Battery Chargers & Isolators

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K

KevinB

Here's the general part of my question: The archives have lots of posts about installations of shore power chargers and I don't see any mention of modern battery chargers needing isolators when they are connected to two or more banks. Does this mean that most/all modern "smart" battery chargers have built in capability to block one battery from draining into another? Now here is my specific problem: I just hooked up a new ProMariner ProSport12 battery charger to my two battery set-up (a cranking and a deep cycle battery). The ProSport12 is a 12 amp charger with 2 outputs. It charges fine but when the AC is disconnected one battery drains into the other (i.e. the voltage on one drops, while the voltage on the other climbs above 12.8). BTW, the batteries are off the boat, which keeps the troubleshooting very simple. I called ProMariner on Thurs but haven't talked to them yet (you have to leave your name/number, and they call you back; and they are a 9-5, M-F operation). I talked to my Chandlery (where I bought the charger) and their "electronics" expert claims that all battery chargers of this type have to have an external battery isolator. None of this is mentioned in the ProMariner docs., or other places I have looked so I kind of don't believe him. I just want to make sure I understand how these multiple output chargers work so I can tell if I am talking to someone who knows the subject or is just guessing. Thanks Kevin
 
K

KevinB

Here's the general part of my question: The archives have lots of posts about installations of shore power chargers and I don't see any mention of modern battery chargers needing isolators when they are connected to two or more banks. Does this mean that most/all modern "smart" battery chargers have built in capability to block one battery from draining into another? Now here is my specific problem: I just hooked up a new ProMariner ProSport12 battery charger to my two battery set-up (a cranking and a deep cycle battery). The ProSport12 is a 12 amp charger with 2 outputs. It charges fine but when the AC is disconnected one battery drains into the other (i.e. the voltage on one drops, while the voltage on the other climbs above 12.8). BTW, the batteries are off the boat, which keeps the troubleshooting very simple. I called ProMariner on Thurs but haven't talked to them yet (you have to leave your name/number, and they call you back; and they are a 9-5, M-F operation). I talked to my Chandlery (where I bought the charger) and their "electronics" expert claims that all battery chargers of this type have to have an external battery isolator. None of this is mentioned in the ProMariner docs., or other places I have looked so I kind of don't believe him. I just want to make sure I understand how these multiple output chargers work so I can tell if I am talking to someone who knows the subject or is just guessing. Thanks Kevin
 
K

KevinB

Here's the general part of my question: The archives have lots of posts about installations of shore power chargers and I don't see any mention of modern battery chargers needing isolators when they are connected to two or more banks. Does this mean that most/all modern "smart" battery chargers have built in capability to block one battery from draining into another? Now here is my specific problem: I just hooked up a new ProMariner ProSport12 battery charger to my two battery set-up (a cranking and a deep cycle battery). The ProSport12 is a 12 amp charger with 2 outputs. It charges fine but when the AC is disconnected one battery drains into the other (i.e. the voltage on one drops, while the voltage on the other climbs above 12.8). BTW, the batteries are off the boat, which keeps the troubleshooting very simple. I called ProMariner on Thurs but haven't talked to them yet (you have to leave your name/number, and they call you back; and they are a 9-5, M-F operation). I talked to my Chandlery (where I bought the charger) and their "electronics" expert claims that all battery chargers of this type have to have an external battery isolator. None of this is mentioned in the ProMariner docs., or other places I have looked so I kind of don't believe him. I just want to make sure I understand how these multiple output chargers work so I can tell if I am talking to someone who knows the subject or is just guessing. Thanks Kevin
 
K

KevinB

Here's the general part of my question: The archives have lots of posts about installations of shore power chargers and I don't see any mention of modern battery chargers needing isolators when they are connected to two or more banks. Does this mean that most/all modern "smart" battery chargers have built in capability to block one battery from draining into another? Now here is my specific problem: I just hooked up a new ProMariner ProSport12 battery charger to my two battery set-up (a cranking and a deep cycle battery). The ProSport12 is a 12 amp charger with 2 outputs. It charges fine but when the AC is disconnected one battery drains into the other (i.e. the voltage on one drops, while the voltage on the other climbs above 12.8). BTW, the batteries are off the boat, which keeps the troubleshooting very simple. I called ProMariner on Thurs but haven't talked to them yet (you have to leave your name/number, and they call you back; and they are a 9-5, M-F operation). I talked to my Chandlery (where I bought the charger) and their "electronics" expert claims that all battery chargers of this type have to have an external battery isolator. None of this is mentioned in the ProMariner docs., or other places I have looked so I kind of don't believe him. I just want to make sure I understand how these multiple output chargers work so I can tell if I am talking to someone who knows the subject or is just guessing. Thanks Kevin
 
Aug 3, 2005
181
Morgan 33 O/I Green Cove Springs FL
Sumthin Yer saying Ain't quite Right

Ahoy Kevin, Are the two batteries hooked together in one bank? I rally dont understand what you are saying. Are tha batteries hooked to anything? There is no way possible one battery could be charging the the other, unless one battery is broke. All they will do is equalize. They will be of equal voltage. They do not need an external isolator. The only thing I can even remotely think of, is the charger is feeding back through itself. But again I cannot see how one battery can go to a higher potential than the other unless they are hooked to something. Do this for me. After charging the batteries disconnect the charger from everything including the charger. What happens now? Fair Winds Cap'n Dave
 
Aug 3, 2005
181
Morgan 33 O/I Green Cove Springs FL
Sumthin Yer saying Ain't quite Right

Ahoy Kevin, Are the two batteries hooked together in one bank? I rally dont understand what you are saying. Are tha batteries hooked to anything? There is no way possible one battery could be charging the the other, unless one battery is broke. All they will do is equalize. They will be of equal voltage. They do not need an external isolator. The only thing I can even remotely think of, is the charger is feeding back through itself. But again I cannot see how one battery can go to a higher potential than the other unless they are hooked to something. Do this for me. After charging the batteries disconnect the charger from everything including the charger. What happens now? Fair Winds Cap'n Dave
 
Aug 3, 2005
181
Morgan 33 O/I Green Cove Springs FL
Sumthin Yer saying Ain't quite Right

Ahoy Kevin, Are the two batteries hooked together in one bank? I rally dont understand what you are saying. Are tha batteries hooked to anything? There is no way possible one battery could be charging the the other, unless one battery is broke. All they will do is equalize. They will be of equal voltage. They do not need an external isolator. The only thing I can even remotely think of, is the charger is feeding back through itself. But again I cannot see how one battery can go to a higher potential than the other unless they are hooked to something. Do this for me. After charging the batteries disconnect the charger from everything including the charger. What happens now? Fair Winds Cap'n Dave
 
Aug 3, 2005
181
Morgan 33 O/I Green Cove Springs FL
Sumthin Yer saying Ain't quite Right

Ahoy Kevin, Are the two batteries hooked together in one bank? I rally dont understand what you are saying. Are tha batteries hooked to anything? There is no way possible one battery could be charging the the other, unless one battery is broke. All they will do is equalize. They will be of equal voltage. They do not need an external isolator. The only thing I can even remotely think of, is the charger is feeding back through itself. But again I cannot see how one battery can go to a higher potential than the other unless they are hooked to something. Do this for me. After charging the batteries disconnect the charger from everything including the charger. What happens now? Fair Winds Cap'n Dave
 
Sep 25, 2008
7,689
Alden 50 Sarasota, Florida
isolation

Kevin The charging circuits for the shore power charger should be connected independently to both batteries. Shore power chargers with multiple battery outputs provide the required isolation between batteries and independent regulation for each battery. Leads from the positive terminals of the charger to the positive terminals of the batteries should be protected with fuses near the battery in the same manner as the positive power leads. Fuses should be rated at 150% of the charger capacity.
 
Sep 25, 2008
7,689
Alden 50 Sarasota, Florida
isolation

Kevin The charging circuits for the shore power charger should be connected independently to both batteries. Shore power chargers with multiple battery outputs provide the required isolation between batteries and independent regulation for each battery. Leads from the positive terminals of the charger to the positive terminals of the batteries should be protected with fuses near the battery in the same manner as the positive power leads. Fuses should be rated at 150% of the charger capacity.
 
Sep 25, 2008
7,689
Alden 50 Sarasota, Florida
isolation

Kevin The charging circuits for the shore power charger should be connected independently to both batteries. Shore power chargers with multiple battery outputs provide the required isolation between batteries and independent regulation for each battery. Leads from the positive terminals of the charger to the positive terminals of the batteries should be protected with fuses near the battery in the same manner as the positive power leads. Fuses should be rated at 150% of the charger capacity.
 
Sep 25, 2008
7,689
Alden 50 Sarasota, Florida
isolation

Kevin The charging circuits for the shore power charger should be connected independently to both batteries. Shore power chargers with multiple battery outputs provide the required isolation between batteries and independent regulation for each battery. Leads from the positive terminals of the charger to the positive terminals of the batteries should be protected with fuses near the battery in the same manner as the positive power leads. Fuses should be rated at 150% of the charger capacity.
 
K

Kevin B

Don, regarding fuses.....

the ProSport12 comes with inline fuses built into the output cables. Kevin
 
K

Kevin B

Don, regarding fuses.....

the ProSport12 comes with inline fuses built into the output cables. Kevin
 
K

Kevin B

Don, regarding fuses.....

the ProSport12 comes with inline fuses built into the output cables. Kevin
 
K

Kevin B

Don, regarding fuses.....

the ProSport12 comes with inline fuses built into the output cables. Kevin
 
K

KevinB

Capn Dave, here is more info....

Capn Dave, I have the two batteries off the boat. They are both grp 24s; one cranking and one deep cycle. They are not cabled together; I am treating them as two separate banks as they would be on the boat. Only the battery charger is connected to the batteries; no other loads are on them. The two sets of charger outputs are separately wired to each battery. Here is what happens. While in the float stage both batteries read 13.31VDC, which is per the ProSport12 specs for lead acid batteries. If I unplug the AC and leave the charger connected to the batteries after about 2 hours one battery reads approx. 12.35 VDC and the other 12.85 VDC. BTW, if I swap the charger output leads between batteries the problem follows.That is its always the battery connected to the first pair of output cables that drains into the other. If after charging I disconnect all of the charger outputs from the batteries and wait 4-5 hours I get normal readings from both batteries; about 12.7 for the cranking and 12.75 for the deep cycle. In other words the ProSport12 charges OK. I think you and Don have answered my key question by confirming that battery bank isolation is built into these types of chargers. I shouldn't need isolators as I am being told. Thanks Kevin
 
K

KevinB

Capn Dave, here is more info....

Capn Dave, I have the two batteries off the boat. They are both grp 24s; one cranking and one deep cycle. They are not cabled together; I am treating them as two separate banks as they would be on the boat. Only the battery charger is connected to the batteries; no other loads are on them. The two sets of charger outputs are separately wired to each battery. Here is what happens. While in the float stage both batteries read 13.31VDC, which is per the ProSport12 specs for lead acid batteries. If I unplug the AC and leave the charger connected to the batteries after about 2 hours one battery reads approx. 12.35 VDC and the other 12.85 VDC. BTW, if I swap the charger output leads between batteries the problem follows.That is its always the battery connected to the first pair of output cables that drains into the other. If after charging I disconnect all of the charger outputs from the batteries and wait 4-5 hours I get normal readings from both batteries; about 12.7 for the cranking and 12.75 for the deep cycle. In other words the ProSport12 charges OK. I think you and Don have answered my key question by confirming that battery bank isolation is built into these types of chargers. I shouldn't need isolators as I am being told. Thanks Kevin
 
K

KevinB

Capn Dave, here is more info....

Capn Dave, I have the two batteries off the boat. They are both grp 24s; one cranking and one deep cycle. They are not cabled together; I am treating them as two separate banks as they would be on the boat. Only the battery charger is connected to the batteries; no other loads are on them. The two sets of charger outputs are separately wired to each battery. Here is what happens. While in the float stage both batteries read 13.31VDC, which is per the ProSport12 specs for lead acid batteries. If I unplug the AC and leave the charger connected to the batteries after about 2 hours one battery reads approx. 12.35 VDC and the other 12.85 VDC. BTW, if I swap the charger output leads between batteries the problem follows.That is its always the battery connected to the first pair of output cables that drains into the other. If after charging I disconnect all of the charger outputs from the batteries and wait 4-5 hours I get normal readings from both batteries; about 12.7 for the cranking and 12.75 for the deep cycle. In other words the ProSport12 charges OK. I think you and Don have answered my key question by confirming that battery bank isolation is built into these types of chargers. I shouldn't need isolators as I am being told. Thanks Kevin
 
K

KevinB

Capn Dave, here is more info....

Capn Dave, I have the two batteries off the boat. They are both grp 24s; one cranking and one deep cycle. They are not cabled together; I am treating them as two separate banks as they would be on the boat. Only the battery charger is connected to the batteries; no other loads are on them. The two sets of charger outputs are separately wired to each battery. Here is what happens. While in the float stage both batteries read 13.31VDC, which is per the ProSport12 specs for lead acid batteries. If I unplug the AC and leave the charger connected to the batteries after about 2 hours one battery reads approx. 12.35 VDC and the other 12.85 VDC. BTW, if I swap the charger output leads between batteries the problem follows.That is its always the battery connected to the first pair of output cables that drains into the other. If after charging I disconnect all of the charger outputs from the batteries and wait 4-5 hours I get normal readings from both batteries; about 12.7 for the cranking and 12.75 for the deep cycle. In other words the ProSport12 charges OK. I think you and Don have answered my key question by confirming that battery bank isolation is built into these types of chargers. I shouldn't need isolators as I am being told. Thanks Kevin
 
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