[cf100]

I have a Fly Fly 90mm on 6S Hawk on a 3 year old 6S 30C blue Zippys, 2.5 years in storage, just started flying them this September. They don't seem to have the punch of 30C.

I am a warbird gas flyer that dabbles in EDF so I need your thoughts and experience. I also have a Fly Fly F4 to be assembled.

I do have a couple of 4S 5000 (40C & 55C) ChinaHobby Line that performed very well on a .46 Extra 300. I'd like to add a 2S or 3S to these packs and try them out in my EDF Hawk.

Does the 2S or 3S have to be around the same C as the 4S packs?
exactly same MAH?
does it have to be the same manufacturer?

My plan is to buy a 2S 40 to 50C pack to go 2 + 4, and buy a couple of 3S 40 to 50C packs to go 3 +3 or go 3 +4.

I don't think I will buy any more 6S packs.
Any flaws in my logic?

Since shipping and broker fees are up there, I am thinking of shipping the packs to the border and picking them up there.

This spring I hope to buy some well performing 40 to 50c lipos - from whom and from where.

Please give me your feedback.

cheers - ken k.

[SARPLT]

Hi Ken

I have been doing some testing this past year with batteries specifically trying to determine which ones have the lowest voltage drop under load because this ultimately means more power in the edf world. My Thread on Voltage Drop Concerns will give you some details on this. From my testing (Zippy, Turnigy, Great Hobbies, Eflite, Rotor Geeks, ZOP and Graphene) the Graphene have performed the best so I have decided to go exclusively with these for all my applications (4000mah 6S 65C and 5000mah 6S 45C). The last order I put into HK had free shipping (FEDEX) and no other brokerage fees so that helps keep the price down. I am sure that other readers will comment on what they prefer but from my testing I can say that all batteries are not created equal.

Prior to my testing I was mixing and matching batteries to get the right cell count and I found it best if I added batteries together that had the same mah capacity per cell and same C rating. For example adding a 3000 mah 4S to 3000 mah 2S to get a 6S battery otherwise the lower capacity battery got warm quicker so you will want to closely monitor this if you do this. IMHO it is best to use a single battery for each application as it also reduces the requirement for extra connectors and wiring which just adds weight to the model. When you move above a 6S application then you pretty much have to use multiple batteries.

Hope this helps.

Marty

[cf100]

Originally Posted by SARPLT

Hi Ken

I have been doing some testing this past year with batteries specifically trying to determine which ones have the lowest voltage drop under load because this ultimately means more power in the edf world. My Thread on Voltage Drop Concerns will give you some details on this. From my testing (Zippy, Turnigy, Great Hobbies, Eflite, Rotor Geeks, ZOP and Graphene) the Graphene have performed the best so I have decided to go exclusively with these for all my applications. The last order I put into HK had free shipping so that helps keep the price down. I am sure that other readers will comment on what they prefer but from my testing I can say that all batteries are not created equal.

Prior to my testing I was mixing and matching batteries to get the right cell count and I found it best if I added batteries together that had the same mah capacity per cell and same C rating. For example adding a 3000 mah 4S to 3000 mah 2S to get a 6S battery otherwise the lower capacity battery got warm quicker so you will want to closely monitor this if you do this. IMHO it is best to use a single battery for each application as it also reduces the requirement for extra connectors and wiring. When you move above a 6S application then you pretty much have to use multiple batteries.

Hope this helps.

Marty

Hi Marty, appreciate the feedback, how did you havethe HK lipos shipped UPS for Fed Ex, and at the end what was the shipping / broker fees?

[deltawing]

Hello...
When we consider mixing 2 batteries in serial to have higher count, make sure both are the same capacity (mAh) and discharge (C) rating. Otherwise the less capacity one will get hot as it couldn't perform the same.

IMO, It is important to get a charger that could measure (read) the internal resistance of each cell, whether true or relative resistance are good for this purposes. Most chargers on the market are relative readers only as true resistance on battery is hard to measure. We need to monitor the (relative) resistance of each cell and try to match one cell to another within a pack so that they perform the same together.

The internal resistance of a battery pack is directly proportion to its discharge performance; the lower the resistance (in milliohm) equate to higher discharge and better performance. Say one cell has 50% or more of relative resistance than the rest of cells within a pack that cell will gets warmer and starts ballooning first.

So joining two packs of similar internal resistance in series to form a higher count pack is very common and practical, especially for 8 cells and above.

my 2cents, Phi

[stegl]

Ken:
With regard to doing that round trip to the border to pickup lipos , consider the cost of fuel, most drop off points for UPS or Fedex charge a handling fee of from 4-5 dollars per package sometimes making it false economy . A lot depends on where the batteries come from. If shipping from China , better off shipping direct to Mb.
My last lipo order was from Great Hobbies and bought GensAce brand. If buying from HK , I found the Turnigy A Spec batteries to be very good.

Again as suggested get the highest C rating and keep the brands the same. Don’t mix , only match.

[Beers]

I myself have tried to mismatch and I have come to see it just is not a good ideal for the life of the battery I was running 2 3s (pulse)2200mah 1 30c and 1 40c
and when I was done flying the 30c was very warm almost hot I would never run mismatch batterys again I think I was border line on a melt down.i all ways run
match batterys now by brand mah`s and c rating(just ant worth the chance)

[4stripes]

Running packs in series requires cells of equal capability and strength to work. If one cell is weak the whole system is compromised as that cell will now be stressed beyond normal limits. If you are lucky the low voltage protection or telemetry will prompt the pilot to land or the heat will build up in the sagging cell to the point of bursting into flames.

[Beers]

yes I agree eric mis matching is just asking for trouble for that matter.
and even just 1 bad cell with matched packs can be a problem

[SARPLT]

Ken

I ordered two separate battery orders from HK just before Christmas when they were advertising free shipping. You had to spend $150USD to get the free shipping. The first order was sent by UPS and I was charged $55Cdn for brokerage fees at the door on an order of $278USD. The second order came by Fedex and there were no additional charges. It seems to be hit and miss but I have found that UPS seems to charge more than Fedex. If you can select a delivery without a courier then often it will come directly to the house without any additional charges but unfortunately that is not an option for ordering Lipo batteries. I see HK has the same deal of free shipping to Canada on orders over $150USD so if you can buy the Graphene batteries when they are on sale it is not a bad deal. Good luck shopping.

Marty