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sveines avatar image
sveines asked

Victron Battery Balancer for 24V battery system

Hi!  
In the boat I have 4 x 180Ah batteries that are connected in series 2 x 2 to 24 volts. Has mounted Victron Smartshunt on the battery bank so I can follow the charging status. There are indications that one, some or all of the batteries are defective. Have not disconnected yet and measured one and one battery yet. The batteries are not more than 3 years old.  

After searching online, I have come across several discussions about damage that can occur to batteries that are connected in series, including different charging and difference in voltage between the batteries.  

The following happens when shore power is disconnected and battery charging is terminated:  
18:00 Charging ends, battery voltage before charging is stopped is 26.94V and 100% charged 
19:00 Battery voltage 23.7V and 99% charged 
20:00 Battery voltage 22.96V and 98% charged 
21:00 Battery voltage 22.85V and 96% charged 
22:00 Battery voltage 21.23V and 95% charged 
23:00 Battery voltage 20.68V and 94% charged 
06:00 (After 12 hours) Battery voltage 16.67V and 82% charged  

It's something I can not live with, it does not take long before equipment turns off. Based on this data, what is the most likely thing that has happened to my batteries?  

When I need to replace the batteries, I need a 24 volt solution. Victron has a product called "Battery Balancer for 24V battery system". Could this be the salvation for a configuration with 2 x 2 12 volt batteries for a 24 volt solution?
cerbo gx
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5 Answers
klim8skeptic avatar image
klim8skeptic answered ·

At 26.94v it is unlikely that your batteries are fully charged.

What batteries are they?

What charge profile does the manufacturer recommend?

Such low voltages (below 11v) are damaging.

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sveines avatar image
sveines answered ·

It is GEL batteries, 3 years old. Details are aas follows:



GEL battery - WhisperPower

ominal capacity (C20) 180 Ah
Nominal voltage 12 VDC
Type Deep cycle GEL battery with 12 years floating design life. Superior design for frequent cyclic discharge applications under extreme temperatures. Strong grid construction to ensure reliability under frequent deep discharge use. Over 400 cycles possible at
CHARGE/DISCHARGE PARAMETERS
Constant voltage Charging (IU, float) 13.60 to 13.80 VDC @ 25C
Cyclic Charging ( IUU, absorption) 14.25 to 14.60 VDC @ 25 C
Recommended charging current limit (higher possible) 36 A
Temperature cut-off ratio 4mv/cell/°C
Discharge cut off voltage 1.75 VDC @ (A) <= 0.2 C

1.70 VDC @ 0.2 C (A) <= 1.0 C
100% depth of discharge d.o.d. 1.65 VDC @ (A) >= 1.0 C
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klim8skeptic avatar image klim8skeptic ♦ commented ·

Your post ^ re battery specs is pretty straight forward.

As a standby battery, charge and hold battery voltage at float "13.60 to 13.80 VDC @ 25C ".

For a daily cycler battery (charge/discharge daily), charge to "14.25 to 14.60 VDC @ 25 C ".

While this is simple to point out, such small mistakes cost ppl money.

Sorry.

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sveines avatar image
sveines answered ·

But why can batteries that is supposed to live for "12 years loating design life" as producer Whistler Power states be damaged after only 3 years, and has hardly been used in these years?


When I buy new ones, is it anything I shoudl do to prevent new batteries from being damaged? Is the Victron Battery Balancer for 24V battery system something that is neccesary, or not?

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Is the SmartShunt wired correctly? Is every current going through the shunt or are there some loads connected directly to the batteries? What

As klim8skeptic wrote, the voltage at the end of charging seem to low.
As the spec sheet says you have a absorption voltage of 28,5-29,2V and a float voltage of 27,2-27,6V. How long did you charge the batteries?

Try to disconnect all all batteries and charge them individually with the correct current/voltage for 12h. After that disconnect the charger, wait 1-2h and measure the voltage of the battery.
If the battery is ok the voltage should be around 12,7V.

Maybe only one battery is defective.

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sveines avatar image sveines commented ·

Disconnected all batteries and measured them individually. It was clear then that it was one battery that was completely damaged.


When I removed them it became abious why, the side had "exploded" on the last battery. It was not vicible for eye when mounted.


If it had been possible to measure the voltage on each individual battery then I could have discovered it right away.


I have taken all batteries home in my garage. It was hard work as they weigh 53kg each :-)


Why does this happen? Is it wrong use? Wrong installation? Or I am only unlucky as it can happen? And how to prevent that for future installation?


The exact same brand will might be difficult to get hold of as WhisperPower is not widely sold in Norway. But if I can not get same, will a GEL battery of 180Ah of different brand work?

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sveines answered ·

The resistance on my batteries are to be around 6, and I test 3 batteries to be 4.4, 5.0 and 6.2


I consider to keep the two best ones as one half of my 24V bank, and but two new ones. In addition to buy a Victron Balancer.

Do you think that will work?

Is it the battery with highest or lowest resistance that must go?

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