noelex
Well-Known Member
The battery will self limit the current. Large alternators and chargers are quite safe in marine systems providing the regulator is doing its job
Will I cook my starter battery by fitting a smart charger
- Thread starter superboots
- Start date
BabaYaga
Well-Known Member
Very interesting thread, this.
Returning to the OP’s question ”will I cook my starter battery?” I would suggest that the only way to do so would be to feed it with a voltage that is too high (over 14,4 at normal temp) for an extended period of time.
As I see it the danger, if any, lies in using an external voltage regulator that boosts the voltage in order to reduce charging time (I believe Sterling does this, as opposed to Adverc).
These high voltages , perhaps 14,8 or so, would occur towards the end of the charging, when the service bank is almost fully charged (and the starter battery long since so).
For very long engine runs, a manual switch for disconnecting the starter battery from the charging circuit might be a good idea (at least for peace of mind). Anyway that is how I have arranged my own system, a service bank of 240 ah wet cells that is paralleled with a smallish AGM starter battery.
Returning to the OP’s question ”will I cook my starter battery?” I would suggest that the only way to do so would be to feed it with a voltage that is too high (over 14,4 at normal temp) for an extended period of time.
As I see it the danger, if any, lies in using an external voltage regulator that boosts the voltage in order to reduce charging time (I believe Sterling does this, as opposed to Adverc).
These high voltages , perhaps 14,8 or so, would occur towards the end of the charging, when the service bank is almost fully charged (and the starter battery long since so).
For very long engine runs, a manual switch for disconnecting the starter battery from the charging circuit might be a good idea (at least for peace of mind). Anyway that is how I have arranged my own system, a service bank of 240 ah wet cells that is paralleled with a smallish AGM starter battery.
boatmike
Well-Known Member
Under AN INTRODUCTION TO SPLIT CHARGING on their website
For those still in doubt reproduced here
SmartBank
While VSR’s are suitable for smaller boats
and service vans, they aren’t smart enough
for the demands of larger electrical systems
found on ocean cruisers, motor boats,
ambulances and where charge sources are
limited compared to the size of load (relay
chatter being the most regular issue).
SmartBank was designed to be simply
the most effective split charging system
available today.
Operating in a similar manner to VSR’s,
SmartBank is Bi-Directional. This means
it senses voltage on all battery banks -
allowing it to manage ALL charging sources
on board. In fact you’ll never need to buy a
split charging device ever again! (Any charge
source will charge all battery banks).
SmartBank works by monitoring both
battery banks. When it senses that either
battery (i.e. engine from alternator or auxiliary
from a solar panel) is being charged, it will
allow power to flow through to the other
battery. Under no circumstances will batteries
be overcharged or allowed to discharge into
the other.
Relay chatter is prevented by having an
adjustable connect/disconnect hold feature.
It also provides the installer with the ability
to ensure that the electrical charge balance
between engine and auxiliaries is right for
any given installation.
Unlike all other split charge devices,
SmartBank’s settings (connect/disconnect/
hold on/hold off) are fully adjustable – this
means that you can delay allowing power
to other batteries. For instance, you could
ensure that the engine battery is charged
almost fully before allowing power through
to auxiliaries – ideal for systems where
alternators/chargers are undersized.
SmartBank is also fitted with an
emergency parallel switch – allowing you
start your engine from auxiliaries or, use an
emergency device from the engine battery if
auxiliaries are flat.
SmartBank also uses DSP (Digital Signal
Processing) to ensure that it isn't confused
by transient voltage and noise.
Further development of SmartBank is
the SmartBank Advanced. This combines
our renowned SmartGauge Battery Monitor
& SmartBank to provide the most advanced
split charge and monitoring system available.
As SmartGauge learns about your batteries,
it automatically adjusts connect/disconnect
voltages to gain maximum system efficiency
while providing valuable battery monitoring
information. SmartBank Advanced is
available with or without SmartGauge, so
existing SmartGauge users can upgrade
their split charging later if preferred.
sailinglegend420
Well-Known Member
Why don't you believe anybody? Boatmike has just beat me - here is the full link:
"An introduction to split charging" for more on SmartBank
http://www.merlinequipment.com/markets/group.asp?groupid=18
SmartBank is an intelligent relay - yes the same voltage to both batteries - so when one is fully charged it disconnects the volts to that battery - unlike a VSR that keeps both connected until the primary bank is fully charged.
I posted another link above to a good source about large alternators overcharging batteries - but I don't suppose you believe that one either.
I was going to point out my signature to you - but I thought that would be just too rude.
pvb
Well-Known Member
Yes, I'm still in doubt.
You originally said that "as soon as the engine battery is fully charged it will disconnect".
The blurb you've reproduced doesn't say that - indeed it suggests the opposite, that the Smartbank can wait until the engine battery is charged before connecting.
pvb
Well-Known Member
I do believe people when they're correct. Both you and Boatmike are wrong about Smartbank. It does not disconnect charge once a battery is fully charged. Read the bit in their Technical Description, where it says "SmartBank essentially monitors two battery banks and if either bank is being charged it parallels both battery banks."
If you don't believe me, I suggest you email SmartGauge Electronics and ask them to explain it to you.
Mistroma
Well-Known Member
Smartbank Advanced
I have a SmartBank Advanced system with 2 relays connecting 3 battery banks. I installed the system and can confirm that the alternator charges one bank first and then connects both other banks.
All three banks remain connected as long as charging is available. Disconnection only happens when current drawn from domestic bank is greater than current supplied (for a reasonable time, with a delay to stop relay chatter).
I used the wiring diagram supplied with the unit and this does not allow for one battery to be disconnected after charging starts.
One bank has charging priority and is the only one charged initially. When the priority bank has a reasonable charge the others are connected into the charging circuit.
I chose to give the start bank priority but could just as easily have made the domestic bank the priority. However, this would still not have resulted in the start battery being disconnected once fully charged if the other batteries were still being charged.
PS I've never had any need to add more water to the start battery than the domestic bank. Others may have different experience if they fully charge batteries for long periods at higher voltage.
I have a SmartBank Advanced system with 2 relays connecting 3 battery banks. I installed the system and can confirm that the alternator charges one bank first and then connects both other banks.
All three banks remain connected as long as charging is available. Disconnection only happens when current drawn from domestic bank is greater than current supplied (for a reasonable time, with a delay to stop relay chatter).
I used the wiring diagram supplied with the unit and this does not allow for one battery to be disconnected after charging starts.
One bank has charging priority and is the only one charged initially. When the priority bank has a reasonable charge the others are connected into the charging circuit.
I chose to give the start bank priority but could just as easily have made the domestic bank the priority. However, this would still not have resulted in the start battery being disconnected once fully charged if the other batteries were still being charged.
PS I've never had any need to add more water to the start battery than the domestic bank. Others may have different experience if they fully charge batteries for long periods at higher voltage.
boatmike
Well-Known Member
PVB..... You are turning a simple question into an argument to no avail. I hope my other post convinces you that what I said about smartbank is true. I should know because I have it fitted and it does indeed sense both batteries. The relay is fitted between the batteries and will disconnect one from the other when either is fully charged. This however does mean that one has to prioritise the charging. Normally with one alternator I would suggest that it should be connected directly to the service batteries because the starter battery is seldom run down to a deeply discharged state and only needs "topping up". The service bank on a sailboat is often more deeply discharged. This however is only the basic system. With smartguage added you can indeed do more but lets keep it simple.
As far as lead acid batteries are concerned you are half right. In fact it is the alternator controller that senses the battery voltage and will compare to the voltage it is set at and charge appropriately, not the other way around. The reason the other poster can boil his batteries with an on board generator could be because he has not set it up to be battery sensing. Very dangerous actually as it could lead to exess gassing and even an explosion. But read on. He is not wrong! We were both correct in my view originally though in that any normal battery sensed alternator of any size within reason will reduce the charge as soon as the battery voltage has risen. The original point I made was that this is only true so long as there is not another battery in circuit that is not sensed. In this case it could become overcharged. There is indeed a point to be made about VERY large alternators with small batteries though and it concerns trying to charge at a rate of amps higher than the battery will accept. Within the limits of the original posters question though this is unlikely. Put a very big generator on a little battery though and battery sensed or not the battery wont like it. It is not in this case a matter of voltage, its amps, so the other poster is technically correct, the battery could see more amps than it can take.
superboots
Well-Known Member
Many thanks for all the detailed answers. However, I am still unsure of what I should do - I am not a techie and don't know much about battery charging. I used the word "buffer" because thats what it says in the manual. The engine start battery is always given priority and service bank is only charged after the engine battery is full. I believe this is a multı battery isolator - model 702 made by Sure Power Industries Inc - dating from 2000 when the boat was made - its rated 70 amps which may also be a problem if I increase size of alternator.
pvb
Well-Known Member
There are simply so many mistakes in your post that I can't be bothered to point them out.
I would, however, continue to challenge your assertion that Smartbank disconnects batteries when they're fully charged. It doesn't. I say so; Smartbank say so; Mistroma says so. The fact that you've apparently got a Smartbank and still don't know how it works is worrying.
pvb
Well-Known Member
The Sure Power 702 is simply a blocking diode - it can't give priority to the engine battery.
If you want to fit the 90A alternator, I'd suggest you dispose of the Sure Power diode and fit a VSR or a more advanced parallel relay like the Smartbank.
sailinglegend420
Well-Known Member
I don't have a SmartBank but have looked into it carefully. It can be programmed to do all sorts of things - but maybe its too clever for Mistroma.
Your are right about one thing pvb - the SmartGuage website does not make things crystal clear. But maybe someone else who actually uses SmartBank and SmartGuage can post because I'm getting fed up with the negative comments here.
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boatmike
Well-Known Member
Actually you are quite correct with the standard set up. It does not start on both and disconnect one when fully charged. It does the reverse. Sorry if I confused everybody. However the result is the same. Because the system SENSES both banks it will only connect the second bank when the priority bank is up to the preset values. This ensures that at no time should a battery be overcharged. However if it were mine I would on a sailboat prioritise the service bank. But that's just my preference.
The key point is that both batteries are sensed not just one.
Actually I have the 3 bank system too. In my case I have two engines with identical alternators as I have now moved from sail to power in my old age. I let one prioritise the engine start batteries and the other the service bank. Works a treat!
pvb
Well-Known Member
I'm sure Mistroma will be delighted with your verdict on his capability! I thought his post sounded knowledgeable and intelligent.
If you don't believe me or Mistroma, why would you believe anyone else with a Smartbank?
pvb
Well-Known Member
Finally you admit you've been misleading people about the Smartbank. Hopefully, sailinglegend420 will catch up in due course.
boatmike
Well-Known Member
Frankly pvb you have done it again. I used to post regularly on this site but stopped doing so because of the rudeness of you and other posters like you. You turn a perfectly simple question into an argument any way you can. You INSISTED that smartbank didn't sense both batteries. You INSISTED that you can connect any size of alternator to even the smallest battery.
You were totally wrong on the first count and the second statement which I initially only agreed to within the limit of fitting a 90amp alternator to a normal size battery bank is also academically incorrect as others have agreed. When I get details wrong (as I did) I apologise. What I said does not affect the outcome though. Your posts have been not only wrong but arrogant. I tend to agree with the other poster who suggested that you confine your wind-ups to the lounge.
For those who want to know more about the excellent products that Merlin provide and their effect on the original problem posed I suggest you read what it says on the site and if it's not clear talk to Merlin. Ask for Sam. He will spend as long a you need explaining and unlike some others does not have his head stuck up his bottom.
Boatmike out (probably now permanently)
VicMallows
Well-Known Member
Pity, I was really looking forward to finding out how, having paralleled the batteries, it was going to determine when one or other was fully charged.
Vic
boatmike
Well-Known Member
Pity, I was really looking forward to finding out how, having paralleled the batteries, it was going to determine when one or other was fully charged.
Vic
Because Vic it has a sense wire to each battery bank not just one wire to one of them! Now I really am out. It's Sunday and I have better things to do
Mistroma
Well-Known Member
Smartbank "Programming"
It might be too clever for me, though I did earn money for more than 20 years programming in everything from machine code to numerous high level langages.
I have the start battery as the "priority" with Smartbank and the wiring will not allow it to be disconnected from the alternator whilst still charging the domestic bank. I could re-wire to allow this but then the domestic bank could not be disconnected from the alternator.
i.e. One bank is charged directly from the alternator and the others are connected when charging is in progress and isolated when it isn't.
So programming doesn't really enter into it. Perhaps you were talking about the various user configurable options when you mentioned programming. These are pretty basic and easy to understand so don't really count as programming. I could see that these options could be combined with additional hardware to disconnect user selectable batteries based on all sorts of criteria. However, the resulting system would need to be wired very differently in order to achieve this aim.
The standard system just allows 2 states:
1) One battery to be charged with others disconnected.
2) All batteries to be connected for charging from same source
I hope that this is of some help.
It might be too clever for me, though I did earn money for more than 20 years programming in everything from machine code to numerous high level langages.
I have the start battery as the "priority" with Smartbank and the wiring will not allow it to be disconnected from the alternator whilst still charging the domestic bank. I could re-wire to allow this but then the domestic bank could not be disconnected from the alternator.
i.e. One bank is charged directly from the alternator and the others are connected when charging is in progress and isolated when it isn't.
So programming doesn't really enter into it. Perhaps you were talking about the various user configurable options when you mentioned programming. These are pretty basic and easy to understand so don't really count as programming. I could see that these options could be combined with additional hardware to disconnect user selectable batteries based on all sorts of criteria. However, the resulting system would need to be wired very differently in order to achieve this aim.
The standard system just allows 2 states:
1) One battery to be charged with others disconnected.
2) All batteries to be connected for charging from same source
I hope that this is of some help.
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Stu Jackson
Well-Known Member
Quote From Balmar:
"Forget the rumor that an oversized alternator will destroy your batteries ... the truth is that the acceptance rate of your batteries will dictate how much amperage the alternator will provide."
This is an interesting discussion, I particularly liked the poster who said he puts priority to charging his service (house) bank first, even though he's not an American!
The issue in charging is to avoid overcharging and to provide proper battery sensing to the regulator, regardless of what type of regulator you may have.
Automatic charging relays (ACRs over here and VSRs your way) will avoid overcharging if they are properly battery sensed.
For example: Older combiners, like the one I have on my boat, does not do that, it only combines battery banks when the available charging source is above a preset voltage (NOT current, 'cuz current is limited by the acceptance of the bank(s)). If the house bank is the one that is sensed with this older combiner system (or any other) AND the banks are combined, then there is the possibility that a smaller start bank could be overcharged NOT by current but by the higher voltage for extended periods of time. It is high voltage over time that will boil the wet cell fluid, which is why charging regimens cutoff the volatge at around 14.4V, maintain the voltage until the charge current reaches about 2% of the "C" and then drops voltage to float in true three stage (phase) charging. That's why the old combiner literature suggests installing a cutoff switch in the negative lead of the combiner if motoring for long periods of time on a depleted house bank. I know this from learning about it, I didn't know much when I bought the boat in '98, but I read a lot.
If newer VSR technology senses BOTH banks and can interrupt flow to the already charged bank (i.e., the BANK'S voltage has risen to the set point WHILE the other bank is still rising in voltage below the set point), then it would seem to be a very good solution.
However, in reading the Smartbank literature, I agree that it does not appear to disconnect a fully charged battery.
If you think about it, with only ONE charging source to two separate banks, even if the VSR sensed both banks, it couldn't do anything more than either open or close the relay, right? So, if charging IS present, it would close the relay and charge both banks, but AS LONG AS THE CHARGING SOURCE WAS PRESENT, it wouldn't open the relay.
Nowhere in the Smartbank literature does it say it will. And i know of no other relay, on either side of The Pond, that will.
That is the real issue.
Another real issue is the one where a particular vendor utilizes higher charging voltages to provide a "rapid" charge. This is one that without proper controls could really damage a smaller start bank.
Any automatic combining method that avoids relay chatter is much preferred.
It would seem that in order to avoid "argument" the most appropriate way to do it would be, as suggested, to "rtfm" or to talk to the designers and vendors of the products being considered for your particular application.
Also, continuing to be "'lecktrily" challenged should imply an opportunity to learn more about the issues. There's plenty of information out there, including on this message board and in the vendors' literature.
"Forget the rumor that an oversized alternator will destroy your batteries ... the truth is that the acceptance rate of your batteries will dictate how much amperage the alternator will provide."
This is an interesting discussion, I particularly liked the poster who said he puts priority to charging his service (house) bank first, even though he's not an American!
The issue in charging is to avoid overcharging and to provide proper battery sensing to the regulator, regardless of what type of regulator you may have.
Automatic charging relays (ACRs over here and VSRs your way) will avoid overcharging if they are properly battery sensed.
For example: Older combiners, like the one I have on my boat, does not do that, it only combines battery banks when the available charging source is above a preset voltage (NOT current, 'cuz current is limited by the acceptance of the bank(s)). If the house bank is the one that is sensed with this older combiner system (or any other) AND the banks are combined, then there is the possibility that a smaller start bank could be overcharged NOT by current but by the higher voltage for extended periods of time. It is high voltage over time that will boil the wet cell fluid, which is why charging regimens cutoff the volatge at around 14.4V, maintain the voltage until the charge current reaches about 2% of the "C" and then drops voltage to float in true three stage (phase) charging. That's why the old combiner literature suggests installing a cutoff switch in the negative lead of the combiner if motoring for long periods of time on a depleted house bank. I know this from learning about it, I didn't know much when I bought the boat in '98, but I read a lot.
If newer VSR technology senses BOTH banks and can interrupt flow to the already charged bank (i.e., the BANK'S voltage has risen to the set point WHILE the other bank is still rising in voltage below the set point), then it would seem to be a very good solution.
However, in reading the Smartbank literature, I agree that it does not appear to disconnect a fully charged battery.
If you think about it, with only ONE charging source to two separate banks, even if the VSR sensed both banks, it couldn't do anything more than either open or close the relay, right? So, if charging IS present, it would close the relay and charge both banks, but AS LONG AS THE CHARGING SOURCE WAS PRESENT, it wouldn't open the relay.
Nowhere in the Smartbank literature does it say it will. And i know of no other relay, on either side of The Pond, that will.
That is the real issue.
Another real issue is the one where a particular vendor utilizes higher charging voltages to provide a "rapid" charge. This is one that without proper controls could really damage a smaller start bank.
Any automatic combining method that avoids relay chatter is much preferred.
It would seem that in order to avoid "argument" the most appropriate way to do it would be, as suggested, to "rtfm" or to talk to the designers and vendors of the products being considered for your particular application.
Also, continuing to be "'lecktrily" challenged should imply an opportunity to learn more about the issues. There's plenty of information out there, including on this message board and in the vendors' literature.
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