Adding a third domestic battery?

single

single

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I currently have x2 110Ah domestic batteries charged via X-Split charger from a 50A alternator. Is at as simple as just adding a third to that bank or would i be better having a completely separate system for the third battery.The reason i want a third is for non essentials like tv,heating,stereo etc
 
Better as part of a 2 bank system rather than a 3 bank system IMO, so add the new battery to the current domestic bank. This allows each individual battery to be discharged relatively less rather than having one battery being knackered by regular significant discharge. I think it also increases the charging speed. It also prevents you needing a new split charge system.
 
Try and get the same make and size as current ones, then just add it to the bank. That is the simple way, but I am guessing from your post that you want to have it for non-essentials so if they discharge it the other systems are not affected.
If that is the case add it to the existing bank via a VSR and then rewire so the non essentials are fed from that new battery.
 
single said:
I currently have x2 110Ah domestic batteries charged via X-Split charger from a 50A alternator. Is at as simple as just adding a third to that bank or would i be better having a completely separate system for the third battery.The reason i want a third is for non essentials like tv,heating,stereo etc
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Add the new battery to the existing service battery, then supply the non-essential loads via a low voltage power lock-out relay set at 12.0 / 12.2 volt. Fitting the third battery in a system that will run it flat will drastically reduce it's life. By having a large bank you maximise power before 50 % capacity is reached, you are recharging two batteries at equal discharge level, and maximise battery life.

Brian
 
No problem to add a third battery to a bank, but be careful how you arrange the common negatives to ensure equal discharge through each battery.

This explains: http://www.smartgauge.co.uk/batt_con.html

By the way, even if you're not interested in Smartgauge, their website is packed with information and deals with most of the battery charging questions which frequently crop up here.
 
Adding a third battery to my two-battery domestic bank has transformed their health. Running a fridge 24/7 in Greece, we would often see battery voltage down to 12.0 or even less first thing in the morning before the solar panels got going. With three 110 Ah batteries the voltage is never less than 12.4 and often more than that. It's cycling to low voltages that kills batteries and I confidently expect these three to last for many years. I did nothing except add cables and arrange a starter battery elsewhere. 55 Amp alternator, Sterling controller and 125 watts of solar panel through a Sunworks dual-bank controller.
 
vyv_cox said:
Adding a third battery to my two-battery domestic bank has transformed their health. Running a fridge 24/7 in Greece, we would often see battery voltage down to 12.0 or even less first thing in the morning before the solar panels got going. With three 110 Ah batteries the voltage is never less than 12.4 and often more than that. It's cycling to low voltages that kills batteries and I confidently expect these three to last for many years. I did nothing except add cables and arrange a starter battery elsewhere. 55 Amp alternator, Sterling controller and 125 watts of solar panel through a Sunworks dual-bank controller.
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Well that sounds like exactly what i will end up with, except i have Aero4gen rather than solar.The biggest pain is voltage dropping too low for the Webasto to work in the morning.
 
vyv_cox said:
I have a dim memory that numerical capacity values of batteries have been changed recently although the actual battery remains exactly the same. Google may assist you.
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Thats pretty much what they said.Is it a big problem adding a new one to the two that are a few years old?
 
single said:
Thats pretty much what they said.Is it a big problem adding a new one to the two that are a few years old?
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When I originally combined my two domestics with the one previously used for starting they were several years different in age but went on for another few years. When they failed two replacements were fitted as a stop-gap and the third added a year later. All are working well four years down the line. I believe that provided any existing ones are working well with no bad cells then adding a new one will not be a problem.
 
vyv_cox said:
When I originally combined my two domestics with the one previously used for starting they were several years different in age but went on for another few years. When they failed two replacements were fitted as a stop-gap and the third added a year later. All are working well four years down the line. I believe that provided any existing ones are working well with no bad cells then adding a new one will not be a problem.
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and it help spread the cost
 
vyv_cox said:
When I originally combined my two domestics with the one previously used for starting they were several years different in age but went on for another few years. When they failed two replacements were fitted as a stop-gap and the third added a year later. All are working well four years down the line. I believe that provided any existing ones are working well with no bad cells then adding a new one will not be a problem.
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Have done the same on Storyline when the boat yard mysteriously lost one of our matched batteries and had to supply a new replacement. All still going strong four years later.
 
I am going to buy a third battery plus a set of jump leads. I also have 2 x 12v 110 Amp batteries which are described as Leisure Batteries but are probably rubbish as for £80 new they cant exactly be very good.
 
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