Wiring My Battery Charger to the Battery Switch ?

[Shoalcove]

My boat has a 30 amp shorepower charger which I've never used since I've always been on a mooring or anchored out. Recently I disconnected the wires that were connected directly to the batteries while moving my battery boxes. Now, I find myself at a marina (a bit of culture shock!) and would like to reconnect them. Is it better to take the outputs to the 1,2 Both Battery switch and gain the benefit of the fuses between the switch and the batteries or should I wire it directly to the POS post of each battery bank and call it a day? The NEG will run to the NEG busbar regardless of the POS setup. Thanks! Shoalcove

[CharlieJ]

My recommendation would be to connect the B+ outputs from the battery charger to each battery, or battery bank, you want to charge.

It is considered best and safest practice, and to be in compliance with the ABYC Standards, to place a properly rated fuse in each B+ conductor as close to its connection to the battery B+ terminal or bus bar as is possible. The ABYC Standard requires 7" maximum distance but there are exceptions.

A very easy method to comply with the requirement is to use the Marine Rated Battery Fuses (MRBF) manufactured by Cooper, re-packaged by Blue Sea Systems and sold by West and others. Here are the links to the Blue Sea web pages:
Fuse block; Terminal Fuse Block (MRBF - Marine Rated Battery Fuse) - Blue Sea Systems Fuses; Terminal Fuses (MRBF - Marine Rated Battery Fuse) - Blue Sea Systems

Charlie

[Shoalcove]

Right now I have ANL fuses in line from my battery banks to the battery switch. I guess what I'm asking is " Is there a safe way to utilize the same fuses for both jobs?" Wouldn't running the B+ outputs to the existing fuses accomplish this? I appreciate your experience and advice with this and certainly can't quarrel with your suggestion. I'm just wondering if there is a simpler, cleaner and to be honest, less expensive way to do this.
Until this year, my 30 yr old boat never had a fuse other than on the switch panel. I've replaced and upgraded the battery cables and added fuses as per information I've read here and have no intention of doing a second rate job but like to investigate my possibilities.
Best regards,
Shoalcove

[gettinthere]

I would think those ANL fuses you have are pretty heavy duty. Oversized for anything you would likely have from the charger. So the fuse would not blow if the charger went goofy on you. You need properly sized fuses for the application

[Shoalcove]

Well now, that does make sense doesn't it? I was not thinking that the charger could "runaway" and was more concerned about a short from a loose wire or such. I think you make a good case. Thanks!

[btrayfors]

The terminal block fuses recommended by Charlie will certainly do the job.

Another way to go would be to use the Blue Sea Systems Maxi Fuseholder, with a 40A Maxi fuse. We use a lot of these and they're first rate:

http://bluesea.com/category/5/21/pro...e/overview/127

You can probably find them online for as little as $22.

You didn't say how many B+ wires your 30A charger has. How many? And, what battery setup?

BTW, which Cheoy Lee 35 do you have? The Robb?

Bill

[CharlieJ]

My recommendation was based on eliminating the battery switch from your battery charging circuit. You could connect the conductors to the battery switch #1 and #2 battery studs BUT, when you start loading up the studs with ring terminals the switch begins to get hard to service, troubleshoot, etc.

The ABYC Standard requires over current protection devices (OCPD) at both ends of a conductor that are connected to sources; i.e., the battery bank at one end and the charging source at the other end. The requirement for an OCPD at the charging source is eliminated IF the charging source is self limiting. In other words, if the capacity of the charging source is less than the ampacity of the conductor.

Bill-Maxi fuses have an ampere interrupt capacity (AIC) of 1,000 amps which is adequate for a branch circuit connected to a battery of < 650 CCA. The AIC required for a main feed from a 650 CCA battery is 1500 amps and a Maxi is not suitable for this application. ANLs have an AIC of 6,000 amps and are suitable for banks with a CCA of 1100 amps or more. The MRBF's I cited previously are even more robust with an AIC of 10,000 amps. They also have a very small form factor and can be mounted on the battery terminal or a terminal block. Very sweet!!

This whole subject of OCPDs and AICs is going to be opened for discussion in the near future because of the emergence of lithium iron phosphate (LFP) batteries and their very high energy density. Matching the OCPD's AIC to the CCA of the battery is going to have to be improved on but it is all that we have for now.

Hope this helps.
Charlie

[Shoalcove]

Hi Bill,
I've got the Bob Perry designed 35'. We like it alot. I see you also have fine taste in boats My 30 amp charger has up to 3 outputs but I only had 2 wired: one to the housebank (2x6volt golf cart) and one to the starter battery.
Charlie, Thanks for the clarification. I'll put in dedicated fuses for the charger. I'm thinking 40 or 50 amp which will be well below the capacity of the cable.
Best regards, Shoalcove

[btrayfors]

Charlie,

Absolutely right! Thanks for the catch. AIC is an important consideration for circuits connected directly to large battery banks. It will be interesting to follow the debate on AICs and OCPDs on LFP batteries and others capable of outputting a gazillion amps :-)


Shoalcove,

Use 40A ANLs on each B+ leg, near the batteries.

I don't know the Perry-designed 35-footer by Cheoy Lee. Will have to look it up. Love my GW42!

Cheers,

Bill

[JimboUK]

I agree!

[Shoalcove]

Thanks for the info Bill. Bob Perry's book has a good chapter on the Cheoy Lee's he designed. A good read for us fans.