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⚡ Charge smarter, not harder — the pro’s choice for battery health!
The OTC 4619 Professional Battery Hydrometer is a precision tool designed to measure the specific gravity of battery electrolyte between 1.100 and 1.300, providing an accurate state-of-charge reading. Featuring a built-in thermometer for temperature compensation and a flexible rubber tip for easy access to all battery cells, this compact, durable hydrometer ensures reliable diagnostics for professionals and enthusiasts alike.





| ASIN | B0050SFVHO |
| Best Sellers Rank | #91,835 in Automotive ( See Top 100 in Automotive ) #96 in Battery Testers |
| Brand | OTC |
| Brand Name | OTC |
| Color | Red |
| Customer Reviews | 4.1 out of 5 stars 1,137 Reviews |
| Global Trade Identification Number | 00731413039898 |
| Included Components | Battery Tester |
| Item Dimensions | 3.8 x 14.3 x 0.6 inches |
| Item Type Name | Battery Tester |
| Item Weight | 4 ounces |
| Item dimensions L x W x H | 3.8 x 14.3 x 0.6 inches |
| Manufacturer | OTC |
| Measurement Type | Specific Gravity |
| Model | 4619 |
| Part Number | 4619 |
| Power Source | Battery Powered |
| Style | Classic |
| Style Name | Classic |
| UPC | 731413039898 |
| Unit Count | 1.0 Count |
| Warranty Description | Limited lifetime warranty |
M**E
Function for many years
Great product and its exactly the same as one I've had for 45 yrs. The old bulb got hard over the years of use and cracked and became none fictional.
K**B
great value but agree it's fragile
great value, well made easy to read -- I think I will be quite happy with this tool. But it is fragile! I read every review here, noted the fragility so I made a nice little case for it from 2" PVC pipe but I still broke the thermometer when I went to disassemble it for cleaning the second time I used it. I think it comes apart easier than others reviews lead one to believe. A little careful rotation of the rubber parts on the glass breaks the rubber free and allow you to carefully slide it off for thorough cleaning. having read the float was quite fragile, I made sure it was laying horizontally and fully in the middle of the glass tube away from the rubber parts I was removing from the glass. but I wasn't thinking about the unsupported thermometer as I twisted that portion and I snapped the tiny tube. (yes I know mercury is dangerous, even the tiny bit in this tiny thermometer - I sealed the remainder with some hot glue because the little bulb of the thermometer penetrates the rubber tip so you have to leave the broken part to seal the hole from dripping electrolyte everywhere). Oh well, where my batteries are mounted, I don't have to deal with huge temperature changes and I can check my SG after the batteries have relaxed for a while on float charge.... the SG scale is quite easy to read but I still made an enlarged version and attached it to my case so I can easily differentiate the numerical value of my actual readings. And be advised the specific gravity of electrolyte varies by battery manufacturer, I was a little surprised to see that my SG target value (what my marine batteries come with) was just a couple tiny marks into the green.
K**O
Quality hydrometer thats more accurate than pointer types.
Up until recently I had been happy with the pointer type hydrometers but the newer ones are awfully inconsistent. So I decided to try this glass hydrometer. Having reads the reviews I was prepared to get a broken one and sure enough I did. So along with the replacement I decided to order another one as well. Both of the new ones arrived in great shape. I did notice the floating glass bulb was a 1/4" longer on one along with the alignment of the graph that was about 3/8" different. But to my amazement they both read EXACTLY the same. So this proves to me that each bulb is checked for weight. Since I use mine frequently I wanted to hang it up by the provided hole. To keep the bulb from banging against the side during storage I installed a 5 1/4" piece of 1/4" hard plastic tubing over the tube top so that the tubing fits over the thin glass top all the way down to the weighted section. When installed the glass buoy will snug up against the rubber on both ends. Tubing on one end and glass bulb on the other. For usage you still have to remove the rubber bulb to remove the plastic tube but this only takes a few seconds. For storage with this plastic tube installed the floating glass bulb will not move around at all if the proper length of tubing is installed. I'm happy I switched over to these glass hydrometers even I did knock off a point because of the fragility. kd
C**N
Old school tool at a great price.
I remember a day when these testers where super expensive. Now thanks to time and marketing they are so reasonable. If you do battery service on batteries that can be checked you need this tool. The specific gravity test is a much more accurate way of determining the condition of the battery. One thing to be mindful of. When you are done using it. Carefully take it apart and clean it. Over time the acid from the battery will dry it out and destroy it. This tool goes back to my youth in automotive service. It is well made and works very well.
B**S
Run Away ! It's junk !
I ordered this to use on my golf cart, thinking it had to be better the the ones that I can get at the car parts stores. I especially liked that it was temperature compensated. When I took it out of the box I saw that the attached thermometer was broken. I immediately repackaged it and tried to have it exchanged on Amazon. They told me that it cannot be returned! What is the incentive for the manufacturer to make a quality product if they know that the customer is stuck with it, no matter how bad it is? With that being the case I decided to go ahead and use it, but quickly found out that the battery acid leaks out of the small hole where the bottom of the thermometer goes into it! Because of that I spilled several drops of battery acid onto the epoxy floor in my garage. Amazon and the manufacturer both suck for allowing such a piece of junk to be sold, knowing that it cannot be returned for being defective.
R**.
This is a very nice item. It's on the big side
This is a very nice item. It's on the big side. I have a 51R Honda battery (For a CRV) and these batteries do not have a-lot of water covering the very top of the lead plates, inside this battery. So you may have trouble getting enough fluid into the hydrometer, to float the bulb, to get a good reading. This is not OTC's fault, or Honda's. It's just a way to get more power out of a smaller battery. Ok-I have not used this device at this time. When it arrived, I knew it was too big, and tried to return it. Amazon gave me a full refund, and I did not even have to return the item to them! WOW. I was very impressed by this! (So why is this wacko Trump guy so mad at Amazon??) Just kidding, but anyway, just make sure the batteries your using this on, have enough liquid on top of the battery, to float the bulb, to get a good repeatable reading. Or use one of Amazon's smaller battery hydrometers. Yes-even the ones with the little float balls will work. Just check the size of the battery hydrometer, before u buy it. My 2 cents.
B**E
The best electrolyte hydrometer for a good Price.
It is very useful to maintain the car battery. During the hot weather water evaporate from the electrolyte. You need a accurate Hydrometer to find and restore the right level and density of electrolyte. Second most off the shelf, so called new batteries, needs to correct the level of electrolyte, and needs charging before use to recover some of the capacity. The state of charge voltage is related with specific gravity of electrolyte too. So a good battery charger and this hydrometer gives you one more chance to give the battery some longevity. Keep in mind that most of store batteries has 12.4 V open terminals voltage. That means the battery is discharged 25 % and wont't be installed in the car, without restoring the level and specific Gravity of electrolyte, in relation with the state of charge. Rule of thumb. Never buy a brand new Led Acid Battery, with open terminals voltage under 12.6 volts, regardless of the Brand of the Battery.
V**1
The idea is great but didn't translate well.
I first want to say that perhaps I am the one messing up. This hydrometer is great in the fact it includes the temperature gauge and the translated battery readings all in one. When I could get a good reading, it worked swimmingly. However, 9 out of 10 times using it, water droplets/battery acid would get on the inner sides of the tube and would not let the float bob freely in the hydrometer. The top of the inner gauge would click to the side where moisture was and I would have to try to flick at the outer glass in an attempt to get the inner reader unstuck and get it freely floating. Usually I would flick it and it would just jump to the other side and become clung to that side. When I could get it freely floating it would be significantly higher that where it was clinging to the sides of the hydrometer. Some type of hydrophobic coating on the inner sidewalls could possible remedy this.
A**R
Excellent
Just what we needed to test battery acid level!
G**Z
BUEN PRODUCTO
Me permite reparar baterias indicando el nivel de peso del acido. Si deciden comprarlo cuidenlo mucho ya que tanto el pesaacidos como la botella son de vidrio. cuando los adquirí tuve que realizar el cambio ya que me llegó quebrado el pesaacidos.
A**R
GOT IN BROKEN CONDITION TWICE
The first time I ordered this item , we sent it to our customer as it is without checking and the customer informed me that the glass is broken . Unfortunately the return window had closed by then . Second time I personally received the item and opened it in front of delivery executive and it was in broken condition again in the same spot . This time item is returned and I am now ordering for the 3rd time . Item seems to be delicate and not upto the mark. Will update rating once item is received in okay condition
A**R
Better go for other products
Work as expected I suspect, "Plastic parts" used is of low quality It may not work for long. Better go for other products
A**S
Quality built tool with glass not plastic tube.
I don't have a picture to post with my review. The battery I was going to use this hydrometer to check for state of charge and condition was not the type where the cells can be opened. The battery was the sealed type so I couldn't use this tool but I will put it to use in the future. It takes a little science to use one of these but it's not that hard to use. I owned one of these in the 1970's but it got broken and I never did replace it until now. With the newer cars if the battery is weak or less than 12v the car won't run thus one of these hydrometers is a tool box must have.
Trustpilot
1 month ago
2 months ago