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Liam Porter

LiPo batteries, LiFe batteries and a suitable charger.

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As I plan on getting a new gun pretty soon, it comes wired to Deans Connectors, so I think this may be a good time to change from NiMH batteries.

 

I'll be upgrading it to ~500 FPS and locking to semi, so what I'm after is a nice trigger response, a battery that will be suitable for tapping away on semi-auto rather than full auto bursts, and one that will last the whole day. The gun has a full sized stock, so the size of the batteries isn't too much of an issue.

 

So, what would be best; 7.4V Li-Po, 11.1V Li-Po or 9.9V Li-Fe, all of the highest mAh I can find?

 

Would I need a MOSFET, Li-Po alarm, or anything else?

 

 

 

And for a charger, I'm seen iMAX B6 mentioned loads as a decent, cheap charger for batteries, but what's the difference between these two?

http://www.amazon.co.uk/iMAX-B6-LiPro-Balance-Charger/dp/B004A6QEJ6/ref=sr_1_1?ie=UTF8&qid=1382034155&sr=8-1&keywords=imax+b6+charger#productDescription

http://www.amazon.co.uk/Digital-Battery-Balance-Charger-Connector/dp/B007EJQNVU/ref=sr_1_3?ie=UTF8&qid=1382034155&sr=8-3&keywords=imax+b6+charger#productDescription

 

For a £7 price difference, they don't seem to actually do anything different...

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if your gun is happy with a mosphet then only good things... i'd not go for a complicated one tho.

 

A 7.4v LiPo with 2200mAh should be more than enough for semi auto

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I have the second one. Good piece of kit but the manual is a confusing piece of crap.

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I have a Turnigy Accucell 6 which is the same machine as the iMax B6, just more expensive from Component Shop than it is on Amazon - it is good. It has bells & whistles which I don't use now and probably never will, but the fact that it can charge just about anything I'm likely to want charging provides that nice smug-ish feeling of money well spent. The manual for mine was shit as well.

 

Re: battery

 

I've got a 7.4V LiPo in my G36 extendable stock - 5000mAh - 30C

 

If you want to buy it, PM me. It's hardly had any use: 2 days skirmishing and a bit of shooting to test new mods.

The rest of the time I've used my charger to automatically set it at a correct storage voltage, so it is in tip top condition electrically.

 

TBH I would use an 11.1V LiPo for what you intend, or higher.

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For 500fps it'd be daft to use anything less than an 11.1v LiPo.

 

More than that would be better still. The motor's going to need all the juice you can give it, as well as being excellently geared, shimmed and fitted with a MOSFET of the cycle completion variety.

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Yeah I was thinking 11.1V, would a higher mAh in a Li-Po give faster ROF/better trigger response, like it does in a NiMH?

 

Also, these C ratings, what does it mean? Does higher C = motor turns faster?

 

 

About gears etc. I made a topic about a week ago, but it's had zero views/replies, because I put it in the right part of the forum.

Any chance of it being moved to a place where it'll at least be seen, like General Discussion, or am I allowed to create a new one there?

 

 

Oh yeah, and happy birthday Ed, have a good day!

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Cheers Liam, I'll move it into general discussion for you.

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Yeah I was thinking 11.1V, would a higher mAh in a Li-Po give faster ROF/better trigger response, like it does in a NiMH?

 

Also, these C ratings, what does it mean? Does higher C = motor turns faster?

 

 

About gears etc. I made a topic about a week ago, but it's had zero views/replies, because I put it in the right part of the forum.

Any chance of it being moved to a place where it'll at least be seen, like General Discussion, or am I allowed to create a new one there?

 

 

Oh yeah, and happy birthday Ed, have a good day!

 

 

The C rating is a measure of the ability of the battery to deliver power. It's basically a multiplier on the rated current so if the battery is for the sake of argument a 4A 30C battery it can deliver 30x4 A peak current - 120A. Someone asked this in a status thing the other day and posted a link to a video and this was explained in the comments.

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The C rating is a measure of the ability of the battery to deliver power. It's basically a multiplier on the rated current so if the battery is for the sake of argument a 4A 30C battery it can deliver 30x4 A peak current - 120A. Someone asked this in a status thing the other day and posted a link to a video and this was explained in the comments.

 

 

Thanks, that's what I thought was said, didn't watch the video though. Will have a search for it now.

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What you need to be concerned with, Liam, is the time it takes from the moment of initial contact across the switch for the battery to ramp up to full power. Although it is the voltage which determines ROF, ie the ultimate RPM of the motor, and this obviously determines how fast the trigger response can be, that theoretical trigger response time is increased by however long it takes for sufficient current to flow for the motor to begin pulling the spring. A high C rating will give your battery way more potential burst power than your motor can use, but this excess capacity means that it will deliver what you need very quickly.

 

Using a MOSFET also helps with this, because then you don't have the main power current flowing through a pair of contacts which begin each trigger pull with a high resistance micro arc and over time lose efficiency due to oxidisation and pitting of their surfaces. Literally the microsecond that any degree of contact is made across the switch, the semi conductor switches to "on" and the full power can begin flowing immediately.

 

Can't say I've had much experience with different types of MOSFET, just King Kong Burst Wizard (which I'm not sure whether I really would recommend, because although it's got all the bells and whistles, it's a really complicated pain in the arse to make it do anything other than factory settings, so complicated in fact that I'm not sure whether it's me that has cocked something up, or the one i bought is faulty :lol: ) and a Pico SSR, which is tiny and waterproof, very simple and works a treat for increasing trigger response time - it doesn't do anything like full cycle though. As Ed said, I think that may be important to you using a heavy duty spring...

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Also the mAh rating of a battery is effectively its endurance - how long it can deliver a steady current for. So a 2200mAh battery will deliver 2200mA for an hour (or 22 mA for 100 hours). The burst current (which is more to do with the C rating as above) allows the motor to spin up faster. Basically any electric motor requires a spike of energy to get it going as it has to overcome inertia, internal friction, losses in the gear train etc. Once the motor has started moving then the current drops away. A battery that can deliver a high burst current will allow the motor to spin up faster but if the steady state current rating isn't high enough then the rate of fire will quickly drop off. The best combination is a battery with a high burst current AND a high steady current rating AND a high mAh rating. That way you should always have more current available than you need, your gun will work a treat and all will bow down to your l33t skillz.

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Okay, so relatively high C rating and high mAh rating would be what I'm after. Thanks for the help, I now understand batteries a little better :P

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