Loose battery terminal connection inadvertently leads to a battery test showdown

Joined
Dec 9, 2023
Messages
4
Hi

First post, first thread.

The other day my son's 1998 Chev Monte Carlo Z34 wouldn't start. I grabbed my multimeter and did a quick check for battery voltage. The battery is buried beneath the washer fluid tank and you can't easily get onto the terminals. I measured off the positive jumper terminal and the frame - no voltage reading? I should've realized right there what the problem was. Instead I started trying to check for voltage elsewhere and in the process after pushing on the battery cables I got a reading. Voltage reading was below 12 volts. I boosted his battery, got it running, drove it a bit, brought it back, shut it off, tried to start again, and it wouldn't start.

Now that I had his car in the garage I decided to take the battery out, place it on the charger, and test it in the morning before work. Next morning I used my Schumacher BT-100 load tester to check the now fully charged battery. Battery passed the test and I went to work. While at work I had a conversation with a co-worker about my son's car problem and he gave me a Snap-On EECS500 battery tester that staff use for testing the emergency generator's starter batteries. It was Friday so I had it for the weekend. Cool. $800 Snap-On tester vs my under $100 BT-100 tester. After work I tried the Snap-On tester and the result was "Replace Battery". Well, I thought I should try it one more time after making sure the battery was fully charged again.

Next day, battery fully charged, waited 30 minutes, tried the Snap-On tester and again, CCA were half of rated CCA. Again result showed "Replace Battery". Was not convinced it was a bad battery. I kept thinking about not getting a voltage reading when I first checked it in the car AND it was a quality battery purchased in February. I tried the BT-100 tester again. Once again it showed 800 CCA and the needle never left the "good" zone. Waited about twenty minutes and tried one more time. This time I connected my Fluke meter to the battery with alligator clips so I could see the voltage drop during the load test. Starting voltage was 12.65, connected the BT-100, 10 second test, voltage dropped to just above 11 volts (very good), and I got the same reading as the last two BT-100 load tests. Removed the BT-100, left the Fluke connected, voltage jumped up to slightly above 12, and within a few minutes it was reading 12.62 (very good).

Cleaned the battery terminals, put the battery back in, made sure the connections were tight, re-assemble all items I needed to remove to get the battery out, and tried starting 3 times. No problem. Took the Monte for a rip, brought it back home, shut it down, and started it again. I think it is good to go!

Sub $100 Schumacher BT-100 (with an assist from the Fluke 117) stomped the $800 Snap-On EECS500.

I will be happy to return the Snap-On tester to work on Monday and suggest they check it for accuracy. In reality it may have been dropped or had some other issue because I suspect it should be able to give a better result than it did. Nonetheless, I won't be tempted to buy an electronic handheld tester until I can no longer get by with what I have.
 
Could've been a combination of low battery & poor connection. It sounds like you dug into it to investigate & solve the problem. I'm sure the son is happy to get his functional Monte back.
 
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