Battery Pack Assembly & Care Guide By: Kilo Bravo Echo Echo

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Battery Pack Assembly & Care Guide By: Kilo Bravo Echo Echo

Postby faden » Mon Jul 21, 2008 8:43 am

Many People upgrade and modify their AEGs in so many ways, but few actually know about the electrical systems ( or care to know about it, preferring to just "plug 'n play ) , particularly the battery, so I would like to share some of my know-how with other hobbyists, I'll try and keep it basic.

Prep Work :

-Heat-shrinking your cells and why it's important, Insulation if the negative part of the cell ( the entire body of the cell IS negative ) contacts another cell's negative part then you have yourself a short, this can do a few things to your battery A. Drain The Battery and Destroy one or more cells B. heat Up The Battery & cause an explosion, so shrink wrap the cell ( if it doesn't already come shrink wrapped ) except the positive "button" and a part of the bottom to serve as a negative solder point

-Soldering points what is it for ? There are two points to solder the battery tab to, the positive "button" and the negative bottom side, you start by sanding those points lightly, just enough to have some "scratches" for the solder to stick to.

-Soldering Flux do I really need it ? the answer is depends on how well you managed to make the solder stick to the solder point, if it doesnt want to stick, well ... put a lil dot of it then add the solder.

-some "stick pack assembly kits comes with everything you need, battery bars,shrink wraps, stick pack end caps etc.

-"stick" refers to a single line of cells soldered together, stick pack refers to a battery pack assembled in an inline manner,saddle packs are 2 sticks connected by wire, side-by-sides are either stick pack or saddle pack with the cells side by side instead of inline.

-you can only make a pack out of same output cells ( ie. same cell size, same maH rating etc. )

Technique :

-Solder the Tabs as Fast as possible, to avoid overheating the battery ( higher wattage soldering iron heats faster and works better )

-Do Not leave the iron unattended, it will burn through most anything.

-If the battery gets too hot to handle, stop and wait a few minutes before resuming, as the heat may damage the battery if continued

- When soldering tabs to battery points, take care to only solder it to the one polarity ( most common mistake when soldering to the positive point is soldering it to the rim with residual solder lead )



Assembly :


Fig 1.0

Initial Soldering ( one cell to another )
Begin By Placing two cells side by side ( one upside down ) straighten the solder wire ( aka "soldering lead" ) then carefully place the tip on the soldering iron until it begins to melt & pool on the tip ( a tiny amount will do ) now apply the iron's tip to the positive "button" without touching the "rims" as the rim is most definitely negative and will cause a short, leave a bit of solder on the positive "button" to cool, now apply a small amount to the battery tab ( aluminum,copper bars fairly thin, with good flex ) then put the bar on top of the solder point and apply a bit of pressure to it with the soldering iron, you will feel the solder lead melt away, lift off the iron and do not move the battery or the bar, wait until lead re-solidifies and bar is securely attached, now solder to the other battery, this time to the negative point on the other battery, solder 3 cells to each other this way before moving on to the next task.

Fig 2.0

Bending The Tabs To Turn It Into a Stick Pack, you need to bend the Tabs so that the cells all line up, be careful not to undo your soldering when doing this, remember not to compress the tabs just yet, you will have to inspect if the shrink wraps prevent the cells from touching ( body to body, or the "rim" of the positive end with the negative on the next cell ) Don't worry if there's a little excess tab, just fold it so it lines up without protruding out the sides ( remember I told you to use pliable bars, or thin aluminum sheets ) once done with this you end up with something like this ( on a odd cell battery like 7 cell or 9 cell, you put a tab on each end of the last cell ) :

Fig. 3.0

Compressing The Pack Only perform this after inspecting the solder points ( check if it came loose, or if the rims on the positive end will contact the negative part of the next cell ) after that "fold" the solder tabs if necessary prior to soldering both sides or the battery pack together

Final Assembly IF you have decided to go with a group solder ( solder all cells in one long chain then align them ) then all you need to do is apply the stick pack wrap ( large shrink wrap ) to form a stick pack. You can also go for a saddle pack ( 2 sticks connected by wires instead of a tab ) this is great for foregrip packs like those on an M4 you split the pack in 2 and have 8 cell-2 sticks instead of 7 cells in single stick pack form.


Charging, Conditioning, & Care


Types Of Charging-

-Trickle Type is a type of charging method where a transformer allows a small ( fixed ) amount of current to flow into a battery, very stable very safe ( very slow ) it often does not charge a battery after the battery reaches it's peak-resistance value ( more on resistance later )

-Timed-Resistance Type the principal problem with this charge type is that while the battery is filling up, it starts to provide less amps for charging ( it does not overcome the resistance ) you also need to crank up the timer manually ( i suggest starting with 5 minutes then adding 5 min intervals until you find max charge, more on finding max charge aka "peak charge" later ) most common type of charge method ( even cars use this type for in-home chargers )

Peak Type, This is a charging method that involves a "smart card" or digital type controls, it "forces" amps into your battery ( 2 amps for small,4 for standard, & 6-8 for competition ) so it forces a constant amp level into your battery cells regardless of resistance values, the nearest analogy i can think of is when you put gas in your gas gun you use a larger tank with higher pressure to fill a smaller tank, this is the same principle, you then get "bottled up" power ( just don't over do it )

Types Of Chargers-

-Wall Charger, we've all seen this ( it's the one that comes with your AEG ) while altogether not bad, it's main cause of unpopularity stems from 2 of it's major cons 1>It Needs an AC ( Alternating aka household current ) to run 2> It takes at least 2- 4 hours to charge a small 1100maH battery, it's fine if you can wait, now for the other little problems, it's a transformer type "charger" that trickle charges

-Mechanical Charger, this is the next model up charger ( at roughly $6.00 - $8.00 @ hobby people why not ? ) this charger is a variable amp charger ( amp is the amount of current that goes into your battery ) it works by starting with a fixed amp output ( shown on the built in amp meter ) that gradually gets lower because your battery gets "full" it develops resistance to amp flow, the optimal charge for small battery is 15 minutes ( that's right OMG from 2-3 hours to 15 minutes ) it also has a built in "discharge function using a resistor, be careful as it's not automatic, so as soon as the battery goes "zero" you need to unplug it, can't be good to have a negative value there ... ) The one major con I can relate to is that you need to hand crank the timer several times for large batteries ( anything exceeding 7 cells, or 2000 maH ) and it's not "automatic" what it does have is the ability to plug into a DC power source ( 12 volt battery in your car for some field charging, just don't start the car while you are charging as this will cause a power surge, do not plug BOTH the AC & DC at the same time - BOOM )

-Peak Chargers, Airsoft GI sells a lot of different kinds of peak chargers ( or automatic chargers ) namely the old and reliable MRC super brain, to the universal charger, I own quite a few of these ranging in price from $24.00 to somewhere around $300.00 ( the charger in the picture is a basic peak charger, 2 amps or 4 amps it was around $24.00 when it first came out ) most of the basic models lacks a discharge function because it does not have the Resistor that the mechanical charger has. the more pricey ones ( like my Orion Delta-Peak Charger ) will even automatically cycle & condition your battery with up to a 1 month schedule for competition batteries ( which we have no need for AEGs )

-Discharger What do I need this for ? Can't I just Fire My AEG until It's "dead" ? One of the biggest misconceptions in battery care is that the battery cycle must end when the gun is no longer able to crank off a round, couldn't be more wrong !! that's why we have a discharger, it helps us condition the battery ( more on conditioning later and why it's supposed to be a must ) it helps prevent an early battery demise, believe it or not you are killing your battery every time you "discharge" it by firing until the last shot can't crank anymore ( it causes some of the cells to have a negative charge by then ) Airsoft GI sells a basic discharger that is essentially a resistor clad in plastic to keep them trigger fingers from being crispy ...


in the picture below you can see the effects of conditioning on my standard 7 cell "7.2 volt" battery pack, it outputs a steady 7.90+ for the ENTIRE duration of it's firing life ( it dumps after about 4 minutes continuous firing which is around 13-15 high caps ) more on "battery dump" later, it's also wise to use a battery adapter plug/pigtail of some sort as this will allow your charger or discharger ( even your AEG ) to handle a wide variety of plugs employed in airsoft guns. The Discharger is a former mechanical charger that I used to house some 2amp automotive headlight bulbs in series configuration ( "daisy chained" to draw out 20 amps from my batteries, more on the "why's" later )


- Concept OF Conditioning, To Condition your battery is to train it to discharge at it's peak power as opposed to discharging gradually ( the best analogy is a high flow valve for your gas gun, you need to "train" the battery to discharge a high volume of power at a certain draw, the draw depends on your AEG for this tutorial we will assume it's 20 amps, so you need to make that battery discharge at 20 amps every time, instead of it discharging 5 amps at a time ( most of you would have experienced a "weak" battery and taught it either a lemon or dead, it's just not conditioned to discharge at a high rate or you unknowingly "trained" it to do so by running it low power or charging it low power, it "trickles" out it's power as a result of memory )

- Conditioning Guidelines :

1>Always Charge it at the same rate ( or time ) try not to deviate as it's key that the cells get used to a certain charge rate.

2>Always Discharge it at the same rate ... this is why you need a Discharger ( if possible ) it's easier to keep a discharge rate uniform using a controlled system rather than an AEG's highly variable amps ( it can be less draw when the piston is forwards, more when it's getting pulled ) draw.a battery on it's last 20 seconds of power should not be run anymore. ( my discharger's lights suddenly dim at the cut-off point )

Benefits Of Conditioning-

-The Battery Will Almost always peak higher than rated, it will also make the battery discharge at full voltage for the entire duration rather than lose voltage as it goes ( wouldn't you rather have a full 7.2volts + until the last shot ? as opposed to around 7.2 volts and dropping ?! )

-Piston pull & torque remains the same, eliminate the mid-field battery weakness ( when it gets weak as play progresses )

- You will know exactly when the battery is spent, the power drop is very noticeable in a 7-cell it's 7.90 to a sudden 7.2 instead of it grinding to that voltage )

- The Battery is fully charged when it's warm 'n toasty ( not hot and roasted )

Signs Of An Unconditioned Battery-

If you have experienced the following symptoms the battery using may have indeed suffered from lack of conditioning :

-Battery Weakness ( when it just feels "lethargic" )
-Mid Capacity Dump ( Starts Firing Weak half way then just "dies" slowly )
-Charging Takes Less & Less time ( will no longer accept a full charge )

sorry if the battery care part is a bit elaborate, conditioning batteries is a bit of a chore and requires patience.


Battery Types-

-Ni-Cad ( Nickel Cadmium ) The Most common type of rechargeable cells out there, one of the toughest most forgiving cell out in the market, fairly easy to solder and resists heat damage the most.

-Ni-MH ( Nickel Metal Hydride ),these cells are known to have more storage capacity than the Ni-cads but they are in turn slightly more prone to heat damage, they have a slightly lower max-peak charge capability ( a Ni-Cad can safely charge at 4 amps with no cell damage, most Ni-MH can go at 3 amps )

-Li-Poly ( Liquid-Polymer ) is the newest contender in the high output market, a great battery all in all for it's compact size and rectangular build, but it does have quite a few drawbacks for performance oriented hobbies ... 1> it requires "cell isolation" charging periodically ( charging individual cells instead of the whole pack ) as such they require even lower amps to charge than Ni-MHs 2>They are quite pricey for the output rating ( analogy = Red Gas aka butane )


Common Battery Problems & Solutions :

Problem : My AEG has reverse Wiring, Where Can I Find A Better Battery For it ? ( Some Manufacturers Like AGM has this "feature" )

Solution : All You Need To Do Is Take A Small Flat Screwdriver, And Relieve the Flat Metal Prong That Holds The Wiring Inside The Connector So You Can Slide it Out, Then Simply Flip The Polarity ( By Putting The Red Wire Prong Where The Black One Was Previously & Vice versa ) - pic coming soon

Problem : OMG I Killed My Battery By Leaving It Connected To My AEG For Months /sniffle/ now my peak/smart/automatic charger won't charge it !!

Solution : This is a Bit Tricky As It Requires 100% Attention ( If you have a short attenttion span, have someone else do it for you ), You Need a Higher Voltage Battery Source To Give Your Battery Some Much Needed "CPR" :shock: About 90% Of The Time You Can Still Save That Battery !!
Ok, Here's How !! First You Need Wires ( 2 Pieces ) Or a Spare Connector, You Need To Connect A Higher Voltage Battery To Your Smaller Battery For A Very Limited Time ( Normally A Count Of 3 Or 5 ) I Use a 12 Volt Sealed Type Battery That I Keep In My Shop, I Connect It Via Wiring Harness I Made, DO NOT LEAVE THE BATTERIES UNATTENDED !! A Fire Or Explosion May Occur ( I'm not just saying that, It happened to me when I was a wee electronics newbie and it wasn't pleasant having yer clothes melt from the acid cloud, thank gawd for the emergency wash station nearby :shock: ) holding the battery is a good idea, you can feel it get a lil wam after a count of 3 , simply disconnect and it should charge fine on those peak chargers ( super brain & other "smart chargers" won't charge a battery that has fallen below minimum voltage, so you may think it's broken )


-As time has allowed me to use Li Poly extensively I have a few observations that may be of some use.

-ASGI Li Poly Bag, this is probably one of the smarter investments in terms of safety ( worst case scenario that one or more of the cells erm ... explode ) the bag will contain about 99% of the battery elements if you somehow blow up your batteries, in fact I recommend keeping your batteries inside such a bag if your AEG's battery space allows it. let's just say I somehow failed to account for this hot california weather coupled with charging time on a none automatic charging source, the result is a loud bang, some noxious fumes, one helluva mushroomed bag, and one embarrased tech moderator. - be careful, be safe, have fun ( and live to yak about it )

Coming Soon :
-Pics For The Above Battery Solutions Section
-Connector Types & Useful Wiring Splices For Batteries+ Pics

whatever your selection or preference may be, remember to be careful and weight in your options first.

I'll add more as time allows, for further questions please feel free to PM me (Kilo Bravo Echo Echo)

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