# help with a power problem.



## raser13 (Jan 21, 2008)

hey guys, i'm new here, and typically stick to sci-fi model building. but i need help for a project that i believe that you guys would be more suited to help with. what i'm wanting to do is light a model on battery power kind of like this guy did:






the only difference is that i don't want to float it in water. i want to have it float above a stand suspended by rare earth magnets, so it's just hanging there in space with no wires but still lit up.

my questions are.....

1) what kind of battery would you suggest to do something like this. i would need something with long battery life that can handle somewhere around 10-20 led's.
2) is there a way to recharge the battery with out removing it from the model? like say could i hide a power jack some where on the ship? or would i have to make a removable door somewhere on the ship to get the battery out?
3)what would be the cost of a set up like this?


any info would be great. thanks for the help.


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## trackman (Aug 5, 2006)

I'm no scientist by far but maybe I can make a suggestion that will help out somehow.


raser13 said:


> 1) what kind of battery would you suggest to do something like this. i would need something with long battery life that can handle somewhere around 10-20 led's.



With either type of battery (Nicd, Nimh, Lipo etc,) you will need a charger that will charge the type of battery you are useing. Maybe you could borrow a charger from a freind that will do the type of battery you choose to use.
I would suggest give a little more details for the craft such as, How much amperage your lights will require due to size of the LED lights you choose,
How big is the craft , (for example) Is it big enough to accomadate AA, A , 2/3 , Sub-C , C , 1, 2 or 3 stick lipo and how many batteries in size will it hold.
Brightness of you lights will be determined by the voltage of the batteries you use. Rechagables are 1.2 volts where as standard alkalines are 1.5 volts and I think a single stick lipo is 3.7 volts .

How long do you need the lights to run , Long run time can be different from person to person, 2 hours 4, 8, 24....
Run time of a battery is specified by the Mah, The higher the Mah of a battery the longer the run time of it. The higher the Mah the higher the price of it.



raser13 said:


> 2) is there a way to recharge the battery with out removing it from the model? like say could i hide a power jack some where on the ship? or would i have to make a removable door somewhere on the ship to get the battery out?


Sure you could charge the battery inside the craft with something like a pigtail from the source of the battery , They do make R/C planes with a lipo battery that can be charged while sitting in the craft.
Personnally though I would want to remove the batteries/pack system from the craft do to if the batteries get hot or explode during chargeing the craft/project itself would not get damaged. 




raser13 said:


> 3)what would be the cost of a set up like this?


Starting with the basics and you wanted a AA rechargable 4 cell Nimh 2200 system that can be bought most anywhere including the charger minumun price is around 20 to 40 bucs or if you wanted you could go with the 2,3,4,5,6,7,8,etc.. AA alkaline batteries and batteyr tray for starting price of around 10 bucs

These are just some ideas that come to mind not knowing fully what the requirements of the system are.

Anyway good luck with the project!


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## raser13 (Jan 21, 2008)

i don't know how familiar you are with star trek models. but, it's the motion picture version of the enterprise in 1/350th scale. the same one that the guy turned into the submarine in the link. this thing is a monster! basically it has room enough for me to put any sized battery setup i need in it. as for the led's i haven't bought any yet because i wanted to wait and see what type of battery set ups there were available. 

as for battery life i was hopping for a few hours(two or more) as when i get done with her i was hoping to enter her into modeling competitions and she would have to be lit the entire time.

in reference to having the battery sealed up or have it removable or not. i'm hoping to have it sealed up for the most part because i really don't want to have a hatch that i have to remove each time. that way i have less chance to have the finish screwed up.

also i intended to buy the entire set up to charge the battery and the battery itself i'm just trying to find out the ball park price and what i should ask the dealer for so i get what i need. BTW do they sell the battery housings for r/c batteries to go in the vehicles or do those normally come in the car/plane/whatever?


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## Zerodefect (Jul 28, 2009)

google for hobby city (hong kong). They have tons of small lipo batteries and chargers with fairly accurate specs for size and weight.

lipos will have the best power to weight ratio.

How much force do your magnets have? Sure you have room, but you don't want too much weight. Just remember even though lipos have the power and weight you need, you'll have to wire in a voltage cutoff so that the Leds don't discharge the battery too much. The cutoff will turn the model off before the voltage drops low enough to damage the model.

Don't worry bout a battery box, its not going to slamming into stuff like our planes or cars. Just stuff the battery in there however you want, maybe with a little foam wrap or something..

nihms and nicads will be too much of a pain to maintain for a static model. Lipos are fairly freindly as long as you have a cutoff and a lipo charger.


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## IndyRC_Racer (Oct 11, 2004)

Check out the Model Lighting forum here on Hobbytalk (http://www.hobbytalk.com/bbs1/forumdisplay.php?f=305). Someone there should be able to help.

You should also check out the Science Fiction Modeling section here on Hobbytalk (http://www.hobbytalk.com/bbs1/forumdisplay.php?f=99).


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## DJ1978 (Sep 26, 2001)

I agreew with the other guys.
I would suggest going with a Lipo. You can get a relatively small 3s pack that we use for our radios and it puts out over 12V. with a LONG run time. 
Check out Max Amps for a wide variety of batteries to choose from.
You will need a Lipo cut off. I would suggest a hatch and remove your battery when charging for safety. You will need a lipo compatible charger. 
there are tons of LED kits on the market for many different applications. solid light, blinking lights ect. Have fun with this project and keep us posted please.
You can expect to spend $75 -$150 on a good AC/DC Lipo charger. The smaller batteries are not that expensive. I would say you would have about $200-250 into the whole package.


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