Doesn't charge batteries under 3V charge.
343241
My car battery was dead, sitting at 0.025 volts.  This charger wouldn't charge it, the instruction manual said it only charges batteries that are already charged to >3V.  That's right, a battery charger that cannot charge dead batteries.  I jumped instead.
2973520
Batteries work fine but the charger is incapable of charging two depleted batteries at once.  If a second battery is set in to charge, the screen flickers and eventually it turns itself off.  I've tried with a super thick USB cable and different plugs but no luck.  Shame I didn't use it enough to figure this out until the return window ended.  I would have sent it back...
2993123
Didn't recognize a run down nine volt and two d cell batt's  as needing a charge. I bought this as a way to recharge some alkaline batteries a few times... but it wouldn't even indicate the batteries were already putting out less than a fourth of their charged voltage ( said the batt's were o.k.) Wouldn't recommend.
3803111
Doesn't provide anough power via USB. RaspPi3 is very unhappy about voltage:

[ 2870.391684] Under-voltage detected! (0x00050005)
[ 2874.551432] Voltage normalised (0x00000000)
[ 2876.631483] Under-voltage detected! (0x00050005)
[ 2880.791415] Voltage normalised (0x00000000)
[ 2882.871614] Under-voltage detected! (0x00050005)
[ 2887.041457] Voltage normalised (0x00000000)
[ 2889.111481] Under-voltage detected! (0x00050005)
[ 2893.271470] Voltage normalised (0x00000000)
[ 2895.351482] Under-voltage detected! (0x00050005)
[ 2903.671570] Voltage normalised (0x00000000)
[ 2916.151649] Under-voltage detected! (0x00050005)
[ 2920.311481] Voltage normalised (0x00000000)

Spent the whole morning trying to organize power cables around this outlet just to realize that it doesnt fit my needs. Very frustrated, will test it for a week, and probably will return.

No speed charging either - my Pixel2 charges at the same speed as via regular USB.
2584593
This product does not work with all the batteries that I have to recharge although they all have the same identity.  I do not know if it is the battery charger that is the problem or whether it is the batteries.
2893808
It says in the description that it is good for gel and AGM batteries. But the unit itself does not have a way to set it to charge those kinds of batteries.
472630
I like the way it looks. I want to like it. But it doesn't charge batteries. Not most of my batteries, anyway. I used it for the first time a few days ago and have been trying to get it to work since then. I had eight rechargeable AAA batteries that needed recharging. Eight batteries, three different brand names. None had been in a charger before. Of the eight batteries, only two were recognized by the charger. Right now, I have four batteries in the charger, the charger is plugged in, and the display is dark. Pressing the discharge button does nothing. Holding the button down does nothing. If I swap one of these unrecognized batteries out with one of the two the charger does recognize (there's nothing special about these two -- there are others in the bunch that are the same brand as the two working ones and were purchased at the same time, have never been in a charger, and aren't recognized by the charger) then the display will come to life and show the location of that one fully charged battery, while indicating that the three other charging slots are empty -- even though they're not. I can move the batteries around. It still only recognizes two of the eight. I don't see how the problem could be with the batteries, so I have to assume the charger simply doesn't work.
2740413
<div id="video-block-R2O3TFADWB3LWI" class="a-section a-spacing-small a-spacing-top-mini video-block"></div><input type="hidden" name="" value="https://images-na.ssl-images-amazon.com/images/I/A1eXcRBWffS.mp4" class="video-url"><input type="hidden" name="" value="https://images-na.ssl-images-amazon.com/images/I/A1Zuxlht9oS.png" class="video-slate-img-url">&nbsp;The battery is pretty nice, but when I first tried to charge it the charger would not. My B6 charger reported that one of the cells had a voltage of ~1V and I had to override the shorted cell error a few times to get it to a reasonable voltage, after I got it above 3 volts it put a full charge on the battery and it's been working fine ever since. My friend was trying to return his battery of the exact same model from hobby king because it wouldn't charge so I checked his and one of the cells was at 0v, but after the same process its up and running (unbelievably). These batteries are not supposed to even be able to work after the cell goes below 3v so I have no idea how much their life span has been shortened if any at all but they are working good as far as I can tell right now. I gave 4/5 stars because technically there is no way to safely charge the battery for first use in the state that I received mine, but after bypassing safety features I got it to work which is all i really care about.

Also it comes in a fancy box with a fancy fabric bag
2070133
Doesn't charge AAA batteries. Charges for a minute or two then turns green indicating battery is charged...however they aren't.  Would not recommend this charger.
2781729
I purchased this to charge batteries on my model airplanes that use an electric motor.  It doesn't work.  The battery draw for charging  is only 1.5 amp so this must be made for really small devices that draw very little power.
3071796
Won't charge the battery of the Alienware, but it does allow it to turn on when plugged in. Would not buy again if I knew that the battery wouldn't charge.
2719525
Item is either defective, or not compatible with the phantom 3 professional charger. With 3 batteries plugged in only one charges.  I will be returning for refund.
2491203
This charger is designed to charge AA, AAA, and 9V batteries. I removed the charger from its container and tried to charge a pair of 9V batteries, but even after overnight the batteries were not charged.  I also tried AA batteries and it did not work.  I have an old AA and AAA battery charger and it worked fine.  This showed that it was not the charge indication lights that were faulty.
4725970
Plugged in (12V or 110V) or not, it will not charge an iPad.  Forget about it.  And it won't even charge an iPhone IV while you use it (must be standby/off).  The internal battery takes hours to charge.  This is unfortunate because this is a beautifully designed charger.  Great function.  Tight swivels.  Neat little battery status indicator. But the engineers completely undersized the power transformer within.  I'm so disappointed.  It's a beautiful paperweight.  The search for a GOOD do-all charger/battery pack goes on.
3101805
I used this power supply to charge my Lipo batteries for my RC planes.  This power supply worked fine when I was charging at 3A continuous.  However, the Voltage dropped to an unacceptable level when I tried to charge at 5A.  Even 4A did not work very well.
2633875
Bought 2 of these batteries for my ATV's. Both defective. I put a 1 amp trickle charger on the first one for 2 days with a charging voltage of 13.2 V. The battery would only charge up to 12.4 V. When I put it in the ATV, it wouldn't even turn the starter over.  Amazon replaced that one. Replacement ok. Charged to 13 V.  ATV starts ok. Put the second one on the charger for 3 days.  It initally charged up to 13v. I let it set for a couple of days and it's voltage dropped to 4.78 V. Tried to charge it again and my charger's LED went out, indicating a shorted battery. Sent email to seller.  See if they will back up their batteries. Not happy customer.
3093465
It charges fine but the light indicating the batteries are fully charged never comes on. You are guessing as when the batteries are actually fully charged.