"nd leisure battery

TissyD

TissyD

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Good morning. I am installing a second leisure battery and I was just wondering if the MTTP will still display 13.6 volts or will it display 27.2 when both batteries are charged. many Thanks Tissy D
 
TissyD said:
Good morning. I am installing a second leisure battery and I was just wondering if the MTTP will still display 13.6 volts or will it display 27.2 when both batteries are charged. many Thanks Tissy D
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If your batteries are in parallel the voltage will be around 13.6v when floating. Just make sure you connect the second battery +ve to +ve and -ve to -ve.

Cheers

H
 
TissyD said:
Good morning. I am installing a second leisure battery and I was just wondering if the MTTP will still display 13.6 volts or will it display 27.2 when both batteries are charged. many Thanks Tissy D
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how old is the first battery? Depending on what your setup is I would not automatically expect to get the full capacity of the battery bank. e.g. If you are adding a 100Ah battery, you are unlikely to get 100Ah extra (and I don't mean about only going to 50% etc, I mean total capacity).
 
The original battery is 8 months old. They are both 110ah. I was just wondering if the readout would stay at 13.6 even if both batteries are fully charged or if it shows the total voltage stored. i.e, 1 Battery 13.6, 2 27.2, 3 39.8 etc.
 
TissyD said:
The original battery is 8 months old. They are both 110ah. I was just wondering if the readout would stay at 13.6 even if both batteries are fully charged or if it shows the total voltage stored. i.e, 1 Battery 13.6, 2 27.2, 3 39.8 etc.
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As has been said, it is down to how connected. There is no such thing as a "voltage stored". Your 12V battery is made up of 6 cells each 2V each connected in series so you get 12V at the terminals. If you were to connect the 2nd battery in series (you shouldn't!), then you would have in effect 12 2V cells in series giving 24V. In parallel, the group of 6 cells in battery 1 are connected across the group of 6 cells in battery 2.

Adding another battery you are adding Power (WattHours).
If you connect two in Parallel (+ve to +ve, -ve to -ve), you are doubling Ah's, but keeping voltage the same. If you are connecting two in Series, you are doubling Voltage, but keeping Ahs the same. Identical to how you work out Solar Panel connections.
to do the sums (and using 100Ah instead of 110Ah to make it Maths easier)
100Ah battery at 12V = 1200Wh of power
Adding a second 100Ah battery... In series, (12V + 12V) * 100Ah = 2400Wh; In parallel, 12V * (100Ah + 100Ah) = 2400Wh. Same result, just different way to get there.
 
When I wanted to do this I was told that the Sargent charger would be damaged by the increased current requirement.
I installed a switch widening used in some boats that allows you select battery 1 or battery 2 which means if one of my batteries is getting low I just switch to the other. You have to charge them one at a time.
 
Glass man said:
When I wanted to do this I was told that the Sargent charger would be damaged by the increased current requirement.
I installed a switch widening used in some boats that allows you select battery 1 or battery 2 which means if one of my batteries is getting low I just switch to the other. You have to charge them one at a time.
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I never did . Both charged at the same time as it would with a 220. Amp battery. That’s the two 110 amp batteries together as per the drawing post #4

However we also have solar.
 
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With lead acid technologies the battery charger should be 10 to 15% of the total Ah. Most OEM chargers in vans are not that good or smart, even the Schaudt gear was advised not to go over the 15% and that wasn’t cheap stuff. With the Schaudt though you had the option of adding a second charger so it could all go through their system until you went much over 300Ah.
 
Just make sure both batteries are equal i.e. have the same voltage and amperage before connecting, otherwise it's possible one will always be over charged and one under charged.
 
TissyD said:
Good morning. I am installing a second leisure battery and I was just wondering if the MTTP will still display 13.6 volts or will it display 27.2 when both batteries are charged. many Thanks Tissy D
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If it says 27.2 you’re in trouble! See trevskoda’s post #4.
 
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