I'm contemplating making my own battery monitoring system on my . I can make a system that will select between two banks for volts and amp rate for about $80. No cumulative amp hours out or % charge remaining. My real question? How valuable is having your battery capacity displayed on a weekend cruiser? I mean, I if I know the approx. discharge rates, I can rough estimate how many amphours I have consumed and limit my amps out to less than 50%. Really now, for you engineers, how important is that detailed info. Heck, they flew to the moon with less data onboard.
I have a Xantrex Link 20 and I think it's worth every blasted penny. It gives me a very accurate understanding of how much each item draws, how much battery power remains, etc. The Link 20 is small, compact and trouble-free.
I mounted mine on my X right at the forward end of the cabin, in the vertical piece of glass between the forward dinette seat and the port galley seat. This puts it right next to my batteries which are located in the V-berth storage area. I can see the meter nicely from the cockpit or anywhere in the cabin.
Yes, I know it's a great instrument, but with my proposed install I will be able to read how much a load pulls and rough estimate amp hours out. A Link 20 cost about $350. I'm not disputing how good of an instrument it is, if I was cruising blue water I wouldn't think twice about getting that high end of an instrument. But has it saved you from going dark unexpectedly or high and dry unable to start your motor??
paj637 wrote:But has it saved you from going dark unexpectedly or high and dry unable to start your motor??
Yep, it sure has, and it's worth every blasted penny. (Got mine new on eBay and saved quite a bit.)
Here's a copy of a post I made earlier in another thread...
kmclemore wrote:If you have two batteries and you plan to use them independently (starter / house) then IMHO the best meter is the Xantrex (aka "Heart") Link 20. I have one on my boat and it's just great. Gives you battery voltage, amps being used and capacity remaining in really simple digital readout, and if you don't understand that it gives it to you in a linear readout of coloured lights.
If you choose to get it, also get the custom 'twisted-wire' hook-up cable for the Link... although I made my own, if you're a 'newbie' you may want to avoid the hassle... there's about 8 colours of wires that need to be properly twisted in pairs (x-many turns per inch) and then assembled into a harness.... not fun, but do-able... takes about 1/2-to-1 hour depending on your skills.
Color-coded, twisted pair cable (eases installation). Available in 25 (part#84-2014-00) or 50 foot lengths (part#84-2015-00).
I put mine in the aft wall of the V-berth, in between the dinette seat and the port setee, so that when the companionway is open I can see it from the helm and it's also visible to anyone in the cabin. (It helps that my batteries are also located under the V-berth, too.)
It's hard to believe that a scout master and someone with your technical savy didn't have redundancy and could even have the possibility of going dark! Isn't your motto always be prepared? I assumed you would have a auto start generator with automatic bus transfer. All kidding aside, I was hoping to hear from the Admirals. I'm on the fence on this one. I've been researching for a few days and wanted some "expert" Mac advice. Thanks.
paj637 wrote:It's hard to believe that a scout master and someone with your technical savy didn't have redundancy and could even have the possibility of going dark!
That's why he has the Link 20...
paj637 wrote:I assumed you would have a auto start generator with automatic bus transfer.
On a 26' trailerable boat?You got to be kidding... I probably have one of the more "overkill" electrical systems of anyone. But, even I'd never consider autostart generation or auto transfer switch. That kind of complication is simply unwise here... The only thing I want "automatic", in this realm, is my bilge pumps... Anything else should be "controlled"...
Exactly how much do you think an autostart generator and/or automatic transfer switch would cost? That Link 20 sounds like a cheap source of the needed information, such that you don't ever get to a situation where you need an autostart generator and/or automatic transfer switch...
All kidding aside, the question you need to ask yourself, is how are you going to replace the power you use?
Last year, I had a slip with shore power. So, the boat sat in the slip all week with an onboard 20amp charger doing its thing. With my insanely large house bank, I simply can't use all that power in a weekend. So, I had no need of a Link 10/20.
I'm mooring this year. But, I have a 120w of solar and 300w wind generator (that I still need to mount). I also have a 1000w generator that I'll probably bring along on weekend trips. So, again, I doubt I can get in a situation where I need accurate information about my charge level.
But, if you have a more sensible house bank and/or don't have comparable charging opportunities, the Link 10/20 is probably a good thing to have. I can tell you it is SIGNIFICANTLY cheaper than either my solar system, wind system, or generator.
It gives the key measurement, amp hours used, needed for managing the batteries (of course it does do volts and amps as well)
The key thing you have to understand is while voltage is a good measure of battery state, it is only accurate for this when the batteries have been at rest for 24 hours. If there is any load or has been a load on the battery recently, gauging it's charge state by voltage will not work. When actually out using the boat the voltmeter is of no use.
That leaves you with a momentary load measurement (amps) and your watch to estimate how much power you have used. Certainly not something I want to try (or even possible) to work out with 5 people on board constantly turning things on and off. Not to mention that it's not a straight line equation. They talk about the formula in the link 10 manual and it's more math than I want to do when I'm trying to enjoy my boat trip.
I recently found the Xantrex Link 2000 on eBay. It's not that I ever expect to install their fancy inverter/charger ... can't afford it. But the L-2000 is what was available.
Like you, I was opposed to the idea of West Marine pricing .. So setup an eBay watch.
I got the L-2000 for $135, delivered.
paj637 wrote:It's hard to believe that a scout master and someone with your technical savy didn't have redundancy and could even have the possibility of going dark! Isn't your motto always be prepared? I assumed you would have a auto start generator with automatic bus transfer. All kidding aside, I was hoping to hear from the Admirals. I'm on the fence on this one. I've been researching for a few days and wanted some "expert" Mac advice. Thanks.
Hmmm ... I just read this post in greater detail. Looks to me that you've already heard from the group whose advice that I accepted ... sent me to search on eBay, just like I suggested to you. Are you really looking for an expert" opinion, or just someone to confirm your advance conclusion?
Okay ... you're right, the Link is overpriced and worthless if you spend any more than 80 bucks. Furthermore, since home-brew stuff is frequently crappy anyhow, maybe you should just install an extra battery for 50 bucks, eh?
Here's a word of advice ... don't let that fence poke you in the "sitter."
It's hard to believe that a scout master and someone with your technical savy didn't have redundancy and could even have the possibility of going dark!
Ouch!
Isn't your motto always be prepared?
Ouch again!
I assumed you would have a auto start generator with automatic bus transfer
Can't be sure but.. Ouch again!
All kidding aside, I was hoping to hear from the Admirals. I'm on the fence on this one. I've been researching for a few days and wanted some "expert" Mac advice. Thanks.
Kidding, not sure that was funny.
Might have already received the best free advice from a very generous and knowledgeable ADMIRAL already
Then the response..
Right.
Good luck then. Hope you find your 'expert'.
Cheers.
Might not have been what I would have said as I don't always understand other peoples versions of what humor is.
If I were KM, I might have been a tad..... offended by your kidding around.
. I can make a system that will select between two banks for volts and amp rate for about $80. No cumulative amp hours out or % charge remaining. My real question? How valuable is having your battery capacity displayed on a weekend cruiser? I mean, I if I know the approx. discharge rates, I can rough estimate how many amphours I have consumed and limit my amps out to less than 50%. Really now, for you engineers, how important is that detailed info. Heck, they flew to the moon with less data onboard. 
