Swytch Pro/Max yellow battery connector secrets revealed?

[Cisco-man]

1. 
   It doesn’t matter if both battery’s are connected at the same time not good practice but your still only supplying 36v as they in parellel and not series

Surely if the batteries are at different charge levels then there’ll be a potentially large current flow between the two packs? That’s my thinking, but I can accept that there may be current limiting factors.

 

[Nealh]

Paralleling battery voltages need to be similar unless blocking diodes are used.

 

[Cisco-man]

Paralleling battery voltages need to be similar unless blocking diodes are used.

That’s what I think too.

 

[Solarbake]

I’ve done it and used the Swytch max battery 5,0 amp hr and the Bosch 11 amp hr both fully charged plugged in at the same time the draw is even until the smaller battery start getting low .You notice no voltage sag as both battery’s are trying to give even voltage .Im currently building a mega 40 cell molycell 16.8amp battery pack with P42a which can supply 30 amp discharge if needed.
I know the Swytch can pull 15.5amps on the watt meter when I had it connected .

 

[saneagle]

I’ve done it and used the Swytch max battery 5,0 amp hr and the Bosch 11 amp hr both fully charged plugged in at the same time the draw is even until the smaller battery start getting low .You notice no voltage sag as both battery’s are trying to give even voltage .Im currently building a mega 40 cell molycell 16.8amp battery pack with P42a which can supply 30 amp discharge if needed.
I know the Swytch can pull 15.5amps on the watt meter when I had it connected .

Before connecting any lithium batteries in parallel, you must make sure that they're at approximately the same voltage, otherwise you can to a lot of damage to them. Also, you must never attemt to charge one of them while they're still connected in parallel because one will charge the other through the discharge wires , which bi-passes the safety controls for charging.

 

[Cisco-man]

Surprised to see that with a measured 38v at the output pins, that the battery status on the battery still showed all five LEDs lit. Swytch users - don’t believe those LEDs!

 

[Cisco-man]

For those who have Swytch Air or Max battery packs. The charge connections - which are the centre two (O and D) on the yellow plug - are EC2 connectors, but with the O and D positions reversed. You can make up a charger adapter by cutting the EC2 in half and hot gluing it together in the Swytch orientation.

 

[mta102]

1. 
   It doesn’t matter if both battery’s are connected at the same time not good practice but your still only supplying 36v as they in parellel and not series

Can you (or indeed anyone else) confirm that connecting an external battery in parallel works as well as the normal swytch battery?

 

[Nealh]

Can you (or indeed anyone else) confirm that connecting an external battery in parallel works as well as the normal swytch battery?

If the cells are decent then yes it will.

 

[sjpt]

Can you (or indeed anyone else) confirm that connecting an external battery in parallel works as well as the normal swytch battery?

Make sure they are very close in voltage before connecting them, or use a protection circuit.

 

[mta102]

1. 
   It doesn’t matter if both battery’s are connected at the same time not good practice but your still only supplying 36v as they in parellel and not series

hi,
did you have to open up the controller box and cut + solder the new "alternative" battery wires? it's the only way i can think of doing it, and was wondering if you did it in a better way thanks.

 

[Cisco-man]

Opening the controller up is the best way. Some screws are torx and some philips - watch out for the little rubber gromits on the yellow connector screws. There’s just about enough room to join your red and black extension wires to the existing red and black wires that run between the yellow plug and the controller, and run them out the bottom of the controller housing.

 

[mta102]

Opening the controller up is the best way. Some screws are torx and some philips - watch out for the little rubber gromits on the yellow connector screws. There’s just about enough room to join your red and black extension wires to the existing red and black wires that run between the yellow plug and the controller, and run them out the bottom of the controller housing.

super clear - thanks! may attempt it this weekend.

 

[mta102]

Opening the controller up is the best way. Some screws are torx and some philips - watch out for the little rubber gromits on the yellow connector screws. There’s just about enough room to join your red and black extension wires to the existing red and black wires that run between the yellow plug and the controller, and run them out the bottom of the controller housing.

Mission accomplished. Now offloading my Max battery as I can use third party batteries indefinitely. Thanks to everyone on this forum for the tips

 

[heythisisdave]

Wow @mta102 - trying to do the same thing, can you share any pictures of how it ended up looking? What kind of battery are you considering buying? I just did it on my Brompton and am looking at some bottle batteries that could go in my Brompton bag.

 

[heythisisdave]

For those who have Swytch Air or Max battery packs. The charge connections - which are the centre two (O and D) on the yellow plug - are EC2 connectors, but with the O and D positions reversed. You can make up a charger adapter by cutting the EC2 in half and hot gluing it together in the Swytch orientation.

Is there a diagram of polarity of the O and D terminals?

 

[Cisco-man]

Is there a diagram of polarity of the O and D terminals?

The O-side is positive, and the D-side is neg.
You can confirm this by putting a meter onto the output plug of your Swytch charger, so just wondering why you needed to ask?
Don’t try taking power from the O & D connector - it’s power INPUT to the battery pack only,

 

[heythisisdave]

Sorry, in hindsight was a dumb question as I could've just run a multimeter to the two ports.

I'm getting some anxiety about building my own charger using a cut-in-half EC2 connector and buying something like this: https://www.amazon.com/YYHQQBAD-Battery-10Series-Electric-DC5-52-5MM/dp/B08CRGS9WY/ref=sr_1_6?keywords=36V+2A+charger&qid=1705261506&sr=8-6 and then splicing it to the EC2 connector.

 

[heythisisdave]

So it looks like the polarity of the battery O D connector is opposite of EC2 polarity?

 

[Cisco-man]

I can’t follow your link, but anyway I would be very careful when buying any charger - it’s dangerous territory. There’s a few genuine Swytch chargers for sale on ebay. These are excellent quality and trust-worthy. Yes, they are around £30, but cheaper ones are risky.