Charging 4 banks from 1 alternator?

[skipmac]

Originally Posted by Davidhoy

Hi Raymond, can you elaborate on the issues you had? I prefer to learn from the mistakes of other ;-)


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The problems with manual switching systems, typically using the 1-2-BOTH switch are obvious. Switch to BOTH for charging but you're tired, stressed or whatever, forget to switch away from BOTH and you run down the start battery. Or you could have a helpful guest switch to BOTH for you.

I have heard about zero problems with the brand name auto combiners like the Yandina Combiner or the Echo charge or Duocharge so know of no downside. Of course they are electrical devices and can fail but their track records are pretty darn good. If you monitor start battery voltage as a final check you're 99.99% safe.

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[btrayfors]

Skipmac has it exactly right.

To summarize:

1. connect ALL charging sources directly to the HOUSE bank (which should be run as a single, high-capacity bank); and

2. keep the start battery charged via a smart combiner (I prefer the EchoCharge which is totally automatic, very reliable, and works with mixed battery chemistrys).

You don't need a separate generator start battery. Either run it off the house batteries (as I have successfully for over 26 years) or the start battery.

Monitor the voltage of all batteries.....you don't need an amp-counter device; they can be deceptive. One which isn't but is a bit pricey is the SmartGuage.

That leaves the windlass/thruster battery. Many people use heavy cabling to connect this battery to the house battery bank. Some instead use a combiner device, like the EchoCharge, to maintain that battery. I use a dedicated 120VAC battery charger (an Iota DLS-55/IQ4) powered either from the generator or an onboard inverter.

My setup: 6 golf-cart batteries in a single bank for the house batteries; 1 group 31 start battery; 2 golf-cart batteries for the windlass up forward. I've just completed a 3.5-month cruise in Maine this summer during which my boat -- a 42ft sloop -- was not plugged into shore power even one time. Only thing I'd add would be solar power, but that's for the future.

Bill
s/v Born Free

[smac999]

I wouldn't bother charging a gen battery from a engine alternator. The gen will have its own alternator and will Maintain its own battery. I would however have a shore power charger hooked up to it for dock / storage maintenance. You should have a manual parrellel switch from engine battery to gen battery for emergancy gen starting. This also means If you really needed to charge the gen battery from engine you could turn this on.

Echo charger or acr from house battery to engine battery is good. (With alt direct to house bank)

The thruster battery is tricker as it will draw lots off current throug those wires. So you still need very large wires to the front. And a large rated acr. The echo charge may be enough if you don't use it much. They are limited to 15a so will take a while to charge if you used the thruster a lot. a isolator like the victron one alt To the 3 banks is also good.

[BambooSailor]

+1 for combining all house batteries into one bank and use Echo charge to charge start batteries. Beside simplifying your wiring, you'll get much better life from your house bank. And get good battery monitor.

[Davidhoy]

Originally Posted by BambooSailor

+1 for combining all house batteries into one bank and use Echo charge to charge start batteries. Beside simplifying your wiring, you'll get much better life from your house bank. And get good battery monitor.

All the house batteries are already one bank. Sounds like I can really simplify things, and simpler is always better. I ordered a Blue Sea M2 SoC monitor, which seems to combine the best of what Ah monitors do with actual state-of-charge monitoring.

This is why I enjoy hanging out on this forum. Hopefully one day I'll be able to give back as much as I'm getting now.




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[RaymondR]

Originally Posted by skipmac

The problems with manual switching systems, typically using the 1-2-BOTH switch are obvious. Switch to BOTH for charging but you're tired, stressed or whatever, forget to switch away from BOTH and you run down the start battery. Or you could have a helpful guest switch to BOTH for you.

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This was the first bad one. After me spending about 15 minutes explaining about voltage spikes and never switching the battery selector switch via the Off position he did so and blew all the instrumentation.

Then I have had voltage sensitive relays which were not so the alternator did not get switched to the house bank and since I was running all the nav equipment from the house batteries ended up with fairly flat house batteries in the middle of the night.

Then I burned an alternator up because most of them are only rated to their full rating for about five or ten minutes before they start to seriously overheat and dropping 800 amp hours of well discharged house batteries onto the alternator will make it go to it's rating for an extended period.

Then there is the complicated systems problem when you are trouble shooting and everything is connected via the earth system.

I also like the redundancy of having two alternators on a single engine boat (My boat actually has two starter motors on the engine as well)

Life just got a lot simpler with two separate systems each with it's own alternator.

[skipmac]

Originally Posted by RaymondR

This was the first bad one. After me spending about 15 minutes explaining about voltage spikes and never switching the battery selector switch via the Off position he did so and blew all the instrumentation.

Easy cure for this problem is to wire the alternator (and all other charging sources) directly to the house battery and bypass any switches. If you have a combiner of some type for the start battery there's no reason at all to wire any charging source through a switch. Just make sure the wires to the battery are properly fused. I think the Blue Sea Systems terminal fuses are the perfect solution for this.

With the house batteries as one bank and charging sources connected directly there's no routine need to ever move that switch. I use a plain ON/OFF switch for the house banks. Some do divide the house batteries into two banks, keep the switch to BOTH but have the option to use bank 1 or bank 2 individually for maintenance or repair.

Originally Posted by RaymondR

Then I have had voltage sensitive relays which were not so the alternator did not get switched to the house bank and since I was running all the nav equipment from the house batteries ended up with fairly flat house batteries in the middle of the night.

Again, charging connected directly to the house batteries will solve this. Then the relay to connect the start battery for charging, voltage monitor to verify the start battery is getting charge.

What brand or model VSR were you using? I know some of them must fail but again I have personally heard of no failures with the units from Xantrex, Balmar, Yandina. I think Blue Seas may also make one and I like their kit a lot.

Originally Posted by RaymondR

Then I burned an alternator up because most of them are only rated to their full rating for about five or ten minutes before they start to seriously overheat and dropping 800 amp hours of well discharged house batteries onto the alternator will make it go to it's rating for an extended period.

I also like the redundancy of having two alternators on a single engine boat (My boat actually has two starter motors on the engine as well)

I assume from your description one alternator charges the house bank and one the start battery? If so, that doesn't solve the problem of overheating an alternator because one alternator is still charging a big house bank that can be at a low SOC. The cure for this is a programmable regulator or a bigger/better alternator or both.

If you have room on the engine for two alternators (and two starters?) then that's not a bad thing but lots of engines or boats just can't fit that. It can also be rather expensive to build a custom mount for a second alternator if the engine isn't designed for it. I once spent over $500 modifying an engine to upgrade from the stock 60 amp alternator to a 120 amp Leece Neville. The stock brackets and pulleys wouldn't handle the bigger unit so all had to be modified or replaced. I think adding a second alternator would cost at least as much if not more.

My solution is to carry a spare alternator with internal regulation. Then if either my main alternator or its external, smart regulator dies I have a quick, easy swap out.

[ramblinrod]

Originally Posted by skipmac

Hi David,

If you spend a few minutes with the forum search functions on charging multiple banks, the 1-2-BOTH switch you will find hours of reading.

Short summary, my opinion and that of many experts and very experienced cruisers this is a simple, foolproof way to wire a boat.

1. All house batteries wired together in one large bank.

2. One good start battery isolated from the house banks and used only to start the engine.

3. ALL charging sources (alternator, solar, wind, battery charger) connected directly to the house battery bank.

4. Install an automatic battery combiner like the Yandina Combiner, Balmar Duocharge or Xantrex Echo Charge. This will connect the start battery to the charging system only when charging is happening. When the engine is off and the alternator is no longer charging (or the sun is down and solar not charging, etc) then the start battery is automatically disconnected so it will always be charged and ready to start the engine.

If the house batteries are the same brand or at least the exact same type and same age then they should charge and discharge equally.

Some alternative suggestions:

1. Consider installing a 1/2/B/Off isolation switch to split the house bank. The normal condition will be for all house batteries to be combined. The isolation switch may be used in an unusual circumstance to isolate a failed battery from the rest of the house bank, until repairs can be effected.

I don't recommend an isolation switch for each battery (unless only a two 12Vdc battery bank), as it makes the system overly complicated and costly and introduces unnecessary potential failure nodes. One isolation switch, splitting the bank in half, regardless of the number of batteries in the bank.

The alternate solution is of course to pull the battery terminal to isolate a defective battery from the bank, but an isolation switch is very convenient for this purpose.

In addition, the 1/2/B/OFF switch allows one to easily and positively disconnect the DC distribution panel from the house bank, for vessel DC electrical system servicing.

4. For a windlass/thruster battery, any of the devices indicated are OK. For the start battery, I recommend only a device that the user can manually combine the house bank and start battery in an emergency, (i.e. start battery is dead) such as the Blue Sea ACR.

[ramblinrod]

Originally Posted by Davidhoy

Let me preface this with the fact that I have a tremendous amount to learn about marine electrics! If my question or terminology are a little off, please help me to understand things better :-)

I have 4 banks of batteries on my boat - 4x deep cycle house batteries, 2x engine start batteries, 1x generator start battery, and 1x windlass/thruster battery. I'd like to have all four banks charge off the alternator when the engine is running. Firstly, is this realistic? If it is a reasonable thing to do, what is the best way to do this without lots of manual selector switches? I've been looking at battery combiners and isolators, they seems to do what I want. However, there do not seem to be any that take a single input and 4 outputs. Can I connect the alternator to two dual-output devices instead of a single quad? Or use a dual input, quad output version? Are there better ways to achieve what I want?

Regards,
David


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One more thing in addition to my last post. Check the generator manual. Most have their own charging system to recharge the generator start battery, and therefore there is no need to connect it to a main engine alternator. This way, one can be at anchor indefinitely, running the AC and DC electrical systems, (assuming AC generator or DC with large AC inverter) and never need to start the primary engine.

[skipmac]

Originally Posted by ramblinrod

Some alternative suggestions:

1. Consider installing a 1/2/B/Off isolation switch to split the house bank. The normal condition will be for all house batteries to be combined. The isolation switch may be used in an unusual circumstance to isolate a failed battery from the rest of the house bank, until repairs can be effected.

This idea can be very useful and would also allow quick isolation of a bad battery in the rare but not unheard of case of a shorted battery. However it will add some complexity to the wiring and in the fairly common case of six pairs of 6V deep cycle batteries you end up with different sized banks or adding another switch to isolate each bank.

Originally Posted by ramblinrod

For the start battery, I recommend only a device that the user can manually combine the house bank and start battery in an emergency, (i.e. start battery is dead) such as the Blue Sea ACR.

For emergency starting I use a 1-2-BOTH switch. Output to the starter of course, 1 to the starting battery, 2 to the house bank. Keep the switch always on 1 or OFF unless house needed for emergency starting. Dead simple and cheap.

[ramblinrod]

Originally Posted by skipmac

This idea can be very useful and would also allow quick isolation of a bad battery in the rare but not unheard of case of a shorted battery. However it will add some complexity to the wiring and in the fairly common case of six pairs of 6V deep cycle batteries you end up with different sized banks or adding another switch to isolate each bank.

For emergency starting I use a 1-2-BOTH switch. Output to the starter of course, 1 to the starting battery, 2 to the house bank. Keep the switch always on 1 or OFF unless house needed for emergency starting. Dead simple and cheap.

Any/every 12 Vdc charging system review requires consideration of:

1. User Needs and Desires.
2. Existing Components.
3. Space Available.
4. Loads.
5. Battery Storage Capacity.
6. Charging Source Capacity.
7. Servicing.
8. Budget.

The OP provided some great info, but still insufficient to make a complete and proper recommendation.

Because the house bank was declared as "4 batteries" and the preference for few manual switches was declared, the recommendation to use a 1/2/B/Off switch to split house bank and an ACR to combine the start battery, is the best recommendation I can offer (especially if the vessel is already equipped with a 1/2/B/Off switch to isolate the start bank, which can be reconfigured).

The bow thruster / windlass battery bank requires more owner info to come up with a definitive recommendation.

Options include:

1. The second output of the AC charger. (Existing equipment, low cost, but only works on shore power or generator.)
2. A dedicated AC charger forward (may be easier to wire and will not detract from house bank charging, but still needs shore power or generator).
3. An echo charger (may take a long time to recharge with 15 A limit, and may draw down the house bank substantially if charge sources aren't delivering).
4. A second ACR. (Higher cable cost, only works while engine is running.)
5. A second alternator. (Higher cable, component, and installation cost, only works while engine is running).

[ramblinrod]

Originally Posted by skipmac

For emergency starting I use a 1-2-BOTH switch. Output to the starter of course, 1 to the starting battery, 2 to the house bank. Keep the switch always on 1 or OFF unless house needed for emergency starting. Dead simple and cheap.

An ACR with manual house/start combine switch is a better solution than an echo charger and 1/2/B/Off switch combo.

That a 6 volt battery system may split unevenly, is actually another argument for sticking with 12 Vdc batteries.

However, in an emergency situation, whether the house bank is split evenly is of little importance; the most important issue is to isolate the bad battery from those being relied on to supply the house loads until repairs can be made.

With a 6 x 6 Volt system, you may have 4 battery capacity or 2 battery capacity until repairs are made, but at least the bad battery is isolated.

Some means to isolate is vastly superior to none.

One could alternatively have an isolation switch for each 2 x 6 Vdc bank with an ACR (c/w manual combine switch) to charge the start bank, which is a very good solution, but adds more complexity and leaves one with an unnecessary 1/2/B/Off switch (if originally equipped).

[Dockhead]

Originally Posted by RaymondR

Been through all the manual switching and automatic switching relay setups and sooner or later one comes to grief with them. The only really reliable way to do it is entirely separate the house and cranking systems and put two alternators on the engine, one for each. Probably the lowest cost in the long run.

This, absolutely

Best practice is not to connect start battery and charging system, and domestic system, in any way. It's a serious failure waiting to happen.

I would suggest:

1. Charge your generator start battery from the generator's alternator.
2. Charge your engine start batts (I guess it's 24v, hence two batts?) from the standard engine alternator.
3. Charge the house bank from a second, high output, heavy duty school bus alternator, regulated with Balmar or similar.
4. Charge the bow thruster batt with an echo charger from the house bank.


Don't use a 1-2-combine switch. If you need to emergency start one machine from other batteries, use jumper cables.

But you'll never need to do that, if your system is set up like this, because there is almost nothing to go wrong.


The second alternator may be relatively expensive to install (you will need brackets, an extra double-belt pulley, and SPACE for all of that), but it's worth its weight in gold if you can do it. It solves the problems in the OP, and on top of that gives you real reliable bulk power production. A car-type alternator like your engine came standard with, is not designed to put out full output continuously. You will burn it up trying to charge all those batteries with it, unless you carefully regulate and derate it, but then it won't put out much power.

[ramblinrod]

Originally Posted by Dockhead

This, absolutely

Best practice is not to connect start battery and charging system, and domestic system, in any way. It's a serious failure waiting to happen.

I would suggest:

1. Charge your generator start battery from the generator's alternator.
2. Charge your engine start batts (I guess it's 24v, hence two batts?) from the standard engine alternator.
3. Charge the house bank from a second, high output, heavy duty school bus alternator, regulated with Balmar or similar.
4. Charge the bow thruster batt with an echo charger from the house bank.


Don't use a 1-2-combine switch. If you need to emergency start one machine from other batteries, use jumper cables.

But you'll never need to do that, if your system is set up like this, because there is almost nothing to go wrong.


The second alternator may be relatively expensive to install (you will need brackets, an extra double-belt pulley, and SPACE for all of that), but it's worth its weight in gold if you can do it. It solves the problems in the OP, and on top of that gives you real reliable bulk power production. A car-type alternator like your engine came standard with, is not designed to put out full output continuously. You will burn it up trying to charge all those batteries with it, unless you carefully regulate and derate it, but then it won't put out much power.

Best practice according to whom?

While a second alternator is an option, it certainly is not the only one, and not even the preferred one in most cases, in my opinion.

While a second alternator affords some redundancy, alternators are fraught with problems like loosening and smoking belts, regulator failures, over heating, worn out brushes, worn out bearings, etc.

A properly installed ACR should be problem free far longer than any alternator will be, is much easier to install, takes less space, no moving parts, etc.

[skipmac]

Originally Posted by ramblinrod

Best practice according to whom?

Are you referring to best practice by isolating the start and house batteries? That is best practice according to experience, common sense and the best and brightest marine electrical pundits.

Yes one can make up special setups and unusual systems where one could argue that combining house and start makes sense but not for 99.9% of the boats and boaters. A dedicated, isolated, protected start battery can be critical. In some situations it could mean save or lose a boat or even a life.

I can really think of no negatives at all for having an isolated starting battery for anyone.