Wanting to Install T105 6 Volt Batteries
- Thread starter buddybear
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good plan... the 4 T105's may be more than you need. we have 2 T125's and we can run the wallas heater and lights (LED) for about 4 days without needing to charge.... if we had more batteries, we could go longer, but it also takes a much longer time to recharge properly...
unless you have a refrigerator with a good solar charge system, or plan for it soon, the 4 batts may be overkill... if you dont have led lights, the money you save on two 105 batteries would put led lights in your cabin, and be a much better investment....
basically, the only down side to having more batteries than you actually need, is the recharge time needed to bring them back up when they get pulled down too far... and if they dont get brought back up to full charge, it can damage the batteries in the same way as being drawn down too much, too many times...
unless you have a refrigerator with a good solar charge system, or plan for it soon, the 4 batts may be overkill... if you dont have led lights, the money you save on two 105 batteries would put led lights in your cabin, and be a much better investment....
basically, the only down side to having more batteries than you actually need, is the recharge time needed to bring them back up when they get pulled down too far... and if they dont get brought back up to full charge, it can damage the batteries in the same way as being drawn down too much, too many times...
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I agree with centerline. I ended up using 2x12 T125's + 1x6 T105's starter and it worked out really well. The added solar panel just adds a little more to the package.
Cheers
2 OLD PIRATES
Cheers
2 OLD PIRATES
I think it might be overkill, I do have refrigeration and estimate around 120 amps a day for everything, I do have Led lights and fans. I am a little confused with the batteries you have you said 2 T125 and 1 T105. That would be 6 volts to start the engine. Is your starter 6 volts?
confused here... the T105 and the T125 are both 6v batteries.I ended up using 2x12 T125's + 1x6 T105's starter and it worked out really well. The added solar panel just adds a little more to the package.
Cheers
2 OLD PIRATES
using 2 of them as starter batteries is detrimental to the purpose of both the battery design and the system they are being used on, for at least 2 reasons...
1.... it is a waste of the deep cycle capacity to use them as starting batts.
2.... they are not designed to deliver "cranking" amps, which need to be supplied much quicker than the batteries want to deliver. they like giving up their amps slowly over a long period of time
2 of them can be severly damaged if you ever have any need to do any heavy duty cranking due to the large amount of draw from them over a short period of time. if you had 4 of them to draw from, it would be much better because it will greatly lessen the amount being used from each battery in the same amount of time.
but then the cost is much higher, and only greatly increases the waste as mentioned in reason 1. it doesnt make sense to use them as starting batts....
1 12volt starting battery is the best option for the starter circuit.
exception... on much much larger boats, powerboats usually, they may have 2 or 3 banks of 8 or more batteries each, and if wired correctly, there is enough batteries in the circuit to allow for the deep cycle banks to be used for starting without unnecessary damage.
with the refridgeration, your next upgrade should be SOLAR... this is the next best addition after the autopilot
I have it on our 25, and have the components ready to install on our 34, but I need to weld up the frames im going to mount the panels in.
it is my planned fall project, as we dont need the heater in the summer so we dont consume hardly any power in the few days at a time that we normally spend on the boat away from the dock.
even then if we run low, we can fire up the motor and charge up while motoring to another anchorage for a change of scenery...
We changed from the stock pair of group 24 batts to a large house bank of two Trojan T-145 six volt batts, many many years ago. that bank runs everything including the fridge and starts the diesel after a couple days at anchor. Those two GC batteries live in a plastic box that occupies (all...) of the physical space formerly used by the pair of group 24's.
Note that the small diesels on boats like yours and mine can use most any standard 12 volt batt as a "starting" battery -- they do take a lot of current, but it's only for a few seconds.
I do have a spare 12 volt battery, sized about group 27, for emergency starting if needed. It's a spiral cell agm and can go six months at a time without topping up due to extremely low self-discharge. I put it into a custom holder under the aft berth.
Loren
Note that the small diesels on boats like yours and mine can use most any standard 12 volt batt as a "starting" battery -- they do take a lot of current, but it's only for a few seconds.
I do have a spare 12 volt battery, sized about group 27, for emergency starting if needed. It's a spiral cell agm and can go six months at a time without topping up due to extremely low self-discharge. I put it into a custom holder under the aft berth.
Loren
...basically, the only down side to having more batteries than you actually need, is the recharge time needed to bring them back up...
I've seen this a couple of times. How does one conclude this?
If I have a 200 ah bank and take out 50 ah, I have to replace 50 ah.
If I have a 400 ah bank and take out 50 ah, I have to replace 50 ah.
What difference does the size of the bank make to recharging if you have the same daily draw?
A larger bank for the same daily draw will increase the life of the bank.
I've seen this a couple of times. How does one conclude this?
If I have a 200 ah bank and take out 50 ah, I have to replace 50 ah.
If I have a 400 ah bank and take out 50 ah, I have to replace 50 ah.
What difference does the size of the bank make to recharging if you have the same daily draw?
A larger bank for the same daily draw will increase the life of the bank.
I wont disagree and to a certain point and balance this is correct when applied to amp hours, but not so much when applied to percentages. and it always looks much better on paper to those that may not have a full understanding of batteries.
I know you are aware that its really all about power management, into and out of the battery but not everyone takes this into account.
for some that will read this and wonder, I will attempt to explain my answer to the question you propose...
if an average boater buys more battery capacity thinking they are going to solve all their power problems they are having because they can not currently go a week without charging, they may be disappointed to learn after they spend hundreds of dollars on batteries that it now may take anywhere from 6-10hrs running the engine to get topped back up...if the person does not care to run the engine that long so they can get topped back up, its bad for the batteries.
so if a person is NOT going to manage the power each way and the batteries themselves, what is the purpose of spending the money trying to improve the system, when its not the number of batteries that is the root of the problem?...
how many boaters do we all know like this?
the original statement was made more as a "know before you go" statement than it was a fact-of-use, because I dont know how the OP manages his batteries
Bank sizing & management
Thanks centerline, very good explanation. That might be a "keeper" to use instead of the original statement which could be misleading to newbies, too. Thanks again.
Thanks centerline, very good explanation. That might be a "keeper" to use instead of the original statement which could be misleading to newbies, too. Thanks again.
point taken... ive edited the original a little.
no matter how well one tries to explain what they are trying to convey, there is always some little bit that can be forgotten to be included or taken out of context of how it was meant to read... thanks for keep me on the straight and narrow
I will mention this once again....
There is;
NO REAL NEED FOR USING A STARTING BATTERY ON SMALL AUX SAILBOAT DIESELS.
Why?
*These batteries are bottom of the barrel batteries. Cheaply produced with bottom of the barrel components.
*They are 100% not necessary for this application
*Because they are starting batteries they do very, very poor service when called upon as a reserve or emergency battery where you may need to cycle them
I'd strongly suggest not wasting your money on a starting battery or even a dual purpose battery for a sailboat AUX engine.
Any good quality deep cycle battery will start your small diesel without so much as breathing heavy. It will last longer and can be used as an emergency back up battery without damaging it.
Don't take my word for it, I think Trojan puts the mythical lore to bed nicely.......
"Trojan Battery:
Can I use my deep-cycle battery as a starting battery?
Deep-cycle batteries can be used for engine starting but starting batteries should not be used for deep-cycle applications. A deep-cycle battery may have less cranking amps per pound than a starting battery, but in most cases a deep-cycle battery is still more than adequate for the purpose of starting an engine."
Why waste your hard earned money on a cheap starting battery when you can get ample double duty out of a deeper cycle product. Remember that someday that cheap starting battery may need to "limp you home" and in that scenario I will take the deep cycle battery every time...
You can always buy a dual purpose or starting battery but you are really buying a fairly low level short lived battery with no measurable benefit for our use on sailboats.....
As for four 6V GC2's on a Catalina 31? The more batteries the better on that boat. We used to use 85 - 120Ah's per day between refrigeration, AP etc.. The refrigeration system on our 310 was an energy hog and quite poorly sized & designed.... We had a 320Ah bank on that boat and it was woefully inadequate if peace and quite for a day or two is what you want...
Remember if you are out cruising and start with 112.5 usable Ah's, out of a full 225 Ah bank, on day one, by day two you only really have approx 67.5 usable Ah's before you hit 50% SOC. After the first day away from the dock you will be cycling between 50% and 80-85% SOC, unless you have 10+ hours to run the motor....... 80% of a 225 Ah bank means 67.5 usable Ah's before you hit 50% SOC and that is simply an inadequate bank for a C-310, at least based on my own experience having owned a C-310.... If we had kept our boat longer it would have been four 6V batteries plus a group 27 deep cycle....
There is;
NO REAL NEED FOR USING A STARTING BATTERY ON SMALL AUX SAILBOAT DIESELS.
Why?
*These batteries are bottom of the barrel batteries. Cheaply produced with bottom of the barrel components.
*They are 100% not necessary for this application
*Because they are starting batteries they do very, very poor service when called upon as a reserve or emergency battery where you may need to cycle them
I'd strongly suggest not wasting your money on a starting battery or even a dual purpose battery for a sailboat AUX engine.
Any good quality deep cycle battery will start your small diesel without so much as breathing heavy. It will last longer and can be used as an emergency back up battery without damaging it.
Don't take my word for it, I think Trojan puts the mythical lore to bed nicely.......
"Trojan Battery:
Can I use my deep-cycle battery as a starting battery?
Deep-cycle batteries can be used for engine starting but starting batteries should not be used for deep-cycle applications. A deep-cycle battery may have less cranking amps per pound than a starting battery, but in most cases a deep-cycle battery is still more than adequate for the purpose of starting an engine."
Why waste your hard earned money on a cheap starting battery when you can get ample double duty out of a deeper cycle product. Remember that someday that cheap starting battery may need to "limp you home" and in that scenario I will take the deep cycle battery every time...
You can always buy a dual purpose or starting battery but you are really buying a fairly low level short lived battery with no measurable benefit for our use on sailboats.....
As for four 6V GC2's on a Catalina 31? The more batteries the better on that boat. We used to use 85 - 120Ah's per day between refrigeration, AP etc.. The refrigeration system on our 310 was an energy hog and quite poorly sized & designed.... We had a 320Ah bank on that boat and it was woefully inadequate if peace and quite for a day or two is what you want...
Remember if you are out cruising and start with 112.5 usable Ah's, out of a full 225 Ah bank, on day one, by day two you only really have approx 67.5 usable Ah's before you hit 50% SOC. After the first day away from the dock you will be cycling between 50% and 80-85% SOC, unless you have 10+ hours to run the motor....... 80% of a 225 Ah bank means 67.5 usable Ah's before you hit 50% SOC and that is simply an inadequate bank for a C-310, at least based on my own experience having owned a C-310.... If we had kept our boat longer it would have been four 6V batteries plus a group 27 deep cycle....
The time to full is not dependent upon bank size.... The time to full is governed by bulk current and then when you hit absorption voltage (constant voltage) and how much time it takes from that point forward to put 110% to 130% of removed energy back into the bank.I wont disagree and to a certain point and balance this is correct when applied to amp hours, but not so much when applied to percentages. and it always looks much better on paper to those that may not have a full understanding of batteries.
I know you are aware that its really all about power management, into and out of the battery but not everyone takes this into account.
for some that will read this and wonder, I will attempt to explain my answer to the question you propose...
if an average boater buys more battery capacity thinking they are going to solve all their power problems they are having because they can not currently go a week without charging, they may be disappointed to learn after they spend hundreds of dollars on batteries that it now may take anywhere from 6-10hrs running the engine to get topped back up...if the person does not care to run the engine that long so they can get topped back up, its bad for the batteries.
so if a person is NOT going to manage the power each way and the batteries themselves, what is the purpose of spending the money trying to improve the system, when its not the number of batteries that is the root of the problem?...
how many boaters do we all know like this?
the original statement was made more as a "know before you go" statement than it was a fact-of-use, because I dont know how the OP manages his batteries
A 225Ah battery bank at 14.4V will take the same amount of time to reach full as a 450Ah bank also at 14.4V. No matter how much current you place behind that 14.4V limit the battery can not take any more current at that voltage and that SOC....
The only part of charging you can speed up is the constant current stage (called bulk) and even then you simply hit absorption earlier with a larger charge source. A 225Ah bank with a charge source sized at 20% of capacity will charge just as fast as a 450Ah bank with a 20% charge source.... The CV stage is what takes the time to reach full, all you can do is slightly shorten bulk speed.
Just to bring this back around to Mark's original question, here are my thoughts and experiences. You can read all of the details of my battery system upgrade on our blog.
You can not fit 4 golf cart batteries and one group 24 battery in the proper orientation in the battery compartment on a Catalina 310. I tried every possible configuration. In the end I had to accept that two of the batteries are not orientated correctly. I was willing to do this because of our cruising plans. If I was simply doing weekend cruising/say sailing with a couple of vacation cruises mixed in I would not do this setup. I would probably do a primary bank of 2 12 volt golf cart batteries and a reserve bank of 1 group 24 or 27 battery. As Maine Sail pointed out, 225 Ah is a little small for the primary bank. The 2 12 volt golf cart batteries would be around 300 Ah.
This brings me to my second point. Eliminate the terms "battery #1", "battery #2", "house bank" and "starting battery" from your vocabulary. Think instead in terms of "primary bank" and "reserve bank". As Maine Sail pointed out, you don't need starting batteries on our boat. I have started the engine at least a dozen times from a group 24 battery. I have only used the group 24 just to test it. Because the primary bank of 4 golf cart batteries fires up the engine with ease and keeps me in plenty of juice. With the addition of our solar panels (man, I really need to write that post already. sorry) we don't need shore power. It has been 6 weeks since we last plugged in. That's 6 weeks of full time live aboard with the refer, water pump, TV, fans, stereo, etc. running. During one stretch of 3 cloudy days in a row the worst I got was down to 65% SOC.
The way to size the bank is to work out your power consumption and then see how many days you want to go without charging. My estimate had my max usage at 178-195 Ah per day. Our real world experience has been closer to 40-80 Ah per day. I think the big reason is two fold, 1st I am installing the inverter this weekend. So I haven't had that use on the batteries at all yet. Second, the refrigeration system. I did some tinkering, recharged and bled the system, changed out some gaskets, etc. I also only keep it just cold enough to make ice in the freezer section. So it's typically only 28 degrees in the freezer and 35-45 degrees in the fridge portion. This is warmer than you house fridge but more consistent than just having a block of ice. Right now, we use about what we can put back in every day.
Good luck and fair winds,
Jesse
I have a question to help with the understanding of this... if one has the original stock alternator, using either 2 deep cycle batts vs using 4 deep cycle batts, if one was to draw the bank down to 40% of charge (NOT 50amps), would it take the same time to bring these banks back to full charge, or even within and hour of each other?
I can understand the principal behind the so called smart chargers and the super alternators with the external charge regulators, and even good solar chargers being able to have better balanced and much quicker charge cycles, but I didnt think it was possible for a stock 55-85 amp alternator to accomplish this.
but if it were possible, then one would think that having 2 banks of 4 GC batteries each would be the best option available for our little boats... to let one of the banks run down to 50% before switching banks is a LOT of power delivered with the other bank still full to run the components for the same amount of time that the spent bank gave us.
and even at 50% or 40% the 4 GC batteries will still have plenty of amps left to crank our small 4 cyl diesels over quite strongly...
and still be brought back to full charge within a reasonable time frame that a 12v start batt and 2 GC batteries would be?...
my original reply may or may not have been spot on, but was just my thoughts assuming the OP has a stock setup... as in most cases I would think someone with much more power available probably already knows and has, what they need.... so yes, I am assuming a lot and making my comments based on what I assume without actually knowing what he has, and its very possible that I could be wrong... again
With the same charge source current the larger bank takes longer due to the longer bulk time. The absorption time will be similar though the larger bank will attain the limit voltage a bit higher in the SOC curve thus utilizing the max potential of the alt for a bit longer.
Let's assume a C-310 with a 55A stock alt and a voltage regulation point of 14.4V. Let's also assume that in bulk the alt can't produce more than about 45A due to heat and we are using 50% of bank caapcity.
The 225Ah bank is charging at 0.2C or about 20% of its Ah rating. This battery will attain the limiting voltage of 14.4V at approx 75% SOC and bulk charging will take roughly 1 hour. From this point forward the charge acceptance rate at 14.4V and XX SOC is governed by the battery and determines how long it takes to get to full. With a brand new battery you are upwards of 7 hours and as it sulfates closer to 10 hours or more.
You used 112.5Ah's and in 1 hour you were able to return about 43Ah's before your charging speed began to decline to a point where you were no longer using your alternator in an effective or efficient manner. If you do 1 hour per day of charging then you essentially have about 43 usable Ah's when off cruising, unless you want to run the motor and alt in a less efficient manner. You are also discharging the bank and cycling it between 50% SOC and approx 75% SOC.
The 450Ah bank is charging at 0.1C or about 10% of its Ah rating. This battery will attain the limiting voltage of 14.4V at approx 85% SOC and bulk charging will take roughly 3.5 hours. From this point forward the charge acceptance rate at 14.4V and XX SOC determines how long it takes to get to full. It will essentially be the same duration as the smaller bank once absorption voltage has been attained.. With a brand new battery you are upwards of 7 hours and as it sulfates closer to 10 hours or more.
If you used 225Ah's over a few days in 1 hour you still return 45Ah's. If you run the full bulk period this will take approx 3.5 hours but you are returning approx 157.5Ah's in bulk vs. 43Ah's. Also due to the C rate being smaller you get to a higher SOC before the alt begins cutting back current based on battery acceptance. Due to the lower C rate your alternator is getting the batteries to a slightly higher SOC point before voltage limiting begins. With 1 hour per day of charging you are still easily able to get 43-45Ah's of use but if you keep up with that 1 hour per day your 450Ah bank can remain at an overall higher cycling SOC every day than does the 225 Ah bank..
This means longer life from the larger bank plus the ability to go a few days in between charging episodes, if you are willing to run the engine longer for bulk replenishment after not running it for two or three days. Usually this can be planned around a windlass day but you get the option and the bank, if you keep up with 1 hour per day, remains at a higher SOC than the smaller bank which can lead to dramatically longer life...
Course Peukert has also not been accounted for and the larger bank will be drawn down at a lower percentage rate so it can actually deliver more Ah's than the 450Ah face value rating.. If we figure 100Ah's per day then the average load is about 4.2A and your Peukert corrected bank size, assuming 1.27 Peukert, at that load, grows. The 225 Ah bank also grows at that load. The larger the bank and the lower the load the more effective gain you get from Peukert. While both banks have a net Peukert gain at a low discharge rate, the large bank gains more effective capacity, as a percentage, due to Peukert in relation to the same discharge rate.
This is a good battery manufacturer chart that sums this up:
Given the time yes even a dumb regulated alternator can full charge a battery. Bulk is bulk and absorption is absorption. A 14.4V limit from a smart regulator will not charge any faster than a 14.4V limit from a dumb source if the current source is the same. Of course other things such as voltage sensing can affect this but 14.4V at the battery terminals is 14.4V.. The battery has no clue who or what is putting that 14.4V there.... Often times a dumb regulator (a truly dumb one not a "super dumb" one eg: Hitachi/Yanmar) can actually charge a bank faster than a smart regulator due to the lawyer safe settings and "premature floatulation".. For a more in-depth understandingof regulation this is a good read:
Musing Regarding External Regulation
Here is Nigel Calder's take:
My additional thoughts are below:Nigel Calder said:
One large bank is best for reasons beyond even what Calder touches on.
#1 It is far more efficient to charge one bank rather than two unless using 100% free energy. Even then "finishing" two banks is still a less efficient use of the free energy due to the longevity of the time acceptance limiting and "finishing" the battery takes while using free energy. What goes out is not what goes back in. We need 110% to 130% of removed capacity to go back in and this simply takes time. If this takes 7-10 hours for each bank you need 14-20 hours to get both banks full. If it is one large bank the absorption time is still dictated by voltage and SOC so you literally cut the time to full for one large bank nearly in half vs. two split banks..
#2 The larger bank will also not be as dramatically affected by Peukert and you'll actually get some more usable amp hours out of a larger bank with the same load than you do with a smaller bank with the same load.
#3 An often overlooked benefit of a larger bank is the banks ability to support higher voltages for your equipment for longer periods. Things like heaters and refrigeration run more efficiently at higher voltages. Starter motors work better with less voltage sag as do windlass batteries. With a single larger bank you not only combine Ah's of capacity but you also combine cranking amperage. A larger bank even at 50% SOC will start the motor with less voltage sag than will a smaller bank at the same or even higher state of charge.
#4 The batteries stay much better balanced so that when you do need them in parallel they are all working as evenly as they can be. Wiring pathways can make a difference in the intra-bank balancing over time.
#5 The shallower the discharges, for the same load, the less sulfation you create and this is why a single large bank, cycled less deeply, yields more cycles.
#6 Splitting/alternating a house bank makes for a monitoring nightmare with a battery monitor or even a Smart Gauge.
*Charge efficiency is better
*Cycle life is better
*The batteries ability to support voltage is better
*You get slightly more usable capacity at the same average load
Great Thread
I am not even going to try and top Mainesails explanation. What I will say is that I went to 4 6V Golf Cart batteries last year and this year we are just coming off cruising the Chespeake Bay for a week. About 4 days ago I angered the smoke monster in my battery charger and it got out and rampaged throughout my boat. So for 4 days I had no way to recharge my batteries. I was running my refrigerator, bilge pump, fresh water pump, some electronics and some lights (most are LED now). Batteries got down to 62% according to my Victron. On our last day we had to motor most of the way home and the batteries were back to 98-99% after 7-8 hours. I am too lazy to do the math, but I am happy. They fit into the space where my old twin 4Ds were.:dance: I actually just run these as a single bank these day.
I am not even going to try and top Mainesails explanation.
What I will say is that I went to 4 6V Golf Cart batteries last year and this year we are just coming off cruising the Chespeake Bay for a week. About 4 days ago I angered the smoke monster in my battery charger and it got out and rampaged throughout my boat. So for 4 days I had no way to recharge my batteries. I was running my refrigerator, bilge pump, fresh water pump, some electronics and some lights (most are LED now). Batteries got down to 62% according to my Victron. On our last day we had to motor most of the way home and the batteries were back to 98-99% after 7-8 hours. I am too lazy to do the math, but I am happy. They fit into the space where my old twin 4Ds were.:dance: I actually just run these as a single bank these day.Attachments
thanks. thats a very good explanation. one that anybody with even the most basic knowledge of batteries should be able to understand....
....
What size 6V batteries?I am not even going to try and top Mainesails explanation.