Privacy

Last updated 31 August 2026.

Who we are

OneWatt is operated by [legal entity name] of [registered address], [company number, if a company]. We are the data controller for the information described here. You can reach us at ukonewatt@gmail.com.

What we collect

Your account. Your email address, and your password stored only as a one-way hash — we cannot read it, and neither can anyone who obtains a copy of our database.

Your battery readings. Voltage, current, power, state of charge, individual cell voltages, temperatures, cycle counts and fault flags, together with the Wi-Fi signal strength and uptime of the logger. Readings arrive every few seconds.

Your logger. Its serial number, the firmware it is running, and the names you give it and your batteries.

Ordinary web logs. Our server records IP addresses and requests, as web servers do, for security and fault-finding.

Why we collect it, and our lawful basis

• To provide the service — showing you your battery, keeping its history, sending you a password reset. This is necessary to perform our contract with you.
• To keep the service secure and working — logs, fault-finding, and the record of any administrator who opens your page. This is our legitimate interest in running a service that is safe and can be supported.

We do not use your data for advertising, we do not profile you, and we do not sell or share it with anyone for their own purposes.

How long we keep it

• Detailed readings — 7 days at full resolution.
• Minute-by-minute summaries — 90 days.
• Quarter-hour summaries — 12 months.
• Your account and logger details — for as long as you have an account with us, and then deleted.
• Backups — kept for 14 days, then overwritten.

Where it is kept

Our server is in the United Kingdom (London), so your information is not transferred outside the UK. Off-site backups are kept on equipment we control, also in the UK.

Everything travels encrypted — your browser to us, and the logger to us.

Who else touches it

• InterServer, Inc. — hosting (United States).
• Resend — sends your password-reset emails. They receive your email address and nothing else.
• Cloudflare — our domain names and security certificates.

That is the complete list. There is no analytics, no advertising network and no tracking of any kind on this site.

Cookies

One cookie, ow_session, which keeps you signed in. It is strictly necessary for the service to work, so we do not ask for consent and there is no banner to dismiss. We set nothing else — no analytics, no third-party cookies, no tracking pixels.

Who can see your battery

You, and anyone you give your sign-in details to. Each logger can only ever reach its own data, enforced at the server rather than by convention.

Our staff can open your page when supporting you. When that happens the page says plainly that an administrator is viewing it, and the visit is recorded in a log we keep.

Your rights

Under UK data protection law you have all of the following, and we apply them to everyone regardless of where they live:

• To know. What we collect, why, and who else sees it — which is what this page is for.
• To see it. A copy of the information we hold about you.
• To correct it. If something is wrong, tell us and we will fix it.
• To have it deleted. Subject to the few things the law requires us to keep.
• To take it elsewhere. In a portable form — though you need not ask us for this: the Download section of your own page gives you your readings as a spreadsheet whenever you want them.
• To restrict or object. To tell us to stop doing something particular with it.

Email ukonewatt@gmail.com and we will respond within one month.

If you think we have got something wrong you can complain to the Information Commissioner’s Office at ico.org.uk, though we would rather you told us first so we can put it right.

Changes

If we change how any of this works we will update this page and say when. If a change matters to you, we will tell you by email.