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What Voltage readings are normal for new batteries?

ThomasHJ

ThomasHJ

Messages
117
Location
Netherlands
Vehicle
T5 SE 140
I serached and searched and there's a lot to be found, but I can't seem to find the answer to my question. I recently had all 3 batteries replaced (the car-battery and both leisure batteries). Had just bought the second hand cali (A VW T5 2011) and had a big checkup done. Turned out the batteries all needed replacing. Honestly I didn't check what the voltage readings were at that time but all seemed to work fine (fridge, heater, lighting, etc) but I trust the VW-dealer who did the checkup.

Now however, with my new batteries in place, I am wondering, what are normal voltage readings? So, when on hookup, what should it read in the control unit? And when I unplug it (So not on hookup, but with fully charged batteries), what should it read?

any help would be greatly appreciated.
 
MartG

MartG

VIP Member
Messages
568
Location
Scotland
Vehicle
T6 Ocean 150
Fully charged 12V lead acid battery should read between 12.75 and 12.85V. When being charged, the battery requires 13.5-14.5V to re-charge. 50% battery is around 12.3 - 12.4V. Fully discharged is around 11.8V, continuing to discharge past this will cause harm to the cells. Keeping the battery above 12.4V, preferably as high as possible, maximises it's life.
 
WelshGas

WelshGas

Retired after 42 yrs and enjoying Life.
Top Poster
Lifetime VIP Member
Messages
14,531
Location
Cowbridge
Vehicle
T5 SE 180 4Motion
I serached and searched and there's a lot to be found, but I can't seem to find the answer to my question. I recently had all 3 batteries replaced (the car-battery and both leisure batteries). Had just bought the second hand cali (A VW T5 2011) and had a big checkup done. Turned out the batteries all needed replacing. Honestly I didn't check what the voltage readings were at that time but all seemed to work fine (fridge, heater, lighting, etc) but I trust the VW-dealer who did the checkup.

Now however, with my new batteries in place, I am wondering, what are normal voltage readings? So, when on hookup, what should it read in the control unit? And when I unplug it (So not on hookup, but with fully charged batteries), what should it read?

any help would be greatly appreciated.
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This is what I go by. On Mains Hookup the voltage will go upto about 14.4v at first then possibly fall back to about 13.6. With engine running upto similar values . The Leisure Batteries need to be kept above 12v . The fridge and/or Parking heater will switch off at 11.5v .
 
Last edited:
TripleBee

TripleBee

Messages
1,511
Location
melkwegstelsel
Vehicle
T5 SE 140
An unused battery will keep it's charge steady at about 12,65V after days and weeks.
In the car, there will always be current drawn from the battery(ies), so after a couple of weeks they will get lower and lower. Anything below 12,2V is highly unwanted, like the diagram here above.
After 2 hours after hookup disconnection, the batteries will still show about 12,8V.
 
AndyWT

AndyWT

Messages
28
Location
Italy
Vehicle
T4 PopTop
Battery state of charge is misleading here as temperature has not been taken into account, high temp gives a lower state of charge conversely low temp give a higher value, for battery voltage of 12.7 it needs to be about 15c and have been float charged which alternators rarely do.

My van battery is 12.6 volts charged by alternator, leisure battery is 12.7 volts charged by solar, both are high quality sealed lead acid less than 1 year old.
 
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