Charging different size banks

[Pascal]

I have installed two ProMariner ProNautic on my 53, one is a 12v30amp and the other one a 24v 30amp. They are "smart" chargers with three output

For now the 2430 is just charging a new house bank consisting a two 4Ds. In the future I may add a second bank which would be the same

The 1230 is for charging the mains and the generator banks. Each main (12v C series Cummings ) will have a single 8D but the generator only has a group 31. All regular lead acid flooded

I know you can't mix battery types but will there be an issue if one of the three battery is smaller ? I ve read the manual and no warnings against that.

[doc g]

I believe that as long as it is on separate output (separate bank) on the charger it will not make any difference........Pat

[Reefgeorge]

One of the things that you have to watch out for is that a battery or bank is not getting constantly overcharged because a seldom used battery is on the same charger as a frequently discharged battery. Chargers can have different outputs but they are driven the same circuit, just isolated by diodes. I had a single charger when my boat was new where two of three outputs were used for the two banks (starting and house). I was killing starter batteries because they got overcharged as the house bank needs were being met. I only use one charger per bank with temp sensors on the batteries now and all is well.

George

[doc g]

Seems to me that that is the point of having different banks and different outputs from a charger ....if one bank is down it charges only that one and does not over charge the other banks ..... Pat

[Reefgeorge]

Seems to me that that is the point of having different banks and different outputs from a charger ....if one bank is down it charges only that one and does not over charge the other banks ..... Pat

From a major charger manufacturer:

"Most multi-output battery chargers have only one program running to control all outputs. Therefore, the outputs proceed through bulk, absorption, float, and equalizing charging stages together."

Even if this is the case the separate outputs of the charger do isolate the banks with blocking diodes but the starting bank will still be getting higher charging voltages longer than necessary. This is somewhat self limiting because the internal resistance of the battery gets higher and limits current as it gets fully charged and is less of an issue if the banks are used equally but the whole point of float voltage once the battery is fully charged is to increase battery life.

While there are chargers that may operate with completely separate charging circuits that arrive at the 3 stage levels at different times, another key to extending battery life is to have a charger which can use temp senor(s) at the batteries to derate the charging voltage levels with increased temperatures and vice a versa. It's easy enough to see what you have. After everything is fully charged and the charger is in float, start the engines a few times and then measure the voltage at each bank. If your starting bank went into bulk charging mode and your house bank stayed at float voltage then you have a more sophisticated charger.

My original system had a charger with the 2 banks I needed but only one charging algorithm for both, no temp sensor at the batteries and a poorly ventilated battery box. I murdered my first set of batteries in less than a year. Now my system is 2 separate chargers, temp sensors and battery box ventilation and I don't kill batteries any longer. Also I now have redundancy which has already been used when one charger died and I used the remaining charger for all banks until a repair was made.

George

[bobk]

My new three bank Blue Seas smart charger is set for wet lead acid batteries. I can confirm that when one bank gets discharged, only that bank gets charged. This occurs every morning after anchoring over night so it's easy to confirm. The charger has three digital readouts, one for each bank. Only the house bank shows appreciable charger current when the generator is started.

Bobk

[Reefgeorge]

My new three bank Blue Seas smart charger is set for wet lead acid batteries. I can confirm that when one bank gets discharged, only that bank gets charged. This occurs every morning after anchoring over night so it's easy to confirm. The charger has three digital readouts, one for each bank. Only the house bank shows appreciable charger current when the generator is started.

Bobk

That set up is much better for the health of your batteries, good choice. Many
chargers don't operate that way. I assume that you bought the new P12 charger
which I see has three individual monitors and even shows the battery sensor
temperature which is very nice. Unfortunately it's very hard to determine how
most chargers actually operated because some use marketing BS in their
literature saying that the charger addresses the lowest battery first and then
directs charging current to the other batteries. That's just summarizing the
effect of the changing internal resistance of the batteries. All batteries still
see bulk charging voltage even if they don't need it ... In your case Blue Seas
does not even brag about this excellent feature in the top level literature but
the three separate displays is a pretty good clue.


George

[bobk]

That set up is much better for the health of your batteries, good choice. Many
chargers don't operate that way. I assume that you bought the new P12 charger
which I see has three individual monitors and even shows the battery sensor
temperature which is very nice. Unfortunately it's very hard to determine how
most chargers actually operated because some use marketing BS in their
literature saying that the charger addresses the lowest battery first and then
directs charging current to the other batteries. That's just summarizing the
effect of the changing internal resistance of the batteries. All batteries still
see bulk charging voltage even if they don't need it ... In your case Blue Seas
does not even brag about this excellent feature in the top level literature but
the three separate displays is a pretty good clue.


George

Right on George. P-12, 40 amp. The thing is really neat. I can even tell if a small 12V load goes on just by looking at the amp meter.

Bobk

[doc g]

I actually bought a charger last week that has 4 outputs each individually hooked up to my 4 (8Ds) it supposedly senses each battery on each leg and charges the one needs a charge and will ignore another battery that is in the same bank . We will see . It is a powermania . All waterproof and sealed . You can check the status of each battery by its own LED ..... Pat