Model Boat Mayhem

Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: gwa84 on May 17, 2010, 07:30:07 pm

Title: wiring bat packs together
Post by: gwa84 on May 17, 2010, 07:30:07 pm
i am in no way electronicly minded so haw would you wire 2 7.2 volt buggy packs together to get the save voltage but more run time

thanks
Title: Re: wiring bat packs together
Post by: chingdevil on May 17, 2010, 07:38:12 pm
positive to positive negative to negative, that puts the packs in parallel and gives you the longer run time. You can not charge them like that though, as one pack might not be as discharged as the other.

Brian
Title: Re: wiring bat packs together
Post by: Martin (Admin) on May 17, 2010, 08:10:38 pm
Yes, as Brian says.
 I usually make up a "Y lead" for the boat with sockets for two batteries and a plug for the output.
Title: Re: wiring bat packs together
Post by: Shipmate60 on May 17, 2010, 09:16:40 pm
Component shop, Modelpower both sell the "Y" leads at about £2-00

Bob
Title: Re: wiring bat packs together
Post by: gwa84 on May 17, 2010, 09:23:01 pm
thanks guys
Title: Re: wiring bat packs together
Post by: Martin (Admin) on May 17, 2010, 09:37:32 pm
 :-)
Title: Re: wiring bat packs together
Post by: Peter on May 17, 2010, 09:59:20 pm
Hi Martin,

Nice clear pics, but it should be pointed out that this is the 'other option', the batteries connected in series to give double the voltage, with the same Ah capacity as the original single battery.

Not as per the original query.

Peter
Title: Re: wiring bat packs together
Post by: PMK on May 18, 2010, 02:24:49 am
Not only that, there is also the issue of parallel batteries self-discharging through each other.
Might I suggest that you point your browser here for more info.....

http://www.action-electronics.co.uk/pdfs/P103.pdf
Title: Re: wiring bat packs together
Post by: Martin (Admin) on May 18, 2010, 09:10:30 am
Hi Martin,

Nice clear pics, but it should be pointed out that this is the 'other option', the batteries connected in series to give double the voltage, with the same Ah capacity as the original single battery.

Not as per the original query.

Peter

How embarrassing is that!   :embarrassed:

This is the correct Y lead.... I hope!
 It's for 2 Lead-acid / 6v Gel cells for my Springer.
Title: Re: wiring bat packs together
Post by: Peter on May 18, 2010, 10:01:23 am
Hi Martin,

Again, good clear pictures, and exactly what was asked for.

It may have been one of them there 'senior moments', I know am more and more prone to them with each passing day :embarrassed:

Still, not to worry, all down to the ravages of time I suppose.

Peter
Title: Re: wiring bat packs together
Post by: hazmat on May 26, 2010, 02:22:28 pm
Small point, batteries in parallel have a habit of discharging each other or the stronger one cross charging the lesser / weaker pack.
In extreme cases the lesser pack gets 'charged' rapidly and destructively (BANG!).

Better to put a couple of diodes in the lines rated at the ESC's limit. i.e.

(http://s4.postimage.org/szbjS.png) (http://www.postimage.org/)

or buy the cheapy board from action electronics. http://www.action-electronics.co.uk/pdfs/P103.pdf

just a thought.
Title: Re: wiring bat packs together
Post by: malcolmfrary on May 26, 2010, 05:17:36 pm
Not really, they just "even out".  There CAN be a large circulating current as a result in theory, but if the voltage of each is about the same, they can be regarded as one battery when wired up.