

🔧 Don’t guess—know your battery’s health in seconds with EZRED precision!
The EZRED SP101 Battery Hydrometer is a professional-grade, rugged tool designed to provide quick and accurate readings of battery acid specific gravity (1.100–1.300). Built for durability and ease of use, it eliminates complicated float readings and temperature corrections, making it ideal for mechanics, technicians, and DIYers. With universal fit and a limited lifetime warranty, it’s the trusted choice for reliable battery maintenance and diagnostics.





| ASIN | B000JFHMRU |
| Best Sellers Rank | #13,295 in Automotive ( See Top 100 in Automotive ) #20 in Battery Testers |
| Brand | EZRED |
| Brand Name | EZRED |
| Color | Red |
| Customer Reviews | 4.6 out of 5 stars 3,351 Reviews |
| Global Trade Identification Number | 00008965001070 |
| Included Components | SP101 |
| Item Dimensions | 0.5 x 11.4 x 1.3 inches |
| Item Type Name | EZRED SP101 Battery Hydrometer |
| Item Weight | 0.15 Pounds |
| Item dimensions L x W x H | 0.5 x 11.4 x 1.3 inches |
| Manufacturer | EZRED |
| Measurement Type | Specific Gravity Meter |
| Minimum Operating Voltage | 2.1 Volts |
| Model | SP101 |
| Power Source | Battery Powered |
| Style | 1 pack |
| Style Name | 1 pack |
| UPC | 008965001070 |
| Unit Count | 1.0 Count |
| Warranty Description | Limited Lifetime |
J**S
Great tool, great price...easy to use and understand
Worked well for monitoring/bringing back 6v batteries on my lift. Batteries were charging for 3days while I monitored the PH with this tool and was able to see it increasing daily vs assuming if batteries were improving. Let's you know if they'll hold a charge or if you're wasting your time charging. Use only "distilled" water if refurbishing/filling
L**N
Perfect, Great value, perfect
Works very well. Excellent build quality. Ease of use and design is good. Able to use as a transfer from one cell to another. I squeeze the top slowly to absorb the material into unit. Extremely sensitive readings with this product which worked great for me. Do not breathe the fumes so this works very well in doing that. Be safe. Wash it up and put unit back into the package it came in. Awesome. Thanks
K**I
Cheap, easy to use battery tester
I use this to check SG off a forklift battery that I'm using in my off-grid solar system. It seems to be working and SG tracks voltage as expected. It's easy to use and does the job. I didn't know how accurate it is as I didn't have anything to compare it to. I have a couple of criticisms, I wish it had numbers marked between fair and good so I don't have to estimate, and I see small cracking around the edges which I know can come from the method used to weld the 2 halves together or if solvent is used to clean it in the manufacturing process, but to be fair, I have also left this under the metal cover of my battery outside, so it has been exposed to the elements and temperature swings below freezing. So far no leaks but even if the long term durability isn't there, it's cheap enough to just buy another one.
G**F
What’s that electrolyte reading?
Works great. Bought this new one since I was needing one. My old one got lost somewhere. Have used it numerous times now and I am not disappointed at all. I recommend this to anyone needing an over handy hydrometer around the shop.
T**A
Good Tester
This has helped me check my battery conditions along with my 12v tester on batteries that actually have access to the fluid.
S**Q
Easy to read-small-plastic thus tougher than glass hydrometers.
The EZRed hydrometer works as well as a floating bulb hydrometer. Easy to read. No leaks. Works very well and made in the USA--no china manufacture. This hydrometer does require more battery liquid than a small ball hydrometer. Checking the condition of a small battery such as a motorcycle battery could be difficult because of insufficient volume of liquid.
D**D
other comments on difficulty reading are spot-on
This feels like a well-manufactured tool. Accuracy is good with the only solution I know the specific gravity of (pure water). I'll give them the benefit of the doubt that it remains accurate throughout the scale. Other comments talking about how hard it is to read the numbers on the clear plastic housing are completely legit. You've got multiple different colors of writing (none of them high-contrast like BLACK for example) printed on clear plastic. No background. You need perfect lighting and possibly a white piece of paper to hold behind the meter to have any chance of reading it. This can be difficult to manage with just two hands depending on where the batteries you're measuring are located, even if you free up a hand by using a head lamp. All of course while making certain not to drip acid on anything important.
W**.
Good tool for checking battery acid
Easy to use tool to check your battery acid. Helped with rejuvenating riding mower battery. Price was good but delivery was delayed. Think it was Amazon side. Brick and mortar places had to order and were more expensive.
Trustpilot
1 month ago
2 months ago