Adding A Starting Battery

[lbertran]

I'm almost done with my Frigoboat install and my next step is to add a starting battery so I can wire my existing two batteries in parallel to increase my house bank capacity. I've read Nigel Calder's book as well as all of the excellent articles on the Blue Sea web site. But before charging ahead , I thought I'd lay out my plan for your comments and ask a couple of questions. I tried searching for earlier threads on this subject but didn't find anything that addresses my very basic questions.
I have a Universal M25 XPB with the stock alternator. I plan to install a new Blue Sea Dual Circuit Plus battery switch to replace the current Off-1-2-Both switch. I already have a Blue Sea Automatic Charging Relay and a Xantrex 2 Bank charger installed. I'll be putting the new starting battery on a shelf behind the motor, just aft of the stuffing box. I'll be running a battery cable from the starting battery positive to the battery switch and a cable from the starting battery negative to the negative bus bar. I will connect the starting battery to the battery combiner and to the Xantrex charger. I'll connect the house bank to the battery switch and to the combiner and charger.
Now, here's my biggest question. The current Off-1-2-Both switch has three connection posts, one each for the two current batteries, and one that according to my multimeter appears to be the lead from the starter. There are two smaller wires connected to the battery wire posts from the panel meter, and there are three other connections to the post with the starter wire that appear to be hot leads to the panel. But I can't figure out how the alternator output gets to the batteries. I can't trace any wire coming from the alternator and going to the batteries or to the battery switch. Obviously, the alternator is currently charging my batteries and I assume that this will continue to be the case and that the combiner will take care of sending that charge to the new starting battery, is this correct?
Thanks to all of you for reading this far and for any guidance you can give.

 

[Maine Sail]

You do not need to replace the 1/2/BOTH/OFF switch they are great switches when wired appropriately. The factory wiring is not "appropriately"..

Your alternator is most likely connected directly to the starter and it follows the starter wire back to to the battery switch where it can then be "selected" as to which bank it charges.

The simple fix is to run a new wire from the alt output B+ terminal directly to the HOUSE bank. The ACR will automatically take care of the start bank. This new wire should be fused at the battery or within 7".

You now have a good system that automatically charges both banks and one that can't fry the alternator diodes by passing through the OFF position.

When you get to your boat simply turn the switch to HOUSE/1 and leave it there. I like bank #1 as the "primary" or "house bank" and the #2 position as secondary/start as it is easier to remember.

The only draw back to this system is the slight potential for the voltage dropping below a devices threshold when starting. With a sufficiently sized house bank and properly sized wire this should not be an issue.

When you get to the boat simply switch to bank 1. When you leave the boat simply switch to OFF. You'll use the house batts for everything.. By doing this you'll only ever need to use position #1/House yet your emergency (start) bank will always be sufficiently charged if and when it is needed because you've also upgraded to an ACR/VSR type charging device.

The charging of the start bank can all be done behind the scenes and is automatic by adding an ACR or Echo type charger thus the need to use BOTH is non-existent. Doing this avoids the large "human error" factor of memory lapses.


What happens if I kill my house bank?

If you kill a bank don't fall into the trap of combining the dead bank with a perfectly good one by using the BOTH feature. Simply switch to the second fully charged reserve bank when you need to. Combining a good bank with a dead bank only bleeds off precious cranking amps from the good battery which is usually a small group 24 type.

Can my house bank really start my engine?

YES, of course. If you are practicing good battery management and never discharging the house bank below 50% state of charge you should always be able to start your engine just fine using the house bank and will only ever use the battery switch when you get to the boat to flip it to position #1/House. When you leave turn it to OFF.

We have three group 31 batteries on our boat. Even though they are deep cycle they still produce a combined CA (cranking amps) rating of well over 3000 amps at about 70 degrees F. My single group 31 reserve battery, in comparison, only has 1000 CA at the same temp.


It takes VERY LITTLE from your bank to start a small diesel. In fact I can not even measure .1 Ah of consumption from a 240 Ah bank, using a Xantrex Link Pro when I start our 44HP four cylinder diesel.

Starting the engine requires very, very little from a battery, many folks over think this and believe it requires a lot more than it really does. The peak in-rush current draw, for a split second, on my 44HP four cylinder Westerbeke is about 160 amps (peak split second current). The starter motor on my Westerbeke is a 1.5 kW an the starters on the average Universal M-25's are .8 kW. Even if it peaks for .2 seconds at over 200A this is nothing to a multi-thousand amp bank.

The 1/2/ALL/OFF switch is a great device, if wired appropriately. When wired in the fashion most builders do, it sucks and thus gets a bad rap.

The 1/2/ALL/OFF switch wired this way retains all the original features & benefits yet looses the frying of diodes and the switching back and forth if you wire the alt direct to house and use an ACR, Echo type charger to top off the start bank.

For instance if your ACR or an Echo Charger type device failed, which could potentially happen, you can always use the ALL/BOTH feature to charge both banks from the alt just as you always did.

No repairs or jumper wires just flip the switch to ALL, for charging, and you're back in business.. You will not however fry the alternator diodes because it always has a load on it by wiring directly to the house bank.

It is a good idea to add a fuse/breaker within 7" of the battery for the direct feed alt wire. It is also a good idea to fuse your banks.

As always there is no one right way to wire banks, unless you do it dangerously, but on small boats it makes little sense to ditch a perfectly good 1/2/ALL/OFF when a simple re-wire will give you everything you need with simplicity and total redundancy should the combiner fail..

#1 Assign house bank to batt switch position #1
#2 Install reserve battery to position #2
#3 Wire alternator output directly to the house bank with sufficient size cable & fuse.
#4 Install ACR or Echo Charger between banks.
#5 Use boat in position #1 for starting AND house loads. Switch to OFF when you leave it's that simple.



So why do I want to wire my alt direct to the house bank??

I prefer to feed the alt directly to the house bank and not the reserve bank as the start bank is for back up or emergency, in this situation, and would usually be at or near 100% SOC anyway..

1- No more worries about fried diodes.

2- Accurate voltage sensing & less chance of voltage drop over factory wiring.

3- If you were to use an Echo Charger you need to do this anyway.

You should not however wire the alt directly to the house battery unless you have either a VSR/ACR (voltage sensitive relay/ automatic charging relay) or a unit like the Echo Charger or Balmar Duo Charger.

Follow me on this one.

If you sense/wire directly to the house bank, bank 1, but do not have an ACR or Echo type unit installed, this means you could physically select the battery being used via the 1/2/BOTH/OFF switch.

If you select bank two as your source and the alt is connected to bank 1 you will draw down bank two and not replenish it unless the ALL function is selected during charging. In short, without an ACR or Echo type charger I would not wire directly to the house bank and instead would leave it wired through the common post of the battery switch.

With an ACR/Echo you can still select bank 2 but it will automatically be getting charged via the combiner or Echo even with the house bank being direct wired...

Some folks complain of voltage drop out for electronics when starting off the house bank. I have never experienced this in any of my installations. I can start our engine and not reset any of my electronics even down to about 35-40% state of charge. This is the same for the many customer boats I have re-wired in this fashion. If this is a concern then your batteries may be ready for replacement or you have bad connections or a wire gauge that us insufficient. To avoid this you can simply start the motor, then flip on the instruments.

I am not a big fan of the Blue Sea Dual Circuit system as it loses a lot of the redundant features of the 1/2/BOTH switch..

 

[Tom Metzger]

Laura - There is no way I can produce the number of words that MS writes, but I will offer my ideas.

I agree with MS on keeping the 1-2-both-off switch. They are very reliable. I will assume since you have been using it for years with no problems that you can continue.

I agree that the house bank on the #1 position is the best choice. I also agree that the alternator is wired to the starter solenoid (I checked the diagram).

http://www.westerbeke.com/WiringDiagrams/12B-82B_108C_(39144_rev_j).pdf

I would not disconnect the alternator/solenoid connection. My thinking is that should the house bank fail (shorted cell or other failure) you can not charge the start battery. MS assumes that the house bank is just discharged.

I recommend that people test their starting battery periodically to make sure it can start the engine. It should be done with the engine cold. Not having an ACR I test mine when I have been away from shore power for a few days.

If both the house bank and the start bank are low do not be afraid to combine them. Combined you will get more starting current than with just one bank.

I make no claim that my methods are significantly better than MS's, only different, and they work for me.

 

[rwthomas1]

How about another opinion?
I have my setup exactly as MaineSail describes with the exception that I have a Blue Seas Dual Circuit Plus switch. The original off-1-2-both switch had black terminals and the Dual Circuit was on sale at the time. It has worked fine for me.

While I would agree that using the "both" feature of the Dual Circuit, provided one bank or the other is dead, will bleed off precious amps is valid, I don't worry about it too much. If I ever needed the "both" feature I would likely be just to start the boat. The amp loss will not be critical in that short period of time. If for some reason a battery bank is damaged, on my boat it is a pretty simple thing to move cables. The batteries are easily accessed in less than 30 seconds and the cables are long enough to allow for this.

I also do not like the idea of an emergency battery just sitting around unused. My experience with batteries of all types is they like "exercise", regular use, not abuse, prolongs life. Starting the engine with a dedicated start battery makes sense to me. Keeps the voltage drops, if that is a concern to you, isolated as well.

I have a Blue Seas ACR. It works wonderfully. They no longer make the model I have but it has been trouble free.

Regarding hooking up the Xantrex charger. My ACR works with ANY CHARGING SOURCE! You may not need the second bank feature. Wire it to the house bank and the ACR will connect it to the start battery automatically. Check to see if the ACR you are looking at will do this. I'm guessing it may be a bad thing if the Xantrex is trying to charge two banks and the ACR then kicks in and latches them together?

When I replaced the battery cables I used very heavy cable. The whole thing, including the alternator output and ground is done with 0000 cable, IIRC. Way overkill but certainly no voltage drops or lack of amps to the starter or otherwise.

Works for me!
RT

 

[Maine Sail]

The risk of the BOTH feature comes into play when a house bank is considerably larger than the start battery or when using AGM's or other high acceptance/high discharge batteries. With wets it won't hurt too badly unless the start battery is nearing the end of it's life or the house bank is very large, but why bother if you don't have to. If you have a dead bank that won't start the motor simply switch to the known good bank. By switching to BOTH the good start battery is both trying to raise the voltage/charge the dead bank, and to also start the motor. This is a lot to ask of the typical small starting batts we often use.

Lifeline batteries can accept a 5C inrush or 500 amps for a 100 amp hour battery. Take a 400 Ah bank of Lifeline's at dead and a 65 Ah AGM start battery and this transfer of current can be rapid and the voltage drop very fast. As the voltage begins to drop the current slows but is still being whacked by the dead bank. I have done this on the bench and and seen over 85 + amps flowing out of the smaller starting battery shortly after being combined.

The reason I worry about this is because it happened to my buddy Tom with his bank of Lifeline's. I have also seen a known good starting battery combined with a dead 450 Ah bank that was barely able to crank the motor. We switched back to bank 2 from BOTH and vrooom, no issues even after having just been combined. I was doing this to show a customer why I don't suggest using BOTH in an emergency situation. He was sold after seeing & hearing the before and after cranking performance.

Again, not as critical on wets but on AGM's the transfer of current can be quite fast due to the high acceptance rates of these batteries.

Keep in mind that when a battery is dead enough so that it can't start or crank your motor you really gain little by combining it as there are so little CA's left that it only serves to whack the good batt and ask it to do double duty..

 

[lbertran]

Great Ideas!

Maine Sail, Tom, Rob-
Thank you all so much for taking the time to educate me. This is all very helpful and has really helped me understand the underlying reasons for the various wiring options. I think a great case has been made for keeping the Off-1-2-Both switch and I now plan to do that. I will make the house bank #1 and the new starting battery #2. I already have a Blue Sea CL 7600 Batterylink ACR which I will use to combine the two banks.
As I understand your posts, I don't have to run a wire from the battery charger to the new starting battery as long as I have it connected to the combiner, right?
I would also prefer to leave the starter/alternator connection at the battery switch rather than lead it directly to the house bank. If I read your posts correctly, that will work, right?

 

[Maine Sail]

As I understand your posts, I don't have to run a wire from the battery charger to the new starting battery as long as I have it connected to the combiner, right?

That is correct.

I would also prefer to leave the starter/alternator connection at the battery switch rather than lead it directly to the house bank. If I read your posts correctly, that will work, right?

That will work fine but will leave you with the potential for frying the alternator diodes if you pass through OFF with the motor running. Having dealt with soooo many fried diode situations I find it much easier to simply direct wire to the house bank, but no it is not necessary. The only time it is "necessary" is if you were using an Echo Charger or Balmar Duo Charge device. With an ACR/VSR not necessary..

 

[Bob Robertson]

Hi Laura,

This topic was discussed earlier in this thread. Please let me know if I can be of help.

Enjoy,
Bob

 

[lbertran]

Alternator Wire

Thanks, Maine Sail and you too, Bob.

That's a good point about frying the alternator by switching through the Off position. It's something I've been successful in avoiding doing all my years on boats but like they say, there's always a first time.

BTW, Maine Sail, I'll also be installing a Victron battery monitor using your exquisite instructions. Thanks for that too.

 

[Tom Metzger]

Operating on the house bank exclusively, as MS & I both do, eliminates the need to touch the battery switch while the engine is running so popping diodes is not really a problem.

As far as combining batteries for starting, if a battery has enough strength to barely crank a diesel it is not dead and can be useful. The at rest voltage will not be so low that you will hurt the typical starting battery for a few seconds before you hit the start switch. I would not do it unless the starting bank was also weak.

If you have a 400 ah AGM house bank the design should take this into consideration from the beginning. I would probably not use a 1-2-both switch. That said, I can't think of a reason to have that large of an AGM bank on an Ericson. Too much money - too little value.

 

[Loren Beach]

Those cables

I wonder if our "factory" wire diagram would be helpful in this discussion. (?)
I drew this after installing the shunt for the AH meter, but the rest is "stock."
The alternator wiring is not shown -- next opportunity to trace and label wiring, maybe I can include it.

Loren

 

[lbertran]

Trojan 145 Golf Cart Batteries

My current house bank is a pair of group 27's. My plan is to upgrade to a pair of Trojan 145 GC's. So given that all are wet cells and even the upgrade to the Trojans will only take me to 260 AH, I think I'm ok.

Thanks for the wiring diagram, Loren.

 

[rwthomas1]

FWIW, I understand the points made, but they way I have it works, and I know the pitfalls. If the house is truly dead, I can simply take it out of the mix by disconnecting it. I have (3) three groups 31's for the house and a commercial group 31 truck starting battery for start. All are wet cells. With the cable size I have it spins the Universal effortlessly.

RT

 

[MarkA]

I don't like to use the 1-2-all-off switches, unless there are two; one for the house distribution, and one for the starter. I recently replaced my old Perko with a Dual Circuit Plus (Blue Sea 5511E) so the two circuits are kept separate. To me, it is important to keep the house distribution and the starter circuits completely separate and independent of one another.

I've never had a reason to combine batteries for starting and, if I did, I would think twice about it. It's better to switch to the good bank than combining good with bad. I cannot do that with my switch configuration, but I can run jumper cables from the house bank to the starter motor if needed.

My house bank consists of two Trojan 145 Plus in series, and I have a group 27 12-volt starter battery.

I have three chargers: the alternator, an a/c shore power charger, and a solar panel. All three are connected to the house bank; none go to the starter battery. However, the starter battery is connected to the house bank via a Blue Sea ACR 7600, which is wired to monitor both banks, and also has a manual open/close/auto switch and LED indicator on my distribution panel.

I monitor all this with a Xantrex LinkPro, and it works perfectly. My solar panel juices the system with 3.5 amps when needed, so I rarely discharge much, even running all the electronics and creature comforts.

Regarding earlier comments: I may have misunderstood, but I think someone said to fuse the alternator wire within 7 inches of the battery--that is incorrect. The fuse must be within 7 inches of the power source which, in this case, is the alternator and not the battery. But more importantly, and this is debatable, most people do not recommend fusing the alternator wire at all because when that fuse blows, you'll fry the diodes on the alternator! (And, come to think of it, mine is connected to a bus bar that is fused at the battery terminal, hmmm....)

 

[Maine Sail]

Regarding earlier comments: I may have misunderstood, but I think someone said to fuse the alternator wire within 7 inches of the battery--that is incorrect. The fuse must be within 7 inches of the power source which, in this case, is the alternator and not the battery.

Actually Mark that statement was correct. Under ABYC E-11 most all alternators would be considered a "self limiting" device and does not technically require a fuse at that end of the wire unless the wire is 40" or longer but it does require one at the source of power. The fuse should be within 7" of the "power source". If not run to the power source/battery or then there are exceptions for that.

E-11 considers the battery the main power source on the DC side. On the AC side power sources are generator, inverter and shore power. The fuse is not to protect the alternator it is to protect the wire, just as battery fuses are in the event of a dead short. You can alternatively sheath the wire from the alt to the battery but it can't exceed 40" before needing a fuse.

Battery chargers connected directly to a battery should be protected internally at that charger and at the battery. Basically any direct connection to a bank should have and OCPD sized properly for the wire.

I'd personally rather deal with fried diodes in the event of a dead short than a boat fire. This fuse under E-11 can technically be up to 150% of the Table VI ampacity rating but I try not go above 100% and would rather use bigger wire than go to 150%.

Of course you don't even have to wire your boat to ABYC standards so you could use 16 GA wire run through a bucket of grounded barbed wire and no one is going to tell you not to, except maybe your insurance company after an insurance survey..



11.10. OVERCURRENT PROTECTION

11.10.1 LOCATION OF OVERCURRENT PROTECTION - DC CIRCUITS

11.10.1.1 General Requirements

11.10.1.1.1 Overcurrent Protection Device Location - Ungrounded conductors shall be provided with overcurrent protection within a distance of seven inches (175mm) of the point at which the conductor is connected to the source of power measured along the conductor.

 

[rwthomas1]

You can alternatively sheath the wire from the alt to the battery.

MS, can you explain this? The alternator wire to the house battery bank on my boat is 2 feet long, tops. Its also run though a length of clear PVC hose for chafe protection. There isn't much that would chafe it as the run is so short and its through wood cabinetry..... There is currently no fuse, so does the hose count as sheathing or should it be fused at the house bank connection?
Thanks, RT

 

[Bob Robertson]

I installed a second 1 2 both switch as discussed in the thread I referenced earlier.

This combination of switches allows me to use the house and engine batteries to start the engine or to just use the house or engine battery to start the engine.

I can also use either the house batteries and or the engine battery to run the house.

Bob

 

[MarkA]

Actually Mark that statement was correct. Under ABYC E-11 an alternator is considered a "self limiting" device and does not technically require a fuse at that end of the wire. The fuse should be at the "power source" which is the battery bank. The fuse is not to protect the alternator it is to protect the wire, just as battery fuses are in the event of a dead short. You can alternatively sheath the wire from the alt to the battery.

I'd personally rather deal with fried diodes in the event of a dead short than a boat fire. This fuse under E-11 can technically be up to 150% of the Table VI ampacity rating but I try not go above 100% and would rather use bigger wire than go to 150%.

Of course you don't even have to wire your boat to ABYC standards so you could use 16 GA wire run through a bucket of grounded barbed wire and no one is going to tell you not to, except maybe your insurance company after an insurance survey..

Thanks, I stand corrected about the true "power source" in this context. Next question: Are all alternators considered self-limiting?--or only those with internal regulators? I should buy a copy of the standards.

My banks are fused at the positive terminals, well within 7", and I replaced the barbed wire with 4/0 AWG Ancor Marine (though I misplaced my lug crimpers, so I scotch taped the ends to the terminals--that's ok, right?--just until I locate my crimpers?)

I'm with ya on the dilemma of sacrificing the alternator versus burning down the boat. But I rarely motor, and my solar panel takes care of most charging needs here in Southern California. If I ever really used the alternator, I'd probably sheath that 4-foot 6 AWG and remove the fuse.

 

[MarkA]

I installed a second 1 2 both switch as discussed in the thread I referenced earlier.

This combination of switches allows me to use the house and engine batteries to start the engine or to just use the house or engine battery to start the engine.

I can also use either the house batteries and or the engine battery to run the house.

Bob

I haven't read the thread, but I concluded that was the ideal setup just after replacing my switch. I might do that.

 

[Maine Sail]

MS, can you explain this? The alternator wire to the house battery bank on my boat is 2 feet long, tops. Its also run though a length of clear PVC hose for chafe protection. There isn't much that would chafe it as the run is so short and its through wood cabinetry..... There is currently no fuse, so does the hose count as sheathing or should it be fused at the house bank connection?
Thanks, RT

Rob,

I would consider a PVC tube a "sheath" but the sheath only counts if not "directly connected". With sheathing you can go as far as 72" before a fuse, but you still need one.

The wording is confusing that is why I have asked for clarification from John Adey on this. Alt's are self limiting thus a fuse/ocpd is not necessary at the alt end despite confusing wording in the standard which is a hold over from the days of generators. Because this wording is still in the CFR it is still in E-11 despite attempts to change it.

This is why you don't see boats with fuses at the alternator even when built to ABYC standards. The bottom line is that you are probably more than "safe" but if you want to do it to the "standard" then unless it is a "cranking motor" conductor it should be fused as close to the battery as possible.

On smal AUX engines I fuse both banks as the rational behind the cranking motor exemption makes little sense on small motors. Been fusing them for about 18 years and never once had a "nuisance blow". I did have a direct ground short that took a big chunk/weld out of my motor mount on our 2005 Catalina. Catalina had routed the wire to tight to the mount and when the motor moved forward under load the starter wire chafed. Luckily I had fused that bank before taking delivery.

When you get to big honking diesels in sport fishing boats OCPD protection becomes very difficult and very expensive so the cranking motor exemption still stands.