Battery Connections? Series or Parallel

[NIGEL CASTLE]

I have bought 14.8 volt 3350mAh Lipo packs to replace my existing NiMh battery packs, also thinking that I would get a great saving on weight for my Electric Glider.

Fantastic weight saving, but the amount of lead needed to balance the plane means there is no weight saving at all.

How do I go about coupling two lipo packs together to still give me 14.8 volts, as this will bring the C of G back to the right place and also give me a much greater run time as the battery will double up to 6700mAh

 

Do they need to be coupled in series or parallel?

Can they be stacked one on top of the other with velcro or do I need to put something between them?

 

Many Thanks for your help.

[Chris Bott - Moderator]

 

Hi Nigel, welcome to the world of electric conundrums. Can you get one futher forward to sort the C/G?

 

To use two, they need to be in parallel to keep the voltage the same Nigel.

 

I would think that stacked on top of each other would be fine. There are already 4 cells effectively touching each other in each pack, so cooling can't be too much of an issue.

[Tom Wright 2]

Nigel.

Quite a few things to think about here,in principle parallel lipos are often used , but if permanently connected balancing becomes a problem,

.

The LIPOs are likely to be to much for a brushed motor ,or is a brush-less motor installed?

 

Personally i would look at a mod to bring the cg in limits using a single lipo.

 

Do you have a dedicated LIPO charger.

 

Perhaps you could post a pic of the glider is it by chance a Spectra ?

 

Tom

Edited By tom wright 2 on 22/05/2011 15:38:19

[NIGEL CASTLE]

Thank-you Chris, this being the case does anybody make a harness to connect in Parallel using XT60 connectors, i can only find connectors for series connection

[NIGEL CASTLE]

As you can see, very short nose, batteries fit very snugly behind brushless motor.

 

Lipo packs will be charged on their own, with dedicated balance charger.

 

The other reason for wanting to double battery capacity is that using the Electric Motor Calculator the estimated full throttle run time for my set up with one 3350 battery is only 2 minutes 25 seconds, so to double it to nearly 5 minutes would be great.

[Tom Wright 2]

Blimey that's around 65 A or 900W sounds a bit much? Not familiar with the model Nigel it sounds like the its very fast with a high wing loading ,its hard to determine the span from the photo.

Tom.

Edited By tom wright 2 on 22/05/2011 16:16:49

[Tim Mackey]

If you get a harness to parallel the balance plugs together also, then you have no worries about balancing.

XT60 parallel loom

[NIGEL CASTLE]

2.4 M span running Aveox 1406/2Y 3.7 to 1 gear ratio and a 13x8 prop

 

80 amps and 904 watts aprx

 

Goes like a bat out of somewhere?

 

Vertical from static hand launch.

 

I do not know the model as I bought it second hand.

 

Would be nice to fly it slower, might look at putting a larger lighter wing on it, and then balance for one lipo.

 

Any suggestions?

[Tom Wright 2]

Nigel.

You could keep that one as your "hot ship"and then look for a tamer thermal model even a Albatross or bluebird are floaters by comparison ,and will perform well on a 2.2A single lipo, with a 250-300W motor ,no gearbox required.

Tom.

[Tom Wright 2]

ALBARTROSS. 2M EP ARTF £60 .

 

Edited By tom wright 2 on 22/05/2011 17:23:34

[Tom Wright 2]

Or if your serious about gliding this.............

 

Edited By tom wright 2 on 22/05/2011 18:07:56

[NIGEL CASTLE]

What is this one Tom?

 

Ava?

 

Much more what I'm after......

[Tom Wright 2]

That's the one Nigel not cheap but highly recommended.2hrs or more flight time possible from one modest lipo and a single charge.

I flew it yesterday ,evening no lift a all but still got over 1hr .

Its the Hyper AVA .

Tom.

Edited By tom wright 2 on 22/05/2011 21:04:12

[Tom Wright 2]

[Kozmyk]

If you do decide to go parallel and you're up to a bit of soldering: