Battery Charger/Maintainer

[CnJ88]

I recently purchased a NOCO Genius Battery Charger Maintainer that will charge 6 volt or 12 volt batteries. And, I have two house batteries connected in series with 12 volt output. The manufacturer of the NOCO recommends to charge these 6 volt batteries separately. However, these house batteries are normally being charged by the RV's 12 volt alternator. I've measured that charging voltage to exceed 14 volts, at times. My question is: if the house batteries are normally being charged by a 12 volt system. Why couldn't I charge them on a 12 volt setting with the NOCO battery charger?
The NOCO manufacturer doesn't explain his answer. Just makes a statement.

[jd4010]

Personally, I would leave them connected and charge them as a single 12v battery. One of my bigger tractors has two 6 volt batteries in series and I charge/maintain (using a BatteryMinder) as a single 12. Works fine.

[FollowTheSun]

Originally Posted by CnJ88

...
... Why couldn't I charge them on a 12 volt setting with the NOCO battery charger?
... .

Hi CnJ88,
As jd4010 stated: “leave them connected and charge them as a single 12v battery.”

Flooded lead acid batteries are made by connecting a series of ≈2.12-volt cells in series. Thus, 3 cells X 2.12 volts ≈ 6.4 volts; 6 cells X 2.12 ≈ 12.7 volts. Your observation that charging voltage sometimes exceeds 14 volts is normal during the bulk phase of the charging cycle. I suspect that the NOCO Genius Battery Charger Maintainer provides, at least, the following three basic modes while charging (12-volt) batteries:

• Bulk Charge 14.4v – 14.7v (constant current, increasing voltage)
• Absorption Charge 14.4v – 14.7v (reducing current, constant voltage)
• Maintenance Charge 13.4v – 13.8v (constant voltage, low current)

The charger might also provide:

• Equalization Charge 15.6v – 16.2v (high voltage, low current)

[CnJ88]

Thanks for the quick reply jd4010.



Someday I might want to completely disconnect the two six volt batteries and charge them separately, but not today nor this winter.

[CnJ88]

Originally Posted by FollowTheSun

Hi CnJ88,
As jd4010 stated: “leave them connected and charge them as a single 12v battery.”

Flooded lead acid batteries are made by connecting a series of ≈2.12-volt cells in series. Thus, 3 cells X 2.12 volts ≈ 6.4 volts; 6 cells X 2.12 ≈ 12.7 volts. Your observation that charging voltage sometimes exceeds 14 volts is normal during the bulk phase of the charging cycle. I suspect that the NOCO Genius Battery Charger Maintainer provides, at least, the following three basic modes while charging (12-volt) batteries:

• Bulk Charge 14.4v – 14.7v (constant current, increasing voltage)
• Absorption Charge 14.4v – 14.7v (reducing current, constant voltage)
• Maintenance Charge 13.4v – 13.8v (constant voltage, low current)

The charger might also provide:

• Equalization Charge 15.6v – 16.2v (high voltage, low current)

Factoid: I just purchased a BatteryMinder Plus model 1510 to charge/maintain the RV house batteries. In the back of the manual it shows three common multiple battery configurations: two 12 volt batteries in parallel; two six volt batteries in series; and, four six volt batteries in series-parallel. Each configuration has 12 volt output. Also, each configuration shows where to connect the BatteryMinder Charger.



Thank you for the great info and thank jd4010 for the great advice. I put both to good use.