Bare, unshielded battery pins on extra connector. No thanks!
344810
Yikes. I bought a similar board to this a while back and ordered this one thinking it would be the same. The board I received does not match the board in the pictures, as it has an extra Deans connector below the 6 XT60 connectors. The pins on this extra connector are bare, which means that depending on what batteries I'm charging, there will be between 8 and 25 volts present on these completely unshielded pins. A shock from these pins probably wouldn't be fatal, but isn't the kind of exposed voltage source I want laying around, either. If these pins somehow got shorted while a battery was connected it would definitely start a fire. I suppose I could desolder this connector and somehow block off the holes it will leave in the board, but that shouldn't be my job so I'm just going to return the board instead. I know it is for attaching another parallel board in sequence, but I don't really have any interest in doing that. That's why I bought a 4 port charger, after all. Amusingly enough, the board I ordered previously shows the pins in the picture, now that I look at the listing again, but does not have them on the physical product. Go figure.
3364434
connectors to the battery inside are cheap and broke very quickly.
2599639
Could do without.  Charger is so so, worst part one of the batteries were fried!
3262749
I just got two of these. Both of them have the exact same design flaw: a battery compartment with inadequate means of securing the battery! No matter how hard I pushed on the things, they would not stay put, and as soon as I closed the door (which has this weird little plastic latch that looks like it'll snap off if you so much as look at it the wrong way), the battery slid out of place by about a millimeter and cut the power. If I tilted or shook it right, the battery would make contact again and the unit would chirp, but it would never stay put. Definitely not about to trust my life to something that can't even get the battery to stay secure.

NOTE: I used to have one of these that I got physically in a store. It had the front-open battery compartment like you see in the picture. The two I got have a rear-open battery compartment that is a pain to open and is all but impossible to secure without jamming something in there (and who wants to do that)? Buyer beware. Returning both of these.
2026883
I don't have to plug it into the power outlet anymore! The battery actually works! Just have to open the unit once more and attach the battery to the side with two-sided scotch tape. I missed that step before I assembled everything and now the battery rattles around in there.
1086635
As I worked on an old car, I kept removing and reconnecting the negative battery cable. I bought this switch to allow me to quickly and easily disconnect without having to use tools again and again. The price seemed right and I figured that it was a straightforward design, so quality couldn't matter too much. However, I was disappointed when I tried to install the switch. The post on the switch designed to mount the battery cable is smaller in diameter than a standard battery post. As such, I cannot tighten the battery cable onto it. The switch's post has a hole in it so one COULD mount a battery cable with flat ends (eye terminals), but there is no way for me to use this as designed with the existing standard battery cable. MAYBE newer battery cables have more adjustability and might work with this, but it is not like my car has an odd sized cable, it is just old. I haven't yet decided how to address this issue, but at a minimum, the switch is not usable out of the box by me for my car.
256319
I used EBL rechargeable batteries (sold here on amazon), and the + sides of the batteries did not make connections at two different locations. I had to use solder to extend the nubs on the + connectors inside the battery case so that it actually worked. There's only two things this battery holder has to do: (1) hold the batteries (2) make electrical connections. Score: fail. If they tested these on more than just Duracell batteries (if they tested it at all) they would have realized that they could shorten the springs that hold the batteries in and extend the metal extrusions on the + side so that this could fit any regular AA battery. For $10 I think that's not asking too much.
1355471
Charger is complete garbage, and that's right where i put it. Only two ports out of four indicated charge, USB plug-in connection was intermittent at best, battery plug-ins fell out if you just moved or touched them.  Good luck getting any use out of that device.  I've received two other usb "chargers" like this, and they've all been useless.  Better to get the individual usb cable adapters and connect them to a regular multi-port usb charging device.

The batteries themselves all took and held a charge, but the size of the batteries is *exactly* the same size as the 300 mah batteries I was hoping to replace (see the attached photo, the 380 mah battery I received is the blue one on top).  Run times seem equivalent to the 300 mah batteries as well.  I am doubtful that these are actual 380 mah batteries.

In short, I received four working batteries, but not the ones specified, and not with a working charger.  I notice they've recently changed the product shipping out; hmm.  You pay your money, you take your chances here.
4044232
Ordered this to replace a phone battery.  Connector would not fit, even though the batter number the phone suggested
4947301
These arrived without the base, turn them over and you see the battery, no cover plate and no way to attach to the wall.  I purchased a single version at the same time and it had both.  The battery is visible and replaceable and therefor I wonder if it really is a ten year. (I saw no similar set up in the one pack version).  The three were loose in a larger-than-necessary box with no official first alert packaging.
3918805
Total junk!  The battery cover cannot be opened, even with the appropriate screwdriver (two guys tried).  As a result, it's useless.  Unfortunately, I waited too late to try to return it, but I hope that this helps someone else.  It may good IF you are ever able to get it open -- we could not
237063
The product looks alright. Arrived on time. When I opened the original box, I was surprised to see that both the battery connectors were missing. I can't even snap the battery. The product is useless with the connectors.
3269729
You could destroy your new gadget due to mis-matched connectors!  The plug on the included battery and the DSO Quad battery socket only interface one way, so this is not a user error.  I plugged the battery into the device, and quickly became suspicious when I felt part of the device warming, even though it was turned off.  I unplugged the battery immediately and did a web search and found this page: [...].  My device ended up not being harmed (afaik), but I reacted very quickly.  Damage *will* happen if you leave it plugged in the wrong way.

In short, the polarity of the battery & plug can be mismatched with the polarity of the DSO's socket.  There is an easy way to fix this.  First determine if your battery connector is indeed wrong, following the guidance in the above link.  Next, examine the plug on the battery wires, and you'll notice two plastic flaps that can be lifted up (with some pointy tool; I used a pen razor).  When you lift the flap up, you can remove the leads.  Swap and re-insert them, and you should be good to go.

This is an incredibly huge mistake, and I'm amazed that it hasn't been corrected yet (reports of this started over a year ago).  Combined with the fact there are actually no included instructions on how to even open the case and insert the battery, my initial impressions were very low.  However, having started to use it, it seems like a pretty nifty tool, and there's not much else on the market like it, so it still deserves some stars.

** Update **
It appears that my unit is indeed fried.  The battery will not charge now, and the red light says on even when turned off and usb is disconnected.
88842
This replacement battery slips into my old Panasonic EY503 Drill and Driver and functions well, BUT, it is impossible to remove with my fingers for charging.  The old batteries do not have this problem.  The battery is removed by pinching the two "ears", but the new battery will not come out.  The only way to remove the new battery is by using a small C-clamp over the "ears" and yanking hard to pull it from the driver.  It appears the locking tabs will have to be filed down to ease the removal process. This is unacceptable and I will be contacting Amazon concerning this issue.
4371629
Not for pros. Metal connectors/plastic sleeve below that. Guess which broke almost immediately?
3179374
1Battery doesn't  insert correctly into battery slot I got one battery looks like a terminal is bent but that battery works and inserted correctly !!????  I'm typing this from work don't have a pic to post otherwise I would
2457507
TL/DR: physically defective, connector pushed right into the casing with the slightest touch!!!! And: kudos for Amazon for a very simple return process (pending confirmation - I *just* submitted the request, but if all goes as stated, yes - thank you for an easy return process).

I'm not one who returns things very often at all. Minor defects don't bother me. I doubt I would've wasted time to complain if this battery had died a year or even 6 months from now, if it had a nick or two, was finicky/tight/loose, smelled funny, etc.... Put in a review, maybe, but not return immediately (well, after creatively swearing at it). No, it takes a serious issue - not a "defective user" or RTFM problem - for me to return anything, let alone spend any time publicly explaining why, and always after a normally-exhaustive process of ensuring I was not simply stupid somehow. It happens. But not this time. It proved defective almost instantly. The battery, that is, not me.

My old laptop is 5+ years old. No real surprise its battery finally bit the dust (if anything, I'm surprised it hadn't happened a long time ago). It's a bit large, an ASUS G53SX "gaming" laptop, that weighs more than a dachshund, and looks like a stealth bomber. As an aside, I didn't buy it so much for gaming as I did to use it as a VM "lab" of sorts, as it's powerful enough to run 5 or 6 virtual machines at the same time with very little resource contention - and I'm a database administrator by profession; it comes in handy to try things out that require a simulation of multiple machines connected to each other. Yeah ok... gaming... is a nice bonus, of course. :) Anyway, the laptop itself still outpaces almost anything on the market now, at least for my primary purposes, so I didn't think for a second about replacing it.. just the battery. I was happy when the new battery arrived.

That lasted less than three minutes.

I popped it into the laptop. I powered it on immediately just to make sure BIOS & Windows would at least acknowledge its presence (knowing full well it needs to fully charge before the battery itself is of any actual use). Nope... "No battery is detected." I pulled it out, figuring maybe it was something, dust or what-not, on the connector.

Nope, nothing "on" it. But the connector looked like it was slightly pushed in. Nah, I'm just imagining that, right? I mean, how often do you actually LOOK at the battery's connector? Maybe it's perfectly normal. "Hey, I'll prove it - lemme just try to nudge it a bit, I'm sure it won't budge even if I lean on it." With the absolute lightest of pressure - as in, a gerbil could've done it - I was able to push it in completely, as if it's not even connected to anything inside the casing.

Now, I know a few things about a few things, and a lemon battery isn't totally unusual. Old/deteriorated cells (maybe it sat on a shelf for a year or four, waiting for someone to buy it), corroded contacts, even a warped plastic casing if it ended up sitting in the wrong place for too long... it happens. If it had been something like this, I'd just ask for a replacement, not a full "no way in [extreme sauna] do I want another one" refund.

But this?????? A physical defect so apparent, never mind inspection of the individual product, there's NO WAY some machine (or person) involved in its assembly wasn't noticeably faulty??? This is not a "stuff happens" incident, it's an incident of complete incompetence by whomever assembled it. In short, my one-star rating for the battery a) would be 0 stars if possible, b) and applied to the manufacturer of this battery as well.

5-stars to Amazon's return process though, I must say.