Power Functions 7745 Advice Request

[roamingstop]

Speaking of battery boxes, hwow good is the lego-offered rechargable one?

That was my next task; but I went cycling instead ;-). Tueday, I need to recharge the battery box first. Note it is heavier than the PP3 so might generate more traction.

[roamingstop]

That was my next task; but I went cycling instead ;-). Tueday, I need to recharge the battery box first. Note it is heavier than the PP3 so might generate more traction.

Tuesday here; I replaced the PP3 / adapter with a Lego brand rechargable battery pack... A 1.3 hour recharge (red light stopped flashing), it has been running continuously for 3 hours (180 minutes) - and will probably keep going for much longer.

Hands down: PP3 is too weak!, but probably sufficient for short shunting options. Otherwise it is time to work out how to hide the rechargable battery box in older models; possibly in a way similar to 10219 Maersk Train.

[Sokratesz]

Tuesday here; I replaced the PP3 / adapter with a Lego brand rechargable battery pack... A 1.3 hour recharge (red light stopped flashing), it has been running continuously for 3 hours (180 minutes) - and will probably keep going for much longer.

Hands down: PP3 is too weak!, but probably sufficient for short shunting options. Otherwise it is time to work out how to hide the rechargable battery box in older models; possibly in a way similar to 10219 Maersk Train.

So the LEGO rechargable pack is really good for its size?

[martyboy70]

Again thanks for the (quick) replies.

If an engine and 4 carriages is an hour and you count the 7745 as an engine and 2 carriages you might reasonably expect to get an hour and a half or thereabouts and this would be ample I think.

As far as batteries go I have enough rechargeables for either option so the main concerns become price and size.

Looking at Ebay there are plenty of both available for around the same price so thats not really a factor.

As far as size goes the PP3 one would certainly be a lot better from a "stealth" point of view as with the AA one the IR box would be shoved right up to the window of the cab and be very noticeable-would it work reversed with the IR box at the rear of the engine and the battery box at the front- so I may go the way of the PP3 but then would have a bit more modification to fit connectors.

I read some reviews about the 8866 motor regarding what you said about fouling and causing derailment issues so I think it is definitely out.

Will my 12v track be OK with a PF motor?-I know its the same gauge.

Thanks for the offers to check for me guys but I cant ask you to spend your precious weekend time doing this.

I have a busy weekend ahead of me sorting out this lot:

Just in case anyone keeping tabs or contributing to this thread(thanks again to all who have)fancies seeing what a carpet covered in bricks turns into Ive started a new thread with pics here:

http://www.eurobricks.com/forum/index.php?showtopic=59517&st=0&gopid=1061428entry1061428

[hoeij]

My favourite set though was always my 7745 HST until I broke one of the wheels off the motor...

I looked into buying a new 12V motor from Ebay but they are very expensive...

A used 12V motor is probably not more expensive than the PF components. I've bought quite a few of them through bricklink and eBay, the price is typically below $50 (a brand new one costs a lot more, I've only bought used ones).

I think that I can repair your motor. I have a few spare parts coming from 2 broken motors that I combined into one working motor. It sounds like all you need is a spare axle, and I have one. To insert it, you'd have to open the motor at the bottom (that's not so easy, it takes a good bit of force). Let me know if this is something you want to try (if not, I'd be interested in your motor).

[martyboy70]

A used 12V motor is probably not more expensive than the PF components. I've bought quite a few of them through bricklink and eBay, the price is typically below $50 (a brand new one costs a lot more, I've only bought used ones).

I think that I can repair your motor. I have a few spare parts coming from 2 broken motors that I combined into one working motor. It sounds like all you need is a spare axle, and I have one. To insert it, you'd have to open the motor at the bottom (that's not so easy, it takes a good bit of force). Let me know if this is something you want to try (if not, I'd be interested in your motor).

Im in the UK and they seem to go for a lot here.

A MIB example I was watching sold for £185 at the weekend and even used examples go for more than the PF parts will cost me plus I already have the RC and IR components sitting here and I have ordered a 88002 from Bricklink for a good price tonight-just need a battery box now.

[roamingstop]

So the LEGO rechargable pack is really good for its size?

Most definitely; I stopped after 3.5 hours to go to so sleep; and will see how much charge is left tonight.

[martyboy70]

OK so things are coming together now.

I have in my possession or on the way the following:

PF Remote Control unit-Brand New

PF IR receiver -Brand New

88002 Train Motor -Brand New

8881 AA Battery box -Light Use

2500 mah Batteries -Light Use

Can I just confirm that this is everything I will need to power the train-am I right in thinking that I wont need any additional cabling or adaptors?

Edited August 31, 2011 by martyboy70

[Sokratesz]

That should be it yeah, but the 8881 battery box is awfully large, but I don't think one of the old 14stud ones works with the PF IR receiver.

- Sok.

[martyboy70]

That should be it yeah, but the 8881 battery box is awfully large, but I don't think one of the old 14stud ones works with the PF IR receiver.

- Sok.

Im planning on trimming it down a bit as the bits at either side can apparently be cut off as they are for technic pins and are not needed for this build so that will reduce it a little.

I have managed to get the 4 bits for about £40 and should be able to sell my transformer,large oval of conductor rail with supply wire and spares or repairs motor for more than this so "free" power functions but without the nostalgia factor of running on 12v.

I cant wait for the motor and battery box to arrive Im so looking forward to letting my son see it running.

Im going to do pics of the rebuild and a youtube video of it running when I get them.

[Sokratesz]

True, you can shrink it considerably with a hacksaw and a steady hand :)

But I'm afraid it'll still be too tall to fit in the loc of 7745. The interior is only 5(1/3) bricks high, with some extra space under the roofing. The battery box is roughly 7x7x4 studs if you cut away the side rails.

*edit I just did the maths and it might be possible to modify the roofing so that the box fits and only the orange on/off switch and the cable protrude above the roof line.

Apparently the LEGO rechargeable battery-box is really good (see posts above here), so while quite an investment it may be worth it for its compactness (4x4x8) and capacity.

- Sok.

Edited August 31, 2011 by Sokratesz

[martyboy70]

Oops is it really that big-oh well i may have to really butcher it then.

Ill get the screwdriver out when it arrives.

Has anyone disassembled one into its component parts without the casing as I really dont want to go out and buy AAAs when I have really good AAs sitting in my drawer.

[Sokratesz]

makes a comparison between various LEGO battery boxes but the rechargable one actually sounds pretty bad according to his specs (1100 vs. 2450 mah), so I'm not quite sure what to make of it.

- Sok

[hoeij]

makes a comparison between various LEGO battery boxes but the rechargable one actually sounds pretty bad according to his specs (1100 vs. 2450 mah), so I'm not quite sure what to make of it.

- Sok

The specs of the 8878 are good, it can deliver plenty of amps, probably more than the substantially larger AA-battery box, and that makes it very good for lego technic constructions. Of course, a train with a AA-box will run longer on a single charge than the 8878 (a content of 2450 versus 1100 mah), but either way a train will run pretty long on a single charge.

All of this is moot anyway, as cost considerations for the poster rules out buying 8878. The battery box with 6 AAA batteries is cheaper than 8878 and has the same size, but the poster had no AAA rechargeable batteries, so that makes the AA box cheaper for him. I don't think that the AA box will fit though, but perhaps he can make some modifications.

My charger for rechargeable batteries can handle both AA and AAA size; my advice would have been to buy the AAA-box and then buy rechargeable AAA batteries. That way, you can use the same components if at some point in the future you decide to buy another train.

Edit: I mistakenly wrote 8886, that should have been 8878 (changed now).

Edited September 1, 2011 by hoeij

[martyboy70]

Yeah cost is a big factor so buying £60 worth of battery and charger is a definite no-no and I would like to use the batteries I already have.

I've just had another thought and thats about lighting.

Looking at the IR receiver the PF system uses four wires and the 12v lights only use 2-I plan to cut one end off one of the grey 12v splice the lights onto the wire between the battery box and the IR unit-so does anyone know which of the four wires is which.

[Sokratesz]

Yeah cost is a big factor so buying £60 worth of battery and charger is a definite no-no and I would like to use the batteries I already have.

I've just had another thought and thats about lighting.

Looking at the IR receiver the PF system uses four wires and the 12v lights only use 2-I plan to cut one end off one of the grey 12v splice the lights onto the wire between the battery box and the IR unit-so does anyone know which of the four wires is which.

The lights should work fine on 9v, a bit dimmer than usual but hey.

[martyboy70]

The lights should work fine on 9v, a bit dimmer than usual but hey.

Brilliant thats exactly what Im looking for I think.

The bit dimmer should be ok as I read somewhere that running the lightbricks at lower voltage is better for their longevity.

[roamingstop]

Brilliant thats exactly what Im looking for I think.

The bit dimmer should be ok as I read somewhere that running the lightbricks at lower voltage is better for their longevity.

If you are going to hack up your box... and are happy with a little tin foil and stiff cardboard... / bolsa wood + glue.... I would recommend making a custom wire to connect the batteries in series to 9V and GND; run this wire into the PF receiver. The recevier will then generate the necessary C1 and C2 signals for ports A and B... you can then make this fit inside the wagon in a easy to replace way.

Good luck

[roamingstop]

Most definitely; I stopped after 3.5 hours to go to so sleep; and will see how much charge is left tonight.

I got another 50 minutes from the battery pack this evening; total over 4.5 hours....

[Toastie]

Most definitely; I stopped after 3.5 hours to go to so sleep; and will see how much charge is left tonight.

Folks,

this topic has discussed "7745 advices", "how well does 8878 perform", and also "cost" issues.

Here are my 2 cents on 8878 ... maybe off topic; 7745 was the original post (8886 is the PF extension cable ... I guess this reference may be in error?)

8878 is indeed rather powerful and - if you'd ask me - quite sophisticated with respect to performance. As already pointed out in this thread, TLC is asking for a serious amount of money. Let me re-iterate a couple of thoughts, you may want to check out this thread and RailBricks Issue 7 as well.

1. 8878 incorporates a Lithium Polymer (LiPo) based rechargeable battery pack. LiPo's don't show any noticeable fatigue over time; once charged, they keep that charge for the longest time, as compared to most other types (NiCd, NiMH, ...) In addition LiPo's have a fortunate mass to charge ratio.
   
2. 8878 incorporates a powerful charging circuit as well. You simply don't need the LEGO power supply - just use plain vanilla 9 ... 18 V DC power supplies to charge 8878, it works.
   
3. That said, 8878 makes entirely sense, even at that cost, when you consider charging "on the fly" [e.g., using modified train motors, picking up (largely changing) voltage from the powered track]. It does not make sense when you prefer charging off-line - in that case, battery boxes loaded with NiMH rechargeables are the way to go.
   

Best regards,

Thorsten

[martyboy70]

When we refer to 7745 its a 12v era set:

http://lego.wikia.com/wiki/7745_12_Volt_High_Speed_Train

[peterab]

Yeah cost is a big factor so buying £60 worth of battery and charger is a definite no-no and I would like to use the batteries I already have.

I've just had another thought and thats about lighting.

Looking at the IR receiver the PF system uses four wires and the 12v lights only use 2-I plan to cut one end off one of the grey 12v splice the lights onto the wire between the battery box and the IR unit-so does anyone know which of the four wires is which.

If you are going to hack up the battery box anyway, it's probably cheaper and better space-wise to just buy a cheap battery holder for your AA's from an electronics shop, and mod the connection wire to the receiver. Might be too late now you've bought the Lego battery box though.

[martyboy70]

I did look into this but my local Maplins only had battery holders for 4 or 8 cells and its the only place locally that does this sort of thing.

[roamingstop]

Maplin are ok... but Farnell and RS Components are often much better stock

6 Battery Holders

Small ones for around 4 pounds (pack of 5). Long Flat ones for around 5 pounds each.

Edited September 1, 2011 by roamingstudio

[Sokratesz]

Hm that looks nice actually. With 8x AA rechargeable cells of 1.2 you'll get 9.6 volt and awhole lot of capacity :D

- Sok.