Batts Series/parallel?

[porkus]

So i read a thread not that long ago and someone mentioned the fact that if u connect batts up in series the cell count adds up but if you connect them in parallel then the mah adds up.

What are the advantages/disadvantages of both ways?

Its batt prices that put me off going bigger than 450 and a nitro will just be too expensive for me too build

[gazza131]

heres a handy site that will help you

Parallel LiPo Charging – The Faster & Safer Way To Charge?

[bolders]

First of note that it does not matter if the packs are in parallel or series the amount of energy available is the same. Furthermore, this is a bit of an open ended question, for which the answer is really determined by the electrics and gearing of your heli.
However, as a general rule it would be better to run the packs in series - this will provide 2x the voltage of one pack at the same capacity (This is ONLY if your heli is configured to run at higher voltages).

By running with a higher voltage, the current is lower for a given power (P = VI) and therefore there will be fewer losses in the form of heat due to I^2R losses. Also you can also get away with a lower C rating pack.

Bear in mind that if you want to run higher voltages you need an ESC that is rated for these voltages and a motor and gearing that will produce the required headspeed.

A bit more detail of what you have got and what you want to do would help us to provide you with a more concise answer

[porkus]

Lol u lost me at I=P lol

I was just wondering cos if I ran 2 packs in series I thought(without thinking) that it might be cheaper to achieve a a 6s pack with 5000mah with 2 3s 2500 packs if u get my drift

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[Si Goodchild]

Your original post was correct about how volts or mah adds up. Take a look on this forum and see the thread about the chap who wants to convert his TREX 600E from 6s to 12s. In this situation many folks use 2 6s 3000mah batts to make a 12s 3000mah pack. They could, just as easily, connect the packs up in parallel to make a 6s 6000mah pack. The energy in the batts will be the same, however the 6s setup will be geared up to deliver a higher current and therefore be less efficient becuase high current systems generate a lot of heat and therefore wastage.

The 12s setup seems more attractive, but you have to realise that you can't just plug a 12s pack in to a standard 600E becuase the ESC is only rated for 6s and motor and gearing is only set up for that voltage too. Running at 12s will require a new (more expensive) high voltage ESC and the motor will have to be swapped out for one with a lower KV rating (a measure of how many rotations the motor gives out per volt applied). The standard Align motor is about 1200kv, a typical 12s motor is about 630kv. Even then you need to carefully tune the gearing between the motor and rotorhead by selecting the right pinion with the right number of teeth.

It's not a small undertaking and each step needs to be carefully considered as part of the whole.

What are you hoping to achieve by joining batts up?

[cjcj1949]

It won't be that much cheaper. You can't gain twice. You either gain cell count or volts and keep the same mah, or you keep the cell count and gain the mah. To go from a 3S 2500 pack to a 6S 5000 pack you'd need 4 not two. Gazza131 had a similar idea.

Chris

[bolders]

OK when considering parallel or series - put very simply you cant get anything for nothing. You get an increase in capacity or voltage (depending on configuration) but not both.

So if for example we have 2x 3S 2200mAh lipos (typical 450 lipo)

If we connect in parallel we have (capacity doubles)
11.1V, 4400mAh

If we connect in series (voltage doubles)
22.2V, 2200mAh

If you wanted a 6s 5000mAh lipo you would need 2x 3S 5000mAh lipos.

I would guess that a single 6S 5000mAh lipo would be cheaper than 2x 3S 5000mAh lipos as it is a more common size and less materials are used (e.g. cabling and pcbs etc)

[Balders]

It's a question that has certainly cropped up a number of times before and will crop up again no doubt.

If you are thinking bigger heli, then battery prices certainly do come into the equation in your overall spend, as does a decent charger. However, the good news is that big capacity batteries are coming down in price, especially if you order from the DE version of HobbyKing's site. I've bought 4 packs off there delivered for less than the price of two from the UK and so far, they are performing fantastically. There is a fair old initial outlay, but at least you don't have to feck around with new ESC's, motors/pinions as well as worrying about shorting packs out, connectors etc. I also recently bought a 150W charger from HK (took a while as was the hong kong shipment) but it came down at 38 quid delivered! Absolute bargain, and with my converted HP server PSU supplying it 12V at 36amps, I charged a 6S (not empty) last night in a shade over 20 mins

The packs I use in my Trex 600 leccy are Turnigy 6S 5000mah's. The power they push out is frightening

[Balders]

Found a link to the batteries I bought:

HobbyKing Online R/C Hobby Store : Turnigy 5000mAh 6S 40C Lipo Pack

[Mark_T]

If it helps, this is the link for the same packs from the German warehouse :

HobbyKing Online R/C Hobby Store : Turnigy 5000mAh 6S 40C Lipo Pack (DE Warehouse)

[porkus]

Well my outset was to save money and possibly consider building a bigger heli, but its just batteries that put me off and I thought as a little mind out burst after I read the thread, that would be cheaper but as I didn't understand properly till I asked here what the differences are.

Just out of curiosity how long does delivery take from hobbying? de and hk warehouses

Thanks for the info everyone

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[Balders]

Sorry, I got the link wrong, I meant to find the DE warehouse. Mine took about a week IIRC.

[Mark_T]

Just out of curiosity how long does delivery take from hobbying? de and hk warehouses

I'm sure it varies, but in my experience a week or less from Germany and 2-3+ weeks from HK.

But, do consider that although ordering from HK can be cheaper up front, you may have to pay VAT and a handling charge if they get caught by Customs on the way through. Ordering from Germany does not have that risk as the VAT is included in the price.

[Balders]

I've not had a problem once with any orders from hobby King

[porkus]

Well $70 is A LOT better than 109 quid it was this that was putting me off but now it seems viable and affordable
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