Battery / switch system upgrade log

F

ferret30

New member
I wanted to stop cluttering other people's threads and start my own to work out issues and track progress with an electrical system upgrade.

My setup currently consists of:

* Suzuki DF90
* Interstate Group 24 cranking battery (6 years old)
* Interstate Group 27 deep cycle battery (6 years old)
* Guest battery switch (A, A+B, B, off)

This type of switch has both house and motor output coming off a single terminal -- the house circuit is always connected directly to the motor. My goal is to upgrade this system to use isolated circuits, and to use identical batteries.

The new items I will be installing are:

* Interstate SRM-24 deep cycle/cranking battery (house)
* Interstate SRM-24 deep cycle/cranking battery (motor)
* Blue Sea Add-A-Battery (parallel switch + ACR)

By using group 24 batteries on both sides, I can fit them in the lazarette hatches without tilting them completely sideways like the group 27s. If I find that one group 24 is not sufficient for overnighting, I can always add a second (parallel) in the port lazarette, which is where the house battery is going anyway.

The switch is different from my existing one in that it only has off and on positions (for normal use at least). When off, both batteries are disconnected. When on, one battery is connected to the house circuit and the other is connected to the motor circuit. So there are 2 input studs and 2 output studs (the Guest switch had a common output). There is a third position (emergency!) that combines the batteries for starting -- same as the old switch.

If I just installed this switch, I'd have a problem... With isolated circuits, I'd never be charging the house battery unless I ran the motor with the combined switch setting. That's what the ACR is for. It is basically a link between the batteries that monitors voltage on either side. When one side has an elevated voltage (due to motor alternator output or battery charger), it connects the batteries and lets the other battery feed off the charge current. It is bi-directional, so a charger placed on either battery will ultimately charge both. The charger will isolate the batteries if a) the motor is being started, or b) the battery that would be receiving current has a voltage below some minimum amount.
 
Now, before I can start I need to work out some details and do some shopping. My switch/ACR are coming in the mail today, and I'll be getting the batteries tomorrow once I get a chance to remove the old ones (for core trade in).

The negative cables will stay exactly the same as far as I can tell.

The positive outputs from both batteries will go to the 2 input terminals on the new switch.

The positive motor lead will connect to the motor output terminal on the switch.

All other wires that were previously connected to the old switch's common output will move to the house output terminal on the new switch.

Up to this point, there is no new cabling required. But when I install the ACR, I will need to choose appropriate cables and fuses for the wires from the ACR to the batteries. Also, I will need a few short runs of 16AWG with inline fuses for the ACR ground connection and the ACR start isolation connection to the ignition output (tells the ACR when the motor is cranking).

So, any ballpark ideas on what cables and fuses should be used to connect the batteries to the ACR? It seems to me that if 2 batteries with different voltages were just connected together (+ to +, - to -), the current would only be limited by the internal resistances of the batteries. Hmmm.
 
Wandering Sagebrush":1na4rqae said:
A group 27 fits nicely in the port lazarette.
Click to expand...

Maybe we have different hatches/openings. I have a 27 on the port side right now, and it won't go in there without tipping it about 60 degrees, which is kind of annoying and/or dangerous. I'm thinking of putting battery boxes in, not just terminal covers, so that would be even more of a challenge with a 27. And as I said, I can easily fit a pair of 24s on the port side if the single 24 isn't enough.
 
As I understand the circuit--and I have not used this specific Blue Seas ACR--the only current you will have flowing to the ACR will be battery charging. The max of that will be the out put of the Suzuki 90. I doubt that you will be using an inverter/charger which will put out 130 amps.
I believe that the Suzuki puts out 27 amps (and you will probably not be using all of that--but figure 30 amps). So you want to figure the round trip from the ACR to the battery--and I would say that it is probably no more than 20 feet. You could get by with #12, but I would use #20.

Any place that you have the full load of the starter, then you would want want to use the same gauge as the engine or more--at least # 1 or 0.
 
thataway":3u4j01oy said:
You could get by with #12, but I would use #20.
Click to expand...

Does the # symbol mean gauge? If so, did you mean that the #12 would be safer? If the max current is 30A, would you use a 30A fuse, or go higher?

Also, is it possible to buy wire runs with inline fuse holders? I've only seen inline fuse holders that look like they need to be connected to the main wire with an crimp connector.
 
Mea culpa --that should have read #10 wire! Sorry. Yes I am using the # to relate to gauge. Yes, if the max charging current is going to be 30 amps, than a 30 amp fuse would be appropriate. The fuse is to protect the wire, and prevent overheating and causing a fire. But if you are to put a 40 amp charger on the circuit--then you definitely want to use #10 wire, and go with 40 amp fuse.
 
My current charger is a Schumacher Ship N Shore Speed charger that does 15A/10A/2A with charge rate monitoring for deep cycle batteries. But I will install 10A anyway. Who knows what I'll be using for charging after our first active season on the boat.

I'm still waiting for the Add-A-Battery thing to come today, and I'll see what comes with it -- ideally it would come with the 16# wire for the ground and starter wires, but probably not!
 
thataway":3hc2buk8 said:
Mea culpa --that should have read #10 wire! Sorry. Yes I am using the # to relate to gauge. Yes, if the max charging current is going to be 30 amps, than a 30 amp fuse would be appropriate. The fuse is to protect the wire, and prevent overheating and causing a fire. But if you are to put a 40 amp charger on the circuit--then you definitely want to use #10 wire, and go with 40 amp fuse.
Click to expand...
How timely ferret30. I'm going through the exact same project for my Suzuki 90 and I was wondering about the fuse from the ACR to the battery.

I believe my 2006 Suzi puts out 40 amps. I have a Guest charger which puts out 10 amps, 5 to each battery. So am I to match the fuse to the 40 amps or the 10 amps (or is it 5)? The wire run from the ACR to the battery will be less than 2 feet. What fuse size should I be using? :?
 
Fuse for the larger source at the origin of the source--for example if you run a long wire to the battery charger, there should be a breaker at the battery charger and a fuse near the ACR. So in the Jazzmanic you fuse the charger at 10 amps (not sure if your charger will put out 10 amps to one battery and 5 to each of two batteries, or is limited to 5 amps per battery--but 10 amps for that circuit works well.

The only issue with an alternator is that you want to have adequate fusing for any spikes. You don't want to have an alternator feeding an open circuit--it will blow the diodes. Thus I would fuse the alternator to 50 or 60 amps. (actually put in a breaker, since that is more practical).
 
A tip on working in the lazarettes. The cover/ hinge comes off easily with the removal of the 8 screws holding it on. It gives you several more inches of opening to work in and around the batteries and to deal with the wires that seem to hide in hidden cracks.

Chuck
 
I spoke to a Suzuki dealer that was fairly sure that the 2006 Suzuki DF90 had fuses on the alternator output, so I might not worry about that right now for my setup. It would be more convenient to have the fuses near all the switchgear, but I can add that stuff in later.

It seems like it wouldn't be an issue unless the switch was turned off while the motor was running, which would almost have to be intentional.
 
Yes, all of the outboards are fused by the alternator. However, you also want to fuse a wire which has current flowing near its terminus,
 
thataway":2d749cpx said:
Yes, all of the outboards are fused by the alternator. However, you also want to fuse a wire which has current flowing near its terminus,
Click to expand...

I haven't started working on the boat yet today, but I just looked at a picture on my phone and there's a 50A thermal circuit breaker next to the switch. I wasn't sure if this was a breaker on the switch output or what, but I noticed it says "Ignition Protected". I'm guessing this is connecting the motor to the switch. Good to know!
 
This breaker is to protect the alternator output circuit.

"ignition protected is to the ABYC standard:
E11.4.15 Ignition protection - the design and construction of a device such that under design operating conditions:

a. it will not ignite a flammable hydrocarbon mixture surrounding the device when an ignition source causes an internal explosion, or

b. it is incapable of relasing sufficient electrical or thermal energy to ignite a hydrocarbon mixture, or

c. the source of ignition is hermetically sealed.


This is different than a circuitry such that if the breaker blows, that the alternator diodes will not fail. For example the make before break battery switch protects alternator diodes, The alternator field disconnect, and as does the "Zap Stop" which protects alternators from an open circuit. I am not aware of any similar circuit on outboards--but some may exist on the newer motors.
 
I worked on the boat all day and well after dark. I got the new switch in, new batteries installed, and everything wired back up again. One thing I noticed was that the 50A thermal ignition breaker is actually installed between the switch output and the house panel, not between the motor and the switch as I had thought. But I'm really thinking it would be hard to accidentally turn off the switch while the motor's running.

I had purchased two battery boxes to install the group 24s into, but after giving it a shot in the port lazarette (the less cluttered one), I realized it wasn't going to work. It was impossible to get the lid on the box in the compartment, and this was in the mostly open one and without a battery. I considered taking the hatch off as was mentioned before, but I'd be exposing core and don't want to attack the re-sealing of a hatch right now. Also, I'd have to remove the hatches any time I wanted to inspect water levels, poke around, etc.

So I'm going to stick with the batteries in trays with rubber terminal covers. A lot easier to work with and boxes seem like overkill (now) in the lazarettes.

Tomorrow I'm going to install the ACR box. I ran out of daylight and it started snowing so that wasn't going to happen today. I ended up using 12AWG wire and 30A max waterproof fuse holders since that was the largest I could find at WestMarine. If the fuses burn out I will go online and find larger waterproof fuse holders.

Space is really tight in the starboard compartment! I'm trying to figure out where to put the ACR. It would be nice to go on a side wall of the compartment, but I don't want to accidentally drill through into the motor well or out the side of the boat!

Other things I did today:

* Removed the pivoting kicker bracket from the port side to make way for the swim step. I will probably fill the holes I can't reuse with thickened epoxy (3/8" holes). For now I installed stainless nuts/bolts/fender washers with plenty of butyl tape to keep the water out. I've been reading several articles that say gelcoat over epoxy is fine under certain conditions. Since these holes are relatively small, I'm planning on filling them up with epoxy, then eventually grinding them down 1/32" or so below the surface, sanding and covering them with gelcoat. If it fails I can always take it back to Tern Boat Salvage for more work!

* Installed the iPad RAM mount under the overhead shelf.

* Replaced berth lights with 9 LED units from marinebeam.com.

* Mounted the fire extinguisher on the aft dinette seat box right next to the door. It's actually pretty out of the way there and easy to access from inside or outside. It wouldn't fit between the door and the window on either side, and I didn't want to put it behind the stove.

* Tossed the ol' bulky crusty life ring and put in a floating cushion.

* Put the ACR ditch bag on board (water, condensed food, solar blankets, duct tape, strobes, whistles, flares, flashlight, knife, water purification pills, mirror, first aid kit, waterproof matches, floating VHF, compass, Nalgene bottle, orange distress flag, etc.)

I probably left something out but nobody's going to get this far anyway,,,
 
ferret30,
When I was installing a battery switch in the lazarette I glued a small piece of 1/2 in plywood to the side of the compartment with 5200. This gave me a solid surface on which to mount the switch. Since I knew the thickness of the plywood it made drilling holes and selecting screw length easy. It is still solid after 9 years.
 
I received an interesting and useful response from Blue Sea when I asked them why there isn't a stand-alone AFD (alternator field disconnect) device. I send a question last night at 10pm or so and got a response this morning before 8:30 am:
Thank you for your question. There is no stand-alone AFD product that I am aware of (we don’t sell one, anyway). Further, unless your alternator is really old or really large, with an external regulator, you don’t need AFD. The vast majority of the battery switches we sell are without AFD, and many of the ones we sell *with* AFD are to people who don’t need it.
Click to expand...
If you want to know what AFD is or if it applies to you, here's a helpful explanation: http://bluesea.com/viewresource/91
 
ferret30":3tenvk79 said:
I received an interesting and useful response from Blue Sea when I asked them why there isn't a stand-alone AFD (alternator field disconnect) device. I send a question last night at 10pm or so and got a response this morning before 8:30 am:
Thank you for your question. There is no stand-alone AFD product that I am aware of (we don’t sell one, anyway). Further, unless your alternator is really old or really large, with an external regulator, you don’t need AFD. The vast majority of the battery switches we sell are without AFD, and many of the ones we sell *with* AFD are to people who don’t need it.
Click to expand...
If you want to know what AFD is or if it applies to you, here's a helpful explanation: http://bluesea.com/viewresource/91
Click to expand...

Thanks, ferret30!

That explanation of how an alternator works and how the AFD and battery switches work should be Required Reading for Electricity 101 at the C-Brat University of Boating, Engineering, Fishing, and Pleasure Cruising. Test on Wednesday! :lol:

Joe. :teeth :thup
 
Back
Top