REQ: Service manual or schematic for NOCO Genius G series battery charger

[Git]

I have NOCO Genius G7200 and G15000 battery chargers. The 15A got twisted, frayed wires at the exit of the red & black leads. I opened it up (tin opener job) and with the care of nearly 5 decades of doing this sort of job, replaced the leads with 12AWG silicone insulated wires. Output volts and insulation checked ok, so put it on a battery and let it rip. Seemed to progress normally through the lights to slow green but shortly after it dropped straight down to flashing red and started the whole cycle over. Ad infinitum. Monitoring the battery volts, there was the normal climb and slow fall as it switched power on, then monitored the voltage. However there didn't seem to be as much charging going on as normal after the first red light. There was more of the part where the battery slowly fell as it was monitored, maybe 10mV to 20mV a minute. Now the weird bit - as soon as the voltage dropped to 12.833V the cycle restarted, completely repeatable. Tried it on another battery with almost identical results, this time restarting at about 12.827V. Obviously, I don't *think* I changed or moved anything, but it has to be likely. Unfortunately, I don't know if I charged these batteries with the G15000 before, as it's a bit over the top for 12V 20AHr SLA AGM batteries. The problem didn't recur with the smaller G7200 charger.

I've opened it again, gave it a visual, and can't see anything wrong. I had earlier carefully cleaned one area that was buried in old flux from original soldering of the heavy output wires to the PCB. The only thing that occurs to me is that I may have accidentally knocked a pot, which are very small open frame things.

If anybody has any ideas it would be gratefully received. The thing I really need is a schematic and/or service manual. It's a daunting task without.

Git

[pickit2]

I would say your voltage is a bit low for SLA 13.5V to 13.8V for a 12V battery

[Checksum8]

This NOCO patent has schematics which may help in trouble shooting. Not sure how close this is to your unit?

https://patentimages.storage.googleapis.com/3f/58/81/4759621eb73c3a/WO2021071949A1.pdf

[pickit2]

there is a power supply mode that gives a steady voltage at 5Amps.


https://moundalexis.com/v2/2020/08/10/noco-repair-mode.html#:~:text=Repair%20Mode%20With%20the%20battery%20charged%2C%20it%20was,once%20more%20to%20switch%20to%2012V%20Repair%20mode.

[norkimo]

Did you already check to see what mode the charger is in using the Mode button? Do any of the other modes behave differently? I know on my NOCO it is easy to get it in the wrong mode without realizing it.

[Git]

On the voltage, standard SLA yes, but this is an AGM so 100% charge gives 13.0V.  Anyway, what is happening at this mysterious 12.833V shouldn't happen regardless. It should be charging and the voltage still rising. Instead, the voltage slowly falls until at the magic voltage the whole charge cycle starts over. The Patent info is very useful indeed. Although it is specifically for the "Charge from zero" feature, it has some useful insights. The moundleaxis link is about Repair Mode which all the NOCO G series chargers have. It can revive a really sulpahed old battery back to use. I used it on one of the batteries I tested above and got about 0.2V back. Thanks to you both.
Git


Posted on: 21 March 2022, 19:01:51 - Automerged
norkimo - I know what you mean. They remember the last chemistry charged which imo makes it even more important to check if you're charging several different types. So far I have seen this happen in lead-acid mode and AGM mode, but I've done most of the testing with the AGM batteries.