dogon dory
New member
Sorry, Folks - Post Deleted By Author
12 volt monitor
- Thread starter Plan C
- Start date
I have two Link 10's, one for each battery (bought at a super discount sale for about $175 ea year ago). With kids on board most every trip I watch battery usage carefully. We have a two light rule, only 2 on at any time, unless just for a quick look-see. They also play some video games (restricted to 1 hr max since we're boating and supposed to be enjoying non-home activities...) and generally watch a DVD after dinner. I have a Wallas heater, electric water pump and several other niceties.
A voltage only meter is essentially useless to evaluate how much capacity is used (or remains) while USING the electricity, I routinely see the voltage down around 11.7-11.8 volts during a 4-5 amp draw say using the TV and DVD player.
For a more usable voltage assessment, a couple of hours of non-use would allow the battery to come up to a steady-state voltage to evaluate approximately where you're at with capacity used/remaining. But if you're burning even an anchor light (0.5-1.0 amp), this might not be possible till morning.
All depends how close your setup is to amp-hour capacity vs usage, if you have a large battery capacity, don't sweat it, but for my two 120 amp-hr batteries that also start my engines, I keep a close eye on them (I only power the cabin with one of them at a time). Nice to occasionally watch the amperage to make sure everything is OFF, invariably I find something I forgot to turn off! Peace of mind for me...and the kids.
A voltage only meter is essentially useless to evaluate how much capacity is used (or remains) while USING the electricity, I routinely see the voltage down around 11.7-11.8 volts during a 4-5 amp draw say using the TV and DVD player.
For a more usable voltage assessment, a couple of hours of non-use would allow the battery to come up to a steady-state voltage to evaluate approximately where you're at with capacity used/remaining. But if you're burning even an anchor light (0.5-1.0 amp), this might not be possible till morning.
All depends how close your setup is to amp-hour capacity vs usage, if you have a large battery capacity, don't sweat it, but for my two 120 amp-hr batteries that also start my engines, I keep a close eye on them (I only power the cabin with one of them at a time). Nice to occasionally watch the amperage to make sure everything is OFF, invariably I find something I forgot to turn off! Peace of mind for me...and the kids.
I think "battery-talk" is the most common subject on this site.
A couple of observations:
1. Consider separating house from cranking batteries. Ideally you should use a dedicated battery for cranking and a dedicated battery for house. Granted this adds weight and expense, but generates a lot of confidence in the ability to get up the next morning and go (and recharge the house batts).
2. What matters is what load a battery is capable of supporting, for how long, before it goes to 50% discharge. Amp-hours and voltage give us an indication, but these are insufficient. Why? Because a battery can show adequate voltage and amps yet still be in trouble. These metrics apply to the remaining capacity of the battery - which may be much less than 100% (eg, say the plates are sulphated.) 12.8 volts in a new battery may be 12.8 volts in an old battery, but for much less load over time. In other words, we have 120 amp hours rating on a new battery but over time we may have only 100 amp-hours. In both cases, upon full charge, you will see what appear to be adequate voltages and amps. Hence, the only accurate way to gauge batt condition is with a high load tester - a gizmo which creates a high load whereupon the voltage is tested. The key is: the voltage during high load application (eg, a steady 10.5 V over 15 secs is good; below this and/or if voltage drops off alot = bad. Load testers are not common garage tools, but most mechanics have one - as do NAPA stores. Calder also suggests simply substituting the tester by cranking a diesel engine for 15 seconds. It's safe to assume a gas engine will have less draw, but perhaps this might give an indication of condition. (Obviously do whatever it takes to keep the engine from starting during this test, eg pull the plug wires.) Be sure the batts are fully charged before beginning. If doing multiple tests, rest the starter for at least 5 mins and do not crank for more than 20-30 secs. More info is available in Calder's "Boatowner's Mechanical and Electrical Manual, 1996, pg 44-45.
3. So I dunno. It seems like either voltage or amp-hr meters are fine for use in the field, but beware. They may be giving you a false sense of security. It also seems prudent to test your batts 1-2 x a year with a load test...
Talk to your mechanics about this; what works on my boat may not work on yours...
A couple of observations:
1. Consider separating house from cranking batteries. Ideally you should use a dedicated battery for cranking and a dedicated battery for house. Granted this adds weight and expense, but generates a lot of confidence in the ability to get up the next morning and go (and recharge the house batts).
2. What matters is what load a battery is capable of supporting, for how long, before it goes to 50% discharge. Amp-hours and voltage give us an indication, but these are insufficient. Why? Because a battery can show adequate voltage and amps yet still be in trouble. These metrics apply to the remaining capacity of the battery - which may be much less than 100% (eg, say the plates are sulphated.) 12.8 volts in a new battery may be 12.8 volts in an old battery, but for much less load over time. In other words, we have 120 amp hours rating on a new battery but over time we may have only 100 amp-hours. In both cases, upon full charge, you will see what appear to be adequate voltages and amps. Hence, the only accurate way to gauge batt condition is with a high load tester - a gizmo which creates a high load whereupon the voltage is tested. The key is: the voltage during high load application (eg, a steady 10.5 V over 15 secs is good; below this and/or if voltage drops off alot = bad. Load testers are not common garage tools, but most mechanics have one - as do NAPA stores. Calder also suggests simply substituting the tester by cranking a diesel engine for 15 seconds. It's safe to assume a gas engine will have less draw, but perhaps this might give an indication of condition. (Obviously do whatever it takes to keep the engine from starting during this test, eg pull the plug wires.) Be sure the batts are fully charged before beginning. If doing multiple tests, rest the starter for at least 5 mins and do not crank for more than 20-30 secs. More info is available in Calder's "Boatowner's Mechanical and Electrical Manual, 1996, pg 44-45.
3. So I dunno. It seems like either voltage or amp-hr meters are fine for use in the field, but beware. They may be giving you a false sense of security. It also seems prudent to test your batts 1-2 x a year with a load test...
Talk to your mechanics about this; what works on my boat may not work on yours...
Boy, this sure is a seemingly "mysterious" subject, kinda like batteries were a "black box"- we know what they do, but guessing about how they do it exactly and agreeing on how to treat them depends upon whose theory you subscribe to and what makes you comfortable in dealing with them.
Ordinarily, the more complicated something becomes, the more fun it is, and the more I like it, but this is like discussing religion and hoping for final universal agreement among all the world's peoples and the Great Merging into ONENESS!
So it just makes sense to me to figure out about how much battery capacity you need, then double it, put it in the boat and make a determined effort to keep it charged. After all, there are all kinds of indications in your starting motor, lights, and electronics performance, etc., to tell you to charge them suckers, no?
Then if you carry a back up starter pack and a generator, you have a lot of insurance right there. Personally, I'd rather have a generator than another fancy calculating ammeter device.
This may not be a workable plan for a transoceanic crossing vessel, but on my CD-22 four simple 115 AH deep cycle lead-acid batteries haven't ever come close to not being able to start the motor, even after 4-5 hours of use of an electric trolling motor for fishing (on the troll). All four batteries are usually connected in parallel, another simplifying step, although switches can separate them.
Call me simple, but this to me is the KISS Principle in action w/o delving into the World of MetaPhysical Electrochemical Cosmology.
And all this from a retired science teacher, booooooo!!!
Your Bud,
Simple Joe.
Ordinarily, the more complicated something becomes, the more fun it is, and the more I like it, but this is like discussing religion and hoping for final universal agreement among all the world's peoples and the Great Merging into ONENESS!
So it just makes sense to me to figure out about how much battery capacity you need, then double it, put it in the boat and make a determined effort to keep it charged. After all, there are all kinds of indications in your starting motor, lights, and electronics performance, etc., to tell you to charge them suckers, no?
Then if you carry a back up starter pack and a generator, you have a lot of insurance right there. Personally, I'd rather have a generator than another fancy calculating ammeter device.
This may not be a workable plan for a transoceanic crossing vessel, but on my CD-22 four simple 115 AH deep cycle lead-acid batteries haven't ever come close to not being able to start the motor, even after 4-5 hours of use of an electric trolling motor for fishing (on the troll). All four batteries are usually connected in parallel, another simplifying step, although switches can separate them.
Call me simple, but this to me is the KISS Principle in action w/o delving into the World of MetaPhysical Electrochemical Cosmology.
And all this from a retired science teacher, booooooo!!!
Your Bud,
Simple Joe.
I believe EVERYBODY'S right. Whatever you're used to using and use it consistently, you'll probably be fine. And Falco's right on also, the capacity of a battery diminishes with age (hmmm, so do I), and the Link 10/20's don't allow for that -- which can lead to a 'false' security...!
dogon dory
New member
Sorry, Folks - Post Deleted By Author
Dan-
"Hey, Joe, are these two rules simple enough to qualify for the KISS principle?"
You betcha!
And I'll apologize to anyone who might be offended by what I said or how I said it.
I didn't mean to make fun of or disagree with the rest of what has been said, just that I found a simpler solution that works for me!
Joe.
"Hey, Joe, are these two rules simple enough to qualify for the KISS principle?"
You betcha!
And I'll apologize to anyone who might be offended by what I said or how I said it.
I didn't mean to make fun of or disagree with the rest of what has been said, just that I found a simpler solution that works for me!
Joe.
dogon dory
New member
Sorry, Folks - Post Deleted By Author
I have appreciated the flow of this conversation. As I think I indicated, a significant amount of my knowledge of batteries has resulted from my experience with my electric car, plus reading. I liked Dan's comment, essentially, "know your batteries". In most of our involvement with batteries we don't have much occasion to "know" them. Charging is automatic on our vehicles, and managed by voltage regulators.
The electric car has forced me to be involved with batteries on a daily basis. It is from this that I recommend this simple 15 dollar volt meter. The voltage gives you some indication of what's going on, imperfect, but better than guessing. On my car, on a daily basis, I notice where the voltage is (the battery pack is 120 V), I notice how long it takes to charge, I noticed the amp level while it is charging. With healthy batteries, as you approach a full charge, your amps will taper off to under 4 amps.
I have come to understand that it is important to USE your batteries to keep them healthy. This means you should alternate which battery you are starting with, so that you know that battery is getting a good discharge and recharge.
I am told that with electric cars you will murder your first battery pack, from ignorance. I inherited a pack that was two years old already, and had used it an additional nine months, and it is still healthy. So I may not be doing perfect battery management, but it is working, and I am still learning!
Dave
The electric car has forced me to be involved with batteries on a daily basis. It is from this that I recommend this simple 15 dollar volt meter. The voltage gives you some indication of what's going on, imperfect, but better than guessing. On my car, on a daily basis, I notice where the voltage is (the battery pack is 120 V), I notice how long it takes to charge, I noticed the amp level while it is charging. With healthy batteries, as you approach a full charge, your amps will taper off to under 4 amps.
I have come to understand that it is important to USE your batteries to keep them healthy. This means you should alternate which battery you are starting with, so that you know that battery is getting a good discharge and recharge.
I am told that with electric cars you will murder your first battery pack, from ignorance. I inherited a pack that was two years old already, and had used it an additional nine months, and it is still healthy. So I may not be doing perfect battery management, but it is working, and I am still learning!
Dave
Ref accuracty of analog voltmeters. I still have a high quality analogue volt meter owned by my father who was an EE. It was, and still is a precision instrument, complete with a mirror behind the needle to be exactly sure where the needle reads on the guage--and it could be calibrated against a known standard voltage. (But is is very similar to the collection of high end slide rules I inheirited [including one I used in college]--new technology beats it for much less money). The reality is that we currently have inexpensive and accurate digital meters in todays world. Before good digital meters, I used analog meters, but with much less accuracy. I certainly concur with the philosophy of keeping the battery charged and not allowing it to go below 12.1 (I choose 12.2 volts). Along the way, as I learned, I did run down batteries, and they had a shorter life. However I did have at least two batteries, and always kept a starting battery in reserve.
One of the things I do today is keep a U1 battery as a back up on small boats (a group 31 on larger boats). These relitatively inexpensive garden tractor batteries will start the smaller outboards--and if by some mistake one runs down both house and starting batteries, the U1 will start the outboard. (a group 31 will start almost any recreational boat diesel or gas engine)
Also I am using combiners on the charging ciruits of the house banks. This gets away from the having to switch batteries after running (isolating the start battery--or forgetting to isolate it). As it turns out, the house bank does not charge from either of the engines or the battery charger on my new Tom Cat....That has been rectified as I went thru the circuits and made improvments. Using switches worked fine for me for years--but there had to be an awareness of power usage and battery voltage.
One of the things I do today is keep a U1 battery as a back up on small boats (a group 31 on larger boats). These relitatively inexpensive garden tractor batteries will start the smaller outboards--and if by some mistake one runs down both house and starting batteries, the U1 will start the outboard. (a group 31 will start almost any recreational boat diesel or gas engine)
Also I am using combiners on the charging ciruits of the house banks. This gets away from the having to switch batteries after running (isolating the start battery--or forgetting to isolate it). As it turns out, the house bank does not charge from either of the engines or the battery charger on my new Tom Cat....That has been rectified as I went thru the circuits and made improvments. Using switches worked fine for me for years--but there had to be an awareness of power usage and battery voltage.
Molly Brown
Member
Hey All:
Been watching this over the last couple of days and actually laughed out loud at the give and take. Some of you are really coming out of the closet.
In all discussions on this subject not once has "temperature" been mentioned. Any true indication of a battery state is only valid if it's temperature compensated. I agonized over this when we got the cruiser in 2000 and finally settled on a simple digital meter mounted in the dash and hooked up at the main buss bar behind such. I read the voltage steady state or not and when we got the TomCat in July 2002 did the same. Still on the original batteries and have yet to be stranded. Longest time aboard was 3 weeks straight and about 500 engine hours in that time.
Just couldn't resist and please refrain from replying. LOL.
Been watching this over the last couple of days and actually laughed out loud at the give and take. Some of you are really coming out of the closet.
In all discussions on this subject not once has "temperature" been mentioned. Any true indication of a battery state is only valid if it's temperature compensated. I agonized over this when we got the cruiser in 2000 and finally settled on a simple digital meter mounted in the dash and hooked up at the main buss bar behind such. I read the voltage steady state or not and when we got the TomCat in July 2002 did the same. Still on the original batteries and have yet to be stranded. Longest time aboard was 3 weeks straight and about 500 engine hours in that time.
Just couldn't resist and please refrain from replying. LOL.
Temperature matters, ".004 for each ten degrees below (or above) 78 degrees" It will matter most if you are boating in the winter, when if I recall right, at 32 degrees you have 65% of your battery rating.
Another thing - you should be using a volt level indication prior to charging. After you charge, the voltage will read high. After charging, you need to wait at least 4 hours (12 better) to get the real volt level.
Checking on batteries isn't as simple as reading a gas gauge (better yet, looking at tank levels!). But if you do it over time, you get a feel for it, and at least have a sense of what is going on in the battery.
Dave
Another thing - you should be using a volt level indication prior to charging. After you charge, the voltage will read high. After charging, you need to wait at least 4 hours (12 better) to get the real volt level.
Checking on batteries isn't as simple as reading a gas gauge (better yet, looking at tank levels!). But if you do it over time, you get a feel for it, and at least have a sense of what is going on in the battery.
Dave
Molly Brown-
No response to your post, but good point!
However, I sometimes wonder whether I want to reply to a thread/post, because if I leave a part out, someone will catch me and I'll look stupid!
FORTUNATELY, THE FEAR SOMHOW SUBSIDES AND I HANG IT OUT ANYWAY!
So much for caution!
But actually, I know I'm among friends here and we all know no one is perfect all the time.
We work together to help solve problems and actually really love each other's company and being part of the C-Brats "Club".
Plus a lot of this stuff is a great laugh! LOL
Imperfectt Joe.
No response to your post, but good point!
However, I sometimes wonder whether I want to reply to a thread/post, because if I leave a part out, someone will catch me and I'll look stupid!
FORTUNATELY, THE FEAR SOMHOW SUBSIDES AND I HANG IT OUT ANYWAY!
So much for caution!
But actually, I know I'm among friends here and we all know no one is perfect all the time.
We work together to help solve problems and actually really love each other's company and being part of the C-Brats "Club".
Plus a lot of this stuff is a great laugh! LOL
Imperfectt Joe.