Battery Charger question

[Dhirsh]

So went to put the 336 in the water today after sitting a few weeks and the batteries were dead. They are going on 3 years old so not unexpected. My charger has been working fine but is original and really corroded. I decided that while I was in there with the batteries I’d go ahead and replace it. Original charger was a Promariner 300 Dual. I have the standard two banks 4 battery set up with two switches that are 1-2 ,both and off. The only charger I could find at west was a 3 bank charger At 36 amps. Charger instructions are saying that each bank can only be hooked up to 1 battery. However previously the two batteries were hooked one charger lead and two to the other. Can I just use 2 of the 3 leads from the charger and put them on my Paralleled 2 bank two battery set up, or do I have to use that third lead on a battery regardless To keep the charger from faulting?

 

[dogdoc]

Hum... Seems to me 4 batteries and I assume twin engine would have a set up of following 3 banks
bat 1 start one engine, bat 2 start other engine, bat 3 and 4 house with switches and wiring to mix and match as needed
the new 3 bank charger would fit right in
just a thought

 

[Dhirsh]

Hum... Seems to me 4 batteries and I assume twin engine would have a set up of following 3 banks
bat 1 start one engine, bat 2 start other engine, bat 3 and 4 house with switches and wiring to mix and match as needed
the new 3 bank charger would fit right in
just a thought

Thank you, I’m going to give it a go today and hook the charger up to each start battery and then one of the two additional batteries on the accessory side. I read the wiring diagram in the owners manual and Grady white sets these boats up with Two banks of 2 batteries each. One side for Starbord and one side support.There is no house side And everything is essentially shared. All of the house electrical runs off the starboard bank.So I’m going to put the third charging lead on the second battery of the starboard bank. I think that makes the most sense since it will be getting the most draw from Electronics and other electrical items.

 

[SkunkBoat]

the batteries in each bank are in parallel so the charger sees them as one battery. I don't think having two charge connections will help but read thru the manual. They might tell you NOT to do that.
It is possible to reconfigure the batteries to have a separate "House" bank.
I'm guessing you have a generator on that 336 so setting up a 3rd bank might not be necessary.
IDK how they incorporate the genset into the DC power and battery charger

 

[seasick]

I agree with Skunkboat. Connecting three charging circuits to two sets of parallel batteries would mean that one bank has two charge ports wired to each other and that is not advised and may be asking for trouble.

 

[Dhirsh]

I e

I agree with Skunkboat. Connecting three charging circuits to two sets of parallel batteries would mean that one bank has two charge ports wired to each other and that is not advised and may be asking for trouble.

I ended up putting 1 on the port bank and one on each battery of the starboard bank. Fired it up and the smart charger went thru its startup and then signaled ok and started its charge. I think it just senses the amount charged in whatever its hooked to and adjusts output accordingly. Before I run the charger with the engines and generator running, I’ll call Pro Marnier and make sure its ok. But with just the Charger running it seemed to work fine.

 

[wspitler]

I wouldn't run the engines with the charger energized. The new chargers are "smart" and having a different charging sources can cause problems. No need for both. I always turn off my battery charger before the engines are started so as to not have two sources trying to charge the same battery.

 

[SkunkBoat]

Looks like you did right.

From Promariner FAQs;

Q: What do I do if I have an unused set of DC wires from the charger?

A: Double up the charger output Bank 1 and Bank 2 wires on your “most used” battery. This would be the “House” or “Trolling Motor” battery. That way they can all sense a battery voltage and the unit will charge properly.



One thing to note is how to properly connect to paralleled batteries. In order for the "bank" to be sensed as one battery, you must connect to the Positive of one battery and Negative of the other.

 

[Fishtales]

I e

I ended up putting 1 on the port bank and one on each battery of the starboard bank. Fired it up and the smart charger went thru its startup and then signaled ok and started its charge. I think it just senses the amount charged in whatever its hooked to and adjusts output accordingly. Before I run the charger with the engines and generator running, I’ll call Pro Marnier and make sure its ok. But with just the Charger running it seemed to work fine.

Good to hear it worked out. Pretty intuitive, but you'd be surprised that some don't get the connection points right.

 

[seasick]

Looks like you did right.

From Promariner FAQs;

Q: What do I do if I have an unused set of DC wires from the charger?

A: Double up the charger output Bank 1 and Bank 2 wires on your “most used” battery. This would be the “House” or “Trolling Motor” battery. That way they can all sense a battery voltage and the unit will charge properly.



One thing to note is how to properly connect to paralleled batteries. In order for the "bank" to be sensed as one battery, you must connect to the Positive of one battery and Negative of the other.

View attachment 18823


View attachment 18824

I am sure you have a reason to believe that the first diagram is better than the first but honestly, I don't see it. If the jumpers between the positive and negative terminals are in good shape and about the same length, the voltage at each end will be identical especially when not much load is drawn. What am I not seeing?

 

[SkunkBoat]

I am sure you have a reason to believe that the first diagram is better than the first but honestly, I don't see it. If the jumpers between the positive and negative terminals are in good shape and about the same length, the voltage at each end will be identical especially when not much load is drawn. What am I not seeing?

In this case its the length of wire. The first picture has the same length of wire for both batteries. The voltage across both batteries is exactly the same. It is one battery.
The second picture the voltage across one battery is less the voltage drop of both pieces of wire.
Yes its a tiny amount but we're talking about a "smart" charging circiut and we're tricking it....

 

[Hookup1]

There is no advantage to hooking the unused bank up. The ProMariner chargers will load shift all the amperage to the bank that needs it when finished with the other banks. You could hook them up to a battery but take the fuses out and label it!

What size batteries are in there? what engines? Another option might be to go with two dedicated starting batteries on existing switches and a house battery or two parallel house batteries and a new switch. Your new charger could handle this setup.

3-years isn't great battery life. I consider 5-years about right. But a bad or old charger can "cook" them. If you are going to replace the batteries you should consider the Duracell AGM's from Sam's Club.

Group 34 43.10 lbs. 955 MCA 55 AH. $119.32
Group 24 52.40 lbs. 800 MCA 78 AH. Did not see availability at my store.
Group 27 61.55 lbs. 900 MCA 92 AH. $158.88
Group 31 67.35 lbs. 1,000 MCA 105 AH. $179.74

I used a Group 34M Duracell Marine AGM for my Yamaha F150's. About 9 lbs lighter than a Group 24 and 17 lbs lighter than a Group 27 with higher MCA rating but less capacity.

For the house I use a single Group 27 AGM. You could parallel two new ones. Or do a Group 31.

 

[seasick]

In this case its the length of wire. The first picture has the same length of wire for both batteries. The voltage across both batteries is exactly the same. It is one battery.
The second picture the voltage across one battery is less the voltage drop of both pieces of wire.
Yes its a tiny amount but we're talking about a "smart" charging circiut and we're tricking it....

Maybe if the second battery was in your garage
We are talking about extremely small voltage drops, so small that even an Einstein smart battery charger isn't going to notice it. These charges make decisions on charging rate based on sensed voltage but I doubt that differences of milivolts is going to change the charge characteristics. I wold bet that there is a lot more voltage drop across the charger leads than there is across the battery cables.

 

[Dhirsh]

My primary concerns were how I had them hooked up and if it hurt the charger if I had the engines running at the same time the charger was running. Answers from Pro Mariner when I called them and I paraphrase;

• We don't recommend batteries be hooked up in parallel because if one goes bad the charger has to work harder to charge the bank and will ultimately shorten the life of the charger. That ship has sailed because I'm not changing how the electrical was set up by Grady, so leaving the 2 banks in Parallel . I keep it high and dry anyway and only use the charger occasionally if I want to run the live well overnight to keep bait alive before an early trip
• Put the third DC leg on the second battery of the most used bank. (The side the accessories are on) The second charging lead on that bank makes no difference except it will charge that bank quicker
• Running the engines and therefore having the alternators charging the battery banks at the same time as the Charger is Charging will not harm anything on the charger and is fine. Which makes sense because no current is going back into the charger and all leads are fused anyway.

 

[wspitler]

Good info, but a few years back I was told by Promariner engineers differently with regard to engines charging with their charger energized. Maybe they changed the "smartness" since then? Back then they did recommend a 4 lead charger for two banks with two batteries each. They gave me a deal back then and I have a 4 lead which has worked fine.

 

[seasick]

My primary concerns were how I had them hooked up and if it hurt the charger if I had the engines running at the same time the charger was running. Answers from Pro Mariner when I called them and I paraphrase;

• We don't recommend batteries be hooked up in parallel because if one goes bad the charger has to work harder to charge the bank and will ultimately shorten the life of the charger. That ship has sailed because I'm not changing how the electrical was set up by Grady, so leaving the 2 banks in Parallel . I keep it high and dry anyway and only use the charger occasionally if I want to run the live well overnight to keep bait alive before an early trip
• Put the third DC leg on the second battery of the most used bank. (The side the accessories are on) The second charging lead on that bank makes no difference except it will charge that bank quicker
• Running the engines and therefore having the alternators charging the battery banks at the same time as the Charger is Charging will not harm anything on the charger and is fine. Which makes sense because no current is going back into the charger and all leads are fused anyway.

Again, I don't understand the statement that "if one battery goes bad, the charger will work harder". Does that also mean that if you two batteries not wired in parallel and both just happen to be going bad from age and use, that the charger will die a premature death because both batteries need charging?

I need to understand these smart charges better. Hopefully I can find some technical info on line.

 

[Dhirsh]

Good info, but a few years back I was told by Promariner engineers differently with regard to engines charging with their charger energized. Maybe they changed the "smartness" since then? Back then they did recommend a 4 lead charger for two banks with two batteries each. They gave me a deal back then and I have a 4 lead which has worked fine.

I looked all over for a 4 lead and went to 3 different west marine stores locally. All of them were out and this was my only weekend to do it. So three bank it is. Old and new set up in pics. Old charger was getting wet in the location they had it. I moved the new one into a drier location and elevated it off the deck 1/2 for better airflow and to keep moisture off. New set up before I finished cleaning up wiring.

 

[wspitler]

Looks good! Looks identical to my 4 lead which has worked very well in extending battery life since 2014! I leave it charging 24/7/365 on a lift. Good Luck!

 

[SkunkBoat]

Maybe if the second battery was in your garage
We are talking about extremely small voltage drops, so small that even an Einstein smart battery charger isn't going to notice it. These charges make decisions on charging rate based on sensed voltage but I doubt that differences of milivolts is going to change the charge characteristics. I wold bet that there is a lot more voltage drop across the charger leads than there is across the battery cables.

well, don't want to hijack a thread and I don't want to sound like I think it matters a great deal if the batteries are 6" from each other but..
The battery is a current source not just a resistance with a voltage drop across it. The charger cycles between sensing and charging. The charger is sensing current flow and even the smallest difference in the wire can change the direction of current flow that is sensed by the charger. The capacity of the 2 batteries in parallel (The charger is treating it as one battery) are never exactly the same and that difference is exacerbated by having twice as much wire for one battery vs the other The charger leads are the same length so that is irrelevant. It matters more also if the batteries are heavily discharged and there is high charging current. Given that its just a matter of moving one charger lead to the post on the other battery 6" away, I would opt to do that.

dhirsh, glad you got it done.

 

[seasick]

It turns out that Marinco Guest website has some good diagrams. In addition to that I found some technical documents about smart charging in general.
Although my research was fairly brief, I learned a few things I wasn't aware of, the most important being that multi port smart charges come in two designs; a single common DC ground and individual grounds for each port of course in addition to the individual positive connections.
If your charger has two leads for each port in can also have separate microprocessors for each port. If the charger has a common ground ( for example, a 2 port charger has three output wires) it can not have separate microprocessors.
Separate processors allow a charger to work with different type of batteries at the same time.
The other important detail to insure is that for a multi port individual ground charger, the positive and negative charge leads should be connected to the same battery. The negative and positive wires of a specific port should never be attached to different batteries. That means that the posted diagram for suggested connections for two batteries could be harmful to the batteries or the charger if the charge ports have individual grounds.

The Marinco/Guest manual has diagrams of several different battery configurations.