Battery Charger question...

[SailFysh]

Should have new charger and battery bank installed soon... with help from this forum and guidance from KZW. Thanks.

I was surprised that the promariner tech recommended a 60 amp charger. It is the Pronautic 60. The old charger was 20 amp and I have read that many use a 20 amp.

If I have the formula right... a 20 should work fine but the tech said it would be undersized and could lead to early unit failure.

Total amp hours of house bank will be 430.
Amp hours of starting battery is 105.
Example: if house bank is depleted 50% then
215 amps / 20 amp = 11 hours charge time

Comments?

Thanks

 

[Maine Sail]

Should have new charger and battery bank installed soon... with help from this forum and guidance from KZW. Thanks.

I was surprised that the promariner tech recommended a 60 amp charger. It is the Pronautic 60. The old charger was 20 amp and I have read that many use a 20 amp.

If I have the formula right... a 20 should work fine but the tech said it would be undersized and could lead to early unit failure.

Total amp hours of house bank will be 430.
Amp hours of starting battery is 105.
Example: if house bank is depleted 50% then
215 amps / 20 amp = 11 hours charge time

Comments?

Thanks

When sizing shore chargers a minimum of 10% of Ah capacity, after shore side loads are accounted for, is generally the smallest you'll want. For a 430Ah bank a 40A unit would be the smallest you'd want (.09C) but a 60A (.14C) even better. These batteries can be charged at .2C to .3C depending upon brand. A 60A would be great especially if you ever plan to use a generator or need quick charging in a short duration. You may get some more information from this: Installing a Marine Battery Charger

 

[pk104]

If your 310 is like mine was and you haven't changed it there are inline 20amp fuses at the batteries on the charger cables.

 

[SailFysh]

Yes. I have inline 20 amp fuses in the charger leads at the battery. I guess I need to match the fuse size to whatever new charger size I decide on. Correct?

 

[SailFysh]

Also, the original charger location is in aft port locker near the helm. It is mounted facing aft so you cannot easily see the front of the unit. Has anyone moved the charger to a new location so it is easy to monitor? There is also a temp sensor wire that I need to run to the battery area.
Thanks

 

[Maine Sail]

Also, the original charger location is in aft port locker near the helm. It is mounted facing aft so you cannot easily see the front of the unit. Has anyone moved the charger to a new location so it is easy to monitor? There is also a temp sensor wire that I need to run to the battery area.
Thanks

You can just add a remote control. The temp sensor can be extended and all this info is the the article referenced above. Also the Sterling Pro Charge Ultra is very often less money than the Pronautic P...

 

[Ron20324]

Yes. I have inline 20 amp fuses in the charger leads at the battery. I guess I need to match the fuse size to whatever new charger size I decide on. Correct?

Correct. On my almost-new B323 I changed out the 20-amp for a 40. I overlooked changing the fuses. A trip from Annapolis to Rock Hall was enough discharge to blow the 20s. Lucky to have a West at RH for new 40 MegaFuses. I take it that the batteries (3 x 31) could have used more than 20 amps, but just could not get it.

 

[SailFysh]

Very informative post Mainesail... thanks. I hate to add more stuff such as remote if I can find a better location to mount charger. I think I can leave it in the same place inside the locker but turn it 90 degrees so the front can be easily seen from the helm. I would need to add a mounting board to the locker wall.

 

[DaveJ]

A comment on increasing the fuse size to match the increase capacity of the charger.
The wiring to the charger will need to be sized for the input current of the charger, and the fuses will need to be sized for the size of the wire. If that is a bit confusing; fuses are there to protect the wire, not the charger.
This is also true for the output of the charger, the wire and the fuses may both need to be increased.

 

[SailFysh]

Thanks Dave

 

[Stu Jackson]

The wiring to the charger will need to be sized for the input current of the charger, and the fuses will need to be sized for the size of the wire.

Very important, good summary.

Here's how:

Wire Sizing Charts from West Marine http://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity www.bluesea.com also has good material on this and fusing, but it's a PDF download and doesn't link. Here's the link to the page, scroll down for the PDF download of the Fuse & Wire Sizing Tables: https://www.bluesea.com/support/reference

 

[SailFysh]

Thanks Stu

 

[Ron20324]

A comment on increasing the fuse size to match the increase capacity of the charger. The wiring to the charger will need to be sized for the input current of the charger, and the fuses will need to be sized for the size of the wire. If that is a bit confusing; fuses are there to protect the wire, not the charger. This is also true for the output of the charger, the wire and the fuses may both need to be increased.

My notes here say the 20-amp charger was fused at 25. I don't have all the numbers here, but I reused the breaker-to-charger wires from the 20 to 40 change-out. It was a bolt-in change-over. Likewise, reused the 2 charger to batt wires, #6 I'm pretty sure. It was a larger wire than the charger connecters would accept all the strands of #6, so had to cut off a few. My opinion is that the output fuses are there for the charger . My B323 had 20-amp output, but #6 wire to the batteries. I'm away from my home computer, and have only my wiring diagrams not labeled with wire sizes. The extra size of the cables is for minimum voltage loss delivered to the batts. Actually, on my remote monitor, one battery is always charged at a higher rate due to the longer cable run, I am sure.

update to correct #8 wires are OEM #6.

 

[DaveJ]

On the comment that the charger connectors would not fit a #8 wire, I find that very surprising. The wire needs to be at least a #8, and if the distance to the batteries is 'rather long' (not an engineering term), then should be increased to #6. On the Blue Seas link above there is a wiring ampacity chart. For #8 wire at 75*C and up to 3 conductors in a raceway, the current rating is 46 amps. I doubt using higher temperature rated conductors will help, the termination lugs are 'probably' rated at 75*C, meaning you need to use the 75*C rating. The charger should have larger terminations (but does not), doesn't make sense??? In an application where voltage drop necessitates an increase in wire size....I'm not sure what the termination method would be.
Cheers

 

[Maine Sail]

A few points:

1- A Catalina 310 will have a minimum of 14/3 AWG wire & a 15A breaker for the existing battery chargers AC circuit. A Sterling or Promariner 60A charger will work just fine on a 15A AC circuit & 15A breaker.. No wire or breaker changes are necessary on the AC side.

2- Fusing for a battery charger should be in the range of 120% - 130% of the charger rated output. This prevents nuisance trips and continually running a fuse at more than 80% of its rating, which can lead to nuisance trips.

3- The DC output wiring is always sized for voltage drop over the circuit length. It is always better to err on the side of caution because terminations fuses etc. are not accounted for in the wiring voltage drop calculation. For a charging circuit the maximum circuit voltage drop should be no more than 3%. Ideally you want to aim for 2% or less. A 3% drop at 14.4V leaves you with just 13.97V at the batteries and can hinder charging performance.

4- Many sub 25A charger use terminal strips as opposed to studs. This is sometimes due to land based regulations and UL testing but sometimes simple cost cutting. It can be difficult to get proper battery type lugs in a terminal strip without physically shaving them down with a Dremel. With regard to the Sterling or Promariner chargers discussed here actual terminal studs begin at 30A.

5- Wire used on boat, & what Catalina uses, should be UL-1426 wire which is almost always 105C rated. The max ampacity temperature derating factors are based on the physical heat tolerance characteristics of the wires jacket. A 105C wire jacket has a better tolerance to heat than a 60C wire. This is why the 105C wire is rated for a higher ampacity than 60C or 75C or 90C wire..

6- If you've sized your DC cables for 3% or less voltage drop your fusing, at 120-130% of charger output, will not cross over the max ampacity limits of 105C wire. For example a 60A charger with a 16' circuit (positive and negative) would require 4GA wire to hit 3% VD. The fuse for a 60A charger would be approx 75A and a 4GA 105C wire can be fused at 160A, for over current protection, and comply with ABYC E-11...

 

[SailFysh]

Thanks MaineSail... See all caps replies below each point.

A few points:

1- A Catalina 310 will have a minimum of 14/3 AWG wire & a 15A breaker for the existing battery chargers AC circuit. A Sterling or Promariner 60A charger will work just fine on a 15A AC circuit & 15A breaker.. No wire or breaker changes are necessary on the AC side.
THIS IS GOOD NEWS... I DID NOT WANT TO WORK ON THE AC SIDE!!!

2- Fusing for a battery charger should be in the range of 120% - 130% of the charger rated output. This prevents nuisance trips and continually running a fuse at more than 80% of its rating, which can lead to nuisance trips.
40 AMP CHARGER x 1.2 = 50 AMP FUSE .... CORRECT?

3- The DC output wiring is always sized for voltage drop over the circuit length. It is always better to err on the side of caution because terminations fuses etc. are not accounted for in the wiring voltage drop calculation. For a charging circuit the maximum circuit voltage drop should be no more than 3%. Ideally you want to aim for 2% or less. A 3% drop at 14.4V leaves you with just 13.97V at the batteries and can hinder charging performance.
PRESENT WIRING IS 10 AWG 105C DRY BOAT CABLE ... distance is about 9'... Need bigger wire?

4- Many sub 25A charger use terminal strips as opposed to studs. This is sometimes due to land based regulations and UL testing but sometimes simple cost cutting. It can be difficult to get proper battery type lugs in a terminal strip without physically shaving them down with a Dremel. With regard to the Sterling or Promariner chargers discussed here actual terminal studs begin at 30A.

5- Wire used on boat, & what Catalina uses, should be UL-1426 wire which is almost always 105C rated. The max ampacity temperature derating factors are based on the physical heat tolerance characteristics of the wires jacket. A 105C wire jacket has a better tolerance to heat than a 60C wire. This is why the 105C wire is rated for a higher ampacity than 60C or 75C or 90C wire..

6- If you've sized your DC cables for 3% or less voltage drop your fusing, at 120-130% of charger output, will not cross over the max ampacity limits of 105C wire. For example a 60A charger with a 16' circuit (positive and negative) would require 4GA wire to hit 3% VD. The fuse for a 60A charger would be approx 75A and a 4GA 105C wire can be fused at 160A, for over current protection, and comply with ABYC E-11...

 

[SailFysh]

Take a look at the diagram and let me know what you think... Will it work? Should be ready for completing the install next week. Thanks all.

 

[Ron20324]

On the comment that the charger connectors would not fit a #8 wire, I find that very surprising. The wire needs to be at least a #8, and if the distance to the batteries is 'rather long' (not an engineering term), then should be increased to #6. On the Blue Seas link above there is a wiring ampacity chart. For #8 wire at 75*C and up to 3 conductors in a raceway, the current rating is 46 amps. I doubt using higher temperature rated conductors will help, the termination lugs are 'probably' rated at 75*C, meaning you need to use the 75*C rating. The charger should have larger terminations (but does not), doesn't make sense??? In an application where voltage drop necessitates an increase in wire size....I'm not sure what the termination method would be.
Cheers

Doug sent me a copy of the B323 manual, and it shows OEM #6 wire from charger to batteries

 

[Stu Jackson]

Take a look at the diagram and let me know what you think... Will it work?

What size charger did you get?

 

[Ron20324]

Take a look at the diagram and let me know what you think...

Well, it should work, but if those are actual connection points, you have too many wires on the battery lugs. You need "power posts".