SmartBank Advanced. Circuit diagram question

[Theo]

I installed SG/SB in 2007 and have been happy with it's performance during the past 5,000+ hours of cruising.  I was having a reread of the manual today and this reminded me of something that I find decidedly odd.

I have downloaded Gibbo's diagram from the new site and checked that it is the same as the one that I have printed out from the old site.  To the left of the green and black box at the bottom are the words "Charge sources and alternators may connect to either battery bank."  This statement mystifies me and the manual is very carefully written and full of good info so I suspect that I am not understanding something.

SmartBank is a split charge relay system with some important bells and whistles attached.  One of the bells is that it is designed to ensure that the engine battery is fully charged before energising the relay to parallel the domestics (called "Main auxilliary bank" in the diagram).  This will required the charging source (alternator, battery charger or solar panels) to be connected to engine battery.  That is somewhere along the thick purple wire that I have marked 'B' in the diagram. If you connect to thick purple wire marked 'A' then until the relay connects the engine battery gets nothing and at best the domestics get priority.

So is the statement "Charge sources and alternators may connect to either battery bank." wrong or am I not understanding something.

Nick

SmartGauge-SmartBank query.pdf

[jddevel]

Can you please advise ignorant me what`s the difference between a  battery monitor and a Smart gauge/Smart bank. Is the later yet another piece of equipment I need to research so it`s ready for my marine electrician to get on with things. I ask this because experience has taught me that what the electrician provides will relate to the contact with his wholesaler.

[WotEver]

28 minutes ago, jddevel said:

Can you please advise ignorant me what`s the difference between a  battery monitor and a Smart gauge/Smart bank.

Here's what the developer says:

http://smartgauge.co.uk/chg_summary.html

[Tony Brooks]

51 minutes ago, jddevel said:

Can you please advise ignorant me what`s the difference between a  battery monitor and a Smart gauge/Smart bank. Is the later yet another piece of equipment I need to research so it`s ready for my marine electrician to get on with things. I ask this because experience has taught me that what the electrician provides will relate to the contact with his wholesaler.

In my view the Smartbank is an addition to the Smartgauge that is little more than a good quality and glorified split charge relay so probably not so much use if you have twin alternators. What it will do is ensure you are kept away from some poor quality split charge relays.

Even with only one alternator I feel the claimed advantage of charging the engine battery first is somewhat over done. Unless the start battery is faulty of you have an engine fault the discharge during starting is only a few Ahs so whatever kit you have the start battery will be recharged in less than half an hour in most cases.

Ideally you should have battery monitoring of some sort but as discussed here many times before an Amp hour counter (like a BVM) stands a good chance of encouraging you to ruin your batteries. I would suggest a good quality shunted ammeter to tell you when its time to stop charging and a Smartguage to tell you when its best to start charging.

All in my opinion but I use a voltmeter instead of a Smartguage.

[Theo]

1 hour ago, Tony Brooks said:

In my view the Smartbank is an addition to the Smartgauge that is little more than a good quality and glorified split charge relay so probably not so much use if you have twin alternators. What it will do is ensure you are kept away from some poor quality split charge relays.

Even with only one alternator I feel the claimed advantage of charging the engine battery first is somewhat over done. Unless the start battery is faulty of you have an engine fault the discharge during starting is only a few Ahs so whatever kit you have the start battery will be recharged in less than half an hour in most cases.

Ideally you should have battery monitoring of some sort but as discussed here many times before an Amp hour counter (like a BVM) stands a good chance of encouraging you to ruin your batteries. I would suggest a good quality shunted ammeter to tell you when its time to stop charging and a Smartguage to tell you when its best to start charging.

All in my opinion but I use a voltmeter instead of a Smartguage.

I have to confess that I was somewhat beguiled by the intelligence of the cleverness of the SmartBank.  Theodora was fitted with a 1, 2, Both, Off switch when we bought her and I was certain that was a recipe for trouble.  Forgetting to set it aright each time you start and stop leads to tears later and this was bound to happen at some point. I heard it mentioned on here and Gibbo was pretty convincing in his discussions(!) with Chris W.

I wholeheartedly agree with the point about the ammeter, Tony.

 

Nick

 

[Tony Brooks]

Actually any VSR would do what is claimed for the Smartbank to a degree IF the alternator output went to the engine battery. With a well discharged engine battery the charging current will depress the charging voltage. As long a sit is held below the VSR closing voltage only the battery connected to the alternator would be charged. The downside of that is it is likely to result in high currents through the relay contacts and that tends to shorten their life so best practice is to wire the alternator to the domestic bank. In that case you get domestic battery charging first and as they are usually the most discharged some would say its a good thing.

As the current flowing from a charge source into a battery bank depends upon the voltage difference between the source and battery voltage even a simple split charge relay will allow the charging current to be apportioned between batteries in proportion to their depth of discharge.

I think the Smartbank can initiate a low voltage alarm and perhaps operate a low voltage shut down relay but in my book its just more complication and it may even be the Smartgauge that does that. In my view far simpler to just keep and eye on the battery voltage and act accordingly. On a tolerably well set up boat night and morning seems to be enough unless you are using a lot of inverter driven stuff or long periods.

 

[Iain_S]

5 hours ago, Tony Brooks said:

In my view the Smartbank is an addition to the Smartgauge that is little more than a good quality and glorified split charge relay so probably not so much use if you have twin alternators. What it will do is ensure you are kept away from some poor quality split charge relays.

Even with only one alternator I feel the claimed advantage of charging the engine battery first is somewhat over done. Unless the start battery is faulty of you have an engine fault the discharge during starting is only a few Ahs so whatever kit you have the start battery will be recharged in less than half an hour in most cases.

(snip)

I agree.

When I first installed a Smartgauge/ Smartbank combination, I wired it with the alternator connected to the engine side. After reflection and because it made the Adverc misbehave, I swopped the alternator connection over to the cabin battery and set the 2nd battery to "Aux" rather than "Eng" to disable the "Engine Priority" feature. On further reflection, I changed it back to "Eng", so that the "Engine Priority" is re-enabled, but is actually "Cabin priority". The idea is that the cabin batteries get a bit of a surface charge before the relay connects, thus reducing the current through the relay.

There is another advantage to this, which I found when we had a share in Copperkins. Wired as per instructions, with alternator to engine, the relay would drop out when there was a heavy demand (Hoovering  ). This meant that the cabin battery wasn't getting charged for a minute or so until the relay cut in again. With alternator wired to the cabin bank, the relay still drops out, but now it's the cabin bank which is getting the charge, the relay stays out while the demand lasts and there is less net discharge on the batteries and less wear and tear on the relay.

To answer the original question, whenever the voltage on either bank rises above the set "cut in" voltage, the relay will operate, connecting the engine and cabin batteries together.

 

[jddevel]

6 hours ago, Tony Brooks said:

good quality and glorified split charge relay so probably not so much use if you have twin alternators

Having read the Smartgauge link suggested by WotEver please correct me if wrong but what appears to me to be a tremendous advantage of the Smart Bank is the ability to use "surplus" charging available from my starter alternator once the starter battery is fully charged. Is that correct please and should it sway my purchase especially as family may occasionally use my craft?

[WotEver]

Just now, jddevel said:

Having read the Smartgauge link suggested by WotEver please correct me if wrong but what appears to me to be a tremendous advantage of the Smart Bank is the ability to use "surplus" charging available from my starter alternator once the starter battery is fully charged. Is that correct please and should it sway my purchase especially as family may occasionally use my craft?

As Tony B points out, a VSR would achieve much the same thing for a lower outlay. 

http://www.12voltplanet.co.uk/voltage-sensitive-relay-12v-140a.html

[Tony Brooks]

8 hours ago, jddevel said:

Having read the Smartgauge link suggested by WotEver please correct me if wrong but what appears to me to be a tremendous advantage of the Smart Bank is the ability to use "surplus" charging available from my starter alternator once the starter battery is fully charged. Is that correct please and should it sway my purchase especially as family may occasionally use my craft?

Ah, but does it mention what may happen of the regulated voltage of both alternators differ once both batteries are charged enough to allow the charging voltage to reach the regulated voltage?

ANYTHING that parallels the  two alternators and both battery banks will allow the alternators outputs to be combined BUT once regulated voltage is reached one may shut down and that may produce spurious fault symptoms, not what you want with less knowledgable people running the boat.

As far as the speed of battery charging is concerned I doubt it would shorten it by much more than half an hour or less. Most of the time the alternaator is producing way under its maximum output.

See pinned alternator paralleling topic that has been on display for ages.