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efiste 05-04-2012 01:56 PM

Electrical Upgrades
 
1 Attachment(s)
Thanks to the many wonderful posts on this site and others, I think I am ready to tackle many much needed electrical upgrades on my 1987 Catalina 34. These include upgrading to 4 6V T105s, a high output externally regulated alternator, dedicated starting battery with echo charger, 1800W charger/inverter, and a battery monitor. I have procured the main components and am now zeroing in on wire, connectors, and fuses. I will be completing these upgrades in phases but in order to ensure I have the overall right approach, I have created a wiring diagram of the planned upgrades.

I have based much of my plans on the previously posted electrical upgrade details by others. I am indebted to their generosity in sharing their information, approach, diagrams, and pictures! Part of my plan is the inclusion of a charger/inverter which (as I have read many posts about) requires very large 2/0 wire over a short distance AND a desire to keep the switch disconnects as simple as possible. I have read many discussions about different ways to organize switches. I would like the primary "source" power (DC from batteries or AC from shore power) to be wired to switches on the existing AC/DC panels. I am going to replace my DC battery selector with a new Blue Sea e-series switch with has 3 positions for Off, On, and Combine (Emergency). Specifically, I want to wire all DC loads including the inverter and starting battery echo charger on this same switch. I would rather not have parallel or sub switches even though I do forgo some flexibility. I would also like to use some pre-purchased 1/0 wire and connectors for the battery interconnects but am not sure if this would be recommended with the 2/0 wire required for the inverter as a later part of the upgrades.

I have attached the document I created of my schematic. Please ignore some of my naivety in the diagram symbols. I think I pretty much used (or labeled) things correctly, but I am sure any electrical engineers would notice a few that are not correct ;-). Any help, guidance, or other thoughts would be appreciated. I think I understand the general concepts, but the devil is in the details. It will be frustrating enough to pull the 2/0 and 1/0 wire. I do not want to also set my boat on fire because of a unintentional oversight in the design.

Thanks,
Eric
1987 Catalina 34
s/v Coughlin's Law

eherlihy 05-04-2012 03:48 PM

Re: Electrical Upgrades
 
The Echo Charger should connect directly to the house bank. Right now, if I read your diagram correctly, it will only charge when the off/1/both/2 switch is in an on position.

The Echo charge essentially takes power from the house bank, and uses it to preform a 3 stage charge of the starting battery.

efiste 05-04-2012 04:33 PM

Re: Electrical Upgrades
 
Yes, you are reading my diagram correctly and thanks for the feedback. I am glad you picked up on that because it was one of the areas I needed some opinion on. I have seen other wiring diagrams that have the charger directly connected to the battery, but I was wondering if it was better and possible to connect it through my disconnect. If I do not wire it through the DC disconnect, the charger will continue to pull from my house bank even when I am away. I assumed that the starting battery would typically be charged after starting the boat while I was out using the boat. I assume this is good to maintain the starting battery, but would it be at the cost of the house bank? Perhaps the draw is so low that it does not have any effect even over several weeks away from the boat. In any case, I would prefer to not have any loads without disconnects accept the safety recommended ones like an automatic bilge pump. Thoughts?

Similarly, I have the charger/inverter wired to the main DC disconnect. I did not want to have another switch to remember the state of. This way, either the battery banks are connected or not. It does mean, though, that to charge the house bank when connected to shore power I would need to have the DC switch set to on and therefore the echo charger connected as well. Is this an effective way to install and manage an charger/inverter?

I like the way this setup would work from a boat user perspective, but I do not know if it will or is recommended in order for the attached components to work correctly or effectively. Additional thoughts and feedback are appreciated.

Eric

eherlihy 05-04-2012 05:08 PM

Re: Electrical Upgrades
 
Quote:

Originally Posted by efiste (Post 867296)
Yes, you are reading my diagram correctly and thanks for the feedback. I am glad you picked up on that because it was one of the areas I needed some opinion on. I have seen other wiring diagrams that have the charger directly connected to the battery, but I was wondering if it was better and possible to connect it through my disconnect. If I do not wire it through the DC disconnect, the charger will continue to pull from my house bank even when I am away. I assumed that the starting battery would typically be charged after starting the boat while I was out using the boat. I assume this is good to maintain the starting battery, but would it be at the cost of the house bank? Perhaps the draw is so low that it does not have any effect even over several weeks away from the boat. In any case, I would prefer to not have any loads without disconnects accept the safety recommended ones like an automatic bilge pump. Thoughts?

It is better to have the starting battery 100% charged and ready, than it would be to ensure that the house bank is 95% charged, and the house bank dead. The Echo Charger cannot drain the house bank to less than 12.xx (I forget - you can look it up) volts. the drain of the Echo Charge, when everything is topped up is so low as to be negligible.
Quote:

Similarly, I have the charger/inverter wired to the main DC disconnect. I did not want to have another switch to remember the state of. This way, either the battery banks are connected or not. It does mean, though, that to charge the house bank when connected to shore power I would need to have the DC switch set to on and therefore the echo charger connected as well. Is this an effective way to install and manage an charger/inverter?
I don't have an inverter on my boat, so I am not the expert here. I'll let others with first hand experience chime in.

FWIW - I get on the boat to get away from stuff that uses AC (TV, Microwave, etc - Yes, I am a barbarian, or at least my father in law says so;)). I do use my laptop, but that runs on DC.:)

btrayfors 05-04-2012 05:44 PM

Re: Electrical Upgrades
 
Quote:

Originally Posted by efiste (Post 867296)
Yes, you are reading my diagram correctly and thanks for the feedback. I am glad you picked up on that because it was one of the areas I needed some opinion on. I have seen other wiring diagrams that have the charger directly connected to the battery, but I was wondering if it was better and possible to connect it through my disconnect. If I do not wire it through the DC disconnect, the charger will continue to pull from my house bank even when I am away. I assumed that the starting battery would typically be charged after starting the boat while I was out using the boat. I assume this is good to maintain the starting battery, but would it be at the cost of the house bank? Perhaps the draw is so low that it does not have any effect even over several weeks away from the boat. In any case, I would prefer to not have any loads without disconnects accept the safety recommended ones like an automatic bilge pump. Thoughts?

Similarly, I have the charger/inverter wired to the main DC disconnect. I did not want to have another switch to remember the state of. This way, either the battery banks are connected or not. It does mean, though, that to charge the house bank when connected to shore power I would need to have the DC switch set to on and therefore the echo charger connected as well. Is this an effective way to install and manage an charger/inverter?

I like the way this setup would work from a boat user perspective, but I do not know if it will or is recommended in order for the attached components to work correctly or effectively. Additional thoughts and feedback are appreciated.

Eric

Eric,

The EchoCharge will not drain your house batteries. When the voltage falls below about 12.9 or 13.0, it will effectively disconnect and just sit there doing nothing until it senses a charging voltage (13VDC or higher) on the house batteries.

Both the EchoCharge and the shore-powered charger should be connected directly to the house batteries, with appropriate fuses located near the batteries. They should NOT go thru a switch of any kind.

I haven't studied your diagram, but your alternator also should go directly to the house batteries with an appropriately-sized fuse located near the batteries. There should be no switch in line, because if you break the circuit while the alternator is running you will blow the diodes rather quickly.

Ditto for wind generators.

Solar panels are OK to switch...they won't be harmed.

Bill

asdf38 05-05-2012 10:47 AM

Re: Electrical Upgrades
 
Mostly I wanted to say nice diagram. Visio I assume?

Then, second I'd add that I agree with the feedback above. The Echo is designed to only turn on when it sees charging voltage and is designed not to drain your house bank. Also you should just wire the alt directly to the house. 1) This guarantees you're charging both batteries all the time your engine is running 2) You can never flip the switch off and risk burning out your regulator (although if you're buying a new one you could read up and confirm if this is a problem).

I'm not familiar with shore power systems but the same reasoning seems to apply and I suspect those systems as well are designed to not drain the battery when AC power isn't present.

eherlihy 05-05-2012 03:07 PM

Re: Electrical Upgrades
 
Yes, you should move the connections from the Echo Charge and the Inverter/Charger to connect directly to the batteries without a switch.

Also, I assume that your '87 Catalina has a Universal M25 engine. If so, that 220A fuse on both battery circuits, is WAY too big.

Figure the highest load that you expect to see on the house bank (every light, fan and appliance turned on - say ~50A), and double it. That should be the size of your primary fuse on the house bank.

I have the same engine (different boat, and no inverter) and frequently start my engine on a 90A MRBF. I have a 135A MRBF on the starting circuit, but forget to put the switch in the correct position:o. I have yet to blow the fuse on either circuit.

Maine Sail 05-05-2012 04:02 PM

Re: Electrical Upgrades
 
Quote:

Originally Posted by eherlihy (Post 867587)
Also, I assume that your '87 Catalina has a Universal M25 engine. If so, that 220A fuse on both battery circuits, is WAY too big.

Figure the highest load that you expect to see on the house bank (every light, fan and appliance turned on - say ~50A), and double it. That should be the size of your primary fuse on the house bank.

I have the same engine (different boat, and no inverter) and frequently start my engine on a 90A MRBF. I have a 135A MRBF on the starting circuit, but forget to put the switch in the correct position:o. I have yet to blow the fuse on either circuit.



Any bank that has the ability to start the motor should be fuse protected sized to do this without blowing the fuse under any type of starting circumstances. Under normal starts a 90A fuse could work on a M-25, but if you get into a situation where she starts hard you'll very likely blow the fuse.

These engine draw anywhere from 195A to 330A, short duration in-rush, when starting depending upon temp and battery voltage but this is a short duration and well within the trip time delay curve of the fuse..

You've probably been lucky and the reason is the trip time delay.. MRBF's, ANL and Class T fuses have long trip delays.

For protecting a battery cable, what the battery bank fuse is intended for, you size the fuse to the wires max ampacity or less, if you can get away with it. As large as the wires ampacity will take is what you generally want if you will be starting an engine on the circuit.

Into a dead short, which is what you're protecting against, the fuse will blow quickly. There is really no such thing as a fuse to big when engine starting is in play unless it exceeds the wires ampacity rating. So long as the fuse does not exceed the wires ampacity rating bigger is usually better for cranking and ensures the motor will always start and not risk tripping the fuse. These fuses are for catastrophic shorts not to protect the engine starter or anything else just to protect the battery cables so by definition they can't be "too big" unless they can cause the wire to catch fire by exceeding the ampacity rating.

The ABYC makes an exception for "starting" circuits but it is still a very good idea to fuse starting circuits when you can.

Below are the ampacity tables sorted by wire jacket temp for inside and outside engine compartments. These are non-bundled wires. Most battery cable should be at least 90C but preferably 105C. The ABYC allows for going to 150% of this ampacity table safely when sizing for OCP...

http://www.pbase.com/mainecruising/image/135787605.jpg

What he can't do, and has drawn, is to protect #2 wire with a 300A fuse. The alternator originates inside the engine space and as such with 105C wire has a max ampacity of 178A. At 150% of the Table IV rating he is at 267A so he has still over sized the fuse for the #2 wire. The alt should ideally have it's own fuse or he could drop the bank fuse down to 250A if the inverter will allow for it and he'll be within the 150% rule. I generally prefer not to exceed 100% but sometimes you just have to if you want OCP...

He also does not need a fuse at the alt end of the wire. Alts are self limiting and can't exceed the ampacity of the wire if the wire is sized correctly for the output. The source the needs protection is the battery end of the wiring..

eherlihy 05-05-2012 05:25 PM

Re: Electrical Upgrades
 
You're right. Because I have been able to start my M25 on a 90A MRBF, it does not mean that I am suggesting that it should be done. If I catch that bone-head skipper doing this again, he's fired! :)

However, I do recall reading somewhere that the starter on an M25 should be able to do it's job with <100A. If it is sucking more juice than 135A, I want to know about it, because it means that the starter is acting up. Also I have a spare 150A fuse that I keep - just in case.

Your second point, I believe, is the theory of fusing a circuit; the fuse protects the wire, not the device. For details see; ABYC Wiring Standards

All good stuff!

btrayfors 05-05-2012 09:13 PM

Re: Electrical Upgrades
 
I agree with MaineSail 100% on this: if you're going to put a fuse in the starter circuit -- and I, too, believe this is a very good idea -- don't fool around with 'barely adequate' size fuses. I use a 400A ANL in my start circuit with 2/0 cable on my 4-108, after having blown lesser fuses in the 200A range.

Here's why.

Electric motors, like starter motors, are generally rated in at least two ways:

LRA = Lock Rotor Amps
RLA = Run Load Amps

When a starter is fed current from a dead stop condition, there is very considerable in-rush current, comparable to the LRA rating. This may be 2 times or 3 times the RLA run load amps, or even more. On cold mornings, or if there is sludge in the engine, or if it is hard starting for some reason, these elevated current draws can be much longer than the "normal" in-rush current times.

Example: a starter on a small to medium size diesel may, indeed, only draw 150A or so while it's turning, but the in-rush current can reach 1,000A for a few milliseconds, dropping to 300A to 400A or so for a few more milliseconds before leveling out at 150A when the starter really gets going.

What you most certainly don't want to happen is to have a fuse blow while you're trying to start the engine. Murphy's Law dictates that this might well be at the worst possible time.

The fuse is there to prevent a catastrophic meltdown and fire.

Bill


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