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Graph of Noco G7200 charger working on my dead ATV battery


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#1 Old Crow

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Posted 31 December 2018 - 08:28 PM

     Well, I didn't know whether to add this one to the 'Stupid Things You've Done' thread or start a new one.  In any case, I know a number of WTW members have Noco G7200 battery chargers so I thought I'd post this info...

 

A few days ago I was checking on my vehicle batteries and noticed the LED on the solar battery maintainer wired to my ATV's battery didn't look right.  It's normally yellow or green but this time appeared to be off or very, very faint... it was tough to tell in the bright sunlight.

 

I put a multimeter across the battery terminals and at first thought my meter must be bad.  It was showing 27 millivolts (!!!).  I was mystified as I had recently started up and moved the ATV. But when I turned the key I realized Mr. Easily-Distracted (me) had left it on after that move a few weeks ago.  So apparently the solar maintainer panel couldn't keep up with the ATV's rate of discharge (when the key is left on).

 

I recently bought yet another battery charger and thought I'd give it a try.  After a few minutes it lit the bad-battery-I'm-done indication.  I also tried my G7200 charger and it did the same.  I considered putting my old-school 1980s Exide charger on to get voltage up enough to fool a modern charger into working on it  but at that point it occurred to me the battery might be frozen so I pulled it and took it inside.

 

The next day I was happy to find the battery had spontaneously recovered itself to 3+ volts.  That should be enough for a modern charger to not declare it a bad battery so I put the G7200 and a voltage logger on it.

 

And here's the reason for this post--- the interesting plot of the G7200 running its charging program on the dead battery..

 

(Click to enlarge)

 

ATVrecoveryFrom3v20181230graph.jpg

 

After starting the charger I put the multimeter on and saw voltage changing about every second.  And as I watched I saw it charge at voltages in the 12s for a bit, then in single-digit voltages for a bit.  And when it switched between those ranges, I'd hear a click in the charger.

 

The graphed data can also be viewed as a text file and perhaps it gives a better idea of what the charger was doing.... (this is only the first two of 258 pages of data).

 

(Note- the zero voltages at the beginning were recorded before I connected the logger to the battery)

 

ATVrecoveryDataPage1.jpg  ATVrecoveryDataPage2.jpg

 

I don't know for sure how the battery has come out of this for the longer term.  Resting voltage looked great (12.7-ish) but then it barely passed a load test.  And according to my digital tester, internal resistance is high.  It's a six-year-old battery so perhaps that's not surprising.

 

I put the battery back in the ATV and was able to start it.  That one doesn't start easily so it put a pretty good cranking load on the battery.   I was surprised how well it did.  Still, I wouldn't want to trust it away from home given the borderline load test and its high internal resistance.

 

.


Edited by Old Crow, 01 January 2019 - 06:42 PM.

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#2 PaulT

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Posted 31 December 2018 - 08:53 PM

I've seen similar results with both my NOCO G7200 and G15000 chargers on batteries where my Battery Tender brand charge maintainers were left without weekly manual disconnects and reconects. Unlike the IQ4, the Battery Tenders don't seem to return to the bulk mode periodically from float. In other words, once entering float, they no longer recharge the battery when a discharage occurs.

 

Both the Nocos seem to have the ability to recover the battery by hitting it with a high voltage spike then monitor if an incremental charge has occurred. Over a day or so, the battery is returned to a full charge. Two of my batteries that ran flat have been restored and are doing ok. I'm sure some of the overall battery life was lost but I have not had to replace either battery after more than a year of use following the incident. 

 

If I briefly power cycle and disconnect/reconnect the Battery Tender brand from the battery, they do fine for charging a battery after it has been drawn down and floating it for a week or so.

 

Paul


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#3 Old Crow

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Posted 03 January 2019 - 01:48 AM

Hi, Paul--

 

   Your post prompted me to run a little test today....

 

   This morning I pulled the Battery Tender 800 Waterproof from my lawn tractor and put it, the voltage logger, and a small inverter on the ATV battery.

 

     I also put a 16-watt appliance bulb into a bulb-base-to-plug adapter and plugged that into the inverter's AC outlet.   That would in theory give me a 1.4 amp (DC) load (if we ignore inverter efficiency) I could switch on and off.

 

(click to enlarge)

 

BT charging tst20190102zoomed.jpg

 

The battery was sitting at 12.7 when I pulled the solar tender and plugged in the wired one.  You can see it then charged at 14.6+ for about 15 minutes before dropping to a float voltage of 13.2+.

 

The next event (at about 12:50) is where I turned the inverter on for a half hour and we see voltage drop and level out at 12.25 under the load. 

 

And when I turn the inverter off, we see voltage resumes at the tender's float voltage.

 

Next, at about 14:50, I tried the disconnect/reconnect thing.  I unplugged the battery tender and removed the clamps from the battery for 30 seconds, then put them back on and plugged in the tender.

 

Now the tender decided to charge at 14.6+ (and also varies the voltage in an interesting pattern) until it goes to float voltage. I don't know if this is significant but that was also a 15-minute increment.

 

Battery tender LED indications during the test:  When I first plugged it in, I got a very brief red then the flashing-green indication for 15 minutes until it went into float.  At that point it went solid-green, indicating battery full.  However, I was surprised to see the LED never went out of solid-green (despite the load) until I unplugged the tender.  After the reconnect, the LED flashed green for 15 minutes, then went solid-green again and I could see voltage had dropped back to a float voltage.

 

PS-- Offhand, I don't see the tender's behavior as necessarily a problem.  It clearly can't charge the battery with a 1.4 amp load on it but then again it's only a 0.8 amp charger.

 

PPS- LED indications (and performance) may be different on other Battery Tender models.  My previous 800 Waterproof didn't have the same LED indications this one has, for example.  I believe this one is the current-production model  as I bought this one less than two weeks ago.

 

.


Edited by Old Crow, 03 January 2019 - 12:44 PM.

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