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Extech RF40 Battery Acid and Engine Coolant Refractometer Fahrenheit
From the Manufacturer
The RF40 measures the freeze point of automotive coolants (propylene glycol and ethylene glycol) from 32°F to -60°F. It also indicates the specific gravity of battery acid and provides a quick reference of battery charge condition. It only requires a sample of 2 or 3 drops for fast and accurate readings. Automatic Temperature Compensation provides repeatable results. Comes complete with storage case and a screwdriver and vial of distilled water used for calibration.
HTA-DC
2025-09-03 13:55:39
Product appears to be of high quality, nice plastic case and easy to follow instructions. Have used this tester twice and have positive results!
Dale Lee Sumner
2025-07-20 16:05:18
As an RV tech, I use this tool to check the specific gravity of the house and chassis batteries on any RV that I am working on. Much more accurate than just using a DC Volt meter or hydrometer. Easy and quick to use. I can check all of the cells in just a few minutes. Highly recommended to anyone who deals with lead-acid batteries on a regular basis!
devinda
2025-06-22 13:31:17
Arrived on time. Seems well made. Works well. Reads accurate. Satisfied.
Customer
2025-06-02 13:41:36
Instrument was shipped on time, and was exactly as advertised. I use it to measure glycol levels in hydronic heating systems and it works perfectly every time. Comes in a nice hard plastic case with tools to clean and adjust if necessary.
Christopher Plona
2025-05-10 12:01:08
Bought for use at my off-grid solar powered vacation home.Much easier to take and record accurate specific gravity readings on my batteries. With this easy to use tool I'll be more diligent about watching out for my batteries' health.Recommended.
Sam
2025-03-01 16:04:04
As expected
Hoopdee
2025-02-11 16:46:27
love it works great easy to use and calibrate
TC
2025-02-04 19:56:22
This tool is a jewel ! The featured metal body looks amazing, it's very easy to use and it's very accurate. I love it !
ADi
2025-01-10 12:11:41
If you have ever used a hydrometer to measure specific gravity of battery acid, radiator coolant etc... Do what I did.Close the bonnet of the car on it.Then buy a refractometer.Much more accurate (1% vs 4-8%) only needs 1 or 2 drops of fluid, and so easy to take a reading.A million times better than trying to read a floating hydrometer.When I am king, it will be illegal to use a hydrometer, and refractometers will be mandatory.I like it...
Customer
2025-01-01 13:13:26
We live in an off grid solar home, where the systematic assessment of battery health is a No Brainer. This instrument is so much easier to use than the standard well calibrated hydrometers, and appears to agree quite well with their findings. It certainly saves on performing neck twisting contortions and questioning one's eyesight, in a tightly configured battery box. I have essentially retired my fleet of hydrometers, in favour of the Extech.
Russell Hatrick
2024-12-16 17:01:44
Just like I say, it worked well. With Extech, make sure you get the right one though! They can be hard to determine if you're looking to test battery acid, or coolant.
Ian G
2024-12-04 10:37:44
Price was a little high although it’s great quality.
gil hadar
2024-12-03 21:31:42
First time I've used it it wasn't clear where the line is. Thus I could not tell what temperature the mix is good for. The other thing is that I was hoping to have a tool that can read directly the percentage of mix, glycol vs water.
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