Battery charging.... ideas and thoughts please

[tramcar trev]

I have one of the 6.8 Ah lipo batteries on order (if it actually gets here); http://www.ebay.com.au/itm/261192027140?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Ok I have an idea to charge it inside the steam tram motor.... using an isolated section of track run it onto said short length of track and as the motor block will have contact through the wheels and rather than the power running form the wheels to the motor have the juice running to the battery; apply power to the track and charge it up without having to invert the thing and plug it in. I would propose that a rectifier is inside the works somewhere to ensure that it is not polarity sensitive and this would also block current escaping back into the track. One problem I see is that the rectifier voltage drop may not provide enough volts to charge the battery and I may also need to "extend" the led indicator to let me see when the battery is charged..... Totally Heath Robinson I know but....
Thoughts from the floor?
Oh BTW this is an idea inspired from real life, this system was used in the 1890's in Bendigo with real battery trams, it was a total failure....

 

[treetop]

I have one of the 6.8 Ah lipo batteries on order (if it actually gets here); http://www.ebay.com.au/itm/261192027140?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

I have looked at the battery above, and it all looks too simple!!. Normally LiPos have a balancing plug attached, and you use a special charger for them.
I certainly would never try to charge them in the way you are suggesting.
Too much to go wrong.

 

[tramcar trev]

Having "unwrapped" my blue battery and discovered as others have done that the switch and led perform no real function apart from switching on the led and the output power to the male plug I will go ahead with my plans to charge my as yet to be built steam tram via the method expressed above. I will yet again go boldly where no man has gone before, push the boundaries, open my mind blah blah blah.... And If I am elected Prime Minister I will divert all defence spending to the provision of G sale rail and tramways. I will replace all light rail with even lighter rail i.e. G scale blah blah blah....

I shall simply make up a new charger and use an LM317 regulator and set the output current at 13.9V to compensate for the rectifier on the tram so the charge voltage will still be what it is at present 12.7v..... Plenty of circus diagrams out there for this it could also be made automatic so that it can be "stored" on its charging track ready for immediate action...

I seriously cant see any problem with this, its the "high performance" Li Po's that explode, and charging a 6.8 AH battery with 350mA is not going to overheat it..... No reports of either the blue or black cased ones doing anything except dieing, no reports of mysterious house fires caused by these things, I reckon they must be pretty safe, I mean they can fly them from Hong Kong, yet they challenge ammonium persulphate and Ferric Chloride in sealed containers....

 

[dunnyrail]

Trev I think that your biggest problem with be cleaning the wheels so that you get a charge. Remember now that you have gone Battery No Track Cleaning to speak of, all that crud will make the wheels cruddy too.

Now you can buy small cheep magnets. Our Local Store Maplin sell them with a tab of wire to use as battery Connectors. So you set up 2 sets of these magnets. 2 on the Car and two at the back of the depot on a wire. Walla as the Car runs in to the Depot Magnets being what they are couple up. You turn on the Charger and hey presto job sorted.
JonD

 

[Tony Walsham]

Trev.
Use the charger the battery pack came with. Don't muck around with raw voltage.
Tears are bound to happen.

 

[tramcar trev]

Trev.
Use the charger the battery pack came with. Don't muck around with raw voltage.
Tears are bound to happen.

I am not going to use raw voltage.... I am going to use a proper charger that will in all probability be superior to the one supplied... What came with the battery says 12.6 V @350mA output, its actually 12.7v and can supply 480mA by measurement.... If there is a weakness with the blue clad batteries it my be the very cheap chargers..... Having opened mine I'm frankly amazed it works at all, PCB was just shoved into the case, no cleaning of the tracks, crud and flux everywhere....I'm not game enough to clean it, it may not work afterward....
Some schematics;
sites.google.com/site/donutscience/various-projects/the-easiest-diy-lithium-polymer-battery-charger/the-easiest-diy-lithium-polymer-battery-charger---the-schematic

www.google.com.au/search?q=lipo+battery+charger+circuit+diagram&tbm=isch&tbo=u&source=univ&sa=X&ei=Kp0EUv_-JISrkgW2sIDYDw&ved=0CDMQsAQ&biw=1440&bih=837

 

[tramcar trev]

Trev I think that your biggest problem with be cleaning the wheels so that you get a charge. Remember now that you have gone Battery No Track Cleaning to speak of, all that crud will make the wheels cruddy too.

Now you can buy small cheep magnets. Our Local Store Maplin sell them with a tab of wire to use as battery Connectors. So you set up 2 sets of these magnets. 2 on the Car and two at the back of the depot on a wire. Walla as the Car runs in to the Depot Magnets being what they are couple up. You turn on the Charger and hey presto job sorted.
JonD

Not a bad idea..... maybe the magnets under the car that are to operate the signalling could be utilised. Even a reed switch could be placed to turn on the charger..... All food for thought....

 

[tramcar trev]

It would appear that there is considerable inconsistency in what is supplied.... My charger came with a useless adapter so it was a job for my pliers to bent the 2 flat pins to the proper angle....

I've slept on this and now I'm thinking that as I will make my own charger why not have the lot onboard and supply the track with say 24VAC, wont matter which way the thing sits on the track and the AC will be better at "Ionising" any dirt on the wheels and track.....

 

[Tony Walsham]

With 24 vac on the track to charge the battery which then in turn powers the tram, essentially you are powering the loco by the 24 v AC. Isn't that right back where you started?

 

[tramcar trev]

No... the length of track with the 24VAC across it would be isolated from the rest of the system where the track is not insulated, both rails being negative.... Its only to charge the battery, the rest of the tramway is powered from the overhead and the track....
I'm really exploring charging methods that do not require me to either dismantle or turn upside down to charge it... Turning upside down means smoke fluid could run everywhere and dismantling it is just inconvenient...

 

[gregh]

I like to keep it simple. All my batteries charge in the loco. I have two bare studs that I connect the charger with small alligator clips. I usually use 2mm square brass for the studs. I don't use any switch - the studs go direct to battery - not even via the polyswitch 'fuse'.

I haven't connected them in reverse yet (touch wood) but my chargers detect reverse ploarity anyhow. No prob if you use AC.

[My standard is the Positive is on the left. Like all standards, this applies in all cases, except where it does not apply.]

 

[dunnyrail]

Greg,
The simple ideas are always worth exploring. Great idea.
JonD

 

[tramcar trev]

Hmmmmm yes..... I can see my idea is far too out there.... even though I'm thinking to the extreme realms of practicality maybe just a cuppla alligator clips would do the job.....
So much for trying to be overly smart and innovative.....
I think as I don't know right from left maybe a 1.5mm DC power socket and matching plug might also work.... Could probably get a chassis mount socket to fit the existing plug on the charger?

 

[Dtsteam]

Well, someones gotta try, Trev. I'm sorry it didn't work out as you intended.
I had a dabble at Battery Radio over the winter using a 6v gel battery and a charging track. I came across the problem Dunnyrail mentioned above "Trev I think that your biggest problem with be cleaning the wheels so that you get a charge. " Basically the poor contact played havoc with the reasonably intelligent charger, and so the battery never got a full charge.
The thing is you'll probably only charge the LiPo battery a few times a year.
Full marks for trying, though - keep the flag of innovation flying Trev !
Kudos to Gregh for a very neat idea as well.

 

[Tony Walsham]

Trev, one other thing to consider.
If you are using both layout rails for a common ground you will only be able to have one side of the wheel pick ups connecting. Other wise when the loco is on the charging track there will be a dead short.
Unless of course you have a switch on the loco to isolate one side. In which case you will have to handle the loco anyway making a charge jack a good idea.
There are 5 mm jacks (sockets) that will fit the charger plug. Either a 2.1 mm pin or a 2.5 mm pin. Just be careful where the jack is mounted as the frame of the jack has a voltage potential. They need to be isolated to be safe.

 

[GAP]

Hmmmmm yes..... I can see my idea is far too out there.... even though I'm thinking to the extreme realms of practicality maybe just a cuppla alligator clips would do the job.....
So much for trying to be overly smart and innovative.....
I think as I don't know right from left maybe a 1.5mm DC power socket and matching plug might also work.... Could probably get a chassis mount socket to fit the existing plug on the charger?

Trev,

I use similar connections to gregh for my locos I just disguise them.

Jaycar sell a chassis mount socket that could be hidden underneath out of sight, they also sell a 90 degree plug that when fitted to replace the supplied plug would make connection simple and easy.
I use this to connect a set of skips that house my R/C gear and batteries, an idea I copied from a John Robinson article in Garden Rails, to my loco I also use it to power my stainz from a tender with the R/C gear and batteries hidden in it( multi use tender).

I have learned from years of aviation electronics experience that the KISS principle works the best.

Or if you want to be adventurous you could try a couple of mounted connectors disguised as buffers that connect with a set mounted on a wall, just have to be careful of polarity if mounting them on each end of the tram.

 

[MasterBruce]

You must store them charged, but not fully charged either. Basically, the speed at which a LiPo pack ages relies on both storage temperature and state of charge. For better battery life, we should store LiPo batteries at room temperature and at about 40-60% charged. That equates to around 3.85 volts per cell. A good computerized charger like http://www.mrpositive.co.nz/brands/iCharger.html < Link To icharger will have a setting where you can charge your pack for storage, specifying the % of the battery capacity you would like to charge it to.

 

[tramcar trev]

The chargers mentioned look like they are for cylindrical batteries only. We are talking bigger flat batteries of 3800mA to 9000mA approx.. Altho' the storage advice is valid for all these type of batteries.

Yep the individual cells inside the blue wrapper are flat blocks.... the chargers that come with them I reckon are dodgy.... Mine is erratic, sometimes the green led comes on after a day on charge, sometimes it only comes on if I switch the battery on and off. The only real way is to measure the voltage of the battery.... OR if you were game you could take a wire of each battery terminal and set it up so each cell is charged individually with a balancing charger....

Interesting advice re storage... this chap recommends the fridge; http://www.rchelicopterfun.com/rc-lipo-batteries.html thought he also says that he doesn't worry about that in winter.... I can just see Hyacinth allowing me to store batteries in "her" fridge. As long as they are not stored in a warm place I guess....