Noco Genius - Bad Battery?

[StillLearning]

Hi all,

My Noco Genius1 keeps indicating a bad battery on my 03 Tundra. I have loaded tested it with a 100amp load tester and it tests fine. I have been driving it and it starts right up everytime and doesn't seem to be turning over any slower than usual. Gauges all seem normal as well.

Does anyone know how this charger/maintainer determines the battery is bad? I have tried connecting it to my lawnmower battery as well as the battery in my accord and it charges for a while and then goes into maintaining mode as it should, but everytime I try it on the truck it charges for a while and goes to bad battery?

I had been using it on and off for about a week or two at a time on the truck over the winter when it wasn't being driven to keep the battery topped up and now after taking it out last week it started with the bad bad battery indication.

I would hate to replace a battery that's still good, but I don't want to get stuck somewhere with a no start situation either. Can it tell something a load test can't?

 

[mblgjr]

I went through this with one of my NOCO chargers as well.

In my case, the alligator clips simply weren't biting the connection hard enough. I happened to be in a dark area and saw it ever so barely arc when it tried to charge. It would try a couple times then indicate as a bad battery.

Clean the terminal or wiggle the alligator clamp when you put it onto the connection a little.

 

[Vercingetorix]

My Ctek sometimes doesn’t like a battery I charge with it. Put the battery on a dumb charger for a few hours, then switch back to the Ctek and all is good.

 

[Tdbo]

My Ctek sometimes doesn’t like a battery I charge with it. Put the battery on a dumb charger for a few hours, then switch back to the Ctek and all is good.

This. I have had this happen both with a Ctek and a NOCO.

 

[StillLearning]

I went through this with one of my NOCO chargers as well.

In my case, the alligator clips simply weren't biting the connection hard enough. I happened to be in a dark area and saw it ever so barely arc when it tried to charge. It would try a couple times then indicate as a bad battery.

Clean the terminal or wiggle the alligator clamp when you put it onto the connection a little.

I can't say that I had attempted to reset the clips in between attempts. Makes sense. I will give it a try. Thanks

 

[StillLearning]

My Ctek sometimes doesn’t like a battery I charge with it. Put the battery on a dumb charger for a few hours, then switch back to the Ctek and all is good.

Thanks for the suggestion. Perhaps it's because it is a "larger" battery and only a 1amp charger/maintainer? I am going to try resetting the alligator clips as suggested above first. If that does not work I will give this a try.

 

[JMJNet]

If it is good after load test why are you charging it?
I suspect, the battery is good.

 

[DriveHard]

I had it happen with a NOCO charger because it was an AGM battery, and I had it set on a conventional battery. Tried three different batteries that were all AGM (buried in my boat, installed by PO). I knew all three were low, but I didn't expect all three to be bad. Once I found out they were AGM batteries and selected the correct AGM setting on the charger, it charged all three just fine.

 

[wrcsixeight]

A charger is basically expecting the amperage it applies, to raise the voltage up to a limit. usually in the 14.4 to 14.7v range.
It also expects once it this amperage applied achieves the voltage limit, the amperage required to maintain the battery at this constant voltage will keep tapering.

If the charger sees that the amperage required to maintain voltage increases, it might think there is a shorted cell.

One can likely cause a smart charger to say 'bad battery', by opening and closing doors with small loads such as dome lights turnign on and off, or perhaps larger loads are required, like turning headlights on and off.

This 'bad battery' behavior might only occur when the charger has gotten the battery to its constant voltage stage, and perhaps not while it is still applying its maximum amperage( constant current stage) in order to achieve the maximum voltage where it starts limiting amperage in order to not exceed the voltage.

If one were to employ an ammeter and a voltmeter inline on the chargers output, then this and many other aspects of battery charging become obvious, instead of complete mystery.

This and its many similar clones can handle 25 amps continuous, and as long as the charger does not have a third wire for battery temperature sensing, is very easy to splice inline and will not affect the chargers function.

https://www.amazon.com/Proshopping-Precision-Analyzer-Checker-Measurement/dp/B07Z91FWT9/ref=dp_prsubs_1?pd_rd_i=B07Z91FWT9&psc=1

Do certainly make sure the clamps are contacting as much surface area as possible, and pry the ends apart so your hand strength adds to the spring pressure in order to maximize contact between battery clamp/post and charger clamp.

 

[StillLearning]

Just to update, resetting the the battery clips firmly on the battery posts resolved the issue. I even tried running the battery down a little by leaving the headlights on for a bit to test, and again it charged for a while and switched over to maintaining mode.

Thanks to all for the suggestions and info.

 

[StillLearning]

If it is good after load test why are you charging it?
I suspect, the battery is good.

I use it mostly as a battery maintainer when I know a vehicle will not be in use for a while. In this case I only load tested the battery because the maintainer was indicating the battery needed to be replaced.

 

[garageman402]

I use it mostly as a battery maintainer when I know a vehicle will not be in use for a while. In this case I only load tested the battery because the maintainer was indicating the battery needed to be replaced.

How is that Noco Genius1 working out for you?

 

[repairman54]

I just wire in the quick disconnects for my maintainers. No clip connection issues and easier to use for that quick getaway.

 

[Cujet]

Good that you got it right. However, this brings up a point. These digital chargers often won't work when you need it most. Such as when the dome light was left on for a few days, and the vehicle simply needs to go. Sure, the battery might be toast, but that is no reason to be stranded. It will come back enough to get 'ya goin.

The old-school chargers with transformer and diode internals are the ones that work for this. It is always a good idea to have one around.

 

[Donald]

Load test at 1/2 CCA is the proper load test.