KONNWEI KW720 Review: Shop-Grade Battery Tester at Home

A rugged, shop-grade car battery tester with printer and waveform graphing, the KONNWEI KW720 brings pro-level diagnostics to DIYers and small garages.

Price: $189.99

Rating: 4.3/5 (705 reviews)

Pros

Accurate multi-voltage testing
Built-in thermal printer
Voltage waveform graphing
Long heavy-duty test leads
Clear, bright color display
Solid, workshop-ready build

Cons

High price for casual users
Printer door feels vulnerable
PC software feels dated

When we first fired up the KONNWEI KW720 on a heavily used delivery van, it called a borderline AGM battery "replace"—the same verdict the shop’s Midtronics analyzer had just printed. Over the next two weeks, that pattern repeated across everything from motorcycles to a 24V box truck bank. This isn’t a toy code reader with a battery menu slapped on; it behaves like a cut‑down professional tester, printer and all.

Built Like a Tool, Not a Gadget

Our garage tech was the first to comment on the KW720’s build: “It actually feels like something I can drop.” The housing is thick, slightly rubberized plastic with pronounced ribs along the sides. It’s not a brick like a $1,000 Snap-on analyzer, but it’s far more solid than the cheaper KONNWEI and Ancel handheld testers we keep around for quick checks.

The clamp leads are the biggest hardware win. KONNWEI uses fat copper‑jaw clamps with strong springs and wide, serrated teeth. I deliberately clamped onto dirty, lightly corroded posts without cleaning; contact was still consistent enough that the tester didn’t complain or drop connection. Our electrical specialist measured about 8.8 feet of lead length – long enough to reach from a truck’s front battery to the cab when you want to watch the screen while starting.

Buttons are old‑school membrane keys, but they have a positive click and are spaced far enough apart to use with gloves. We’ve handled plenty of cheap analyzers where the buttons wobble or register double presses; this one behaved predictably.

The only weak spot is the paper door for the thermal printer. It’s not flimsy, but if something is going to break first in a busy shop, it’s that hinge.

Color Screen and Printer: More Than Just Flash

The KW720’s color display is a big step up from the monochrome, low‑resolution screens on budget units like the KONNWEI KW208 or the Ancel BA101. Text is crisp, menus are well‑structured, and—importantly for actual work—the contrast is high enough to read in a sunlit driveway. We did see some glare in direct noon sun, but tilting the unit slightly solved it.

Navigation is logically organized: pick language, pick test type (battery, cranking, charging, waveform), then choose battery standard and rating. After about three or four tests, we stopped thinking about the menu tree entirely.

The built‑in thermal printer feels like a gimmick until you start using it with customer cars or fleet vehicles. Our field tester ran it through 50+ print cycles:

Print speed is fast enough that you’re not standing there waiting.
The printouts show voltage, CCA, internal resistance, state of health, and test verdict.
Text is sharp and legible; even smaller values are easy to read.

We compared it to the AUTOOL BT860 and FOXWELL BT780, both of which also have printers. The KONNWEI’s printout layout is less cluttered and a bit easier to digest quickly. The downside: thermal paper will fade over time, so for long‑term records, you’ll still want to scan or photograph the slips or use the PC export.

Real-World Battery Testing Across 6V, 12V, and 24V

Our team pushed the KW720 on a mixed fleet:

Two 6V deep‑cycle batteries in series on a golf cart
Multiple 12V AGM and flooded batteries (compact car, SUV, truck, motorcycle)
A 24V pair on a box truck

For each, we logged measurements and, when possible, compared against either a known‑good shop analyzer or a controlled load tester.

Accuracy & repeatability

On a healthy 12V AGM rated at 760 CCA (lab‑verified), the KW720 consistently measured between 730–755 CCA across five separate tests, with state of health between 96–100%. Voltage figures matched our calibrated Fluke meter within 0.01–0.02V.

On a tired 12V flooded battery rated at 600 CCA that our carbon pile load test showed was delivering around 350–380 CCA, the KW720 reported 360–390 CCA and flagged it as "replace." Repeated tests—taken hot, cold, and after surface charge bleed-off—stayed within a narrow band.

Where cheaper testers like the KW208 sometimes swing wildly on marginal batteries (we’ve seen 60% health become 80% on a second test), the KW720’s results were noticeably more stable. Our electrical specialist’s comment: “It behaves like it’s actually modeling internal resistance properly, not just guessing from voltage sag.”

6V and 24V behavior

On the golf cart’s 6V deep cycles, the tester identified one weak monoblock with significantly higher internal resistance. The verdict matched the cart shop’s dedicated tester.

On the 24V truck system, we separated the batteries and tested them individually; results helped spot a mismatched pair where one battery was several years older and near the end of its life. The KW720 doesn’t treat the 24V bank as a single battery; you still test each unit, which is what a competent tech should be doing anyway.

Cranking and Charging Tests That a DIYer Can Understand

Where the KW720 really separates itself from the cheaper KONNWEI and Ancel units is in starter and alternator testing.

Cranking test

You connect the tester, select the cranking test, then start the engine when prompted. The KW720 records:

Minimum cranking voltage
Cranking time
Verdict (normal, weak, or abnormal)

On a 2.5L four‑cylinder with a known‑weak battery, the tester recorded a dip to 8.9V and flagged the crank as weak but not yet catastrophic. On a V8 truck with a dragging starter motor, we saw both a low cranking voltage and an extended cranking time, which lined up with the driver’s experience of slow, labored starts.

Charging system evaluation

For alternator tests, the KW720 walks you through idle, rev, and load conditions. It logs:

Charging voltage at idle
Response under load (lights, AC, rear defogger)
Ripple / diode issues

On a sedan with a failing voltage regulator, we watched the KW720’s readings wander between 13.3–15.1V and spit out an "abnormal" verdict. An oscilloscope confirmed unstable regulator behavior.

Compared to something like the Ancel BA301, which technically does charging tests but with very sparse guidance, the KW720’s on‑screen prompts and clear pass/fail language make it accessible to an advanced DIYer who doesn’t live in service manuals.

Voltage Waveform: The Diagnostic Trick Up Its Sleeve

The KW720’s voltage waveform function is what got our diagnostic specialist genuinely interested. Instead of just giving you a number, it can plot voltage changes over time, capturing up to 20 points per second.

In practice, this allowed us to:

Visualize cranking voltage dips as a curve instead of a single minimum value
Spot intermittent charging spikes that a basic multimeter would miss
Compare waveforms before and after repairs using the PC export tool

On a vehicle with suspected alternator diode issues, we captured an unstable waveform at idle with obvious ripple; swapping in a known‑good alternator flattened the curve. It’s not a replacement for a full‑on scope, but it’s a big step forward from the static measurements most “car battery testers” provide.

Here’s how the KONNWEI stacks up against two common competitors:

The KW720 clearly aims above the typical DIY market and below the professional tier dominated by brands like Midtronics. You’re paying extra for waveform capture, multi-voltage support, and a printer in one unit.

Learning Curve, Software, and Everyday Workflow

From a usability standpoint, our experience broke down into two groups:

DIYers with some wrenching experience: After a 10–15 minute walkthrough, they were confidently running battery and alternator tests and understanding the printout.
Working techs: They skipped the manual entirely and were printing reports inside five minutes.

The on‑device interface is the star; the PC software is functional but dated. It lets you:

Export waveform and test data
Save records under vehicle/customer labels
Print reports from a computer if you don’t want to use thermal slips

Connection is via USB; drivers installed without drama on our Windows 10 test machine.

We did hit one minor annoyance: firmware update instructions are terse, and KONNWEI’s website isn’t as polished as bigger tool brands. That said, we were able to update the tester on our first attempt, and it picked up a couple of new battery standards and minor UI tweaks.

Is the KW720 Worth the Money?

At around $189.99, the KW720 is expensive if you only check your own car once a year. For those users, a simpler 12V battery analyzer in the $40–70 range (like KONNWEI’s own KW208) makes more financial sense and will still tell you "good" vs. "replace."

Where this unit makes sense is:

Independent shops that want printouts without buying a $700+ analyzer
Mobile detailers / small fleet managers who need to document battery health
Hobbyists who regularly work on multiple vehicles, motorcycles, and small equipment

Compared with the FOXWELL BT780, the KW720’s advantages are the 6V/24V versatility and voltage waveform graphing; the FOXWELL is a bit cheaper and has a slightly more refined casing but is 12V‑only. Against cheaper Ancel testers, you’re getting far better build quality, more consistent readings, a printer, and a level of diagnostic depth they simply don’t offer.

Knowing that, our shop lead summed it up well: “If this disappears tomorrow, I’ll notice. I wouldn’t say that about most of our little battery testers.”

For the right user—someone who treats a battery tester as a daily tool rather than an occasional gadget—the KONNWEI KW720 justifies its price with reliability, detail, and genuinely useful features instead of gimmicks.

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