Li-Poly

[xmodmaverick]

Ok, I am getting a car with Li-Poly already installed. I am wondering a few basic things about them.


What is a good charger? I heard like "smart charger" and such.
i know you aren't supposed to let them go under 3 volts per cell or else they're toast. do I need a volt meter for that (duh, but is there another way without buying one)
Ok, since I have more power going into the car, I need to know if I can run a hotter motor. I don't know if the FET's will allow that much. It is running a Spinbrush motor right now.
lastly. Would it be good to get 4 of them so I can run 1 set and charge the others?Thank you so much guys. I'm really good at xmods, but electronics is one of my worst "fields" in xmods next to painting and pricing of parts for sale.:lol:

[tommygreen23]

Ok, I am getting a car with Li-Poly already installed. I am wondering a few basic things about them.


What is a good charger? I heard like "smart charger" and such.
i know you aren't supposed to let them go under 3 volts per cell or else they're toast. do I need a volt meter for that (duh, but is there another way without buying one)
Ok, since I have more power going into the car, I need to know if I can run a hotter motor. I don't know if the FET's will allow that much. It is running a Spinbrush motor right now.
lastly. Would it be good to get 4 of them so I can run 1 set and charge the others?Thank you so much guys. I'm really good at xmods, but electronics is one of my worst "fields" in xmods next to painting and pricing of parts for sale.:lol:

1. I dont know about chargers...

2. Once you see preformance dropping, you need to stop and charge. You will definatly be able to tell when the voltage is falling.

3. You can always run a hotter motor to a certain extent. Once your motor starts pulling more amps than the fets can give out, they will burn. Batterys have nothing to do with what motor you can run.

4. Depends on how much you use yours. If its just 2s (2 in series) which most are you will probably have about 750mAh of playtime which is about, hmm... I wanna say 15-20 minutes with a stock motor before youll need to charge. If you want to run longer, then get more packs. But remember your gonna have to stop and let the motor cool every now and then. I have a couple other homemade devices with lipoly cells in them and they take about 12 hours to charge from 3 volts.

Hope this will help ya, Mabye someone else here knows more about chargers :)

[xmodsnut]

Ok, I am getting a car with Li-Poly already installed. I am wondering a few basic things about them.


What is a good charger? I heard like "smart charger" and such.
i know you aren't supposed to let them go under 3 volts per cell or else they're toast. do I need a volt meter for that (duh, but is there another way without buying one)
Ok, since I have more power going into the car, I need to know if I can run a hotter motor. I don't know if the FET's will allow that much. It is running a Spinbrush motor right now.
lastly. Would it be good to get 4 of them so I can run 1 set and charge the others?Thank you so much guys. I'm really good at xmods, but electronics is one of my worst "fields" in xmods next to painting and pricing of parts for sale.:lol:

1 the Li-Pos I run are the Electrifly with smart charger built in, you can get these at hobby shops and for a charger get one that rated for the batteries you are charging. most Li-Po chargers are 12 volt DC current. to bypass this I recommend you buy an AC/DC converter rated higher than what the charger will charge the batteries to and make it work with a wall outlet by cutting off both the aligator clips and the end of the converter, the converter can be found at RS.
2 you can purchase at any hobby store a power shut off, I forget what the real name is right now, that will cut power when the battery is spent.
3 with this setup the motors I have run are helimax HMXE8004 and haven't blown stock fets yet. but make sure you follow the manufacters instructions for what they recommend for their motor.
4 if you get 4 batteries and buy the right charger you can charge all of them while playing with the one. like I said Electrifly makes a charger that can charge 4 Li-pos at once but its like 100 bucks.

also tommygreen23 2s 7.4 volt 750mAh wont even make an xmod move but put in a 4s 7.4 volt li-po 1440 mAh in it and watch it burn rubber for a long time. like I said Electrifly makes one heck of a charger and batteries set up for racing.

[skylinedriver]

Here is a good charger from batteryspace http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1121
The connector used for charging will have to be changed to match the what is on your battery pack. I don't recommend using the clips that are supplied with the the charger, but can be used.

[tommygreen23]

1 the Li-Pos I run are the Electrifly with smart charger built in, you can get these at hobby shops and for a charger get one that rated for the batteries you are charging. most Li-Po chargers are 12 volt DC current. to bypass this I recommend you buy an AC/DC converter rated higher than what the charger will charge the batteries to and make it work with a wall outlet by cutting off both the aligator clips and the end of the converter, the converter can be found at RS.
2 you can purchase at any hobby store a power shut off, I forget what the real name is right now, that will cut power when the battery is spent.
3 with this setup the motors I have run are helimax HMXE8004 and haven't blown stock fets yet. but make sure you follow the manufacters instructions for what they recommend for their motor.
4 if you get 4 batteries and buy the right charger you can charge all of them while playing with the one. like I said Electrifly makes a charger that can charge 4 Li-pos at once but its like 100 bucks.

also tommygreen23 2s 7.4 volt 750mAh wont even make an xmod move but put in a 4s 7.4 volt li-po 1440 mAh in it and watch it burn rubber for a long time. like I said Electrifly makes one heck of a charger and batteries set up for racing.

I'm sorry bro, but you don't know what your talking about. You show me a li-poly pack that fits in a xmod nicely that is rated for 1440mAh. If they are in series you add the voltages which is how you get to 7.4 volts from 2 3.7 volt cells. When they are in series the total mAh of the batteries stays the same. So if you are running 4 AAA 900mAh NiCads you only have 900mAh. The mAh rating of the battery has nothing to do with moving the car. That is the drain rate which should be around 10c or 4.5 amps at continuous current which is what moves the car.
Just in case you don't believe me check out this li-poly kit from atomicmods.
460mAh and 10C rating. Obviously it can move a xmod car...
http://www.atomicmods.com/Products/XMOD-EVO-HD-Lithium-Polymer-Pro-2S-10C-Pack__10398.aspx

Just because you have bigger batteries does not mean your fets can stand more current draw. They will blow up if you put a motor in that draws any more amps than the fets are rated for.

By the way, 4s means 4 in series which would be about 14.8 volts. It sure would burn rubber for a LOOONG time with that.

If you don't know what your talking about, please don't talk.

[xmodsnut]

Well I just checked my booklet that came with my batteries and my battery is actually a 2S2P by the time I put it together and in my titan. it is so fast with the top speed gearing and helimax motor that its not funny. oh and by the way I am running stock evo fets.

[f250]

This is the charger I used and it doesn't take 12 hours to charge!http://cgi.ebay.com/XMOD-EVO-HD-Lithium-Polymer-Li-ion-Pro-Ps2-Pack-Charger_W0QQitemZ120175753632QQihZ002QQcategoryZ34 063QQssPageNameZWDVWQQrdZ1QQcmdZViewItem