Two 12v batteries in parallel charged from 2 sources
River rob said
05:05 AM Nov 15, 2016
Hi
Im in the process of installing solar panels on my van. I'm replacing the existing battery with 2 new 100amp batteries.
My question is can I leave all existing wiring and charging to the original battery position and then connect the solar through the solar controller to the second battery and connect them in parallel?
Not sure if this ok to do. What happens if the batteries are being charged from both ends at the same time?
Or do I need to connect both supplies to one battery?
The reason I ask is I am putting the second battery inside the van, so it is going to be easier to connect the solar to it. The other battery is mounted underneath the van
thanks
Rob
-- Edited by River rob on Tuesday 15th of November 2016 05:15:14 AM
-- Edited by River rob on Tuesday 15th of November 2016 05:26:17 AM
Jaahn said
08:08 AM Nov 15, 2016
Hi Rob
The two batteries should be connected together by heavy cables so there is virtually no resistance between them in both + and - connections. Then what you want to do will be OK. It would be best practice to have them close together but that is not always possible.
Jaahn
River rob said
09:07 AM Nov 15, 2016
Thanks Jaahn The batteries will be about 500mm apart. What size cable do you suggest? Sorry make that about 800mm.
-- Edited by River rob on Tuesday 15th of November 2016 09:32:04 AM
PeterD said
10:57 AM Nov 15, 2016
Starter motor size cable. ie 6 or 4 B&S.
Peter_n_Margaret said
10:57 AM Nov 15, 2016
I would suggest about 30mm2.
At 800mm apart, I wold also recommend a fuse at each end of the +ve that links those 2 batteries. A short of any sort in that cable would be catastrophic.
Cheers,
Peter
River rob said
11:34 AM Nov 15, 2016
Ok thanks guys I'll fit fuses as suggested
River rob said
12:44 PM Nov 16, 2016
Hi Jaahn
i have completed the system and charging from solar panels works fine on its own but when I connect 240 to the c-tek charger the volts go up to 15.5v and the solar regulator cuts out on high voltage. So somehow with both running I can't control the amps.
Is there something I can do to rectify this?
Thanks
oldtrack123 said
01:46 PM Nov 16, 2016
River rob wrote:
Hi Jaahn
i have completed the system and charging from solar panels works fine on its own but when I connect 240 to the c-tek charger the volts go up to 15.5v and the solar regulator cuts out on high voltage. So somehow with both running I can't control the amps.
Is there something I can do to rectify this?
Thanks
Check the Ctek settings & ALL connections ,you could have bad joint
It should not take the battery that high
First check the voltage directly on the battery terminals
I very much doubt that will be 15.5V
work back until you find where the voltage jumps
Tony Bev said
02:23 PM Nov 16, 2016
River rob wrote:
Hi Jaahn
i have completed the system and charging from solar panels works fine on its own but when I connect 240 to the c-tek charger the volts go up to 15.5v and the solar regulator cuts out on high voltage. So somehow with both running I can't control the amps.
Is there something I can do to rectify this?
Thanks
I am not an Electrician
Look at the manual for your model 240 volt CTEK battery charger
Some of them start off in Desulphation Mode, and they can push in, up to 15.8 volts, for as short time
Below is a link to one such 240 volt CTEK battery charger
i have completed the system and charging from solar panels works fine on its own but when I connect 240 to the c-tek charger the volts go up to 15.5v and the solar regulator cuts out on high voltage. So somehow with both running I can't control the amps.
Is there something I can do to rectify this?
Thanks
Hi Rob
I am not familar with the C-tec but a suggestion has been made that it might be in desulphate mode. Probably turn that off if you can anyway. Also check for high resistance connections has been suggested.
Not sure what the other charger is either. But any good chargers mounted together parallel into a battery should have no problem. They each have a maximum voltage and if the other one is higher or equal to that voltage then they do not supply any more. It should not matter whether there is one, two, three or more batteries if there is no resistance between them.
All vans use two chargers or controllers or three, if they have solar and 240V chargers and 12v DC-DC chargers. They should work together OK.
Jaahn
River rob said
04:06 AM Nov 17, 2016
Hi all
As suggested the ctek charger was in recondition mode . Changed it to normal mode and so far all good ?
Can only blame myself for this one.
Thanks again everyone , much appreciated
oldtrack123 said
03:00 PM Nov 22, 2016
Peter_n_Margaret wrote:
I would suggest about 30mm2. At 800mm apart, I wold also recommend a fuse at each end of the +ve that links those 2 batteries. A short of any sort in that cable would be catastrophic.
Cheers, Peter
Ditto
River rob said
08:56 AM Nov 24, 2016
Thanks old track
Sorry for the delayed reply , been off the air for a while.
I'll fit fuses at each end of + cable as you suggest.
Aus-Kiwi said
02:13 PM Nov 24, 2016
Handy to isolate battery . Funny thing is most car or truck Manu don't have them . They say the cable is heavy enough that it won't burn ., My old Fuso bus has a head bar about 30mm long , 2mm thick 1 20mm wide .. These things are designed to STAY on the road ., Ex JDM bus .. Simple and easy fixed .,
Aus-Kiwi said
02:14 PM Nov 24, 2016
Buzz bar . Bloody auto correct !!
swamp said
08:46 PM Nov 27, 2016
hi
Battery cable under a few meters long would not be an issue ,no fuses . Well insulate exterior of cable to prevent rub thru .
It is desirable when connecting twin batteries that the pos cable comes from one battery and the neg comes from the other . Or What can happen is 1 battery is always favoured over the other if wired conventional when being charged and discharged . Potentially shortening the life of the first connected battery .
If using an inverter use the same cable size as the inverter or larger .
If not 35mmsq / 2b&s cable .In parallel the batteries need to function as one unit especially if there is distance between them .
Hi
Im in the process of installing solar panels on my van. I'm replacing the existing battery with 2 new 100amp batteries.
My question is can I leave all existing wiring and charging to the original battery position and then connect the solar through the solar controller to the second battery and connect them in parallel?
Not sure if this ok to do. What happens if the batteries are being charged from both ends at the same time?
Or do I need to connect both supplies to one battery?
The reason I ask is I am putting the second battery inside the van, so it is going to be easier to connect the solar to it. The other battery is mounted underneath the van
thanks
Rob
-- Edited by River rob on Tuesday 15th of November 2016 05:15:14 AM
-- Edited by River rob on Tuesday 15th of November 2016 05:26:17 AM
Hi Rob
The two batteries should be connected together by heavy cables so there is virtually no resistance between them in both + and - connections. Then what you want to do will be OK. It would be best practice to have them close together but that is not always possible.
Jaahn
Thanks Jaahn
The batteries will be about 500mm apart. What size cable do you suggest?
Sorry make that about 800mm.
-- Edited by River rob on Tuesday 15th of November 2016 09:32:04 AM
At 800mm apart, I wold also recommend a fuse at each end of the +ve that links those 2 batteries. A short of any sort in that cable would be catastrophic.
Cheers,
Peter
Hi Jaahn
i have completed the system and charging from solar panels works fine on its own but when I connect 240 to the c-tek charger the volts go up to 15.5v and the solar regulator cuts out on high voltage. So somehow with both running I can't control the amps.
Is there something I can do to rectify this?
Thanks
Check the Ctek settings & ALL connections ,you could have bad joint
It should not take the battery that high
First check the voltage directly on the battery terminals
I very much doubt that will be 15.5V
work back until you find where the voltage jumps
I am not an Electrician
Look at the manual for your model 240 volt CTEK battery charger
Some of them start off in Desulphation Mode, and they can push in, up to 15.8 volts, for as short time
Below is a link to one such 240 volt CTEK battery charger
http://www.ctek.com/Archive/ProductManualPdf/MXS%205.0_EN.pdf
Hi Rob
I am not familar with the C-tec but a suggestion has been made that it might be in desulphate mode. Probably turn that off if you can anyway. Also check for high resistance connections has been suggested.
Not sure what the other charger is either. But any good chargers mounted together parallel into a battery should have no problem. They each have a maximum voltage and if the other one is higher or equal to that voltage then they do not supply any more. It should not matter whether there is one, two, three or more batteries if there is no resistance between them.
All vans use two chargers or controllers or three, if they have solar and 240V chargers and 12v DC-DC chargers. They should work together OK.
Jaahn
As suggested the ctek charger was in recondition mode . Changed it to normal mode and so far all good ?
Can only blame myself for this one.
Thanks again everyone , much appreciated
Ditto
Sorry for the delayed reply , been off the air for a while.
I'll fit fuses at each end of + cable as you suggest.
hi
Battery cable under a few meters long would not be an issue ,no fuses . Well insulate exterior of cable to prevent rub thru .
It is desirable when connecting twin batteries that the pos cable comes from one battery and the neg comes from the other . Or What can happen is 1 battery is always favoured over the other if wired conventional when being charged and discharged . Potentially shortening the life of the first connected battery .
If using an inverter use the same cable size as the inverter or larger .
If not 35mmsq / 2b&s cable .In parallel the batteries need to function as one unit especially if there is distance between them .