Propeller Calc vs Ionic Red Batteries
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Propeller Calc
This utility calculates propeller performance metrics like pitch, gear ratio, RPM, slip, and speed. Input any four values, and the app computes the fifth, helping users understand the relationship between propeller design and boat performance.
- Calculate pitch, gear ratio, RPM, slip, and speed
- Enter any four variables to find the fifth
- Understand propeller slip and its impact
- Supports iPhone and iPad
- Free to use
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This calculator can determine pitch, gear ratio, RPM, propeller slip and speed parameters. Enter any four variables, and it will calculate the fifth. Use the toggle switch to choose which field to calculate. Pitch is the theoretical forward movement for one complete turn of the propeller. Every inch of the boat in contact with the water induces drag. Therefore, the distance travelled differs since the propeller is "slipping" behind the theoretical distance it should travel with each rotation. The difference between theory and reality is called slip. Depending on your application, slip typically ranges between 5% and 20%. A lower number is only sometimes what you are after. Slip of a prop changes with operating conditions and is not a direct measure of efficiency. Please consult professionals for guidance. Happy powerboating
Ionic Red Batteries
Monitor your car, boat, or UTV's battery status remotely via Bluetooth. This app allows for instant battery condition checks and even remote emergency starting, all from your device.
- Remote battery monitoring
- Instant battery status
- Emergency jumpstart activation
- Bluetooth connectivity
- Battery condition analysis
- Discharge and charge time calculation
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IONIC Red Batteries offer smart emergency start and starter batteries which allows battery monitoring as well as remote battery activation from the APP based on Bluetooth technology. Some of the features are instant battery status for monitoring status along with battery condition. *Monitoring include: State of Charge level, calculate discharge time, charge time, voltage, current, temperature, power, cycle life, status, error messages and more etc. *Gives you the ability to jumpstart your car, boat, UTV etc without ever leaving the safety of your driver's seat !
Screenshots
Verdict
The clearest difference is review sentiment: Propeller Calc at 100% against Ionic Red Batteries's 50%. Ionic Red Batteries's advantage is rating (4.2 vs 3.0) and update cadence (every 2 months vs every 21 months). On price, ads, in-app purchases and monetization model there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
Ionic Red Batteries holds the better App Store score, 4.2 against 3.0. That said, the two scores are not equally well evidenced: Ionic Red Batteries has 5 ratings behind it against 1, so its average is the more settled of the two. Written reviews complicate that: 100% of Propeller Calc's written reviews are positive against 50% of Ionic Red Batteries's, so the app with the better star average is not the one people write more warmly about.
Propeller Calc ships an update every 21 months, Ionic Red Batteries every 2 months. The most recent releases landed on September 9, 2026 and July 5, 2026 respectively.
| Parameter | Propeller Calc | Ionic Red Batteries |
|---|---|---|
| Price | Free | Free |
| Rating | 3.0 (1 ratings) | 4.2 (5 ratings) — better |
| Positive reviews | 100.0% of reviews — better | 50.0% of reviews |
| Number of ratings | 1 | 5 — better |
| Update frequency | Every 21 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 17.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 3 MB | 3 MB |
| Age rating | 4+ | 4+ |
| Developer | Frode Rørvik | 深圳市南霸科技有限公司 |
Customer experience
Propeller Calc
Ionic Red Batteries
In-app purchases
Propeller Calc
No in-app purchases
Ionic Red Batteries
No in-app purchases
Questions
Is Propeller Calc free?
Is Ionic Red Batteries free?
Which has better reviews, Propeller Calc or Ionic Red Batteries?
Do Propeller Calc or Ionic Red Batteries have ads?
Which is updated more often, Propeller Calc or Ionic Red Batteries?
Other comparisons
