Installing a dedicated starter battery

[Sven]

Right now we have a two-bank electrical system consisting of 4 105 Ah group 27 AGM batteries in two banks and a 1-all-2 battery switch.

I'm about to tie those 4 AGM batteries into a single house bank with a battery monitor. We are installing a 5th 105 Ah group 27 AGM as a dedicated starter battery which will be charged via a XANTREX ECHO-CHARGE box.

I'm looking for opinions (if there are any :lol3 about hooking all engine functions (starter, shut-off, future fuel pump, instrument lighting) to this one dedicated battery or if I should just have the starter hooked to it. I want KISS which would seem to point to just the starter and starter solenoid, but "as simple as possible but not simpler" is also a concern.

A second question is if a battery shut-off is needed if we're only hooking up the starter and starter solenoid ? While the idea of no battery shut-off switch seems strange at first, the wiring to the shut-off switch might actually add more danger than it prevents ? Are there any regulations (of course there are !) that stipulate if a shut-off is required or not ?

Thoughts ?



-Sven

 

[MarkA]

Personally, I would use the starter battery only for the starter. But since all the other functions you are considering come into play only when the motor is running and the alternator is charging, you shouldn't have a problem. (I am assuming by "instrument lights," you are talking about engine gauges, and not navigation instruments--they should NOT be on your starter battery!).

And YES!!! The cable from the starter battery to the starter and solenoid must be switched! Why? Because when I was bleeding my fuel lines the other day, while forgetting to switch off the batteries, my wrenched briefly grounded a hot wire on the solenoid. No harm done, but it startled the crap outta me and sent potentially dangerous sparks showering onto the diesel fuel I was bleeding.

I recently re-batteried and re-wired my boat. If you're interested, I'll spew the details.

 

[Sven]

I recently re-batteried and re-wired my boat. If you're interested, I'll spew the details.

Of course, please do !



-Sven

 

[MarkA]

Of course, please do !

-Sven

When I bought the boat, it had two Group 27 hybrid starter/"deep cycle" wet cell batteries from Costco. They were connected to the starter and the house through a Perko 1,2,all,off switch. They were also connected to a 50-watt solar panel (and a solar charger with a lousy float profile), the stock alternator, and an AC charger. The two batteries were isolated/combined by a BlueSea Systems Automatic Charging Relay.

The solar charger and it's bad profile kept overcharging the batteries and they would constantly dry out. They were getting pretty weak, so I was extra careful to keep one isolated from the other--but it turns out my system never really isolated the two. I discovered this twice on Sunday mornings in Isthmus Cove. Twice I dropped the mooring under sail and headed home with totally dead batteries. Once I sailed all the way up the Main Channel and into my slip in front of Acapulco. The second time, the solar charger was able to revive one battery enough to start the motor after I reached the Port building at the mouth of the Main Channel. Although I kind of enjoyed the challenge, something had to change ASAP.

So I bought 2 Trojan T-145 Plus 6-volt batteries and wired them in series to create a 260 AH house bank (I have no fridge or windlass, so this is plenty for us--even with RADAR, incandescent lights, etc.). I also bought a group 27 starter battery, which is ONLY for starting the motor!

I scrapped the Perko switch, because it combined the house and starter on the output side. I replaced that with a Blue Sea 5511, which keeps the starter and house circuits separate. The starter battery goes only to the starter, and the house bank goes only to the house distribution panel. It is switchable to on-off-combined. The only drawback is that I cannot switch off the house or starter circuits independently--they're either both on, or both off. A more thorough, though kind of inelegant, solution would be to use two of my original 1,2,all,off switches--one for each bank.

I replaced my solar charger with a smarter one, and installed a switch between the solar panel and the charger so I can shut it off when I want. The solar charger, alternator, and AC charger are connected to the house bank through a tinned copper bus bar. All of this is fused.

The starter battery is charged through the BlueSea ACR, though it's properly hooked up now to monitor both banks. And fused. And I ran an LED and manual switch to the distribution panel so I can see what it's doing, and control it manually if needed.

For Christmas, my fiancé bought me a LinkPro battery monitor, which is doing an awesome job of monitoring both banks. I love it!

I feel so much better knowing the house and starter circuits are totally isolated, and the two battery banks are only connected through the ACR, which now has a manual override for moments if I ever distrust the automatic internal switch.

I had a new distribution panel fabricated, but it's on the shelf while I attend to other tasks. Though talking about it now is making me excited to drill it out and stuff it with breakers and instruments. It will be a great functional and aesthetic improvement.

I also need to rewire the AC and dump the green wire to ground. I've visualized everything--now I need time to do it.

Portions of my DC system were wired with 1/0 battery cables, while others were AWG 9. I replaced all the AWG 9 with 1/0, but I've also been considering upgrading the lines to the battery switch and house distribution panel, as well as all ground cables, with 4/0 to minimize voltage drop. But despite the Raymarine warnings and cautions, I have not experienced any issues running all the electronics through the distribution panel--even when I switch on the bilge pump and macerator pump at the same time. So far, the 1/0 seems sufficient. Still, I want thicker cables.

I need to add that I love the solar charger. People tell you that they're inconsistent and inefficient and you only get current during brief periods of perfectly sunny days. BS. According to my LinkPro, that sucker puts out 3.3-3.5 amps all day long when the batteries are being used, and it drops to about 2.5 amps on foggy or overcast days. When the batteries are fully charged and at rest, it steps down to a float current of .1-.2 amps. The trojans are nearly a year old, and I've never had to add water, yet they're constantly maintained at a full charge. I can't imagine living without it.

 

[u079721]

You want opinions? You came to the right place!

If you really want KISS, I recommend just having one large bank, running everything including the engine starter. That way you have only one bank to turn off and on and charge.

As a back up you keep a separate engine start up battery in reserve, totally isolated from the system, and turned off from the system with its own switch except in emergencies when the house bank won't start the engine. I used this system for about 10 years with good results, staying out about 1 month a year on the hook.

The weakness of this system is then charging the back up battery that is turned off and isolated. While at the dock it gets charged with the multi-bank battery charger. While on the hook I never found the need to charge it at all - at least for up to a month. If you're out longer than that you can occasionally turn the bank on while motoring to give it a charge, IF you then remember to turn it off afterwards. So in that respect it is not totally fool proof, but it takes a lot less wiring that way. This is actually the perfect application for a battery combiner, which I used to use. But I found I really didn't need it so I took it out.

 

[MarkA]

I would NOT recommend running the starter off the house bank. The voltage drop and current spikes that occur when heating the glow plugs turning the starter can wreak havoc with any sensitive electronics you may have. Sure, you can turn everything off before you startup, but what about those moments when the wind dies just outside the rocky harbor entrance on a foggy night in a busy shipping area? That's not the time and place to risk frying your radar and plotter--or forcing a reset. It's also no place to turn everything off and then wait for it to warm up again.

 

[Maine Sail]

Sven,

If you want simple:

1- Wire the alt directly to the house bank and fuse as close to the battery as possible (preferably within 7")

2- Use Echo Charger to charge your "reserve" bank.

3- Use position #1 as your HOUSE/PRIMARY bank and #2 as "RESERVE/START" or SECONDARY bank.

4- Use only switch position #1 for everything, starting, house loads etc.. Turn to #1 when you get to the boat and OFF when you leave. Very, very simple..

5- If you should accidentally kill your house bank switch to #2 and start the engine. One would hope that with expensive AGM's however you are not routinely dipping below 50% state of charge..




The 1/2/BOTH/OFF switch is a GREAT tool and one that offers the most redundancy for emergencies..

 

[Maine Sail]

I would NOT recommend running the starter off the house bank. The voltage drop and current spikes that occur when heating the glow plugs turning the starter can wreak havoc with any sensitive electronics you may have. Sure, you can turn everything off before you startup, but what about those moments when the wind dies just outside the rocky harbor entrance on a foggy night in a busy shipping area? That's not the time and place to risk frying your radar and plotter--or forcing a reset. It's also no place to turn everything off and then wait for it to warm up again.

With four AGM's if he has a voltage drop issue enough to drop electronics, even at 50% depth of discharge, something is drastically wrong with his bank or wiring.

With four 100 Ah AGM's he'll likely have over 4000 cranking amps at 70F... His engine will likely require about 200-400 in-rush then about 125 -150A for an additional 3-4 seconds.

In a properly wired system voltage spikes are not an issue as the batteries act as a filter. I have had an o-scope on a number of boats trying to measure any sort of spike on the panel side of the batts and they simply don't happen unless you've wired your system incorrectly by tapping into a negative or pos wire in the wrong location...

This is starting our engine after three days on the hook and the bank at 52% state of charge. Batteries are group 31 deep cycle wets in parallel, and were nearly five years old when this video was shot.


http://www.youtube.com/watch?v=0Pzna7n1-fw&NR=1

I have been starting marine engines on house banks for over 20 years and never had any issues with drop out when the house bank was sufficiently sized.

 

[MarkA]

With four AGM's if he has a voltage drop issue enough to drop electronics, even at 50% depth of discharge, something is drastically wrong with his bank or wiring. With four 100 Ah AGM's he'll likely have over 4000 cranking amps at 70F... His engien will require about 200-300 in-rush then about 125 -150 for an additional 3-4 seconds.

Good point. On the other hand, it's just as simple, yet fool proof, to keep the house and starting banks, and circuits, isolated from each other. Personally, I sleep better that way.

 

[Maine Sail]

Good point. On the other hand, it's just as simple, yet fool proof, to keep the house and starting banks, and circuits, isolated from each other. Personally, I sleep better that way.

But with the Blue Seas DCP switch you lose a LOT of redundancy. Just ask my customer whom needed this redundancy three weeks ago and did not have it.

He did what the switch maker suggests you can do in a situation like that "combine" the banks. Sadly for him he let a boat yard talk him into this switch when he did not need it. He now wants me to install a 1/2/BOTH/OFF again...

In their situation they had gone to the mooring fired up the motor and motored nearly two hours because there was zero wind, lots of good bulk charging time. Once moored at their destination they then noticed certain devices like their small 300W inverter, used for the Netbook computer, were not powering up?

He hit the toggle switch for the house bank volt check and it was at about 8 volts. They needed to get to shore for dinner with friends and the VHF would not power up to call the launch and the hand held had died because he uses that in the cockpit while sailing.

Following the marketing from Blue Seas he decided to use the "combine" feature to get the VHF working enough to call the launch. After combining the start battery with the dead bank, he did not know it had catastrophically failed, why would he, the start battery was toast and would no longer start the engine and barely powered the VHF on "combine". It shut off within about 2-3 minutes of being combined.

In my opinion a battery switch on a sail boat, where banks are deeply cycled, should not require a user to dig into a battery compartment to physically disconnect a battery bank just to use the VHF or other necessary equipment, which in this situation is what really should have been done to be 100% safe. On this particular boat it would have taken him about 10+ minutes to disconnect the wires at the house bank due to their location.

Adding a simple $15.00 ON/OFF switch to a 1/2/BOTH/OFF can give you a dedicated starting bank and 95% of the redundancy that the 1/2/BOTH/OFF switch offers. Then you can still add an ACR and still be well below the cost of the DCP switch.

On our boat if a bank fails we can simply completely isolate it by switching to the other bank entirely. The only time I would ever use the BOTH feature is if our ACR died and I was in need of charging the "reserve bank".

The DCP switches do however have a good use and that is for fishing boats that shut down and fire up the motor, or two or three motors, some 30-40 times per day all while running expensive fish finders etc. that take time to re-boot. I have installed them in this application and I have also installed a simple ON/OFF in addition to the factory 1/2/BOTH/OFF. I still prefer the latter on sailboats for the redundancy.

The Lifeline's that failed my customer did so in a way I have become very familiar with. They died suddenly, and with little warning. Because they never started the motor on the house bank, and they don't have a windlass, they had little idea the bank was failing. Even a failing bank can support a 2-6 amp draw for a while and "appear" to be fine.

This is one huge benefit of starting your motor off the house bank. By using the house bank for starting loads it lets you know early that your house banks capacity is getting weak. With a DCP many sailors would never know until it is too late. Just like my customers never knew.

The week before they had no noticeable issues and then the bank just died. He assumed the bilge switch might have stuck, but it had not, so the "combine" feature was not such a bad move especially given the marketing messages Blue Seas uses about using the "combine" feature in an emergency.

I charged and attempted to equalize the three Lifeleine batteries that were less than four years old. The start battery went from a paltry 110 cranking amps to 183 cranking amps and the two house batteries went from not even powering up my analyzer to 3 cranking amps and 5 cranking amps respectively AFTER charging. Deader than dead. After nearly 16 hours on the charger, and an equalization cycle, the House Bank #1 came off it and within 15 seconds was down to about 9.3 volts and House Bank #2 was in the low 8's....

These types of failures can happen, and while rare, I have seen a fair number of them enough so that I will do everything I can to talk a sailboat customer out of a DCP. If they want dedicated starting then that is easy with a simple ON/OFF all the while still retaining the 1/2/BOTH/OFF for the redundancy features.

The bottom line is what helps you sleep is what's best for your situation.

 

[MarkA]

But with the Blue Seas DCP switch you lose a LOT of redundancy. Just ask my customer whom needed this redundancy three weeks ago and did not have it. His yard told him he needed a DCP switch and he let them install it. He then had a catastrophic failure of his house AGM bank. His option was to then use the "COMBINE" feature and he promptly killed his dedicated AGM starting battery and was dead in the water.

Which is why I keep my starting battery separate. Kill my house bank, and my starting battery is completely fresh. No need to combine the two.

The ACR will isolate them automatically when the house voltage drops, and I have the manual switch as a backup.

If my starter battery dies for some reason, I'll simply disconnect it and run jumper cables from the house bank to the starter cables. I doubt I'll ever need to do that.

Yes, it would be easier with a 1/2/all/off switch, but the need to use it seems far less likely to occur when the house and starter circuits are kept separate with the BlueSeas switch.

 

[Loren Beach]

1-2-All-Options-Confusion-Choices-Bewilderment

Maine,
I appreciate your time and experience in covering the bases on this.
Our boat (still) has the stock 1-2-all rotary switch.
For quite a while I have been interested in changing over to the BlueSeas model 8080. Partly to get the separation of circuits for starting and house, and partly to get the virtue of a master breaker built-in for the house bank, located within a couple feet of the house bank on our boat.

Given the battery separation and sourcing options available with the stock switch, now you have me reconsidering (which is about one click away from indecision paralysis).

Is it true that current ABYC guidelines call for a hi-amp breaker for the house hot cable, close to the battery bank?


If there's a related already-posted article, just refer me to it. (No need to wear your fingers to nubs on this site if my question has been well-covered elsewhere...)


As always, I appreciate the time that you and other technicians put in trying to guide the rest of us. Electricity on Boats is one of the most confusing parts of sail boat ownership.

OTOH, I do not want to go back to my days with the 20 foot camp cruiser and and its nav light "system" consisting of two flashlights with special lenses and a suction cup on the base of each one!



Cheers,
Loren

 

[MarkA]

MaineSail,

I wrote my last comment before your entire explanation appeared. I was assuming your client combined to start the motor, not run the VHF. That kinda changes things (and it's also why I carry a handheld VHF for backup.)

Good point about testing the house bank with starter loads--and you're making me scratch my head a little.

Where do you put the additional on/off switch?

What seemed ideal to me would be two 1/2/both/off switches, one feeding the house distribution panel, and one feeding the starter. Then I could select bank 1 or 2 for either circuit, while still keeping the circuits isolated. But I made my decision based partly on time constraints (had to sail the next day), space constraints (I would need to rearrange a few things to add a second switch), and a lack of perceived need for the extra flexibility. (Plus, the BlueSea switch only cost $24--gotta know where to shop). Since I know my system and its capabilities (and limitations), I know how to make it work for any contingency. But that's obviously not true for everyone.

Ever since my experiences of sailing home with dead batteries, I've been fastidious about checking them. I know from personal experience that most people are probably not as anal about that as I now am. Once every two months (used to be every month) I check the electrolyte levels, specific gravity, and voltage after leaving them disconnected for 24 hours. Plus I'm working on the boat most days, and exercising the house bank with various systems running, while frequently eyeing the LinkPro. never take batteries for granted!

 

[MarkA]

Maine,


Is it true that current ABYC guidelines call for a hi-amp breaker for the house hot cable, close to the battery bank?



Loren

Yes--or fuses. They must be within 7 inches of the power source (battery). I solved that with these terminal fuse blocks: http://bluesea.com/category/5/21/productline/specs/378 I use the two-terminal blocks so I can run different amperage fuses for the main lines leading to the battery switch, and lower amp fuses for the chargers and ACR. They're inexpensive, easy to use, and they seem to work. I'm wondering what MaineSail feels about these versus other solutions.

 

[u079721]

What seemed ideal to me would be two 1/2/both/off switches, one feeding the house distribution panel, and one feeding the starter. Then I could select bank 1 or 2 for either circuit, while still keeping the circuits isolated.

My system has (or had....) just two separate On/Off switches, one for the house bank, one for the backup engine starting battery. When I went aboard I turned on the house bank and forgot all about it. If during the cruise the house bank would not start the engine (which never happened in 10 years) I would turn it off, then turn on the backup to start the engine (or run the VHF). Only after I had things up and running would I even think about combining them to be sure a possibly shorted house bank would not draw down my backup.

I love hearing about how everyone else sets up their electrical system because I just about always get ideas about new ways to do things. The system that works for you and how you use your boat will probably not work as well for someone else. So there never is a RIGHT answer. For me I like the idea of a backup battery that is isolated and unused, waiting for that emergency.

 

[Maine Sail]

To keep the wonderful safety features of the 1/2/BOTH/OFF you already have you can simply add one more ON/OFF and have both a dedicated start battery and complete redundancy..

1 - If the starting battery goes bad simply turn the 1/2/BOTH/OFF to BOTH and flip the ON/OFF to OFF you can now start your engien and do house loads off the house bank yet still 100% isolate the starting battery.

2 - If the House bank goes bad simply flip to position #2 and leave the ON/OFF turned to ON. This will allow powering house and starting loads from the starting battery and allows it to also act as a reserve.

3 - For normal everyday use flip the 1/2/BOTH/OFF to #1 and the ON/OFF to ON..

 

[MarkA]

Maine Sail,

Thank you! That does exactly what I want, and I'm a little embarrassed that it didn't occur to me. I could use half of my BlueSea switch as the on/off.

My only concern would be potential for confusion. I'd have to label it well, and tape instructions nearby for those moments of sleep deprivation (*cough* inebriation)--or extended periods away from the boat that cause the memory to fade.

-mark

 

[Sven]

A wonderful set of posts and answers.

I thank you all !



-Sven

 

[aquavit]

Sven;

I just changed the battery configuration around on my boat. I am attaching a schematic of what I did. I had help from several members here including Maine Sail. I deviated from some of the advice I received by connecting my starter to the starting battery, not to the "C" post of the 1/2/B/OFF switch. I use the switch strictly for on/off purposes and may replace it with an on/off switch this winter. In my boat, the house loads cannot be connected to the starter battery since I do not want this scenario to ever occur. If you have an external or aftermarket regulator, you may want to talk to the manufacturer about where to connect the sensing wire, either to the house or starting battery. In my mind the house battery makes the most sense but I did not have to worry about this since my alternator has an integral regulator. I have had 2 weekends of use on my boat since I did this change and it works perfectly, so far I have not had any requirement to turn on the shore power charger.

Glenn (Aquavit)

 

[MarkA]

Mine is essentially identical to Glenn's. The only difference is that I have a switch between the starting battery and starter (1/2 of the BlueSea 5511), and I also have a solar charger connected to the house bank.

I'd be interested to know what items people have connected to the house bank BEFORE the switch? Bilge pump? Devices like stereos that need constant juice to retain memory? Battery monitors?

-mark