer unit from Cottonpickers that is USB powered.
several models with charge rates from about 90 ma up to 680 ma and I understand
they just released a new version that goes up to 1200. there is a versions with a digital
voltmeter as well.

Anybody else have experience with this unit?
 

space-cowboy

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He is using TP4054 which is excellent idea (simple)

Pros:

CC/CV provided by TP4054 IC
Voltage display

Cons:
No protection against accidental short circuit (you will destroy charger if those two charging wires get in contact). With magnetic ends that would be easy.
Not a good termination.

This guys is on the right path, but further development (safety features) needs to be done.

If he wants to go commercial, then host, and other improvements will drive price well above Pila.
 

shadowjk

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with "Not a good termination", do you mean the magnetic wires, or do you mean termination of charge? Because the charge termination according to datasheet seems sensible, CC at configured rate until 4.2V, CV until configured rate / 10.
 

Joe Talmadge

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It properly terminates the charge, I'd suggest he means the leads.

I think the danger is real, but easily managed by strictly following the right process. Get a charger with the little voltage display. Before you plug the charger into a USB port, hook the magnetic leads up to the battery. If you hooked it up correctly, the voltage display will turn on. Now plug the charger into a USB port. With the strength of those magnets, I'm not particularly worried that they'll fall off and short. The wrong way to do it would be: plug charger in, then hook up leads to battery -- too many possible bad outcomes
 

fyrstormer

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If I can inject some engineering expertise...

Any charger that uses magnetic contacts attached to loose wires needs to have the magnets opposed to each other, so the same pole of both magnets is facing outward to contact the battery, and the remainder of the magnet and the solder joint needs to be covered with heatshrink tubing. That way the exposed metal surfaces of the magnets will never willingly touch each other.
 

jasonck08

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If I can inject some engineering expertise...

Any charger that uses magnetic contacts attached to loose wires needs to have the magnets opposed to each other, so the same pole of both magnets is facing outward to contact the battery, and the remainder of the magnet and the solder joint needs to be covered with heatshrink tubing. That way the exposed metal surfaces of the magnets will never willingly touch each other.

Hmmm the USB chargers I've used never have a problem with the leads shorting. I've left them shorted for hours.
 

127.0.0.1

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I have seen a small single cell changer unit from Cottonpickers that is USB powered.
several models with charge rates from about 90 ma up to 680 ma and I understand
they just released a new version that goes up to 1200. there is a versions with a digital
voltmeter as well.

Anybody else have experience with this unit?

yes and cottonpickers chargers are awesome. he also sells solar usb charger panels

he does not recommend his with the LED voltmeter in combo with the solar panel because
of course, the LED circuit robs power that could go to charging, so he recommends one of
his non-display versions

cottonpickers has the worlds best coverage plan...no matter where you got one of his chargers
or what is wrong with it, he is happy to replace it if it goes sour. I own 7 cottonpickers chargers
3 basic no display, and 4 with LED voltmeter.
---
I also have an Xtar charger... and it too just plain works, and works well.
 
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space-cowboy

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Excellent. I don't feel so nervous about buying two kits then. :D This should go nicely with my solar-charged battery pack.

Yes, That Xtar charger should go just fine with your battery pack.

Guys I though that this thread is about this Xtar MP2 charger.

Am I wrong?
 

fyrstormer

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If he left the magnetic leads shorted together while the charger was plugged in, then he got lucky and the charger has a circuit breaker inside.

Anyway, the charger arrived a couple days ago, and it works very well. And yes, it is an Xtar.
 

Joe Talmadge

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If he left the magnetic leads shorted together while the charger was plugged in, then he got lucky and the charger has a circuit breaker inside.

That was the point I was going to make. If the charger isn't plugged in, letting the magnets touch isn't a big deal. If it is plugged in, letting the magnets touch is a bad idea -- which is why Cottonpickers recommends hooking the battery up FIRST, then plugging it in.

Your comments about having both north or south poles face each other seems incredibly simple, can't believe I didn't think of it! Cottonpickers magnets are N-S -- they stick to each other pretty hard if there's no battery between them
 

fyrstormer

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I'm one of those engineers who's better at explaining things to my mom than to other engineers. It's just a different mindset. Simple solutions come pretty easily to me.

Cottonpicker's magnetic charger leads are probably N/S because that makes it easy to keep them neat and organized when not in use. N/N or S/S would be more complex -- however, if the wires are soldered onto the sides of the magnets instead of the back ends, then the unused leads could still stick to each other in an N/S arrangement when not in use, so long as the back ends of the magnets are insulated to prevent electrical contact. It would be quite easy to do this using a jar of Plasti-Dip as the insulating material instead of heatshrink tubing.
 
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space-cowboy

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Neodymium permanent magnets (NdFeB) are composed of neodymium, iron, boron.
These magnets are extremely strong, and will stick to each other with pretty powerful magn. force.


That was my whole point.


I am not worried about shorted leads when charger is not under power.


Shipping charger back to UK from USA is not cheap anymore.
 

space-cowboy

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