Rewiring Charger, keep circuit or something new?

[bhostrawser]

Hi All,

So, Series 1 36C, and I'm looking at the wiring. Obviously, at this age, a lot of it has to go, moisture has done its thing. Recently, I discovered the first owner had setup a system to selectively parallel any of the batteries, which is a nice thing to have. Except, the second owner, at some point had effectively connected them all together. I realized this too late, and when one battery started having problems, all of them were toast.

So. New batteries now, all around, and I've got them all isolated. I'm looking and seeing that the source of the original problem appears to be in the back of the engine room, the wiring from the charger to that aft resistor/fuse panel is pretty shot. In fact, that whole panel is pretty badly corroded, so it all has to be redone.

Likely, the whole boat will be rewired, because I don't trust most of what is there at this point. I think there have been some improvements in strategies for wiring this type of stuff, it might be done quite a bit simpler... anyone who has completely rewired one of these beasts can feel free to shoot me down here!

In the original setup, between the charger and the starting batteries, there is a fuse, it appears, and a relay? I would guess the relay is to keep the AC charger output and the alternator output isolated? The fuse looks more like a resistor, I can't tell its rating but it looks pretty massive, so I'm not sure it would really do any protecting since the charger output can't be more than 20-30 amps.

In my ragboat (is that what they are called?) there is no relay, and the fuse is much smaller (10A?) even though the charger is fairly similar. I guess my question is, should I keep the stock setup and just replace it all, or is there a better way to do this now?

Thanks,
Brent

[Vincentc]

I would connect the charger to the batteries according to the instruction from the manufacturer of the charger.
Regards

[bhostrawser]

I would connect the charger to the batteries according to the instruction from the manufacturer of the charger.
Regards

Sorry for not stating my question better. ABYC standards are to now fuse much closer to the battery, but this either implies bypassing the factory setup or doubling the fusing. I'm not sure if there is precedent among the recent rebuilds or knowledgable members that might have insight. I would just as soon consolidate the sub panel in the aft section of the engine room to someplace forward. I don't love the idea of inline fuses but it may be best practice.

[jim rosenthal]

You might start with getting the original wiring diagram from Sam's and seeing how much of the original harness is left. My boat, similar to yours, has much of the original harness in her and it works fine.

As far as the charging system goes, follow the manufacturer's instructions, and make sure you have returns of equal size running from the battery negatives to the charger; the charging current should not have to get back to the charger through grounds. It needs its own low-resistance path.

My Hatteras was rewired several years ago to have one house bank and one charging bank, plus a separate battery for the generator set. This has worked well for me. PM me if you want details. I also had smart regulators installed and a Link battery monitor, since updated. My house bank is two large AGMs and my starting bank is two Group 24s (flooded). Genset is one Group 24.

[MikeP]

"I don't love the idea of inline fuses but it may be best practice."

I share your dislike of In-line fuses and if they are needed, what I like to do is change it to a panel-mount fuse located (and labeled) somewhere in the vicinity of the device itself.

A few years ago I discovered 6 PO-installed in-line fuses in the overhead console on out 53MY. The front panel of the console is removable but it is not a fun thing to do. I relocated all the inlines into panel-mounted fuses on the underside of the console where they are easy to see and change should that become necessary.

Re re-wiring...
I wonder if the issues you note could be corrected with some cleaning and appropriate treatment of the connections. Usually that's where elec problems are located. Breaking the connections and some CorrosionX and a brass-bristle brush/Scotch pad is your friend! Of course, if the wiring is old and non-tinned, corrosion can work into the wire from either connection end and make the wire brittle and increase resistance, which may requiring replacement of the wire itself.

I'd bet that wholesale rewiring is not really necessary though only a thorough inspection will confirm that either way.

Re battery parallel. I installed a manual parallel switch for our battery banks several years ago and they have been combined ever since. FOR OUR USE it works extremely well. It can be manually switched back to individual banks but I have never had any reason to do so. Paralleling the banks makes them into one larger bank which is more efficient. HOWEVER, unless you have a generator that operates with a separate starting battery, I wouldn't do the parallel banks because you could discharge the batts to the point at which you could not start anything.

That has never happened to us but it is possible. Actually, on the hook, running the inverter all night for the fridge and whatever various other items are used- TV/sat dish, stereo, microwave, hair dryer, etc etc, I have yet to see the battery bank below 80% of full charge. On one occasion the boat was out of the water for 36 hours and the batts/inverter ran the fridge for that period and when the boat was put back in the water, the starters spun/started the engines instantly. So I'm a big fan of combining the banks into one large bank.

However, if I did a lot of offshore stuff where I was going out some distance and anchoring overnight in some shallow area, I would probably not be comfortable with combined banks, even with the capability to start the genny/charge the mains and even though the combined bank has demonstrated that overnight does not stress the system at all. So IMO it depends on your usage and your personal comfort level.

[Boatsb]

Do it right the first time.

Im replacing a 30 amp 12v charger installed by someone else with less than a year of real service.

1 its too small for the batteries it serves.
2 its in the er where it can be hot and wet.
3 its wired in so tight I would be lucky to get the new one in without changes.

it will have appropriate breakers and fuses.
it will be In the driest location I can it to. Moving it seems to be the smartest approach.
it will be done ONCE.

[bhostrawser]

You might start with getting the original wiring diagram from Sam's and seeing how much of the original harness is left. My boat, similar to yours, has much of the original harness in her and it works fine.

As far as the charging system goes, follow the manufacturer's instructions, and make sure you have returns of equal size running from the battery negatives to the charger; the charging current should not have to get back to the charger through grounds. It needs its own low-resistance path.

My Hatteras was rewired several years ago to have one house bank and one charging bank, plus a separate battery for the generator set. This has worked well for me. PM me if you want details. I also had smart regulators installed and a Link battery monitor, since updated. My house bank is two large AGMs and my starting bank is two Group 24s (flooded). Genset is one Group 24.

Thanks for the reply. There is nothing wrong with the original harness design, as far as I know. But, mine is shot, so, now is the time to decide on what improvements to make. Good point about the returns not having to go back through grounds, and being equal size. This is a change I will make. I'm going to PM you, because I like the sounds of the regulators and monitor. I installed a link monitor on the sailboat, and really liked it. Ideally, I would like to have a visual status indicator of all banks, at the lower helm or even tied into NMEA and both helms, with alarms. That way, you don't have to go digging for problems, if there is one, you will notice it more quickly.

[bhostrawser]

I share your dislike of In-line fuses and if they are needed, what I like to do is change it to a panel-mount fuse located (and labeled) somewhere in the vicinity of the device itself.

Yes. Good idea. I'll have to figure out where.

I'd bet that wholesale rewiring is not really necessary though only a thorough inspection will confirm that either way.

I'll take that bet. Most of the wiring is original. Some of the wiring is still in fair condition, but in the high moisture areas, I would not trust it for core systems, such as charging and starting. If I posted a pic of that aft fuse panel, I bet you would agree. I think if I look at it hard enough, it will crumble. I think anything required for keeping the boat afloat or under power is worthy of a very picky review. Any doubt, replace it. Wire is cheap.

However, if I did a lot of offshore stuff where I was going out some distance and anchoring overnight in some shallow area, I would probably not be comfortable with combined banks, even with the capability to start the genny/charge the mains and even though the combined bank has demonstrated that overnight does not stress the system at all. So IMO it depends on your usage and your personal comfort level.

This is more typical of our usage.

[bhostrawser]

Do it right the first time.

Im replacing a 30 amp 12v charger installed by someone else with less than a year of real service.

1 its too small for the batteries it serves.
2 its in the er where it can be hot and wet.
3 its wired in so tight I would be lucky to get the new one in without changes.

it will have appropriate breakers and fuses.
it will be In the driest location I can it to. Moving it seems to be the smartest approach.
it will be done ONCE.

I like everything about this. What is your rule for amperage vs. batt size? Also, I need to find that location on a 36C.

[Boatsb]

2 group 31's and a 4d on a 34c with pumps and lights I am installing a 60 amp 12 volt charger. I may need to upgrade fuses and breakers but that is expected.