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Portable Tester Ripple Limit

Sentry-2412 (BatteryDAQ) detected a high Internal Resistance for one battery while voltage is normal. 

Voltage (V) Internal Resistance (milliohm)

Tried to verify with a portable battery tester, it won’t measure correctly for this battery.

Battery looks perfect from front view but it has a crack on the side.

Measured with a multimeter, this battery has about 800mV AC ripple on posts while others only 10mV.

Most portable testers utilize AC method for lower cost, they cannot work with high ripple input due to the signal range limit. They may give wrong result or random data for a bad battery like this one when measure it online.

All BatteryDAQ’s product utilize the proprietary pulsed DC technology. It costs more in production but ensures consistent data for online measurement crossing wide range UPS and charging systems.



Achieve high accuracy with correct installation

The rule is simple as Four-Terminal sensing (4T Sensing): to separate current-carrying path and voltage sensing probing.

For Sentry battery monitor installation, keep in mind that the sensing O-rings have to be in close contact with connection bar without any washer in between. (O-ring shall not be placed between connection bar and battery post. That will compromise battery bank connectivity).

Stainless steel bolt and washer have high resistance. If installed as “RED”, battery#1, #6/#7 and #12 will have wrong measurement, which will lead to wrong battery health “SOH” estimation and trigger alarms.

Enjoy your fine work!

What Hurricanes Harvey and Irma Tell Us about Wireless Carrier Preparedness

Disclaimer: This blog is in no way meant to diminish the concern everyone at BatteryDAQ has for every living creature in the paths of these natural disasters.  We would also like to note that there exist many other ways to disrupt the power grid, both naturally and man-initiated. It is our hope and deepest desire that the effective protections against these type of events continues to improve.

If Shakespeare had penned “A hurricane by any other name is still a hurricane.”, he would have been wrong. They may all meet certain criteria that place them in the category, but the devastation they leave behind can differ, depending on their particular destructive force.

After 12 years without a major hurricane landing on the U.S. mainland, 2 significant storms have severely damaged Houston and nearly the entire state of Florida in recent weeks.  However, when we examine the impact they had on cell tower outages, they tell very different stories.

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Wrong battery numbering has to be corrected

When come to substation for BMS installation, the most frequent frustration is to correct the numbering.

We have to go with standard. Wrong direction, wrong data.

Don’t worry, Sentry-6002NEMA has protection built in so the wrong direction won’t burn the board but you have to re-label all batteries as correct numbering and re-wire all cables. That may take you full day for a 60x2V string. So do check it before you start a installation!!!

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Access Battery Monitoring Data with Smartphone

Using BatteryDAQ’s cloud, scan a 2D barcode on Sentry monitor or battery rack, and your smartphone will show real-time battery data and graphs.  Bank voltage, current, temperature, individual battery voltage and internal resistance etc. (SOH%, SOC% and Runtime minutes for Telecom models) are all available.