New member could use some help in Michigan

Buying and using a digital load tester identifies your battery issues instantly and they are not expensive. I have many 12v battery's to look after & I've got an analogue battery tester (500 amp carbon pile) and a digital one, either are a good investment for the home mechanic I rec
 
Hooked it up to the jumper cables. Started up right away. Let it run for 10-15 minutes. Today won't start again, so I'm going to jump it again. Could you help me understand the malfunction?
If it starts on a jump, the battery is toast. If you have a lithium battery they require a higher charging voltage than a standard AGM and the output of the rectifier does not accomodate that higher output, so the battery is constantly undercharged. If your battery is an AGM (or even liquid acid) then you have either a sulfateing issue or a bad cell (assuming your ground connection is clean and tight).
 
How did the battery stack up on the digital load tester?
I bought one, just got to me yesterday and tried it out today only to find that I'm a complete idiot and don't know what I'm looking for. I set the tester to 12v, touched the battery, the meter read 12.75v, and when I tried to start dipped to 10.56v. Still no clue what that means.
 
Did it come with instructions? Put a pic of it up, someone may have the exact same unit.

You're voltage readings are ok, a little low perhaps if you're using an AGM battery, but still ok. There should be a battery test function, you just connect the battery (don't try to start it) then select from the menus what sort of battery you have (Wet, GEL, AGM etc) then set what you want to test, (there will be lots of different tests you can do, you want CCA. Once you've set it to test CCA you then need to tell it at what level, this is the CCA of the battery when new, I don't know your battery so can't be specific, but probably in the range of 250cca - 280cca would suffice. Once you have the parameters you want to test set, go ahead & it will do it's thing.
It should tell you state of battery health (as a percentage) it's voltage, it's internal resistance (higher is bad) and whether to replace, charge it or it's a good battery.

Oh forgot to mention, selecting the correct 'Type' of battery at the beginning is very important to getting correct results on the battery you're testing. If you test an AGM battery using Wet battery criteria you'll get a false set of data at the end, usually looks better than it is.
 
I went out the the shed & took some example pic's for you. It's an old bike battery, you can see it's resting voltage is 12.72v but it's not a good battery, it just can't supply enough grunt to start a bike, but it's handy for odd 12v things in the shed.

Each pic is a stage in the process, the last one shows it's charge is at 98% full but it's internal resistance is too high & says to replace the battery, it's just too old & tired.

Hope these examples help you get a handle on your new load tester.
 

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