lipo in an e-mag?

[s1im]

I work with lipo batteries in the rc trade, so i have plenty of them around.
Has any one used one in an e-mag which has std board and software?
What is the min and max voltages the board can cope with?
I have a spare battery case and the current battery is knackerd so i could have 2 lipo choices e.g very light pack e.g 800mah and a long duration e.g 3300mah, i know the board works as i used my x-mag pack on it and its ok.
any ideas? :)

[flyingpootang]

The stock battery is rated at 16.8 650 mAH and I think the lowest it'll function at is @ 16.0 and up to 19.0 volts. usually mine read around 18.8 off the charger. I would go with the 800 mAH...

[s1im]

mmm 18.5 volts is ok, thinking 800mah would weigh 115g and take up less than 1/2 of battery pack

[athomas]

What is the max output current that the Lipo packs can deliver? The mag solenoid requires about 3 Amps per actuation. As long as the battery pack can deliver that 15 - 20 times per second, it should be fine. Its that high current requirement that eliminates most of the battery packs from qualification for use in the emag.

I assume the Lipo packs are lithium, given that the ratings are so high in a small footprint. They are probably fine, because RC operation usually has high current requirements too, but check the ratings to make sure.

[PhoenixWolf]

Actually AGD says it'll work down to 14 volts. 14 to 18 volts is the range. You can get different results depending on what type of Lithium-based batteries you use. 3-volt variety, you can get 15 or 18 volts. 3.6 volt, you're limited to 14.4 or 18 (and I really wouldn't recommend 18 simply because you run the risk of frying your board). The ideal battery pack would be an 18-volt+ model that uses a voltage regulator to step down to 16.

Note: I was looking at potential lithium-based battery packs for these things last night. Your average pack can do 2200 mAH at those voltages. Compare this to the stock 650 mAH battery or the upgraded 1000 mAH pack. The only downside is that these packs usually exceed the dimensions of the E-Mag battery pack despite holding more juice. Your best bet would be to get a custom-made pack with 5 cells and a small voltage regulator.

Theoretically, at these ratings, you could also get a smaller pack and actually step the voltage up instead of down.

Incidentally, does anyone know the weight of the stock AGD pack?

[athomas]

Note: I was looking at potential lithium-based battery packs for these things last night. Your average pack can do 2200 mAH at those voltages. Compare this to the stock 650 mAH battery or the upgraded 1000 mAH pack.

Theoretically, at these ratings, you could also get a smaller pack and actually step the voltage up instead of down.

Its not the mah rating that determines if the pack will work. that only determines how many shots you can get. Its the C rating combined with the mah rating that determines if they will work. You could have a battery pack with a 5000mah rating and if it can only put out 500ma of instantaneous current, it won't work. The stock 650mah rated battery pack can put out several amps of instantaneous current, which is why AAA nimh batteries were chosen.

Stepping up the voltage means you need even more current capability.

[s1im]

the packs are going to be 20C packs this will give a continuious current of 16 amps and a max burst of 24 amps so 3 amps really is not an issue!

I can get a custom pack made dimentions wise.
I'd like to avoid a voltage reg but i can go down this route if needed. most regs in modeling take it dowm to around 6v as this is what the servos take.

as I'll have a much bigger capacity than std I'm thinking i could also power the hopper off it too!

[athomas]

Sounds like a great setup.

I'd go with the 18v setup. It will work the solenoid properly. The board uses 5v and has a regulator built in.

[s1im]

i'm going to try it once my spare battery pack arrives. working out a matching red led display that will show voltage that i can put on the pack.

[Chrishew09]

I was thinking of doing this same thing, and I had the same questions and did a search and found this thread.

Anyway, keep in mind that a 5S LiON pack has a working voltage of about 18.5V but its charge voltage is about 21V, so you will need a charger that goes up to 21V for a full charge. Also the linear regulator that is on the board must be able to have a input voltage up to 21V so that it doesn't burn out, same with the solenoid MOSFET.

I am going to hook my Emag up to a lab supply and run the voltage down and see how low I can go and still have the solenoid fire, b/c I want to use a 4S pack (14.8V). Something like this one.

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2672

[athomas]

The solenoid will fire at 14 volts when not running air. If you add air and adverse conditions such as dirt or debris, then the solenoid will not be fully powered.

[Chrishew09]

The solenoid will fire at 14 volts when not running air. If you add air and adverse conditions such as dirt or debris, then the solenoid will not be fully powered.

Okay, what about a 5S pack, will the board be okay with 21V?

Edit: I just looked up both the linear regulator and the MOSFET and they both can handle 30V, so a 5S pack will work.

Linear Reg: LM340 (National)
MOSFET: NDT451ANTR (Fairchild)

[athomas]

A 5S pack is 18.5 v (3.7v x 5 = 18.5v). The charge voltage is only when charging the pack and does not apply to the board being run after the battery is charged.

[s1im]

Was looking at li-po rather than li-ion but still the same rules apply I would not use the std charger as you need a specific charger. This is not a "commercial" projet as no offence to the majority of people, but they would not be carefull enough!

I'm looking at a custom 5s pack, I work with lipo in the model industry so i'm surrounded by them!

[Chrishew09]

Was looking at li-po rather than li-ion but still the same rules apply I would not use the std charger as you need a specific charger. This is not a "commercial" projet as no offence to the majority of people, but they would not be carefull enough!

I'm looking at a custom 5s pack, I work with lipo in the model industry so i'm surrounded by them!

Li-Po or LiON will work the same as long as the voltages are the same.
I also work with LiON batteries but they are all very high capacity large cells, nothing small lying around.