Jump to content

Archived

This topic is now archived and is closed to further replies.

infected

Lithium-Polymer (LiPo) Battery Primer

Recommended Posts

. As you said, Li-Pos need balancing before charging, is it usual for the cells to discharge at different rates, because later on you mention that if they are charged after balancing, they'll drop to the same voltage together, in use? Where would any imbalance come from?

 

Not all cells are created equal. And not all chargers are 100% accurate.

 

2. What's the overall 'life' of a Li-Po, compared with Ni-Cad/ni-Mh (i.e. roughly how many charges before it's 'dead' and no longer useable)?

 

200-300 cycles for most lipos. The round count is still very high as lipo's will give you 2-4 shots per mah compared with the general rule of thumb 1mah = 1shot for nicd/nimh.

 

1) If I put a Li-po battery in a drawer for a month for storage, will it discharge or do anything else I should worry about?

 

Look at lithium CR123's as an example. 10yr shelf life. Lithium batteries maintain their charge for a LONG while. A month idle after being fully charged is nothing, while a nimh may lose as much as 15% of its charge within a week.

 

2) Would it be a good idea to charge and balance the Li-Po every week? Whether it's been used heavily or not?

 

Now you're just being paranoid ;). It's not uncommon for people to only balance them ever 3rd or 4th cycle. As long as it doesn't dip below the minimum voltage you can leave it as is.

Share this post


Link to post
Share on other sites

Another point worth mentioning is that when using the two cell packs, yo typically have to worry far less about running the cells below 3v. Chances are good that an upgraded AEG is going to need more than 6v initial to start the motor.

 

This reduces the chance of overdraw or even the uncommon but always cited explosions or puffing. Besides, a 7.4v typically acts like a large 8.4v anyways.

 

 

 

Share this post


Link to post
Share on other sites
1, Like the majority of most players (I'm guessing) with several AEGs though, making the jump from Ni-Mh/Ni-Cad to Li-Po for all my AEGs is a big(ish) one financially.

 

2. As you said, Li-Pos need balancing before charging, is it usual for the cells to discharge at different rates, because later on you mention that if they are charged after balancing, they'll drop to the same voltage together, in use? Where would any imbalance come from?

3. What's the overall 'life' of a Li-Po, compared with Ni-Cad/ni-Mh (i.e. roughly how many charges before it's 'dead' and no longer useable)?

 

1, Actually no. To get the best out of an aeg, with the conventional batteries you found yourself having to buy a battery or two for each gun. Eg a pair (cos they are only little & you want a back up) of j type 9.6v1600's for your p90 & a pair of 9.6v2000 flat for the fore grip of your G36, then maybe you get the big fore grip & up grade to a (one) 9.6 3600 subc.

 

This is just for two guns, but you then get, say, a star l85 commando & discover none of these will fit & get a pair of 8.4 2000's. In other words, you maximize the space available for a battery, by filling it.

 

So this is 4 different types of battery, & you've doubled up on the smaller ones, 'just in case'.

 

In walks Flight Power's (or another good manufacturer) 30C 7.4V 2000mah lipo. This will out perform all of the above. It will give the similarly high rof as the 9.6 subc, with more shots. & being the same size as an 8.4 mini, it will fit just about any where.

 

So that just about covers all the guns you run on 9.6 or below, all for the princely sum of,,,,,,,,,,,,,wait for it,,,,,,,,,,,£30! yup, less than a 9.6 subc.

 

Obviously you will now have to look at replacing them big heavy 10.8 & 12v set ups, but believe me, it wont be difficult.

 

The one limitation I have found is getting lipo power into an m16-a-like buffer tube. There are a few available, but, as with all batteries, if you are happy with the bat you have, why bother changing?

 

2, All cells (lipo, nicad etc.) have charge/discharge rate variance. As you probably know, they are manufactured to a tolerance. The higher quality manufacturers, will have a smaller variation. After a number of cycles, the weakest cell will inevitably be rendered useless. We have all heard, or experienced this with nicads or nimh's. For no apparent reason, the battery pack eventually loses power & often, this is down to 'one cell having gone'.

 

As nicads/nimh have relatively high recharge counts (in the thousands) it is not seen as economic, to add a loom to check the cells are balanced. It's just not seen as worth it. Chuck the pack away & buy another.

 

Lipo's are high end, but only last a few hundred cycles. Thus, the balancer is introduced to try & maximize this relatively short life span.

 

3, This really depends on use. Some say 100 cycles, some will say 250, or even 500.

 

It is hard to say, because, in lipo terms, what is a cycle? Unlike nicads/nimhs, you cant run them flat, so where do you draw the line. Also, unlike nicads/nimhs they hold their charge, so don't need to be recycled, or topped up if you haven't used them for a while. The longest I've heard of was a 150 mah loss, over a 2 year period. Having said that, I usualy find that I can top up a lipo to the tune of 100-150 mah, at any time after it has been fully charged (even after 5 minutes :huh: ). The longest I have left one is about 6 months & yes, you guessed it, under 150mah loss. Not actualy worth topping up!

 

Obviously you will be able to top a lipo up with a few mah, many more times than 'filling' it up, from, say, 80% empty. & life will be prolonged by avoiding discharge above 80% & regular balancing.

 

Most RC heli flyers date & record their lipo charges (obvious safety reasons) & claim many years regular use without the need for replacement. I am also aware that the UK 3d heli champ has had to 'dump his lipos' after just a few cycles, but this is very unusual. I suspect this was either dodgy cells or discharging beyond recommended levels, during the pressure of competition.

 

 

Greg.

Share this post


Link to post
Share on other sites

I think there's a little bit of confusion here about the charging. There's a lot of combinations of charger/balancer quoted above. I'm just plugging my $40 balance charger (12v input) from Gunner into the balance plug on the battery and it takes care of charging the battery, in about 40 minutes. It flashes LEDs when it's done on each cell, typically there's only 5 minutes between one cell finishing and another.

Share this post


Link to post
Share on other sites
I think there's a little bit of confusion here about the charging. There's a lot of combinations of charger/balancer quoted above. I'm just plugging my $40 balance charger (12v input) from Gunner into the balance plug on the battery and it takes care of charging the battery, in about 40 minutes. It flashes LEDs when it's done on each cell, typically there's only 5 minutes between one cell finishing and another.

 

That's exactly right. With a charger balancer combo, it will balances while charging, which streamlines the whole process. That's why I use the Equinox balancer with my trition2 charger.

Share this post


Link to post
Share on other sites

 

Infected and Greg,

 

First of all I want to congratulate you for creating such an amazing thread and I also want to thank you for all the time and effort you have spent writing your posts and replying to peoples questions.

 

Because of what you have written I'm now satisfied with the performance of Li-po's and I will be getting a 7.4v 2200mah battery for my new HK416 project.

 

Infected, I'll be sending you a PM shortly with regards to your MOSFET's.

 

Thanks guys, Josh

Share this post


Link to post
Share on other sites
That's exactly right. With a charger balancer combo, it will balances while charging, which streamlines the whole process. That's why I use the Equinox balancer with my trition2 charger.

 

 

I concur, it couldn't be simpler.

 

In my case, it's a flight power balancer & pro-peak charger combo. Select battery type & capacity, connect leads, press charge. disconnect shortly after hearing beep.

 

Hardly rocket science.

 

For safety, I do mine in a biscuit tin! :D

 

Please note, that while I balance, every time I charge, (why not? :huh: ) there are many lipo users out there, who consider the whole 'balancing thing' to be a waste of time. As with other multi cell power sources, it is not entirely necessary. But will ensure peak performance.

 

Nomex sox, you say :huh:

 

 

Greg.

Share this post


Link to post
Share on other sites

Hey guys, I really appreciate all the kind words. For me, this is just a hobby, and educating everyone on all that I know is very rewarding when I see what all you guys get out of it. I'm still learning too, and I've got to thank Greg for giving me the push to go li-poly in the first place!

 

Greg:

the nomex socks are something I read on an RC forum somewhere. I've priced them... you could buy a liposack for what people charge for nomex socks. They are used for people who drive race cars for a living, and run almost $30 a pair. I still charge mine in a liposack.

Share this post


Link to post
Share on other sites
Infected and Greg,

 

First of all I want to congratulate you for creating such an amazing thread and I also want to thank you for all the time and effort you have spent writing your posts and replying to peoples questions.

 

Because of what you have written I'm now satisfied with the performance of Li-po's and I will be getting a 7.4v 2200mah battery for my new HK416 project.

 

Infected, I'll be sending you a PM shortly with regards to your MOSFET's.

 

Thanks guys, Josh

 

 

That's really heartening, you are welcome & I'm glad it's helping you to take the plunge.

 

I have to pat Infected's back, his articles are well informed & excellently written.

 

This thread is a million miles away from the one I generated last year. Back when I first took the plunge & 'got lipo'. It ended up a 3 page holocaust list/slaging match, which was mainly negetive & eventualy, just fizzled out.

 

Xaccers (& a few others, whos names I've forgotten) gave very positive feedback in that orriginal thread. This helped me on my way, so it's nice that I can do the same. I'd also say that Farkle is in the know. Thanks to all of them for contributions, new & old.

 

It's great that a year later, airsofters are open to the lipo idea & the fact that Infected is recognised for his good work, & that this has been pinned is testament to that.

 

I have picked up most of my info, from personal experience, & advice from UK RC 3D heli flyers. They have been at the competitive & cutting edge of light weight power packs all along. Their experiences with lipo's stretch back a good few years. The top lipo manufactures like to use them as test beds for new products. As you can imagine, they demand top performance. Having £3,000 worth of heli, chop someones head off, due to electrical power failure is, er, well, :unsure: , as you can imagine. :(

 

Word on their grape vine is that we will be able to look forward to run flat packs & even more mah/g. & as popularity rises, prices should fall.

 

 

Greg.

 

 

Share this post


Link to post
Share on other sites
1, thank Greg for giving me the push to go li-poly in the first place!

 

2, Greg:

the nomex socks are something I read on an RC forum somewhere. I've priced them... you could buy a liposack for what people charge for nomex socks. They are used for people who drive race cars for a living, and run almost $30 a pair. I still charge mine in a liposack.

 

1, You're more than welcome. It's the least I could do. Especially considering all the help you have shown me, re mosfets.

 

2, This sounds like a really good idea, for any batteries, not just lipos. Although I'll stick to the bicky tin, I would recommend this to any one, charging any type of battery.

 

I have had a 'flare up' experience involving Marui's pro light. Thankfully, the biscuit tin (& quick reactions) saved the day!

 

Remember people: BE CAREFUL.

 

 

Greg.

Share this post


Link to post
Share on other sites

I'll add my thanks again to all that have replied, lots of info to consider...

As I said, I'll probably 'dip my toe in' with just the MP7 for starters, to get back to an internal pack but with decent performance.

 

And Greg, I only have one pack for each gun, either large 8.4V~3000-3700mAh or stick* packs 8.4V~1400mAh plus three cheapy 7.2V packs for the MP7.

I can only think of two times where I've needed to change a pack during a day's play, and one of those was the morning of the second day of a weekender :P (Town Assault II).

Trigger-happy I'm not ;)

I'll typically only get through 1000-2000 rounds in a typical day.

 

Edit; * That reminds me of the third thing I wanted to ask...

Are all Li-Po cells the same shape, i.e. thin and rectangular, in the same way that 'normal' cells are all cylindrical?

Are they at all flexible?

Share this post


Link to post
Share on other sites
Edit; * That reminds me of the third thing I wanted to ask...

Are all Li-Po cells the same shape, i.e. thin and rectangular, in the same way that 'normal' cells are all cylindrical?

Are they at all flexible?

 

To my knowledge, they are all about the same shape (not size), and they are not flexible. If they were flexible, that'd open up a whole new area of possibilities.

Share this post


Link to post
Share on other sites

Well, I'm on the other side of the pond here in the USA, but I buy all of mine from www.RCLipos.com . I don't know if they ship internationally or not, but Pat's a good guy and has AWESOME service.

Share this post


Link to post
Share on other sites
1, And Greg, I only have one pack for each gun, either large 8.4V~3000-3700mAh or stick* packs 8.4V~1400mAh plus three cheapy 7.2V packs for the MP7.

I can only think of two times where I've needed to change a pack during a day's play, and one of those was the morning of the second day of a weekender :P (Town Assault II).

Trigger-happy I'm not ;)

I'll typically only get through 1000-2000 rounds in a typical day.

 

2, Edit; * That reminds me of the third thing I wanted to ask...

Are all Li-Po cells the same shape, i.e. thin and rectangular, in the same way that 'normal' cells are all cylindrical?

Are they at all flexible?

 

1, Good to hear. Sorry to repeat: the bat I used for the mp7 is the Flight Power Evolite Ver2 (make sure you don't get the 18C ver1) 20C, 7.4v, 800mah. Often known as a 'Blade Upgrade'. With mine, this gives over 2000 shots. It's pretty straight forward to nick the connectors from a stock mp7 bat & transplant them, but feel free to PM me if you need any help.

 

2, At present, lipos are only available in the 'wafer' format. Rummer has it, that we will see 'coil' (cylinder) types 'eventually' as per other cells. Personally I doubt this will happen.

 

They are not flexible & attempting to flex, or bend a cell will, most likely, result in a battery right off.

 

 

Greg.

Share this post


Link to post
Share on other sites
quick question infected. ware is the best place to get li-pol batteries?

 

I know this wasn't directed at me, but this may help:

 

I use 'Flight power'. They are considered the very best available. They are UK based & I have found them to be very helpful.

 

Check out their web site to see if they offer one that will fit your set up. Give 'em a ring for some very helpfull advice.

 

They don't sell direct, but are available through decent suppliers at the price advertised on the FP web site. I've used various suppliers & find they have all been ok. 'Moore Models' springs to mind. FP will send to their suppliers on a next day basis, so if they don't have it in,,,,,,,,,,,,,they will tomorrow!

 

 

Greg.

Share this post


Link to post
Share on other sites
To my knowledge, they are all about the same shape (not size), and they are not flexible. If they were flexible, that'd open up a whole new area of possibilities.

 

You can shape a li-po battery in any form you want. Albeit not flexible, but while being manufactured, there's ultimately no limit to what the shape of a lipo battery should be.

Share this post


Link to post
Share on other sites
You can shape a li-po battery in any form you want. Albeit not flexible, but while being manufactured, there's ultimately no limit to what the shape of a lipo battery should be.

 

In theory, this is true. Pre production, the wafer format can be cut & formed into almost any shape (hence the term 'coil' for cylindrical shaped lipos: Basically a wafer, rolled up.).

 

There have been prototypes made, but as yet there is not enough commercial demand.

 

The way I see it, there wont be. I don't see much of a market for 3.7v, rechargeable, AA batteries. Most Standard cell size applications are geared up for the std 1.2-1.5v.

 

To gear products up 'against the convention' would be a big step & although possible, very unlikely.

 

It would be nice, things like Surefire torches would be half the size & brighter still.

 

The only similar application I can think of at the moment is the 3v lithium (non- rechargeable) AA used in the Kings Arms 1-3 I.R. scope. The one that copies the Leopold mk4 cq/t.

 

 

Greg.

Share this post


Link to post
Share on other sites

really informative thread infected, we're all really impressed :) im still relatively new to airsoft having only started at the end of may this year (and have been going every week since and already spent 2k+ on it...) and i was hoping you guys could answer some Q's for me?

 

1. with all I've ready in this thread, am i to understand that my stock 8.4v CA MP5A5 would take this battery and provide greater ROF and hold more charge?

 

http://www.rctoys.com/rc-toys-and-parts/TP...2-LI-POLYS.html

 

2. These LiPo's use a "Dean" connector, does any one know anywhere that sells Dean to Tamiya connectors?

 

3. Can some one explain simply what these MOSFET's do?

 

thanks guys!

Share this post


Link to post
Share on other sites
1, Good to hear. Sorry to repeat: the bat I used for the mp7 is the Flight Power Evolite Ver2 (make sure you don't get the 18C ver1) 20C, 7.4v, 800mah. Often known as a 'Blade Upgrade'. With mine, this gives over 2000 shots. It's pretty straight forward to nick the connectors from a stock mp7 bat & transplant them, but feel free to PM me if you need any help....

Thanks. No apology needed, I missed that first time round :P

 

Edit; Nexus01. Two options;

1. Put Deans in you AEG(s). If you're going down the Li-Po 'route' for better performance, you should really ditch those cr##py Tamiya plugs at the same time.

2. Order the Li-Po pack(s) with Tamiya plugs, most sellers will offer this, but it'd be like buying a superbike that has bicycle tyres fitted :lol:

Share this post


Link to post
Share on other sites
really informative thread infected, we're all really impressed :) im still relatively new to airsoft having only started at the end of may this year (and have been going every week since and already spent 2k+ on it...) and i was hoping you guys could answer some Q's for me?

 

1. with all I've ready in this thread, am i to understand that my stock 8.4v CA MP5A5 would take this battery and provide greater ROF and hold more charge?

 

http://www.rctoys.com/rc-toys-and-parts/TP...2-LI-POLYS.html

 

2. These LiPo's use a "Dean" connector, does any one know anywhere that sells Dean to Tamiya connectors?

 

3. Can some one explain simply what these MOSFET's do?

 

thanks guys!

 

1. It should be able to handle a 7.4v 2200 mah 25c lipo. My concern with CA, is their pistons. They seem to be dropping in quality.

 

2. Most lipos that I've seen, come with no connector and you need to supply your own. I know some places allow you to choose the connector on them too. Honestly, if you're using Tamiya connectors, you're really defeating the purpose. I've seen charing inside tamiya connectors from poor conductivity and arcing. That's lost power. I'd suggest upgrading your connectors to deans. It's not really all that hard. See my soldering how to that's stickied in the Technical section.

 

3. wow, I've answered this one a lot. :D Rather than type it all over again, just check out my website with all the moseft info: http://infectedairsoft.wordpress.com/item-...eaking-circuit/ if you're interested in buying one, then hit me up with a pm.

Share this post


Link to post
Share on other sites
really informative thread infected, we're all really impressed :) im still relatively new to airsoft having only started at the end of may this year (and have been going every week since and already spent 2k+ on it...) and i was hoping you guys could answer some Q's for me?

 

1. with all I've ready in this thread, am i to understand that my stock 8.4v CA MP5A5 would take this battery and provide greater ROF and hold more charge?

 

http://www.rctoys.com/rc-toys-and-parts/TP...2-LI-POLYS.html

 

2. These LiPo's use a "Dean" connector, does any one know anywhere that sells Dean to Tamiya connectors?

 

3. Can some one explain simply what these MOSFET's do?

 

thanks guys!

 

Doc & infected have covered it all. :D

 

Sorry to here the CA pistons are deteriorating. I've always been a fan. Up to a point...............about 1800rpm :D . Then they are very reliable.....................at almost exactly 1800rpm, you can rely on them to break! :rolleyes:

 

 

Greg.

Share this post


Link to post
Share on other sites

×

Important Information

By using this site, you agree to our Terms of Use and the use of session cookies.