Topics

[Amel Yacht Owners] First Impressions: Firefly Batteries.


Thomas Peacock
 

I never thought I would need to learn so much about batteries, when my original intention was just to sail.

We have relatively new AGM’s, and notice that they charge (generator running, Heart Interface) at 40 to 50 amps for an hour or two, and then drop down to about 15 amps. The Heart charger is set for wet cell charging, at the recommendations of the Heart people. As it’s an older model, the only other setting was for gels; there is no setting for AGM.

I had been under the impression that the charger determined how many amps were sent to the batteries. A lot at first, and then tapering to acceptance, then float. With your comment about the Fireflys accepting a lot more amperage than AGM, I now question my understanding. Does the battery also determine how many amps flow in? I had thought that if the charger sent more amps than the battery could handle, the result would be toasted battery or worse. Is there some sort of interplay between the batteries and the charger?

Thanks a always to all those who continue to educate me.

Tom Peacock
SM 240 Aletes
Falmouth Harbour, Antigua



On Dec 14, 2017, at 12:06 AM, greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:


In a previous post I explained my rational for purchasing Firefly batteries in this battery replacement cycle.  They arrived a few days ago (finally!) and here are my initial impressions.


Physical fit:  They are Group 31 batteries, which is nothing but a specification on the physical size of the battery case, so they should be drop in replacements, right?  Wrong!  They are a little bit higher than our old Lifeline batteries, so I needed to trim a bit off the wood brace on the bottom of the compartment lid.  Also, the terminals are high enough that the battery terminal fuses I had been using no longer fit under the lid, so I swapped four 125 amp terminal fuses for a single 500 amp ANL fuse.  Neither was a big deal, but both were annoying.


It is very not fair to evaluate batteries when first installed.  Batteries take at least 10 charge/discharge cycles to settle in to their long term groove.  That said...  


One of the reasons I went with these was their higher charge acceptance rate.  Wow.  What a difference.  Our Lifeline AGMs (which are very good at rapid charging) would taper down to 18 amps charge rate by the time they got to 85% charge.  The Fireflys were still accepting over 50 amps at 85% charge...  Once they have settled in and I have a bit more experience with them I'll post more hard data, but so far, they look like they will at least match my expectations.


Again, these are not for everybody. They are expensive, hard to get, and need proper charge voltage control (especially on float) that not every charging system can do. The benefits of the extra cost really depend on how you use your boat.


Bill Kinney

SM160, Harmonie

Fort Lauderdale, FL








Ryan Meador
 

Thomas,
You are correct and incorrect :)  Modern chargers typically operate in three different modes: bulk, absorption, and float.  In bulk mode, the charger determines the current (it is operating as a constant-current source), and that current is usually the maximum rating of the charger.  In this mode, it adjusts the output voltage to maintain the desired current.  The voltage steadily rises as the battery charges until it reaches a certain point, then the charger switches to absorption mode.  In this mode, it operates as a constant-voltage source, and the current is determined by how much the batteries will soak up (it steadily decreases).  Eventually the current drops below a certain threshold (or a timer expires) and it switches to float mode, which is similar to absorption mode but a lower voltage, and the intent is to not have any significant current flowing into the batteries at all -- just offsetting their self-discharge.  Most chargers can provide up to their full current in float mode if necessary, so if you turn on an appliance it is actually the charger providing the power and not the battery (or only a tiny bit from the battery).

Ryan
SM 233 Iteration
Boston, MA, USA

On Fri, Dec 15, 2017 at 1:01 PM, Thomas Peacock peacock8491@... [amelyachtowners] <amelyachtowners@...> wrote:
 

I never thought I would need to learn so much about batteries, when my original intention was just to sail.


We have relatively new AGM’s, and notice that they charge (generator running, Heart Interface) at 40 to 50 amps for an hour or two, and then drop down to about 15 amps. The Heart charger is set for wet cell charging, at the recommendations of the Heart people. As it’s an older model, the only other setting was for gels; there is no setting for AGM.

I had been under the impression that the charger determined how many amps were sent to the batteries. A lot at first, and then tapering to acceptance, then float. With your comment about the Fireflys accepting a lot more amperage than AGM, I now question my understanding. Does the battery also determine how many amps flow in? I had thought that if the charger sent more amps than the battery could handle, the result would be toasted battery or worse. Is there some sort of interplay between the batteries and the charger?

Thanks a always to all those who continue to educate me.

Tom Peacock
SM 240 Aletes
Falmouth Harbour, Antigua



On Dec 14, 2017, at 12:06 AM, greatketch@... [amelyachtowners] <amelyachtowners@yahoogroups.com> wrote:


In a previous post I explained my rational for purchasing Firefly batteries in this battery replacement cycle.  They arrived a few days ago (finally!) and here are my initial impressions.


Physical fit:  They are Group 31 batteries, which is nothing but a specification on the physical size of the battery case, so they should be drop in replacements, right?  Wrong!  They are a little bit higher than our old Lifeline batteries, so I needed to trim a bit off the wood brace on the bottom of the compartment lid.  Also, the terminals are high enough that the battery terminal fuses I had been using no longer fit under the lid, so I swapped four 125 amp terminal fuses for a single 500 amp ANL fuse.  Neither was a big deal, but both were annoying.


It is very not fair to evaluate batteries when first installed.  Batteries take at least 10 charge/discharge cycles to settle in to their long term groove.  That said...  


One of the reasons I went with these was their higher charge acceptance rate.  Wow.  What a difference.  Our Lifeline AGMs (which are very good at rapid charging) would taper down to 18 amps charge rate by the time they got to 85% charge.  The Fireflys were still accepting over 50 amps at 85% charge...  Once they have settled in and I have a bit more experience with them I'll post more hard data, but so far, they look like they will at least match my expectations.


Again, these are not for everybody. They are expensive, hard to get, and need proper charge voltage control (especially on float) that not every charging system can do. The benefits of the extra cost really depend on how you use your boat.


Bill Kinney

SM160, Harmonie

Fort Lauderdale, FL









Mohammad Shirloo
 

Hi Tom;
 
The theory of battery charging is fairly complex. However, if we were to look at it in very simplistic terms, the charger has set charging algorithms designed by the manufacturer of the charger to adjust voltage and hence current output, based on specific battery chemistry that has been set on the charger. This algorithm is designed for safe charging of the battery. How much current the charger will put out is based on how much current the battery will accept, which is mainly determined by the voltage of the battery while being charged.
 
In most cases like our cruising vessels, the charger will work in three stages:
  1. Bulk charge. The charger will put out the maximum rated current (minus the current being used by the systems that are being utilized on board) until the voltage of the battery reaches a set voltage. This voltage is determined by the battery chemistry, type and manufacturer.
  2. Absorption. The charger will keep the voltage constant and will reduce current output to maintain a set voltage.
  3. Float. The charger will reduce the voltage to the float voltage, again provided by the manufacturer and set on the charger, and only provide a trickle charge to maintain the float voltage.
The voltage that the charger "sees", is determined by many different factors, but the main ones are chemistry, age, internal resistance, resistance of wires going from the charger to the batteries, heat etc.
 
So you are correct that the charger determines how much current is put out, but the algorithm within the charger that decides how much voltage and current to put out is based on how it sees the battery reacting. Therefore as the batteries get older, have more internal resistance and are able to accept less current, the charger reduces the amount of current quicker so the maximum voltages are never exceeded.
 
This is a very simplistic explanation of what is going on. You can find volumes of theoretical information online about batteries.
 
Mohammad and Aty
B&B Kokomo
Amel 54 #099


From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Friday, December 15, 2017 10:02 AM
To: amelyachtowners@...
Subject: Re: [Amel Yacht Owners] First Impressions: Firefly Batteries.

 

I never thought I would need to learn so much about batteries, when my original intention was just to sail.


We have relatively new AGM’s, and notice that they charge (generator running, Heart Interface) at 40 to 50 amps for an hour or two, and then drop down to about 15 amps. The Heart charger is set for wet cell charging, at the recommendations of the Heart people. As it’s an older model, the only other setting was for gels; there is no setting for AGM.

I had been under the impression that the charger determined how many amps were sent to the batteries. A lot at first, and then tapering to acceptance, then float. With your comment about the Fireflys accepting a lot more amperage than AGM, I now question my understanding. Does the battery also determine how many amps flow in? I had thought that if the charger sent more amps than the battery could handle, the result would be toasted battery or worse. Is there some sort of interplay between the batteries and the charger?

Thanks a always to all those who continue to educate me.

Tom Peacock
SM 240 Aletes
Falmouth Harbour, Antigua



On Dec 14, 2017, at 12:06 AM, greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:


In a previous post I explained my rational for purchasing Firefly batteries in this battery replacement cycle.  They arrived a few days ago (finally!) and here are my initial impressions.


Physical fit:  They are Group 31 batteries, which is nothing but a specification on the physical size of the battery case, so they should be drop in replacements, right?  Wrong!  They are a little bit higher than our old Lifeline batteries, so I needed to trim a bit off the wood brace on the bottom of the compartment lid.  Also, the terminals are high enough that the battery terminal fuses I had been using no longer fit under the lid, so I swapped four 125 amp terminal fuses for a single 500 amp ANL fuse.  Neither was a big deal, but both were annoying.


It is very not fair to evaluate batteries when first installed.  Batteries take at least 10 charge/discharge cycles to settle in to their long term groove.  That said...  


One of the reasons I went with these was their higher charge acceptance rate.  Wow.  What a difference.  Our Lifeline AGMs (which are very good at rapid charging) would taper down to 18 amps charge rate by the time they got to 85% charge.  The Fireflys were still accepting over 50 amps at 85% charge...  Once they have settled in and I have a bit more experience with them I'll post more hard data, but so far, they look like they will at least match my expectations.


Again, these are not for everybody. They are expensive, hard to get, and need proper charge voltage control (especially on float) that not every charging system can do. The benefits of the extra cost really depend on how you use your boat.


Bill Kinney

SM160, Harmonie

Fort Lauderdale, FL








Danny and Yvonne SIMMS
 

Hi James
I haven't fiddled with weight distribution in the Amel to see changes but in my racing days, a lot. Weight in the bow, in my experience worsens pounding. Take a stick a yard (metre) long, hold one end and swing it downwards and suddenly stop it when it is a right angles to your body. Now add two pounds (1kg) weight to the outer end and try the same. Weight at each end of a boat causes hobby horse momentum by the same physics. The center of the boat is the pivot point, and up and down she goes.
That said, in a cruising boat the reality is we have a lot of stuff to carry and the lockers at each end are a tempting destination but I do try. All my considerable number of tools are in the perfect place, low down in the middle in the underfloor storage. I still have a lot of weight up front, I just wouldn't want the batteries there as well.
Regards
Danny
SM 299
Ocean Pearl

Sent from my Vodafone Smart

On 16 Dec 2017 7:31 a.m., "James Alton lokiyawl2@... [amelyachtowners]" <amelyachtowners@...> wrote:
 

Hi Danny,


   Thanks for the comment but  I am not so sure that I agree with the premise that carrying weight in the ends of the boat always makes the boat slower.   Have you sailed your boat with the weight spread out fore/aft versus concentrating in in the center of the boat to see if you could tell a difference?  Olin once told me to ignore the “logic” of keeping the  weight in the center of my Lokiyawl and he won a lot of races in his day.  Spreading the weight out fore/aft  does have the benefit of increasing the Pitch moment of inertia which can soften the motion and I think is a good thing in a cruising boat.   Perhaps when on the wind in short seas having the weight spread out isn’t a good thing but I am going to avoid those conditions when possible.   For off the wind or reaching on a cruising boat I don’t see how having the weight spread out has any real effect other than perhaps steerage but I would be interested to hear other Amel owners comments on this.  Whether I move the batteries forward or add more chain or trim ballast to counter the addition of the arch and panels the result would be similar.  Regardless,  I think that the boat is better sailed on her designed lines than being down by the stern and I don’t want to carry trim ballast unless I have to so I am trying to plan ahead to avoid that requirement.   I am really hoping that  when the time comes to decide on wether to move the batteries forward that I will be putting in Lithiums which will be lighter and due to the increased energy density I won’t need as many.   I would only consider a batteries that were spill proof in the forward cabin.  

James
On Dec 15, 2017, at 1:51 PM, Danny and Yvonne SIMMS simms@... [amelyachtowners] <amelyachtowners@...> wrote:


Hi James,

anyone who has seriously raced yachts will tell you to keep the weight out of the ends of the boat. Trim is altered by moving weight in the middle of the boat. The huge lazurettes in the stern are a tempting place to put lots of stuff, I try to avoid heavy items there and of course any weight there affects trim. There are heavy items that have to be in the front, anchors, chain rode.  I would not want to add all the batteries.

Regards

Danny

SM 299 Ocean Pearl

On 15 December 2017 at 16:17 "James Alton lokiyawl2@... [amelyachtowners]" <amelyachtowners@...> wrote:

 

Bill,


   This is an interesting discussion,  I feel that I am learning a lot..the good the bad and the ugly….

   The batteries for the Maramu were installed in the engine room by Amel.  On the SM, the pass thru is wide enough to accommodate the batteries but I don’t think that this is possible on the Maramu due to space constraints.  In this location as you point out,  heat could be a significant factor in battery life.  (this is one of the reasons I installed an 8D Gel temporarily under the Vee bunk on the Port side.  The Gel battery is a very clean battery not requiring a battery box.)  I am considering future options to move the house batteries into the bow of the boat which would get them out of the heat of the engine room and also help trim the boat fore/aft.   The large draw items such as the thruster are in the bow so it seems like this might be something that could work…any input?  I am guessing (but do not know for sure) that since the degradatio n is a chemical process that the accelerated deterioration occurs only during the times that the engine is being used?   While damage was done during the heating periods, hopefully there is not ongoing damage when the engine room returns to ambient temperatures, so if this is correct unless one heats the engine room continuously for the life of the battery the life would not actually cut in half?    

    I have been reading that newer sealed  lead acid batteries used as starter batteries for cars are considerably more heat tolerant than those of the past.  The 2015 BCI Failure Mode Study reported an average life expectancy of 55 months under the hood and one additional year if the battery were kept in the trunk.  I don’t know if this benefit has been built into the batteries commonly used in our boats.

& #160;   Lead acid batteries are not too energy efficient so you might lose 15% of the power in charging the battery and if you discharge rapidly, you can lose up to 40%.  How much of that energy loss ends up as heat in the battery I wonder?  You make an interesting point about the Firefly batteries possibly running cooler due to the higher efficiency.  Again, it will certainly be interesting to hear your reports!   Thanks for sharing.

James

SV Sueno,
Maramu #220 

  
On Dec 14, 2017, at 7:12 PM, greatketch@... [amelyachtowners] <amelyachto wners@...> wrote:

Firefly specs the battery output up to as hot as 50C, but it does come with a caveat in their manual:


The optimum operating temperature for a lead-acid battery is 25°C (77°F). As a rule of thumb, every 8-10°C (14-18°F) rise in temperature will cut the battery life in half. 

That's a pretty standard rule of thumb that any chemist would use for a chemical reaction, and  I believe it is at least approximately true for all Lead-acid batteries.

Where Firefly might have a bit of an advantage is they have high charge efficiency, and very low internal resistance (specified as 4 milliohms) so they generate less internal heat during normal charge/discharge cycles.  They MIGHT run a little bit cooler in the same ambient environment than other valve regulated batteries.  On the other hand, a flooded cell that is generating gas will be losing a lot of heat that way, so I won't put money on it either way!

Bill Kinney
SM160, Harmonie
Fort Lauderdale, FL
Almost ready to be out sailing again!



 

 


 




James Alton
 

Danny,

   This is an interesting area of discussion that can affect the way that we use our boats.  I understand the simplistic explanation that you provided but I think that there is quite a bit more going on and suspect that the actual data from testing might seem a little confusing when those tests are done in waves of  varying period and amplitude.  

   I know that on an older traditional design such as Olin’s Dorade that spreading out the weight can work out well.  Dorade was in fact so comfortable (and fast, the restored Dorade is in fact still doing very well racing)  that trips across the Atlantic were chosen intentionally to have the wind forward of the beam because of this fact..and because the boat rolled downwind terribly. (grin)   I think that the reason spreading the weight worked for that type of boat (under most conditions) is because the bow was very fine with little buoyancy as compared to more modern wider boats and with the pitch heavily dampened by both a heavy mast and heavy ends that the bow did not lift enough to initiate hobby horsing.  This makes for a very wet boat of course and I suspect that if the wave period happened to be close to the natural pitching moment of the boat that the weight spreading was probably not a good thing, but this is just a guess.    The Amel hull is so different that perhaps none of this will translate over but it would be nice to know for planning purposes.  Perhaps when I get my boat back to Florida waters I can attempt some testing but perhaps some other Amel owners have already done some experimentation?  

  I completely agree with you about trying to keep the heavy stuff as low as possible.  My heaviest items will also reside in the bilge.  

Best,

James
SV Sueno,  Maramu #220

On Dec 15, 2017, at 3:59 PM, simms@... [amelyachtowners] <amelyachtowners@...> wrote:


Hi James
I haven't fiddled with weight distribution in the Amel to see changes but in my racing days, a lot. Weight in the bow, in my experience worsens pounding. Take a stick a yard (metre) long, hold one end and swing it downwards and suddenly stop it when it is a right angles to your body. Now add two pounds (1kg) weight to the outer end and try the same. Weight at each end of a boat causes hobby horse momentum by the same physics. The center of the boat is the pivot point, and up and down she goes.
That said, in a cruising boat the reality is we have a lot of stuff to carry and the lockers at each end are a tempting destination but I do try. All my considerable number of tools are in the perfect place, low down in the middle in the underfloor storage. I still have a lot of weight up front, I just wouldn't want the batteries there as well.
Regards
Danny
SM 299
Ocean Pearl

Sent from my Vodafone Smart

On 16 Dec 2017 7:31 a.m., "James Alton lokiyawl2@... [amelyachtowners]" <amelyachtowners@...> wrote:
 

Hi Danny,


   Thanks for the comment but  I am not so sure that I agree with the premise that carrying weight in the ends of the boat always makes the boat slower.   Have you sailed your boat with the weight spread out fore/aft versus concentrating in in the center of the boat to see if you could tell a difference?  Olin once told me to ignore the “logic” of keeping the  weight in the center of my Lokiyawl and he won a lot of races in his day.  Spreading the weight out fore/aft  does have the benefit of increasing the Pitch moment of inertia which can soften the motion and I think is a good thing in a cruising boat.   Perhaps when on the wind in short seas having the weight spread out isn’t a good thing but I am going to avoid those conditions when possible.   For off the wind or reaching on a cruising boat I don’t see how having the weight spread out has any real effect other than perhaps steerage but I would be interested to hear other Amel owners comments on this.  Whether I move the batteries forward or add more chain or trim ballast to counter the addition of the arch and panels the result would be similar.  Regardless,  I think that the boat is better sailed on her designed lines than being down by the stern and I don’t want to carry trim ballast unless I have to so I am trying to plan ahead to avoid that requirement.   I am really hoping that  when the time comes to decide on wether to move the batteries forward that I will be putting in Lithiums which will be lighter and due to the increased energy density I won’t need as many.   I would only consider a batteries that were spill proof in the forward cabin.  

James
On Dec 15, 2017, at 1:51 PM, Danny and Yvonne SIMMS simms@... [amelyachtowners] <amelyachtowners@...> wrote:


Hi James,

anyone who has seriously raced yachts will tell you to keep the weight out of the ends of the boat. Trim is altered by moving weight in the middle of the boat. The huge lazurettes in the stern are a tempting place to put lots of stuff, I try to avoid heavy items there and of course any weight there affects trim. There are heavy items that have to be in the front, anchors, chain rode.  I would not want to add all the batteries.

Regards

Danny

SM 299 Ocean Pearl

On 15 December 2017 at 16:17 "James Alton lokiyawl2@... [amelyachtowners]" <amelyachtowners@...> wrote:

 

Bill,


   This is an interesting discussion,  I feel that I am learning a lot..the good the bad and the ugly….

   The batteries for the Maramu were installed in the engine room by Amel.  On the SM, the pass thru is wide enough to accommodate the batteries but I don’t think that this is possible on the Maramu due to space constraints.  In this location as you point out,  heat could be a significant factor in battery life.  (this is one of the reasons I installed an 8D Gel temporarily under the Vee bunk on the Port side.  The Gel battery is a very clean battery not requiring a battery box.)  I am considering future options to move the house batteries into the bow of the boat which would get them out of the heat of the engine room and also help trim the boat fore/aft.   The large draw items such as the thruster are in the bow so it seems like this might be something that could work…any input?  I am guessing (but do not know for sure) that since the degradatio n is a chemical process that the accelerated deterioration occurs only during the times that the engine is being used?   While damage was done during the heating periods, hopefully there is not ongoing damage when the engine room returns to ambient temperatures, so if this is correct unless one heats the engine room continuously for the life of the battery the life would not actually cut in half?    

    I have been reading that newer sealed  lead acid batteries used as starter batteries for cars are considerably more heat tolerant than those of the past.  The 2015 BCI Failure Mode Study reported an average life expectancy of 55 months under the hood and one additional year if the battery were kept in the trunk.  I don’t know if this benefit has been built into the batteries commonly used in our boats.

& #160;   Lead acid batteries are not too energy efficient so you might lose 15% of the power in charging the battery and if you discharge rapidly, you can lose up to 40%.  How much of that energy loss ends up as heat in the battery I wonder?  You make an interesting point about the Firefly batteries possibly running cooler due to the higher efficiency.  Again, it will certainly be interesting to hear your reports!   Thanks for sharing.

James

SV Sueno,
Maramu #220 

  
On Dec 14, 2017, at 7:12 PM, greatketch@... [amelyachtowners] <amelyachto wners@...> wrote:

Firefly specs the battery output up to as hot as 50C, but it does come with a caveat in their manual:


The optimum operating temperature for a lead-acid battery is 25°C (77°F). As a rule of thumb, every 8-10°C (14-18°F) rise in temperature will cut the battery life in half. 

That's a pretty standard rule of thumb that any chemist would use for a chemical reaction, and  I believe it is at least approximately true for all Lead-acid batteries.

Where Firefly might have a bit of an advantage is they have high charge efficiency, and very low internal resistance (specified as 4 milliohms) so they generate less internal heat during normal charge/discharge cycles.  They MIGHT run a little bit cooler in the same ambient environment than other valve regulated batteries.  On the other hand, a flooded cell that is generating gas will be losing a lot of heat that way, so I won't put money on it either way!

Bill Kinney
SM160, Harmonie
Fort Lauderdale, FL
Almost ready to be out sailing again!



 

 


 







Danny and Yvonne SIMMS
 

Hi James, simplistic it may be but that's how it works. You don't have to dress things up it verbiage to state a truth. There may be the odd freak boat out there that doesn't apply to but it has been accepted wisdom for at least 55 years. That's my sailing time.
Cheers
Danny
SM 299
Ocean Pearl

Sent from my Vodafone Smart

On 16 Dec 2017 12:04, "James Alton lokiyawl2@... [amelyachtowners]" <amelyachtowners@...> wrote:
 

Danny,


   This is an interesting area of discussion that can affect the way that we use our boats.  I understand the simplistic explanation that you provided but I think that there is quite a bit more going on and suspect that the actual data from testing might seem a little confusing when those tests are done in waves of  varying period and amplitude.  

   I know that on an older traditional design such as Olin’s Dorade that spreading out the weight can work out well.  Dorade was in fact so comfortable (and fast, the restored Dorade is in fact still doing very well racing)  that trips across the Atlantic were chosen intentionally to have the wind forward of the beam because of this fact..and because the boat rolled downwind terribly. (grin)   I think that the reason spreading the weight worked for that type of boat (under most conditions) is because the bow was very fine with little buoyancy as compared to more modern wider boats and with the pitch heavily dampened by both a heavy mast and heavy ends that the bow did not lift enough to initiate hobby horsing.  This makes for a very wet boat of course and I suspect that if the wave period happened to be close to the natural pitching moment of the boat that the weight spreading was probably not a good thing, but this is just a guess.    The Amel hull is so different that perhaps none of this will translate over but it would be nice to know for planning purposes.  Perhaps when I get my boat back to Florida waters I can attempt some testing but perhaps some other Amel owners have already done some experimentation?  

  I completely agree with you about trying to keep the heavy stuff as low as possible.  My heaviest items will also reside in the bilge.  

Best,

James
SV Sueno,  Maramu #220

On Dec 15, 2017, at 3:59 PM, simms@... [amelyachtowners] <amelyachtowners@...> wrote:


Hi James
I haven't fiddled with weight distribution in the Amel to see changes but in my racing days, a lot. Weight in the bow, in my experience worsens pounding. Take a stick a yard (metre) long, hold one end and swing it downwards and suddenly stop it when it is a right angles to your body. Now add two pounds (1kg) weight to the outer end and try the same. Weight at each end of a boat causes hobby horse momentum by the same physics. The center of the boat is the pivot point, and up and down she goes.
That said, in a cruising boat the reality is we have a lot of stuff to carry and the lockers at each end are a tempting destination but I do try. All my considerable number of tools are in the perfect place, low down in the middle in the underfloor storage. I still have a lot of weight up front, I just wouldn't want the batteries there as well.
Regards
Danny
SM 299
Ocean Pearl

Sent from my Vodafone Smart

On 16 Dec 2017 7:31 a.m., "James Alton lokiyawl2@... [amelyachtowners]" <amelyachtowners@...> wrote:
 

Hi Danny,


   Thanks for the comment but  I am not so sure that I agree with the premise that carrying weight in the ends of the boat always makes the boat slower.   Have you sailed your boat with the weight spread out fore/aft versus concentrating in in the center of the boat to see if you could tell a difference?  Olin once told me to ignore the “logic” of keeping the  weight in the center of my Lokiyawl and he won a lot of races in his day.  Spreading the weight out fore/aft  does have the benefit of increasing the Pitch moment of inertia which can soften the motion and I think is a good thing in a cruising boat.   Perhaps when on the wind in short seas having the weight spread out isn’t a good thing but I am going to avoid those conditions when possible.   For off the wind or reaching on a cruising boat I don’t see how having the weight spread out has any real effect other than perhaps steerage but I would be interested to hear other Amel owners comments on this.  Whether I move the batteries forward or add more chain or trim ballast to counter the addition of the arch and panels the result would be similar.  Regardless,  I think that the boat is better sailed on her designed lines than being down by the stern and I don’t want to carry trim ballast unless I have to so I am trying to plan ahead to avoid that requirement.   I am really hoping that  when the time comes to decide on wether to move the batteries forward that I will be putting in Lithiums which will be lighter and due to the increased energy density I won’t need as many.   I would only consider a batteries that were spill proof in the forward cabin.  

James
On Dec 15, 2017, at 1:51 PM, Danny and Yvonne SIMMS simms@... [amelyachtowners] <amelyachtowners@...> wrote:


Hi James,

anyone who has seriously raced yachts will tell you to keep the weight out of the ends of the boat. Trim is altered by moving weight in the middle of the boat. The huge lazurettes in the stern are a tempting place to put lots of stuff, I try to avoid heavy items there and of course any weight there affects trim. There are heavy items that have to be in the front, anchors, chain rode.  I would not want to add all the batteries.

Regards

Danny

SM 299 Ocean Pearl

On 15 December 2017 at 16:17 "James Alton lokiyawl2@... [amelyachtowners]" <amelyachtowners@...> wrote:

 

Bill,


   This is an interesting discussion,  I feel that I am learning a lot..the good the bad and the ugly….

   The batteries for the Maramu were installed in the engine room by Amel.  On the SM, the pass thru is wide enough to accommodate the batteries but I don’t think that this is possible on the Maramu due to space constraints.  In this location as you point out,  heat could be a significant factor in battery life.  (this is one of the reasons I installed an 8D Gel temporarily under the Vee bunk on the Port side.  The Gel battery is a very clean battery not requiring a battery box.)  I am considering future options to move the house batteries into the bow of the boat which would get them out of the heat of the engine room and also help trim the boat fore/aft.   The large draw items such as the thruster are in the bow so it seems like this might be something that could work…any input?  I am guessing (but do not know for sure) that since the degradatio n is a chemical process that the accelerated deterioration occurs only during the times that the engine is being used?   While damage was done during the heating periods, hopefully there is not ongoing damage when the engine room returns to ambient temperatures, so if this is correct unless one heats the engine room continuously for the life of the battery the life would not actually cut in half?    

    I have been reading that newer sealed  lead acid batteries used as starter batteries for cars are considerably more heat tolerant than those of the past.  The 2015 BCI Failure Mode Study reported an average life expectancy of 55 months under the hood and one additional year if the battery were kept in the trunk.  I don’t know if this benefit has been built into the batteries commonly used in our boats.

& #160;   Lead acid batteries are not too energy efficient so you might lose 15% of the power in charging the battery and if you discharge rapidly, you can lose up to 40%.  How much of that energy loss ends up as heat in the battery I wonder?  You make an interesting point about the Firefly batteries possibly running cooler due to the higher efficiency.  Again, it will certainly be interesting to hear your reports!   Thanks for sharing.

James

SV Sueno,
Maramu #220 

  
On Dec 14, 2017, at 7:12 PM, greatketch@... [amelyachtowners] <amelyachto wners@...> wrote:

Firefly specs the battery output up to as hot as 50C, but it does come with a caveat in their manual:


The optimum operating temperature for a lead-acid battery is 25°C (77°F). As a rule of thumb, every 8-10°C (14-18°F) rise in temperature will cut the battery life in half. 

That's a pretty standard rule of thumb that any chemist would use for a chemical reaction, and  I believe it is at least approximately true for all Lead-acid batteries.

Where Firefly might have a bit of an advantage is they have high charge efficiency, and very low internal resistance (specified as 4 milliohms) so they generate less internal heat during normal charge/discharge cycles.  They MIGHT run a little bit cooler in the same ambient environment than other valve regulated batteries.  On the other hand, a flooded cell that is generating gas will be losing a lot of heat that way, so I won't put money on it either way!

Bill Kinney
SM160, Harmonie
Fort Lauderdale, FL
Almost ready to be out sailing again!