Battery Advice

[rockyrifle]

Making the switch to lipo batteries and looking for some advice on voltage.

 

I'll be running them through a KWA M4, gun fires at 1 joule (playing in Ireland), well shimmed and I'll also be running a gate warfet. I mainly play in semi so trigger response is what I'm after, a ROF ~20rps is fine for me (I'll most likely use the 3 round burst warfet function). 

 

My question is should I get an 11.1v lipo (I've read with a weaker spring one can risk overspin on semi, I'll be using the warfet ROF control for auto to ensure it's ~20rps), or would the response difference with a 7.4 lipo (w/ precocking) be negligable.

 

Both batteries would be 30C/50C burst.

Thanks.

[EDcase]

I would recommend 7.4v

[Iceni]

I would say it depends on the ROF on the gun.

A gun that does <25rps on 11.1 and has a mosfet will be just as good as any other 25rps build for durability.

Equally a <25rps on 7.4v with a mosfet will be just as long term. The advantage the 7.4v build has is the gearing and motor, If you build around 13:1 350fps 16TPA <25rps then the trigger response is really nice. The disadvantage is the cost in upgrades to do that. There is a marked difference in feel for a gearbox done like this, And even without pre-cocking the gearbox should be tight and really snappy. Since doing one gun with this build all of my other guns are been done as well with a similar setup.

A gun without a mosfet I'd only want to run 7.4v in it just to be sure I'm not causing damage. I'm tight, And don't like thinking that I'm potentially causing damage. Saying that some people have ran 11.1v without a fet for years.... Others might not have done so well, One thing the 11.1 will do is show any flaws in the gearbox very quickly.

 

There is no correct answer, It has to be you that makes a decision and then lives with that.


Another advantage of the 7.4v build is battery migration. I can use a 7.4v in any gun barring some fussy fets, I can't run an 11.1 in all my builds, and can't loan those batteries as easily or put them in new un-upgraded guns with the same confidence.

[Adolf Hamster]

With a warfet in semi it wont really matter, the precocking will do more than the nominal voltage.

 

It will make a difference to auto fire but without knowing the specifics of the gun its hard to gauge which would be more appropriate.

 

Either way, the highest c rating and capacity in a battery that physically fits in the gun is fine.

[MadMole]

Dont go LIPO go Titan Li ion. Much safer and much higher capacity. Getting rid of my LIPO's having converted

 

https://www.titanpower.eu/

[Iceni]

16 hours ago, MadMole said:

Dont go LIPO go Titan Li ion

Chemically Li-po and Li-ion are the same thing. They have the same discharge curves. The difference is the electrolyte - Li-po uses a gel and bigger laminated sheets, Li-on uses discs separated by a porous material doped with conductive liquid held under pressure.

Both batteries will set on fire if you short or damage them. The Li-ion requiring that construction pressure to hold the plates close means it has a more durable skin (metal). Both can set on fire if you charge them incorrectly, in fact just about every E-cig/Vape fire you have ever read about will have used a Li-ion of some description and some of the worst accidents been shorted cells in peoples pockets.

There are advantages and disadvantages to both package designs. Li-po is unconstrained in dimension. Li-ion only comes in rigid form factors - 18350, 18500, 18650 ect and doesn't have the same plate to plate surface area so the C ratings for amp draw is always lower to prevent internal heat build up.

There are differences in charging and discharging. A typical Li-ion 18650 Li-Co can not be fast charged without shortening the battery life. And equally a discharge over 1C will shorten the battery life. I don't know what propriety blend of chemicals Titan are using, but for typical Li-Co 3000mAh cells a 3A discharge is the long term limit. Li-NMC on the other hand is slightly different it still retains the 1C optimal charge, and the very best cells having a 2C discharge - 6 Amps continuous for long term life. This doesn't mean these cells can't do 10C it just means there going to be running hot all the time. Some Li-NMC are sold as 40A cells for vaping but you won't get a long life out of them at that stress level, I get about 150 charges out of my vape batteries (35A) and that's running about 6 amps and letting them 0.33C (1A) charge. After 6 months they won't last more than a few hours compared to when new and lasting more than a day.

Li-fe is not on the table - it doesn't charge high enough for titans reported numbers, and doesn't have the mAh capacity. It is available in rigid form factors like 18650 that would fit the titan form factor. This is not to be confused with soft cell Li-fe airsoft batteries - Those are sold correctly with the amended voltages, and are a little safer than regular Li-po chemistry.


Back on charging Li-po can be fast charged. If you look about you will find 5C charge capable cells. Titan can not do this. 5C is 60/5= a 12 minute total charge if you have a charger capable of supplying the amps. This is the one significant advantage of li-po. I have a Giant power 7.4v 5C 2200mAh 35/70C... If I could supply it - it would take an 11A charge. It's also capable of some rather stupid amperages. 77A continuous 154A burst. I don't think it's ever been stressed in it's life for airsoft.

 

[rockyrifle]

I'm going to go for 7.4v, thanks for the help. The titan batteries are a bit expensive for me.

[Iceni]

Read up on lipo safety. And get a decent charger and you shouldn't have any issues.

One thing you will have to consider is where you buy them and what connection those batteries come with.

Mini Tamiya, and regular tamiya connections in arsoft are reverse wired. So you can't buy RC batteries and just use them - the motor will try to spin backwards or worse blow the fet.

Deans are wired the correct way for both airsoft and RC.

Hobbyking sell the Airsoft batteries in the lifestyle section.

https://hobbyking.com/en_us/lifestyle/outdoor-recreation/airsoft.html


They also don't always show if it's 7.4v or 11.1v. They do show 2S (2 cells 7.4v) and 3S (3 cells 11.1v) in the descriptions.


You may also find you have to reverse the red and black wires to the charger if you are using standard cables. It's not really an issue if you have a good charger as it'll tell you it's backwards, but cheaper chargers might not. The charger will need the little white JST connector plugging in and then the red and black via a tamiya block. Most chargers do not ship with a mini tamiya to bannana plug adapter, so read the contents section of the charger description.

If it doesn't have the mini tamiya then you will need one of these.

https://hobbyking.com/en_us/turnigy-9-in-1-multi-connector-charge-lead-w-4mm-banana-plugs.html?queryID=&objectID=85942&indexName=hbk_live_magento_en_us_products
 

You will just have to remember to plug red into black and vice versa on the charger.

As for the charger I would normally say the B6AC but hobby king don't have them in stock stm.

So this one is more powerful and costs the same as a real B6AC It just doesn't look as pretty.

https://hobbyking.com/en_us/turnigy-accucell-c150-ac-dc-10a-150w-touch-button-smart-balance-charger-eu-plug.html?queryID=&objectID=79276&indexName=hbk_live_magento_en_us_products_hbk_price_stock_1_group_0_asc

[rockyrifle]

9 hours ago, Iceni said:

Read up on lipo safety. And get a decent charger and you shouldn't have any issues.

One thing you will have to consider is where you buy them and what connection those batteries come with.

Mini Tamiya, and regular tamiya connections in arsoft are reverse wired. So you can't buy RC batteries and just use them - the motor will try to spin backwards or worse blow the fet.

Deans are wired the correct way for both airsoft and RC.

Hobbyking sell the Airsoft batteries in the lifestyle section.

https://hobbyking.com/en_us/lifestyle/outdoor-recreation/airsoft.html


They also don't always show if it's 7.4v or 11.1v. They do show 2S (2 cells 7.4v) and 3S (3 cells 11.1v) in the descriptions.


You may also find you have to reverse the red and black wires to the charger if you are using standard cables. It's not really an issue if you have a good charger as it'll tell you it's backwards, but cheaper chargers might not. The charger will need the little white JST connector plugging in and then the red and black via a tamiya block. Most chargers do not ship with a mini tamiya to bannana plug adapter, so read the contents section of the charger description.

If it doesn't have the mini tamiya then you will need one of these.

https://hobbyking.com/en_us/turnigy-9-in-1-multi-connector-charge-lead-w-4mm-banana-plugs.html?queryID=&objectID=85942&indexName=hbk_live_magento_en_us_products
 

You will just have to remember to plug red into black and vice versa on the charger.

As for the charger I would normally say the B6AC but hobby king don't have them in stock stm.

So this one is more powerful and costs the same as a real B6AC It just doesn't look as pretty.

https://hobbyking.com/en_us/turnigy-accucell-c150-ac-dc-10a-150w-touch-button-smart-balance-charger-eu-plug.html?queryID=&objectID=79276&indexName=hbk_live_magento_en_us_products_hbk_price_stock_1_group_0_asc

Thanks for all the info Iceni. I've a decent grasp of lipos and general circuits so think I'm all good there. Gun is wired to deans and I'll do the same for the batteries.

 

I'm located in Ireland and hobbyking charges an extortionate rate to ship from the uk (over 20£) so I think I'll order a B6AC elsewhere (and verify it's genuine there seems to be a lot of fakes!)