NOCO Genius 10 keeps saying I have a bad or shorted battery.

[Wayne]

I have a NOCO Genius 10 that acts as a maintainer for the 4 150AH AGM batteries in the trailer. The charger will say that it charges the batteries full, but when I look a day later the display says there is a dead or shorted battery. The red battery with an X is what I always see after the maintainer has been running for a while.

When I unplug the charger and plug it back in, it goes through the automatic detection routine and properly selects 12v AGM. There are actually 4x6 volt batteries. Two pairs hooked in series, then those pairs hooked in parallel for 12v.

It starts charging

Within a few minutes it shows full

When you check the next day, it shows dead or shorted battery again.

I am wondering of the 10A maintainer doesn't have the capacity to do maintenance mode on a 600A/Hr battery set? I did look at the Genius 10 manual and it says up to 230AH, but it doesn't say if that's charging capacity or maintenance capacity.

There is a NOCO Genius Pro 25 that the user manual says up to 1000AH, but it's $350 (with Amazon coupon), so I'd rather make the 10 work if I can.

 

[ctechbob]

I would split all the batteries apart and let it charge each one and see if it singles one out as being weak.

It should be able to eventually charge them, God knows I use my Genius1's to charge all kinds of things beyond their official capacity.

 

[Wayne]

I would split all the batteries apart and let it charge each one and see if it singles one out as being weak.

I think I'll do that tomorrow and see what I get.

It should be able to eventually charge them, God knows I use my Genius1's to charge all kinds of things beyond their official capacity.

As do I. My G750, which is 0.75 AMP maintains my dual truck batteries just fine.

 

[Wayne]

I would split all the batteries apart and let it charge each one and see if it singles one out as being weak.

I uncabled the batteries today and put the charger on each individually. The result is that all four batteries are good and the NoCo 10 had no problems floating each AGM battery in maintenance mode.

All good in float mode

I called my friend, who happens to have a PhD in electrical engineering, and asked him why he thought the maintainer couldn't charge all four batteries in maintenance mode. He said most likely that all four batteries probably have a slight variation in internal resistance and that since they are in parallel and series, that the maintainer would attempt to carry too much amperage. The reason for this is that when one or more batteries have different internal resistance, the maintainer will try to charge all four to the level as the one with the highest internal resistance. Having batteries in series amplifies the imbalance.

He said if I really want to maintain each battery to the optimal float voltage, then I will need to uncable them and put a separate maintainer on each battery. That's what I'm going to do. It's kind of a pain, but I will only have to do this when the trailer sits for more about a month. It only takes about 5 minutes to uncable the batteries.

Uncabling is not difficult, as the batteries are easy to get to.

 

[ctechbob]

You could always wire in some heavy duty Anderson connectors to make the job even easier.

Their Powerpole 180's are good for up to 3/0 wires and 180 amps I believe.

 

[Wayne]

Or something like this.

https://a.co/d/ggBGn4B

I'm not sure they could carry enough current.

 

[Wayne]

I learned that the only NOCO chargers that will change AND maintain a 6V AGM battery are the 10, 25, and 50 AMP versions. I ended up buying 3 more 10 AMP charger/maintainers, which was actually cheaper than a single 25 AMP. I'll post pictures later.

 

[Wayne]

This is the final setup for maintaining the 6V AGM batteries in our trailer. Four NOCO Genius 10s each maintaining its own isolated battery. These maintainers will be connected until sometime next spring. I'll peek at them every couple weeks to see how they are doing. Can you spot my rodent repellent?

 

[Wayne]

I just checked this morning and all four maintainers are in the green and happy. Looks like my EE friend is correct!

 

[ctechbob]

One of these days I'll get around to buying a Noco10. I want it mainly for the power supply function so I can leave the converter in the trailer turned off but still power the 12v system so I can pre-cool the fridge and the other 12v stuff in there to get ready for a trip a few days in advance. I don't have quite enough solar/battery to accomplish it just using the sun, although that will probably be the next upgrade. I'd like to go to at least 200 watts of solar and a lithium battery.

 

[Mbacfp]

One of these days I'll get around to buying a Noco10. I want it mainly for the power supply function so I can leave the converter in the trailer turned off but still power the 12v system so I can pre-cool the fridge and the other 12v stuff in there to get ready for a trip a few days in advance. I don't have quite enough solar/battery to accomplish it just using the sun, although that will probably be the next upgrade. I'd like to go to at least 200 watts of solar and a lithium battery.

Wayne, great thread. I have had the same problem trying to charge both my batteries that are in parallel. I never got around to calling Norco and decided to leave on charge through the motorhome.

It does exactly what you describe. Will charge separately. Thanks.

 

[Wayne]

Wayne, great thread. I have had the same problem trying to charge both my batteries that are in parallel. I never got around to calling Norco and decided to leave on charge through the motorhome.

It does exactly what you describe. Will charge separately. Thanks.

You are welcome and I will thank my PhD electrical engineer buddy.