Multi Bank Charger Operation?

The thread re shore charger not working on gennie raised a question for me.
I have a ProMariner 1250 C3 charger installed and doing some batty bank reconfiguring.
Previously I had 3 banks plus a gen start batty
I'm combining 2 previous banks into one and moving my single engine start over to the thruster bank.
Previously I used the PM 1250 C3 to charge the 2 house banks and thruster bank. I had installed a cross-over Sw that allowed me to combine the house & gen just in case either one was weak and needed a boost. I could also combine to use the PM C3 to top off the gen batty occasionally.

Now that I'd only have 2 batty banks my plan was to hook up the gen to the 3rd charging position.

My question is...
Will running the gen and its alt providing charge to the gen batty signal the PM 1250 C3 to go to float?
I guess I dont know how a 3 bank charger works when one or more banks need charging but other(s) do not?
Does it always sense the weakest bank and charge to its needs?
Or is it controlled by a primary (#1) bank and the others just get less amp flow due to their condition?
If so, is there a chance of over charging especially if the bank size is significantly different?

I'd certainly be comfortable using only 2 banks and letting the gen alt take care of it's own batty charging, especially w the combine SW as a back up. I'd like to optimize charging performance for the larger and more expensive house bank.

The ProMariner 1250 is a relabled Sterling 1250, btw.

The total output of the charger is 50A split between the charger outputs that are connected to batteries according to the batteries' voltage. Connect three batteries and the 50A will be parsed out according to the battery voltage. Connect one battery and the full 50A is available if the battery will accept it.

At one time, unused output ports had to be jumpered to an active port. That changed several years ago to the schema described above.

Maybe ask promarine? What's your manual say, if you do/don't need a jumper to the third positive post for your vintage of this charger.

I say that cause I'm looking at similar, tie in feed from solar panels to my 2 X 2 house bank. My 1240 is old and needs jumper, so I'm gonna tie in somewhere else.

Interested to hear what you decide.

I have emailed questions to ProMariner but no response in over a week.
Manual says jumper unused outputs but not clear how it decides what stage to be in or for how long and what amps.
Doesn't really address battys/banks of different capacity.
I'll try to call and connect live but wondered if others have been down this road.

Since you have “that” vintage charger simply rake a short piece of AWG 14 and crimp ring terminal on both ends. Jump between unused Position 3 and Position 1 or 2. Done.

CharlieJ said:

Since you have “that” vintage charger simply rake a short piece of AWG 14 and crimp ring terminal on both ends. Jump between unused Position 3 and Position 1 or 2. Done.

Click to expand...

I fully understand the directions to jumper unused outputs. That does not in any way answer my questions.
I know all multi port chargers split their output but that wasn't my question.
If all you have to offer is to trash the charger... thanks for your concerns.
I will continue to look for someone that may have some knowledge of how they decide what stage to be in when different battys / banks are at different SOC.
Thanks for your response.

You May have a multi port charger, but doubtful you have multiple profiles to match each bank. If you want that you need something else. For my start batts, I actually went with a Balmar duo charge so the start battery would be charged based on its own needs, which are very different than my house bank, which I’ve intentionally made into a single large bank.

ghost said:

You May have a multi port charger, but doubtful you have multiple profiles to match each bank. If you want that you need something else. For my start batts, I actually went with a Balmar duo charge so the start battery would be charged based on its own needs, which are very different than my house bank, which I’ve intentionally made into a single large bank.

Click to expand...

Never imagined it would have different profiles.
All my battys / banks are AGM.
I am just wondering how the charger decided what stage of charging to be in at any given time when sensing multi battys at different SOC and potentially requiring a different stage of the AGM profile it's programmed for?
I must not be explaining it very clearly but not sure how else to word it.

Bacchus
I really tried to help you based on your OP. I have installed more of these than you have ever seen so your comment:

If all you have to offer is to trash the charger... thanks for your concerns.

Click to expand...

was totally un-called for. I was honestly trying to point out the limitations of this family of chargers.

Good luck.

Bacchus:
And now I note that you are a Site Team Member...well done.

Your manual doesn’t note any particular magic, so there likely is none. So it’s likely going to apply the same initial voltage across all the banks and the one with the least charge is going to proportionally accept the most current. It’s not going to move to the next stage until all the banks are ready. I doubt they will give you anything more specific than that.

Charlie
PM sent
My apologies for being short.

CharlieJ said:

Bacchus
I really tried to help you based on your OP. I have installed more of these than you have ever seen so your comment: was totally un-called for. I was honestly trying to point out the limitations of this family of chargers.

Good luck.

Click to expand...

ghost said:

Your manual doesn’t note any particular magic, so there likely is none. So it’s likely going to apply the same initial voltage across all the banks and the one with the least charge is going to proportionally accept the most current. It’s not going to move to the next stage until all the banks are ready. I doubt they will give you anything more specific than that.

Click to expand...

I guess I suspected that was the case so to rephrase what I'm trying to decide...

My large house and medium size thruster/start bank will likely need much more charging than the much smaller gen batty.

1.) Will applying absorption charge to a fully charged batty over an extended period of time be detrimental? I've always heard that one way to kill an AGM is over charging.

2.) When running the gen and its alt charging its batty signal the shore charger to simply go to float and not charge the house & thruster banks that would need a charge (and one of the reasons to be running the gen to charge them)

3.) Would I be better off using the PM shore charger as a 2 bank for house and thruster banks and let the gen take care of it's own batty?

Bacchus said:

Now that I'd only have 2 batty banks my plan was to hook up the gen to the 3rd charging position.

If so, is there a chance of over charging especially if the bank size is significantly different?

Click to expand...

In my case, that's what seemed to happen. Two 300-Ah banks, one 68-Ah genset start battery, and I found the latter got very hot a couple times and was venting overly much. These were all Odyssey AGMs, so all same recommended voltages.

(Actually, the PM manual for that model did address the issue a little bit; recommended not using the charger on widely disparate bank sizes.)

Bacchus said:

1.) Will applying absorption charge to a fully charged batty over an extended period of time be detrimental? I've always heard that one way to kill an AGM is over charging.

2.) When running the gen and its alt charging its batty signal the shore charger to simply go to float and not charge the house & thruster banks that would need a charge (and one of the reasons to be running the gen to charge them)

3.) Would I be better off using the PM shore charger as a 2 bank for house and thruster banks and let the gen take care of it's own batty?

Click to expand...

I've read more about undercharging killing AGMs, too. Anyway, the battery makers often recommend max voltages but I haven't seen that translated into max current (aside from the normal math involved).

I never could figure out how our original multi-bank charger (an older ProMariner than yours) went to float on each separate bank... but when I removed the genset battery from that charger, and also changed battery brands for one of the big banks (with different recommended voltages), it became a moot point anyway.

In any case, I took our genset battery off the original charger... and let the alternator handle it. Not much self-discharge with AGMs, and it's a start battery, anyway, so not much discharge when starting the generator either. I kept a pair of jumper cables on board, just in case (diesel boat)... but never encountered a problem they could solve.

-Chris

I just rewired to your option #3. Found it problematic to have the dissimilar sized banks off the same charger. It seemed to shorten the life of the smaller one. Plus the isolation of the generator start battery makes me more comfortable having that redundancy.

Chris & Geoff
Thanks for the confirmation.
I think I will go back to having gen isolated. I've had it that way for several years and haven't had any issues yet.

@Baccchus #12
Accepted.

CharlieJ said:

@Baccchus #12
Accepted.

Click to expand...

[emoji106] Thnx appreciate the comments.
Just a bad day for me.

Don, I ran with a 3 bank PM 1230 for years. It was the older model that required a jumper on unused banks. Originally the boat was wired with 3 banks...house, P start and S start so all 3 banks of the charger were used on all FLA batts and all was well, regardless of bank size or alternator input from twin alternators.

When I converted my battery configuration, I went to a larger 660AH house bank and a single G31 start battery. I jumpered the unused bank and all was fine, albeit undersized charge rate for the house. The alternators and charger always played together well until the Voltage was near peak when the V of the generator would overcome the V of the alternator and drop the alternator offline. That's when I'd shut down the generator to allow the alternators to top off the batts while underway, retaining my tach RPM signal from both alternators.