Sinclair C5 Keyswitch Battery Adapter

Posted: Oct 03, 2015

For those lucky enough to own a Sinclair C5, you will probably be aware of the issues with connecting a car or leisure battery to the C5.

While it is possible to use the type 038 batteries with some pole adapters in a C5 in conjunction with the original battery cover or key switch, these batteries have very small capacities (typically about 37 Ah). What we want to use are the larger leisure batteries, which last much longer and are better suited to powering the C5.

Sinclair C5 Key switch Adapter Design

With this design, we can feed a strap through the unit, which allows it to be placed on the battery without it moving around. The 2 brass contacts come from an old UK plug cut to size with some 79 amp-rated cable running from the contacts to the battery, which we attach with some quick-release clamps.

Sinclair C5 Key switch Adapter Printed Out

The key switch can then be clipped onto the adapter in the same way as it would connect to the old battery cover.

Sinclair C5 Key switch Adapter With Key switch Connected

For those with the original Sinclair C5 battery charger, that too can be used:

Sinclair C5 Key switch Adapter With Battery Charger

File Download

Click the link below to download the file(s):

Keyswitch Adapter Model: (160.31kb)

We provide all files as-is, without any kind of warranty, for use in your own personal projects. They may not be redistributed or sold without permission.

Submit a Comment


RayOct 03, 2015 13:38

Well done Dan, more good work by you to keep C5s rolling.

retroveloJul 05, 2016 18:27

Where can I buy this

LeeOct 30, 2016 19:50

Hi, are these for sale? just what I need, thanks

Mansour May 15, 2017 09:22

Hi Dan,
Would you please tell me, Where can I buy it?? If you do not have a 3d printer?
Mansour from Denmark

JochemNov 30, 2017 19:48

Very nice Dan, exactly what I was looking for. Now lets find a printer somewhere ;P

Gordon MacmillanSep 04, 2018 14:56


Im looking for the bootlock kit for my sinclair c5
can you tell me how much and how to obtain?

Very grateful for any help


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