Newb: New to Li-Poly (Possible FAQ)

[joco]

Ok well having only eveyr played with electrics in my R/C car using NiCad... I have a few questions about LiPoly batteries and charging (maybe we need a FAQ for this)

1. What are the standard batteries sizes that are used for 400, 500 and 600 size helis?

2. Can you charge Li-Poly faster then "normal" rate i.e. a fast charge

3. Do you need to balance on every charge?

4. Any ther good general info?

[Hughes500Bob]

Batteries must match the KV demands of the installed motor, BEC, and other electronics. Undersizing a battery is the worst thing to do!

If a battery is a 2200 mah then you charge at 2.2 amps MAX (move the decimal 3 places to the left). You can charge to 95% "quickly" as the last 5% takes a lot more time.

You do not have to balance on every charge .... but balancing is another life extender for the battery. If you can charge and balance at the same time ... that is the best.

Watch the Finless videos on the TP1010 charger and TP210 balancer and you will get a good feel for what is required to charge and maintain your Li-Po batts.

[Pinecone]

Some additional info:

Different people run different battery sizes for different reasons. Also, what do you mean by 400/500/600 size? In some cases the numbers mean the motor size (based on the old Graupner can motor sizes) and in other cases they mean blade sizes. A 400 motor size heli runs about 280 mm long blades, a 400 blade size heli runs a 500 sized (or so) motor. :)

Yes, newer lipos can be charged at higher rates than 1C, but doing so will reduce the longevity of the back (numbr of cycles). Also due to the way that lipos charge, the charge times doesn't go down as dramtically as it does with NiCds or NiMH. Lipos charge in a Constant Current/Constant Voltage mode. For the first part of the charge they charge at a Constant Current, and that current is the 1C or 2C rate mentioned. So 2100 mAH pack charges at 1C at 2.1 amps, or at 2C at 4.2 amps. But once the charge voltage reaches 4.2 volts per call (12.6 volts for a 3S pack) the charger switches to Constatn Voltage mode, holding that voltage an accepting whatever charge rate you get.

So during the initial phase the 2C charge rate will cahrge twice as fast, then for a period of time it will charge at a lowering rate, but still high than the 1C charge, then when the charge gets to 12.6 volts and 1C charge rate, the two will take the same amount of time to finish. And this time is about 15 - 25 minutes.

So charging at 2C doesn't take half the time, but more like 2/3 the time of a 1C charge.

As has been said, it is BEST to balance every charge. The reason is, lipos are VERY sensitive to over voltage. So if your lipo starts out even slightly out of balance, one or more cells can be over voltaged.

Read the threads in the battery section, lots of good info there.

[joco]

Great guys... thanks for the info... now one more question.. I am considering getting a T-Rex 450 and deciding on a charger... I was told that by getting a TP1010 would allow me to charge my packs faster than a cheaper charger like a Triton V2.... thoughts?

[DebianDog]

I think the TP1010 with give you a lot more comfort especially when paired with the 210 balancer.

For speed... the fastest thing -I- have used is the FlightPower V balancer but it does not sync with the 1010. For whatever reason it finishes up quite a few minutes faster than my TP210 balancer when tested with dual packs off my Ion (they always take back almost exactly the same mah per pack)

So you may want to try V-balancer and the Triton.

[kgfly]

Joco,

1. What are the standard batteries sizes that are used for 400, 500 and 600 size helis?

TRex450/miniTitan e325 (325mm blades): 3S ~2100 20C or 4S ~1800 20C
TRex600 (500-600mm blades): 6S 4900 15C but also 8S, 10S and 12S setups

2. Can you charge Li-Poly faster then "normal" rate i.e. a fast charge

Only some, it reduces pack life, going over 1.4C doesn't save much time at all.

3. Do you need to balance on every charge?

No but it is good practise.

4. Any ther good general info?

Here are some notes I put together recently that you might find useful.

Summary
Budget 2S-4S LiXx only: FMA CellPro4S ($70)
Budget multi-chemistry 3S-6S low power: eStation BC6 ($170)
Most convenient mid-range: eStation BC8 ($270)
Best value high-power/future proofing: Hyperion 1210i-A + 2xLBA10 ($240)

FMA CellPro4S for a good, simple, safe 2S-4S LiXx charger that will do 2S-4S packs at up to 3A all for only $65.

eStation BC6 for a more flexible, 2S-6S all-in-one charger (ac/dc power supply, NiCd/NiMH/Pb/LiIon/LiPo/LiFe charger, integrated balancer) that will do 3S lipos at up to 4.5A. It has an optional temperature sensor which is recommended if you want to charge above 1C. A really nice solution since you don't have to buy a DC bench supply or external balancer. Has Normal, Fast and Storage LiPo modes.

eStation BC8 gives you the same features as the BC6 much more output power (150W/7A vs 50W/5A). Still has the benefit of an integrated balancer but DC input only.

eStation 902 + PB6 balancer (12S/200W) or TP1010 + 210 balancer (10S/220W) or Hyperion EOS 1210i + LBA10 balancer (12S/180W) are all excellent high end chargers but probably overkill for you.

==================================================
Personally I wouldn't touch any lipo charger that does not have an LCD display that tells you what it is doing, the voltage of the cells and the total charge put back into the battery.

Choosing batteries and chargers
===============================
Which chemistry ?

LiPo provides the highest energy density and best performance for size but is relatively expensive and somewhat fragile. Packs are easily damaged mechanically and there is a risk of fire if overloaded, overcharged or punctured. They also don't tolerate deep discharge. Hence they require a top quality charger, care in handling and a degree of knowledge to be safe.

Emoli (LiIon) from the V28 packs are 100g/cell at 3000mAh. They are heavy buggers but very robust and don't have the same fire risks as LiPo. They have a precipitous voltage drop at the end of the curve which can catch folks out without anough oomph to recover and land. I personally wouldn't choose them.

A123/M1 (LiFe) from the 36V DeWalt packs ar 70g/cell at 2300mAh. These are heavier than equivalent capacity LiPo but very robust and essentially zero fire risk. They are also lower voltage (3.3V nominal, 3.6V fully charged vs 3.7/4.2 for LiPo) but they tolerate 100% discharge and can be charged at up to 10A (4.3C) which makes up for the lower capacity by getting you back in the air much faster. Testing has shown that for power-system design purposes you should treat them as 16C/33C if you want to get ~500cycles. Unlike the emoli, which strangle around 40A, the A123 cells are capable of very high output, certainly 70A and up to 100A briefly. Basically heat is the enemy of cell life so running them at these very high discharge rates will shorten their life, but it's nice to know they can do it if needed. Under load the cell voltage drops quite a bit, running about 3.1V at 10A and 2.6V at 40A.

The lower cell voltage, particularly under load means you need more series cells than a lipo for the same rough pack voltage. The bigger voltage drop under load (at least compared to premium lipos) means maintaining uniform headspeed can be a bit harder and an ESC with a top class governer (eg Jazz or CC) can be useful.

The market rate for a DeWalt 36V tool pack with 10 A123 cells is about USD$100 plus shipping on eBay. Probably works out to around AUD$15/cell. That makes them very cheap when compared to lipos on a total energy basis. For example a 3S 3700 lipo costs about $185. A 6S 2300 A123 delivers about the same energy for approx $100. Of course it will weigh ~450g vs ~310g for the lipo and take up more space too. By accepting shorter flight times the balance can be adjusted for easier mechanical fit and even greater savings. Hence a 4S A123 will give about 2/3 the flight time for about one third the cost and the same weight. Now only the space may be an issue. At these prices you can have three A123 packs to give you more total flight duration with faster charge times and much lower risk.

Overall I really like the A123 cells for their robustness, inherent safety, deep discharge tolerance and fast recharge ability. However they are best suited to larger helis (Swift, TRex600, eRaptor, Logo10 etc) where their size, weight and voltage characteristics can be balanced out by using HV setups (10S to 15S). Having said that, I know people flying them quite happily as 4S or 5S in TRex450. When I get my EP8 I will be investigating the space/balance issues to see what's possible but my initial thinking based on some dimensions is that it will be hard to make it work.
The A123/M1 datasheet is here: http://www.a123systems.com/html/products/ANR26650M1specs.pdf
For now I would say stick with LiPo but get a charger that can do A123 (LiFe) as they could be a good fit down the track.

Which charger ?
A high quality charger is vital to safety as well as ensuring the best performance and maximum lifetime from your batteries so this is not an area to pinch pennies. There are some excellent choices around. A lot depends on your budget but more on the combination of your current needs and your expectations for the future. If larger models are in your future you might want a higher power charger now than would otherwise be needed if small park flyers are all you will ever fly.

Notes
1) Most chargers require an external DC power supply so budget ~$50 for a 150W one to run one or two low-power chargers or ~$100 for a 250W one to run high-power chargers at full load.

2) For now the only LiFe cells available are the A123/M1 cells from DeWalt 36V power-tool battery packs bought on eBay for ~$100 and which contain 10 cells rated as: 3.3V 2300mAh 16C/33C. They weigh 70g each, can be 100% discharged without harm, present near zero fire risk even if abused and can be charged at up to 10A=4.3C.

3) Two chargers and three batteries will get you more flying time over an afternoon than one charger and four batteries. Obviously more batteries gives more end-to-end flying in one go then you pack up and go home.

FMA CellPro4S (~$70)
- Requires DC power
- LiXx charger: LiIon/LiPo/LiFe
- 2S to 4S LiXx
- Integrated true balance charger (charges each cell separately)
- Normal and Fast LiPo cycles
- ~50W/3A output
- 1C LiPo charge: 3S <= 3000mAh, 4S <= 3000mAh
- A123 charge rate: 3S <= 1.3C, 4S <= 1.3C
- No discharge/cycle features

The best budget charger around for small 2S-4S packs. It won't charge your Tx or Rx packs but at $70 is great value for an intelligent and safe LiXx charger. Cheap enough you can get two and charge two packs at once to halve your waiting time. The 50W/3A output will charge lipo packs at 1C up to about 3000mAh capacity for 2S to 4S. If you don't need NiCd/NiMH support and are sure larger models with larger batteries are not in your future then this can be an excellent low-cost solution.

Hyperion EOS5i AC/DC + LBA10 6S balancer (~$115 + $45 = $160)
- Integrated ac/dc power supply
- Multi-chemistry charger: NiCd/NiMH/Pb/LiPo/?LiFe?
- 2S to 5S LiPo
- Needs external balancer
- Normal LiPo cycles
- ~50W/5A output
- 1C LiPo charge: 3S <= 4500mAh, 4S <= 3400mAh, 5S <= 2700mAh
- Discharge/cycle features

Convenient integrated AC/DC power supply and a proven multi-chemistry charger. Needs an external balancer. Only goes to 5S. Rumour is that there is a new firmware version that adds LiFe (A123) support.

eStation BC6 (~$170)
- Integrated ac/dc power supply
- Multi-chemistry charger: NiCd/NiMH/Pb/LiIon/LiPo/LiFe
- 2S to 6S LiXx
- Integrated 2S-6S balancer
- Normal, Fast and Storage LiPo cycles
- 50W/5A output
- 1C LiPo charge: 3S <= 4500mAh, 4S <= 3400mAh, 5S <= 2700mAh, 6S < 2300mAh
- A123 charge rate: 3S <= 2.2C, 4S <= 1.6C, 5S <= 1.3C, 6S <= 1.1C
- Discharge/cycle features

A great integrated package providing a one-box solution (ac/dc power supply, charger and balancer). The 50W/5A output means it's not well suited to high capacity 6S packs used in say a TRex600, but it will do a great job on most packs you would typically see in anything smaller. Although it initially looks expensive, since it is all 3-in-1 you don't have to buy a DC power supply or separate balancer so in fact it is very competitively priced.

I would definitely choose the BC6 over the EOS5i for its all-in-one convenience, 6S capability, LiFe support and better features (like the Fast and Storage charge modes).

eStation BC8 ($270)
- Requires DC power
- Multi-chemistry charger: NiCd/NiMH/Pb/LiIon/LiPo/LiFe
- 2S to 8S LiXx
- Integrated 2S-8S balancer
- Normal, Fast and Storage LiPo cycles
- 150W/7A output
- 1C LiPo charge: 3S/4S/5S/6S <= 7000mAh, 8S < 5200mAh
- A123 charge rate: 3S/4S/5S/6S <= 3C, 8S <= 2.4C
- Discharge/cycle features

Same features and benefits as the BC6 except DC-only input, 2S to 8S capability and the much higher output power makes this a real option for larger packs or fast charging A123 packs at up to 7A.

Hyperion 1210i-A + 2xLBA10 6S balancer (~$200 with 1xLBA10, ~$240 with 2xLBA10)
- Requires DC power
- Multi-chemistry charger: NiCd/NiMH/Pb/LiPo/LiFe
- 2S to 12S LiPo/LiFe
- Needs external balancer (1 for up to 6S, 2 for 7S-12S)
- Normal, Fast and Storage LiPo cycles
- 180W/10A output
- 1C LiPo charge: 3S/4S/5S <= 10000mAh, 6S <= 8300mAh, 8S <= 6250mAh, 10S <= 5000mAh, 12S <= 4100mAh
- A123 charge rate: 3S/4S/5S <= 4.3C, 6S <= 4.0C, 8S <= 3.0C, 10S <= 2.3C, 12S <= 1.9C
- Discharge/cycle features

A high-power charger that goes right up to 12S for a bargain price. Excellent features (similar to the eStation range) including LiFe support (must be the latest firmware, the -A model) although strangely no LiIon support, which is probably not an issue. While not as convenient as the BC8 (since you need up to two external balancers), this is great value for money and a real contender for long term future-proof performance.

Tough choice between the BC8 and the 1210i-A. I think both are excellent chargers with great features and flexibility and good UIs (at least as far as I can assess from their user guides). I really like the convenience of the BC8's integrated balancer (less boxes, cables and mess) but the 1210i is a fantastic deal and if you only need up to 6S then at ~$200 I might be tempted to put up with the mess.

eStation 902 + 2x PB6 6S balancers ($330 + 2x$65 = $460)
- Requires DC power
- Multi-chemistry charger: NiCd/NiMH/Pb/LiIon/LiPo/LiFe
- 2S to 12S LiXx
- Needs external balancer (1 for up to 6S, 2 for 7S-12S)
- Normal, Fast and Storage LiPo cycles
- 200W/9.9A output
- 1C LiPo charge: 3S/4S/5S <= 9900mAh, 6S <= 9200mAh, 8S <= 6900mAh, 10S <= 5500mAh, 12S <= 4600mAh
- A123 charge rate: 3S/4S/5S/6S <= 4.3C, 8S <= 3.3C, 10S <= 2.6C, 12S <= 2.2C
- Discharge/cycle features

A high-power charger that goes right up to 12S. Excellent features (mostly the same as BC8). While not as convenient as the BC8 (since you need up to two external balancers), this is a real contender for long term future proof performance.

ThunderPower 1010 + 210V balancer (~$375)
- Requires DC power
- LiXx charger: LiIon/LiPo/LiFe
- 2S to 10S LiXx
- Needs external balancer (1 for up to 10S)
- Normal LiPo cycles
- 220W/10A output
- 1C lipo charge: 3S/4S/5S/6S <= 10000mAh, 8S <= 7600mAh, 10S <= 6000mAh
- A123 charge rate: 3S/4S/5S/6S <= 4.3C, 8S <= 3.6C, 10S <= 2.9C
- ? Discharge/cycle features ?

A high-power charger that goes up to 10S. Currently LiXx only (latest firmware added LiFe to the LiIon/LiPo it had before) but there are rumours of a future firmware upgrade that will add NiCd/NiMH/Pb. Unique in this group in allowing end-user firmware upgrades with the purchase of the optional interface cable. This charger is hugely popular in the US with those flying 500 class and bigger helis. The BC8, e902 and 1210i-A are all newer (and BC8 and 12010 are cheaper) and are eating into the TP1010's market share.

Personally I would choose the 1210i over the TP1010 as it is more flexible (12S vs 10S, multi-chemistry) and has valuable additional features (eg fast and storage modes) all for about $100 less.

--------------------
I hope that is some help.

[joco]

Ok stupid question... what does 3S, 4S etc mean....

[joco]

KGfly,

Great thanks for all the info... Now who carries the Hyperion chargers... I cant seem ti find them.

[Hughes500Bob]

DebianDog had some good stuff posted here http://www.helifreak.com/viewtopic.php?t=5872

[kgfly]

There are no stupid questions.

Battery terminology
Lipo batteries are described by the number and configuration of cells, capacity and discharge performance. Hence 3S1P 2100 20/30 means: 3 series cells (3 x 3.7 = 11.1V), each of 2100mAh nominal capacity rated for continuous discharge at 20C and bursts of 30C.

Now "C" or "1C" is the discharge rate to get the nominal capacity delivered over 1 hour. For a call of X mAh capacity 1C = X/1000 amps. So for a 2100mAh cell 1C = 2.1A, 20C = 42A and 30C = 63A

More cells in series increases the voltage (for lipo by nominally 3.7V/cell). More cells in parallel increases capacity. So if you ran two 3S1P 2100 20/30C packs in parallel that would be 3S2P 4200 20/30C. On the other hand if you ran them in series it would be 6S1P 2100 20/30C. Often the "1P is dropped so you see simply 3S 2100 20/30C.

Hyperion chargers
I just use google. I found some excellent combo deals at these sites:

http://www.b-p-p.com/products.php?cat=8
(1210i + 2xLBA10) = $222
(EOS5i DP AC/DC + 1xLBA10) = $133

http://www.allerc.com/index.php?cPath=9
(1210i + 2xLBA10) = $222
(EOS5i DP AC/DC) = $115

[Pinecone]

kgfly, I was called on RCG about the CellPro, it doesn't actually charge each cell separately like the DN Power charger does (I thought it did). The DN Power charger actually has 4 separate chargers.

The Cell Pro has a single charger, but can vary the current across the cell using a varying resistance in series with the cell. There are some pictures of the inside one that clearly shows a single stage charger.

End result is about the same, but it isn't REALLY the same. :)

[kgfly]

OK, thanks for the info. So it has an integrated discharge balancer. It has a great reputation and I still think it is the best budget LiXx charger for 2S-4S if you don't need other chemistries.

[Pinecone]

No, it may actually vary the charge current, but not totally separately from all other cells.

Bottom line is it works, but it is not 4 separate chargers like the DN Power one.