LEGO® Power Functions AAA Battery Boxproduct_label_list_price_accessibility 23 Reviews121FIND MORE PRODUCTS LIKE THISTrainsEnergize your creations with even more power! Sign up or log in to customize your list. Here's how it works: Anybody can ask a question The best answers are voted up and rise to the top For those who have tried, which one is a better option: Rechargeable Battery Box and Transformer/Charger 10VDC ($50 + $25) AAA Battery Box and a lot of AAA batteries ($13 + ?) Obviously $75 is more than $13 + $5 for batteries, but they wear out and the train's speed starts to slow down, before you want to change the batteries. If I spend $75, what other benefit would I get other than not buying batteries? sets shopping trains power-functions The main benefit is consistent performance. The rechargeable battery puts out almost the same voltage until it's almost flat, and whatever current is required with little voltage drop. Disposable batteries have more voltage, but cheap ones can't supply much current.
Expensive ones can supply the current, but cost more. You'd be lucky to get 5 sets of those for the cost of a rechargeable battery. Note that the IR controllers / receivers limit the output voltage to 9V and the current to what the motors can cope with,so there's a limit to how much performance you can get out of the system. But disposable batteries will sit at 9V at least initially, where the rechargeable battery will drop from nearly 8V to 6V as it discharges. If you buy expensive lithium single-use AAA batteries they will cope with the high currents demanded by the Lego motors for longer, so you will get better performance than any other option, but at considerable cost. This thread on Eurobricks has a lot of detail, and there's more here The third option is to build your own battery packs. Either just by plugging "random" batteries into the IR receiver, or by modifying a Lego battery pack to take different cells. It's apparently fine to put three lithium rechargeable cells in series into one, or 8-9 NiMH ones.
If you start with a 6AA battery box it's easy to fit 8 AAA NiMH cells in, or either box can be modified to accept three LiIon cells (you need the right size cells, obviously). Some of the Technic builders are just making packs with three 18650 cells and not worrying about making it look like Lego, but there are quite a few who build extra cells into official battery packs. Obviously, if you want to use the train a lot, you will want to use a rechargeable option. You didn't explicitely address this in your question, but even with AAA batteries, you can either use disposable batteries or rechargeable ones. The cost of using disposable batteries can very fast become prohibitive, but rechargeable ones tend to cost more upfront (especially if you need a charger as well). Even there, you have several options, including "stay-charged" batteries which you may want to consider if you need the train to be available as soon as you want it instead of having to recharge the batteries prior to using it, which can take a long time especially if you don't have enough chargers for all batteries at the same time.
So the first thing is to consider if you're already using rechargeable batteries for other things - if you already have a good charger or two and enough AAA batteries, you'll of course want to start with that and judge if it's enough for you. If you don't have any chargers or batteries, then I'd recommend to start with the official LEGO battery right away, as the cost difference won't be that high. Of course, if you're somewhere in between (say you have chargers but no AAA batteries), you'll have to ponder which route is better. Another factor which may influence you is the convenience. Using AAA batteries and chargers can be cumbersome (again, especially if you've not enough chargers to charge all 6 batteries at the same time), and even the action of swapping the batteries in the battery box can be annoying. The LEGO battery doesn't need to be removed, usually just removing the train roof is enough. All in all, I prefer the official LEGO battery; note that you could spare some money on the charger if you manage to find one which is compatible (although it's officially not recommended).
As for the battery box itself, either you buy a motorized train and you get one with it; either you want to motorize another train and then it's probably worth it to buy the basic city train anyway to get all electrical parts rather than buy them separately (since you get motor, receiver, battery box, remote control, and tracks, it's usually a better deal even without considering the rest of the parts). Sign up or log in Sign up using Google Sign up using Email and Password Post as a guest By posting your answer, you agree to the privacy policy and terms of service. Not the answer you're looking for? Browse other questions tagged sets shopping trains power-functions or ask your own question.I think there are five reasons. This is what I believe, not necessarily true but it is not very likely that the whole truth would be divulged for commercial reasons.1) Reliability of 9V Manufacture. It seems the 9V rail attachment machines were no longer reliable enough for all pieces of track.
As an example, I had to have 3 points replaced because the ends of the rails did not match up with the ends of the plastic parts they were attached to. This meant the metal parts were either loose, protruding, receded or didn't make a good enough electrical connection to the next track piece. Replacements mean the financial return is almost halved for the parts that go wrong; this would not have been sustainable for the company so I guess a decision had to be made whether to renew some machinery or change the system. I guess the machinery had reached its design life anyway.2) Starting Age. Ever since the 1980s system changed to 9V, there has been a desire for kids to be able to start earlier with LEGO trains e.g. a direct transition from Duplo trains. I started with blue rail 4.5V on my 5th birthday but the 9V system with transformer was really for 6+. With the 1980s system kids could have push-along to begin with, 4.5V battery at 6+ and 12V transformer at 8+. This is similar with Power Functions - push-along 4+, AAA batteries 6+ and LiPo batteries for older kids and adults.
The AAA and LiPo batteries fit with the whole Power Functions concept across all themes so the outlet for the parts is not exclusive to the Trains theme and this helps to sustain them.3) Parts Range 1. As the adult fan community has grown, we have been more vocal in asking for more adventurous rail parts e.g. wider radius curves, crossovers, Y-point, double-slip. Quite a few of us would like to make a proper model railway out of LEGO so we need the real-shaped rail parts to do it. Plastic-only rails make this much easier. Some rail modifications have been most impressive by being fully-electrified but more people can have a go at customising rails if there is no electrical connection to worry about.4) Parts Range 2. Descending from reasons 2 and 3, a piece that facilitates younger children getting into LEGO trains is the flexi-track. This enables a child to make a circuit every time. In theory it also allows adults to make any radius they like but it is not so popular with adult fans, partly because of the check rails;
these help keep the train on the track at all angles but look out-of-place for a proper model railway except on the sharpest curves and bridges. The technology became available to do an infra-red receiver and a LEGO LiPo battery so that adult fans would have something better than (heavy) AA or modest-current AAA batteries to power a train. For the Trains theme to remain viable it was important for the adult market to support it; even though adult fans are only a small proportion of the total LEGO market they make up a larger proportion of it for Trains. The LiPo battery gives up to 800mA before the current trip kicks in. Even then it will try to restart the train. The V2 IR Receiver can drive 2 train motors; it was designed to drive 2 L-Motors in Technic Crawler 9398.Unfortunately some adult fans have trains so heavy that they need more than 2 motors, which is where we revisit the question from the AFOL point of view. Whilst it would be just 2 motors per engine, it is important to control all the engines together.
The theory is that each engine with its IR Receiver on the same channel would be fine with that but tunnels or the larger distances involved at exhibitions could cause a problem of derailment if only one engine received the speed command. This is why a slave H-bridge motor driver module is needed - driving many motors from a single IR Receiver. This was much easier with the 9V system even though a bench power supply or high-current regulator would be substituted for the 300mA 9V controller.At the moment the LiPo battery needs a plug to charge it. This needs to move towards inductive charging - stopping the train over a pad between the rails.These issues mean I still have reservations about Power Functions on the main line but I have built two shunting & trip-working engines with it. I have committed to making it work as best I can and sharing this with the community. I just hope Power Functions lasts a lot longer than the 12V or 9V systems lasted as new products because it is taking longer for adult fans to really get into it for trains.