Thanks Dan, I'm sure the schematic would help. I sent you a PM with my email address. The Calder book wasn't in stock, it may be one I ordered--sounds like a good resource for my project.
Regards,
JQ
Regards,
JQ
small cabin light drained battery while on shore power?
- Thread starter JonnyQuest
- Start date
- Status
Higgs,
You really ought to get a battery monitor and/or do an accurate consumption spread sheet. Taking batteries to dead, as you have done, will kill them in very short order and batteries are EXPENSIVE. Two group 27's is not ample enough power for what you are trying to do, let alone using one.
The suggested max discharge depth for deep cycle batts is 50% of rated Ah capacity.
The average group 27 has only 80Ah's. With two @ 160 Ah you will get a max of 80 Ah of usable capacity for two batteries in parallel before hitting the 50% threshhold.
Two Group 27's
80Ah + 80 Ah = 160 Ah's
160 Ah's @ 50% DOD = 80 Ah's (when the batts have been 100% charged)
If recharging while away from the dock, with an alternator, the best you can usually get back to is about 80% SOC.
80% SOC of a 160 Ah bank = 128 Ah's that are usable when cruising.
128 Ah's - 80 (50% SOC) = 48 usable Ah's while out cruising!!!
A fridge can draw 5+ amps. If you figure it runs for 50% of the 24 hour day, you've burned 60 Ah's with JUST the fridge..
A Victron BMV-600 monitor will be the best $175.00 you've spent..
Update: One battery is almost dead
Turns out one of the batteries was half dry on the inside; topping off water levels didn't really help much for charging capacity either.
Other issues:
Galvanix (defunct company) Batt Cat 2 charger apparently will cook off your battery water. Not so good. Doubtful it is a triple stage charger anyway.
Batteries banks appear to be reversed-- battery switch 1 & 2 is hooked to opposite battery terminals on the charger. (Not a big deal, just confusing for a bit.)
I haev a couple of spare batteries, that came with the boat, will need to see what their condition is.
Good news is one of the battereis onboard works pretty reliably. So I am not hard pressed to spend tons of money immediately. Time to figure things out first.
The PO told me the batteries were "pretty old" so no fault there. Wiring isn't the neatest job, so redoing the whole system will be a welcomed upgrade this fall.
Oh, battery containment box is cracked as well.
Thinking I will upgrade to golf cart batteries and relocate them to under the salon seats.
Turns out one of the batteries was half dry on the inside; topping off water levels didn't really help much for charging capacity either.
Other issues:
Galvanix (defunct company) Batt Cat 2 charger apparently will cook off your battery water. Not so good. Doubtful it is a triple stage charger anyway.
Batteries banks appear to be reversed-- battery switch 1 & 2 is hooked to opposite battery terminals on the charger. (Not a big deal, just confusing for a bit.)
I haev a couple of spare batteries, that came with the boat, will need to see what their condition is.
Good news is one of the battereis onboard works pretty reliably. So I am not hard pressed to spend tons of money immediately. Time to figure things out first.
The PO told me the batteries were "pretty old" so no fault there. Wiring isn't the neatest job, so redoing the whole system will be a welcomed upgrade this fall.
Oh, battery containment box is cracked as well.
Thinking I will upgrade to golf cart batteries and relocate them to under the salon seats.
OK, have numbers calculated for house system..how do they look?
Based on tables in Nigel Calders book, calculation guides from Southeast Marine Services online, and concepts discussed here at SBO, here are my calculations (it gets messy, so put on your eye protection now if you've got 'em):
all calculations are as follows:
amps x hrs = daily ah
item quantity x amps x hrs = dail ah (for multiple lights, fans, etc)
vhf receive: 1.5x4=6
vhf transm: 5x.2=1
depth finder: 1x8=8
autopilot: 4x5=20
knotmeter: .1x5=.5
windspeed: .1x5=.5
anchorlight: 1x8=8
runninglights: 3x1=3
bilge: 5x.1=.5
cabin lights: 2x1.5x3=9 (2 old incandescents)
2 fans: 2x1x5=10
TOTAL AMP-HRS: 66.5
total days away from shore power:
2.5x66.5=166.25
Multiply by 3 for 33% discharge level:
166.25*3=498.75 calculated bank capacity
And if an alternator with an output at roughly 20% of capacity to charge batteries is required: 100amp output alternator
OK, so are these calcuations oon target or did I misunderstand the tables?
It sure seems high compared with numbers others have been throwing around here.
Thanks in advance for tutoring me with my calculus homework here.
NOTE: I'm horrible at math, so if I'm way off, then that explains how I got to be an IRS agent.
Based on tables in Nigel Calders book, calculation guides from Southeast Marine Services online, and concepts discussed here at SBO, here are my calculations (it gets messy, so put on your eye protection now if you've got 'em):
all calculations are as follows:
amps x hrs = daily ah
item quantity x amps x hrs = dail ah (for multiple lights, fans, etc)
vhf receive: 1.5x4=6
vhf transm: 5x.2=1
depth finder: 1x8=8
autopilot: 4x5=20
knotmeter: .1x5=.5
windspeed: .1x5=.5
anchorlight: 1x8=8
runninglights: 3x1=3
bilge: 5x.1=.5
cabin lights: 2x1.5x3=9 (2 old incandescents)
2 fans: 2x1x5=10
TOTAL AMP-HRS: 66.5
total days away from shore power:
2.5x66.5=166.25
Multiply by 3 for 33% discharge level:
166.25*3=498.75 calculated bank capacity
And if an alternator with an output at roughly 20% of capacity to charge batteries is required: 100amp output alternator
OK, so are these calcuations oon target or did I misunderstand the tables?
It sure seems high compared with numbers others have been throwing around here.
Thanks in advance for tutoring me with my calculus homework here.
NOTE: I'm horrible at math, so if I'm way off, then that explains how I got to be an IRS agent.
That is too large a battery bank for your size boat. I have a 420 ah bank on a 41' boat but I have solar panels that will put in 100 ah/ day. I would calculate for one days use then come up with a way to recharge. Run engine with standard 55amp alternator (least desireable), one or two solar panels that will put back 20 -30 ah or a wind charger or a combination of the above. I think 210 ah battery bank with solar panel and occasional engine charging would do.
On our 35, we have 2x130Amp Hour deep cycle for the house, and 1x800CCA for the starter. I can run the whole boat for about 8 hours on this set up (including fridge, but not the Air Conditioner) it takes about 2-3 hours to recharge off the standard alternator (55 amp?) For day sailing and overnight trips, with dilligent use of the engine, we have cruised 8 days without issue. We can extend this by killing the fridge and use of ice bottles to keep the booze...I mean food...cold; with that set up we get about 24 hours of run time off the batteries, and again around a 2-3 hour time to charge in the morning. But since the engine heats the water too, this works out well for us. I will probably add solar panels and a 100 Amp alternator in the spring, but that is for another tax return.
Revised numbers
)
I guess my math was correct, but my reality was not. As a point of education, where were my numbers off? Did I estimate reasonable numbers for appliance consumption? Or were my assumptions for 33%DOD and being able to stay out for 2-3 days in this size boat what got me?
I hate getting an F- minus on my homework and having to go back to remedials, but do want to know where I went so far astray in my calcs.
Thanks!
Recalculating for 1.5 days out and a 50% DOD, I now get a bank size of 200ah--more what I was expecting. (not sure if changing the parameters is cheating or being more in tune with reality
)I guess my math was correct, but my reality was not. As a point of education, where were my numbers off? Did I estimate reasonable numbers for appliance consumption? Or were my assumptions for 33%DOD and being able to stay out for 2-3 days in this size boat what got me?
I hate getting an F- minus on my homework and having to go back to remedials, but do want to know where I went so far astray in my calcs.
Thanks!
Demand - storage - Production
You got the demand right JonnyQ. Based on NO recharge in 2.5 days that is the size bank you would need. If you run the engine at all during that time you can decrease the bank size.
Things to note:
Due to the battery being the control on how much charge the alternator puts into it you will not be recharging nearly as fast as the alternators rated max output. A 100 amp alternator will only put that much current into a 400ish AH bank at 50% discharge for about 15 to 20 minutes. The bat voltage comes up and the charge current drops off significantly. The last 10% of charge (going from 90 to 100% charge) will tank you hours no matter how big (or small) your alternator.
A small charge added all the time is much better than a large charge intermittently. The "make it as you use it" rule can drive your production and storage numbers down significantly. Course those solutions are pretty costly. You can't really beat an alternator from the cost standpoint but you do not need a huge one either.
Example: Wind genset that produces 1 amp output would be making 24 ah day. If you have 85% charging efficiency that would be 20.4 AH into the bank each day. So you would only be needing 66.5-20.4= 46.1 AH / day or 345ish AH bank using your numbers. A savings of 500-345=155 AH on your bank size. At 2 amps using the same numbers I get 193 AH for the bank size.
Solar is similar but not as pronounced as it does not work at night. Course when you are in that snug little cove neither does the wind genset!!! This is why most cruisers have both solar and wind and hydro and alternators.
If you know how you will be using the boat then i'd suggest the following; how often are you going to be doing that 2.5 day battery drain? If it is once a year then burn the batteries down to 25% charged on those events. Design the system for the most frequently used situation. The loss of battery life from occasional deep discharge is marginal and can be factored in as part of the total life of the bank.
I have an excel spreadsheet that does all the number crunching for you so you can play with % discharge and bank size without going crazy or getting a blister on your finger. Its free but not what I’d call ready for prime time. It includes, charge and discharge efficiencies and Bulk-absorption-float charging rates. Email me for a copy William-roosa@us.army.mil
You got the demand right JonnyQ. Based on NO recharge in 2.5 days that is the size bank you would need. If you run the engine at all during that time you can decrease the bank size.
Things to note:
Due to the battery being the control on how much charge the alternator puts into it you will not be recharging nearly as fast as the alternators rated max output. A 100 amp alternator will only put that much current into a 400ish AH bank at 50% discharge for about 15 to 20 minutes. The bat voltage comes up and the charge current drops off significantly. The last 10% of charge (going from 90 to 100% charge) will tank you hours no matter how big (or small) your alternator.
A small charge added all the time is much better than a large charge intermittently. The "make it as you use it" rule can drive your production and storage numbers down significantly. Course those solutions are pretty costly. You can't really beat an alternator from the cost standpoint but you do not need a huge one either.
Example: Wind genset that produces 1 amp output would be making 24 ah day. If you have 85% charging efficiency that would be 20.4 AH into the bank each day. So you would only be needing 66.5-20.4= 46.1 AH / day or 345ish AH bank using your numbers. A savings of 500-345=155 AH on your bank size. At 2 amps using the same numbers I get 193 AH for the bank size.
Solar is similar but not as pronounced as it does not work at night. Course when you are in that snug little cove neither does the wind genset!!! This is why most cruisers have both solar and wind and hydro and alternators.
If you know how you will be using the boat then i'd suggest the following; how often are you going to be doing that 2.5 day battery drain? If it is once a year then burn the batteries down to 25% charged on those events. Design the system for the most frequently used situation. The loss of battery life from occasional deep discharge is marginal and can be factored in as part of the total life of the bank.
I have an excel spreadsheet that does all the number crunching for you so you can play with % discharge and bank size without going crazy or getting a blister on your finger. Its free but not what I’d call ready for prime time. It includes, charge and discharge efficiencies and Bulk-absorption-float charging rates. Email me for a copy William-roosa@us.army.mil
Bill's right. Here's another energy budget worksheet http://c34.org/bbs/index.php/topic,3976.0.html that includes three different ways to look at loads: daysail, overnight and sailing all night. Your numbers look fine. Your idea of not charging for 2.5 days is what seems a bit odd, which simply results in a much larger house bank requirement.
Re: Demand - storage - Production
Hey Bill and Stu,
Since reading up on the characteristics of deep cycle batteries, I see that it is OK in my case to plan for the routine daysailing needs and on occasions (likely only 1-2 times per year) allow for +50% discharge.
(Just saved a chunk of change! Now how to spend it...?)
The alternator I have was upgraded to an API 55amp from the original 35amp; which should do fine for daysail usage on a 210ah golf cart battery bank and a new charge regulator.
Regarding chargers, opinions on whether a higher end charger that has an equalization routine is valuable or not for a smaller boat of my size and sporadic overnight usage? I'm considering between:
1. Truecharge 10 / 10TB Battery Charger 20A ($165 at defender.com) 3 stage charging
2. Truecharge 2 20A ($300 at defender.com) 3 stage charging + equalization mode
A bit more change for the upgraded version, but will the $150 more upfront extend battery life and help correct if a battery gets accidentally discharged way low? That's how I am reading things from Don Casey and Nigel Calder. Opinions?
Hey Bill and Stu,
Since reading up on the characteristics of deep cycle batteries, I see that it is OK in my case to plan for the routine daysailing needs and on occasions (likely only 1-2 times per year) allow for +50% discharge.
(Just saved a chunk of change! Now how to spend it...?)
The alternator I have was upgraded to an API 55amp from the original 35amp; which should do fine for daysail usage on a 210ah golf cart battery bank and a new charge regulator.
Regarding chargers, opinions on whether a higher end charger that has an equalization routine is valuable or not for a smaller boat of my size and sporadic overnight usage? I'm considering between:
1. Truecharge 10 / 10TB Battery Charger 20A ($165 at defender.com) 3 stage charging
2. Truecharge 2 20A ($300 at defender.com) 3 stage charging + equalization mode
A bit more change for the upgraded version, but will the $150 more upfront extend battery life and help correct if a battery gets accidentally discharged way low? That's how I am reading things from Don Casey and Nigel Calder. Opinions?
Bill, I have your spreadsheet, thanks
P.S.
Bill, I have your spreadsheet and it is quite indepth; thanks for sending it earlier. A couple of weeks back it was way over my head but I am coming up to speed. For now I am relying on the simpler calculators and being conservative with my estimations.
Yours will be useful for me a bit down the road if/when I plan to go hog wild and add to the house battery bank to keep the margaritas chilled under sail!
P.S.
Bill, I have your spreadsheet and it is quite indepth; thanks for sending it earlier. A couple of weeks back it was way over my head but I am coming up to speed. For now I am relying on the simpler calculators and being conservative with my estimations.
Yours will be useful for me a bit down the road if/when I plan to go hog wild and add to the house battery bank to keep the margaritas chilled under sail!
Last edited:
It's not the size of your boat with the equalization feature on a charger or not, it's you blinkin' wallet. Wanna spend more on batteries or keep the ones you just bought. No brainer answer, get the equalization feature. I did send you to www.amplepower.com, tech tab download the Ample Power Primer, didn't I? If I didn't now I just did.
Thanks Stu, I knew I could count on you to solve that money burning in my pocket problem!
Being a typical guy, bigger, more complex, more costly gadgets get my attention. If I'm not careful I'll be able to launch Space Shuttles off the deck of my O27 when I'm done!
Being a typical guy, bigger, more complex, more costly gadgets get my attention. If I'm not careful I'll be able to launch Space Shuttles off the deck of my O27 when I'm done!
AmplePower Primer
I'm giving this some thought.
I liked their info on ditching the 1-2-both battery switch and wiring the alternator directly to charge the house battery, and then a parallel switch for combining cranking amps if needed for starting emergencies.
I'm giving this some thought.
Don't bother, keep the 1-2-B switch. Combining banks should never be needed, you shouldn't have emergencies.
Read all of this: http://forums.catalina.sailboatowners.com/showthread.php?t=104505
Hi Stu,
Just finished reading your links on 1-2-b switches and keeping #2 bat bank as a reserve only. It keeps things simple, makes a ton of sense too. I'll definitely be going that route when I start my upgrades.
Thanks again,
JQ
Just finished reading your links on 1-2-b switches and keeping #2 bat bank as a reserve only. It keeps things simple, makes a ton of sense too. I'll definitely be going that route when I start my upgrades.
Thanks again,
JQ
Simple 1-2-B Switch Design
JQ, thanks for coming back on this. Maine Sail and I have been promoting that simple design for years, and we've helped many skippers out, offline, with their designs. We know you'll appreciate the simplicity. All the best, Stu
final guidance before making purchases please
This question is primarily for Stu and Maine Sail, but any others please feel free to chime in as well.
In previous discussions on direct wiring the alternator to the house battery, one of the main choices was whether to use the Xantrex Echo-Charge or something like a Yandina battery combiner. Are there advantages/disadvantages of one over the other? (In a much older posting (2005) I read that combiners are heavy duty relays that would consume a significant amount of juice that might render a solar charger inadequate for charging)
Defender has the Echo listed at 150.00 and the Yandina at 62.00.
What are your preferences here and why?
--I'll have a couple of other questions to ask while finalizing purchases, so thanks in advance for the continued help/tutelage.
This question is primarily for Stu and Maine Sail, but any others please feel free to chime in as well.
In previous discussions on direct wiring the alternator to the house battery, one of the main choices was whether to use the Xantrex Echo-Charge or something like a Yandina battery combiner. Are there advantages/disadvantages of one over the other? (In a much older posting (2005) I read that combiners are heavy duty relays that would consume a significant amount of juice that might render a solar charger inadequate for charging)
Defender has the Echo listed at 150.00 and the Yandina at 62.00.
What are your preferences here and why?
--I'll have a couple of other questions to ask while finalizing purchases, so thanks in advance for the continued help/tutelage.
Last edited:
final candidates now for combiner and for charger
1. OK, narrowed down to the Xantrex Echo charger and the Yandina Combiner for combining battery banks, opinions here?
and...
2. between the Xantrex Truecharge2 20A and the Promariner ProTech 1220i for chargers. Both appear to have a three stage charging system, and both appear to have an equalization feature. The ProMariner documentation lists 4 stages, to include a "Recycle/Dockside Power" stage: "if while docked and connected to shore power your batteries have a continuous excessive DC load for lighting, etntertainement, or appliances, etc. The ProTech-i series will return to Mode 1 providing your batteries up to the full amperage rating of the charger to meet the demand of the load and begin charging your batteries." --Question: although the Xantrex does not specifically list this as a feature, shouldn't the Xantrex do this as well? (or not?)
If anyone has ideas or opinions on these choices, I'd appreciate them.
Thanks!
1. OK, narrowed down to the Xantrex Echo charger and the Yandina Combiner for combining battery banks, opinions here?
and...
2. between the Xantrex Truecharge2 20A and the Promariner ProTech 1220i for chargers. Both appear to have a three stage charging system, and both appear to have an equalization feature. The ProMariner documentation lists 4 stages, to include a "Recycle/Dockside Power" stage: "if while docked and connected to shore power your batteries have a continuous excessive DC load for lighting, etntertainement, or appliances, etc. The ProTech-i series will return to Mode 1 providing your batteries up to the full amperage rating of the charger to meet the demand of the load and begin charging your batteries." --Question: although the Xantrex does not specifically list this as a feature, shouldn't the Xantrex do this as well? (or not?)
If anyone has ideas or opinions on these choices, I'd appreciate them.
Thanks!
All I can say to this is, I just installed an XC-3012 on my boat.
As a test, when boarding the first time after a week, I looked at the charger.
It was in READY status, showing 0 amps charging current
Turned on the house lights, and measured 1.8 amps draw with a DC clamp meter.
Looked again at the 3012, it now read 2 amps output.
As a test, when boarding the first time after a week, I looked at the charger.
It was in READY status, showing 0 amps charging current
Turned on the house lights, and measured 1.8 amps draw with a DC clamp meter.
Looked again at the 3012, it now read 2 amps output.
- Status