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Product Information
Technical Details
| Brand | Equus |
| Item Weight | 1 pounds |
| Product Dimensions | 10 x 1 x 6.5 inches |
| Item model number | 3721 |
| Manufacturer Part Number | 3721 |
Additional Information
| ASIN | B000EVWDU0 |
| Best Sellers Rank |
#109 in Automotive (See top 100)
|
| Shipping Weight | 1 pounds (View shipping rates and policies) |
| Shipping | This item is also available for shipping to select countries outside the U.S. |
| Date First Available | July 7, 2004 |
Warranty & Support
Warranty, Parts: Parts
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Product Description
This battery and charging system monitor displays the condition of your battery and charging system instantly. It protects the engine computer and 12-volt accessories from damaging surges when jump starting or recharging. You can easily plug into the vehicle's cigarette lighter or power receptacle to monitor battery and charging system voltage. It has an LCD screen which displays the measured voltage with a bar graph to indicate battery charge level and it also has color-coded LEDs which quickly identify the battery's charge status. The head pivots for easy viewing and angle adjustment.
Customer Reviews
Most Helpful Customer Reviews
101 of 103 people found the following review helpful
By H. Wang
Amazon Verified Purchase
The picture on Amazon site is not correct. This battery monitor shows the voltage value with .01 precision (or two digits after decimal point). That is far more then enought to tell the battery status. I put it in the car, it automatically switches between "battery status monitoring" and "charging status monitoring". When the engine is stopped, it is in "battery status monitoring mode", when engine is running, it will be in "charging status monitoring" mode. Amazon's price is even bettern then Walmart. Definitely a great value buy. Will recommend this item to my friends.
76 of 81 people found the following review helpful
By J. B. Syrett
Seemingly just another auto gadget fortunately the Equus 3721 is more sophisticated than its ponderous description. A breeze to connect to any car's 12 Volt electrical system. Simply push into the lighter socket or an auxiliary power outlet now found in many newer vehicles.
With the engine running the instrument constantly displays battery condition with an LED light; amber when marginal, red if the battery is discharging. A green light indicates a correctly functioning electrical system. All is well with both battery and, most importantly, the alternator.
The Equus is also an accurate voltmeter. Digital read-outs give exact voltage in the electrical system. Potential alternator problems or a failing battery will be indicated by below normal voltages, plus an amber or red light. Extra information is a battery icon graphically showing total battery charge. Tending towards erratic read-outs, and therefore unreliability, it is not the unit's best feature.
Equus's instruction card is easy to understand. The unit is well made, sturdy, easy to connect and to transfer to any 12 volt system not having its own voltmeter. Also, as a supplemental monitor in an RV, or a bigger boat with a remote 12 Volt outlet in a sleeping area far from the main instrument panel, overall battery condition condition can be monitored while camping or at anchor.
Good value for money; very useful. From personal use, recommended.
With the engine running the instrument constantly displays battery condition with an LED light; amber when marginal, red if the battery is discharging. A green light indicates a correctly functioning electrical system. All is well with both battery and, most importantly, the alternator.
The Equus is also an accurate voltmeter. Digital read-outs give exact voltage in the electrical system. Potential alternator problems or a failing battery will be indicated by below normal voltages, plus an amber or red light. Extra information is a battery icon graphically showing total battery charge. Tending towards erratic read-outs, and therefore unreliability, it is not the unit's best feature.
Equus's instruction card is easy to understand. The unit is well made, sturdy, easy to connect and to transfer to any 12 volt system not having its own voltmeter. Also, as a supplemental monitor in an RV, or a bigger boat with a remote 12 Volt outlet in a sleeping area far from the main instrument panel, overall battery condition condition can be monitored while camping or at anchor.
Good value for money; very useful. From personal use, recommended.
27 of 28 people found the following review helpful
By Jesse Knight
Amazon Verified Purchase
The Honda 2005 civic has a marginal charging system. This meter is ideal for determining when it is time to turn off the radio to reduce load on the alternator. Voltage reading is very accurate, much better than 1% as measured against a small Beckman pocket meter, which in turn has been checked against a Powerex Wizard aa cell charger. Warning lights function well.
Some things to note when using this tester: Standard voltage of a 12 volt battery is 12.6 volts. Some deep cycle absorbed glass mat batteries will read 12.8. This is after loading the battery by turning on the headlights for 10 seconds, to remove surface charge. Note that while the lights are on, the voltage drops quickly at first, then the voltage stabilizes. Turning off the lights causes the voltage to rise again gradually. After a few minutes the voltage will stop rising. If the voltage settles at 12.6 (or 12.8 for AGM battery) battery is charged, assuming that the battery is near 68 degrees F. Lower temps raise the voltage, higher temps lower the voltage. For a standard battery figure about 12.66 volts at 32 F and 12.54 volts at 104 F battery temperature, not air temperature.
After a car has been running for awhile with no lights, radio, wipers, AC, heat or window defroster, the alternator may cycle letting the battery voltage drop for a while before kicking in. This is OK provided the charging is steady shortly after turning on the lights. An intermittant alternator will cause the red light to turn on and off when headlights are on.
The bar graph for battery condition is not very useful as the meter has only voltage information.
The instructions do not state that this tester is for negative ground cars only, a small quibble as positive ground is not common.
Had I bought this device six months ago I could have avoided killing a brand new battery in six months.
UPDATE: Still working fine as of May 21, 2013
Some things to note when using this tester: Standard voltage of a 12 volt battery is 12.6 volts. Some deep cycle absorbed glass mat batteries will read 12.8. This is after loading the battery by turning on the headlights for 10 seconds, to remove surface charge. Note that while the lights are on, the voltage drops quickly at first, then the voltage stabilizes. Turning off the lights causes the voltage to rise again gradually. After a few minutes the voltage will stop rising. If the voltage settles at 12.6 (or 12.8 for AGM battery) battery is charged, assuming that the battery is near 68 degrees F. Lower temps raise the voltage, higher temps lower the voltage. For a standard battery figure about 12.66 volts at 32 F and 12.54 volts at 104 F battery temperature, not air temperature.
After a car has been running for awhile with no lights, radio, wipers, AC, heat or window defroster, the alternator may cycle letting the battery voltage drop for a while before kicking in. This is OK provided the charging is steady shortly after turning on the lights. An intermittant alternator will cause the red light to turn on and off when headlights are on.
The bar graph for battery condition is not very useful as the meter has only voltage information.
The instructions do not state that this tester is for negative ground cars only, a small quibble as positive ground is not common.
Had I bought this device six months ago I could have avoided killing a brand new battery in six months.
UPDATE: Still working fine as of May 21, 2013
Most Recent Customer Reviews
4.0 out of 5 stars
battery charge moniter.
I use two aboard a boat to moniter 12V battery charges. It works well and when compared with a volt meter they are .about 95% accurate.
Published 2 days ago by William R. Linder
5.0 out of 5 stars
very good
Works very good. Since getting Equus I replaced my battery and this product constantly keeps me in touch with my battery and charging status
Published 2 days ago by wneem
5.0 out of 5 stars
Some wierdness in the lights, but very-low-power-overhead, and super...
I was at first taken back by the confusing way the colored lights change, because they are different based on when the device determines charging mode vs battery mode, but after... Read more
Published 2 days ago by Sunglass Evaluator
5.0 out of 5 stars
Equus 3721 Battery and Charging System Monitor
I was having problems with my battery and alternator in my 2002 Honda Civic and this worked well with monitoring my battery level and the power output that my alternator was... Read more
Published 3 days ago by Jon
5.0 out of 5 stars
Simple, Functional, just what I was looking for
I bought this based on Steven Harris' recommendations. This tool does the job expected and is very intuitive. I'm using it to monitor a house backup battery bank.
Published 3 days ago by Marcel G Boudreau
5.0 out of 5 stars
Works like a charm
Works as advertised. Convenience is pleasant. I recommend it. Simple, affordable and does what it was supposed to do . . . measure voltage.
Published 13 days ago by Jim Bendt
5.0 out of 5 stars
Works great!
Works just as advertised. It makes checking the status of your battery/alternator extremely quick and easy. I'm very happy with the purchase.
Published 15 days ago by BK
5.0 out of 5 stars
Awesome Product
With the difference between a full battery and a dead one being less than 1 volt, you need the hundredths decimal point. I use this in our boat to monitor battery levels. Read more
Published 25 days ago by Dano
4.0 out of 5 stars
Quick and convient
I use this battery monitor to monitor state of charge of a group of 12 volt deep draw batteries on my emergency power bank outfitted with a car lighter jack. Read more
Published 26 days ago by David A. Pinniger
4.0 out of 5 stars
Handy
This is a handly dandy little gadget. Takes the guesswork out of your electrical system. Wish I had it for a few cars I owned in the past. Read more
Published 26 days ago by Adam Davis
