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Series paralell switching battery pack

Posted: Jun 09 2010 4:12pm
by moostrodamus
Howdy,

I found "instructable" on how to hook 2 motors up with a DPDT switch so you could run them either in series or parallel.

http://www.instructables.com/id/SIMPLE- ... he-switch/

So I used that and came up with this to hook up two 36v batteries to a DPDT switch to run either in series or parallel.
dpdt.jpg
dpdt.jpg (16.04 KiB) Viewed 3808 times
My understanding is top position would be Parallel, middle position off (use for charging?) and bottom position series.

Should this work?
Can i assume i should buy a 30 amp switch as i am using a 30 amp controller?

Lurning is hard. Any comments/ corrections appreciated,

Moo

Re: Series paralell switching battery pack

Posted: Jun 09 2010 5:54pm
by jateureka
Normally DPDT switches have the two centre pins as common and they either connect to the two upper or two lower pins - only some switches have a centre off position, so you would need to check.

A controller rated at 30A may actually put out much higher peak currents for short duration so you should use a switch rated for a minimum of at least double the controller current. You would prabably need to use a battery isolation switch, but they are quite large. You can buy these from boating/4WD/caravan shops. The other option is to use a smaller switch to activate a DPDT relay to switch the hgh currents.

Depending on the battery chemistry you also might want to install some diodes per this thread http://endless-sphere.com/forums/viewto ... =2&t=14744

Re: Series paralell switching battery pack

Posted: Jun 09 2010 7:37pm
by moostrodamus
thanks for the link to that thread, lots of great info.

Thanks

Moo

Re: Series paralell switching battery pack

Posted: Jun 09 2010 9:40pm
by jateureka
You also might want to look at this thread regards the effects of arcing http://endless-sphere.com/forums/viewto ... 95#p276095

Re: Series paralell switching battery pack

Posted: Jul 19 2010 11:27pm
by Kiwi
I am looking at this also, only I want to be able to run 100amps through the switch.

An important consideration is that, as you have to throw 2 switches to change between S and P, one MUST NOT close before the other one is open, or POOF!

So you need either a mechanical connected switch DPDT (Double Pole Double Throw), or 2 stage switching, eg a three position micro switch driving 2 relays, Position One=Series, Position 2= Break Series, Position 3=Parallel

Here are some DPDT Relays I found

100, 200, and 300Amp DPDT Relays. Note these are huge, heavy and draw a bit of current to keep them switched.

http://www.geindustrial.com/products/sp ... actors.pdf

These would suit you, 30amp continuous, also 50amp available.
Image
http://www.rvpowerhouse.com/category.php?cat=10

Another option, which has failed me before due to them not switching at the same time is to use automotive headlamp relays.
You can get up to 150A ones. Get them from 4x4 accessory stores.

Image
Image
http://www.pickercomponents.com/Data_Sh ... _Sheet.pdf

I am planning to try again with these, but this time switch them one at a time, as below

Image

So, you could have a small toggle switch on your bars, with series, disconnect and parallel positions.
Image

You would also need a 12v dc converter to drive the relays.

I have yet to see a high current(100A) manual DPDT switch. Any one know of one?

Re: Series paralell switching battery pack

Posted: Aug 06 2010 3:03am
by Kiwi
Check this out Now thats a switch! $100us though.

Image

http://www.grainger.com/Grainger/NKK-To ... Pid=search

Re: Series paralell switching battery pack

Posted: Aug 06 2010 11:34am
by ambroseliao
The lovely NKK DPDT switch can be bought for around $53 at other online dealers.

http://www.alliedelec.com/search/produc ... KU=8700593
and
http://parts.digikey.com/1/parts/980869 ... 32-ro.html
and
http://www.mouser.com/ProductDetail/NKK ... taPw%3d%3d

There are also much less expensive DPDT or 4PDT center off switches that allow you to switch between series and parallel on the *Bay.
http://cgi.ebay.com/DPDT-Toggle-20-amp- ... 1312wt_886
http://cgi.ebay.com/4PDT-Toggle-Switch- ... 1254wt_886

I am currently installing a 4PDT center off switch in my Bosch Fat Pack setup which consists of 8 BPFs that can be switched to 8 parallel packs 8P (37V) to charge or 2S4P (74V) to run. The center off allows me to switch without worrying about shorting or overloading anything. I'm trying to implement a Cell-log battery monitor as well.

http://endless-sphere.com/forums/viewto ... =3&t=20000

Doctorbass has used this configuration with his Sony/Konion cells for many years without trouble. Of course, he's working on something more powerful and advanced now!
http://endless-sphere.com/forums/viewto ... =14&t=7240

Ambrose

Re: Series paralell switching battery pack

Posted: Aug 06 2010 4:28pm
by moostrodamus
Awesome resources guys! Thanks!

Moo

Re: Series paralell switching battery pack

Posted: Aug 06 2010 5:22pm
by mwkeefer
I may have missed somthing but...

I do this now on my geared setups between 10S/20S and 12S/24S and the first thing I didn't note in your explaination was the controller you will use. It will need to be able to either work with the given voltage range (Tip122 transistor mod) or you will need 2 different voltage divider bridges to the LM317T voltage regulator to handle the different voltages - these will need to be switched while the pack is in disconnect state - the actual state model should be:

1.) Interrupt throttle return (relay)
2.) Remove Parallel Connection between packs - breaking the connection so you have 2 packs
3.) power the relay needed to switch from the 36v divider network to the 72v divider network
4.) power the relays needed to engage in series
5.) re-engage the throttle return.

This will ensure smooth and safe switching between the 2 possible voltage inputs :)

Hope this helps a bit !

-Mike

Re: Series paralell switching battery pack

Posted: Oct 13 2011 9:00pm
by Brent Hasty
Hay all,
Check out these heavy duty DPTD toggle switches 30A Amp rated for $22

http://www.mouser.com/Electromechanical ... |0&FS=True

Check out the Ebike my brother and I are building

http://www.youtube.com/watch?v=lByACVoDoyw

--
Thanks, Brent Hasty
(503)839-5471
http://www.hastyheat.com
See Our Feedback on Facebook
http://www.facebook.com/#!/pages/Hasty- ... 2342720320
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Re: Series paralell switching battery pack

Posted: Oct 13 2011 9:15pm
by AussieJester
Didn't doctorbass use contactors rather than switches
To change battery configuration?

KiM

Re: Series paralell switching battery pack

Posted: Oct 19 2011 2:59am
by DimGr
if I use 2 battery packs of 48V 12Ah(96V in series and 24Ah in parallel) how many Amps should be the dpdt switch?

Re: Series paralell switching battery pack

Posted: Oct 19 2011 3:29am
by amberwolf
How many amps is your controller going to pull from the pack(s)? That's how many amps the switch has to take.

Re: Series paralell switching battery pack

Posted: Oct 19 2011 3:34am
by DimGr
amberwolf wrote:How many amps is your controller going to pull from the pack(s)? That's how many amps the switch has to take.
40-50 Amps almost..

Re: Series paralell switching battery pack

Posted: May 18 2013 11:10pm
by swbluto
Subscribing. This is extremely useful information. I think I'll copy it to the reference area.