Float voltage too high, accept too low?...need ideas

[Stu Jackson]

Originally Posted by brianc

This is starting to seem most likely...it's not really worth repairing, if that's even possible, at this point. Did you eventually replace it because of this? I guess the next question is, what are the pros/cons of not replacing it?

I haven't paid attention to when it's switching to float yet...will do that soon. Which would be worse, leaving the TSC out, so ~14.5/13.6, or leaving it on and having a float over 14.1 with decent amount of gassing from the batteries. I'm wondering what other things that would destroy around the batteries, if anything). This is with the TSC in water of 50 degrees, the temp at the batteries can get lower, so the float may end up being higher if it thinks it's cooler (or is acting that way.)

Brian

I agree with sailorboy1's post #11. Forget the sensor.

Originally Posted by brianc

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It's definitely sounding like the charger itself is not working correctly, and most likely the TSC circuit. Is there another way to confirm that? Like is there a possibility that something wrong with the batteries or elsewhere along the path (there's really just a fuse, a bus, and the cable terminals) that could cause it the output to be altered?

I can hire someone to come look, but I don't really want to spend a day's $$$ in testing because that's probably half the cost of a new charger/inverter.

Aside from replacing it, sounds like remove the TSC and run it that way. However, this will result in some level of chronic undercharging because these batteries are almost always at 60 degrees F or lower (they sit against the hull in water that at best reaches 55 degrees F). Is that going to significantly shorten the life of the batteries?

Thanks again - Brian

Originally Posted by sailorboy1

Trust me me, that Freedom charger NEVER probably charges your batteries regardless. Pretty much all "smart" chargers that you can not program the voltages and amps for what and how long to stay in absorption are more designed to not boil out the batteries, not fully charge them. My Freedom 2500 dropped to float if amps got down to 10. That would only be fully charged if you had 1,000 or more AH of battery bank.

Brian, I have had a Freedom 15 in my boat since 1998 or 1999. I originally just ran it from its own switch, and then in 2003 I installed my Link 2000 to control it. I have been studying battery charging along with Maine Sail for almost 25 years. I think I know what I am talking about and some folks have actually quoted me. Take that for what it's worth, from me, of course, but I have also assembled this handy dandy topic on our C34 website, that also includes the "Gotcha Algorithm" which gets into the guts and details of how a Link 2000 works and how you can avoid getting into what Maine Sail calls "Premature Floatuation." His term, not mine. Take a look:
Electrical Systems 101 (ES101) http://c34.org/bbs/index.php/topic,5977.0.html


Scroll down to the Gotcha link.


In any event, sailorboy1 is right. I recommend forgetting about the temp sensor.

Why?

1. You won't be chronically undercharging because of the temperature "thing" alone as a feature. You could be (NOT chronically) undercharging if you ONLY depend on the Freedom to charge your house bank if you come in with a depleted (partially or fully) bank and switch the charger off when it gets to float, and if you don't have a Link controlling it. That is because otherwise, the Freedom charger is just a dumb egg timer charger and has no way of knowing when to switch to float which should be done based on trailing amps at bulk or acceptance voltage. You just don't have the hardware to do that. What a properly setup Link will do is stop the Freedom from going into float too soon. What this also means is that your acceptance voltage will last longer, which is what is good for the house bank wet cells.

What this means, then, is it becomes a management issue for the Freedom, and for you. You come in after some time out sailing and plug in. The Freedom goes through its stages, but goes to float too soon. This is ONLY critical if you're not being plugged in all the time. That is the ONLY "chronically" thing involved. If you remain plugged in overnight with no loads then you do NOT have a problem, see #2 & #3 below. Read the Battery Acceptance links in ES101.

2. If you're plugged in all the time and on the boat running loads, then one answer, if you don't have a Link, is to simply switch the charger off and then back on every once in a while. This just cycles the charger through bulk, a short acceptance and then float. It WILL fully charge your bank, it just takes longer AT FLOAT VOLTAGE. Yes, battery experts agree that a proper acceptance phase/stage is better for batteries. Is it critical? I think not. But Maine Sail discusses it at www.marinehowto.com in How to Install a Charger. Read that, it's very good, discusses egg timers, too.

3. If you're plugged in all the time, you WILL NOT BE CHRONICALLY UNDERCHARGING. Why? Because 13.6 is still higher than a fully charged battery of 12.7 or 12.8V. You are STILL CHARGING at float voltage. In fact, you might consider NOT keeping your house bank at float if you're not there and there is no load on. Read the "Why Float is Not Full" in the ES101 link: getting to float and stopping is wrong, but being on float for more than a day with no load on doesn't add anything - your batteries are full by then.

I used to live in San Francisco and sailed up here in 2016. I know what cold water is.

But unless you start getting into the minutia of battery construction and charging, you can use what you have if you understand how it works.



Good luck, you can sleep well now.

[brianc]

Originally Posted by sailorboy1

Trust me me, that Freedom charger NEVER probably charges your batteries regardless. Pretty much all "smart" chargers that you can not program the voltages and amps for what and how long to stay in absorption are more designed to not boil out the batteries, not fully charge them. My Freedom 2500 dropped to float if amps got down to 10. That would only be fully charged if you had 1,000 or more AH of battery bank.

Thanks, this is all making more sense now.

[brianc]

Originally Posted by Stu Jackson

I agree with sailorboy1's post #11. Forget the sensor.

Done. It's been creating confusion which I don't thinks help trying to learn.

Originally Posted by Stu Jackson

I have also assembled this handy dandy topic on our C34 website.

Nice, I will dig in. Unfortunately I spent 7 years with my last boat largely ignoring the systems side of things, but I'm making up for it now.

Originally Posted by Stu Jackson

...if you don't have a Link controlling it. That is because otherwise, the Freedom charger is just a dumb egg timer charger and has no way of knowing when to switch to float which should be done based on trailing amps at bulk or acceptance voltage. You just don't have the hardware to do that. What a properly setup Link will do is stop the Freedom from going into float too soon. What this also means is that your acceptance voltage will last longer, which is what is good for the house bank wet cells.

This all makes sense. But...the previous owner removed the Link 2000 because they were "having issues with it". I have no idea what that means, but the Link 2000 was replaced with a Xantrex Basic Remote, so no feedback from the system to the charger. I replaced the 2x2 shunt which used to feed the Link with a Victron Smart Shunt. Without the Link all I had was the analog needles on the panel to go by. So at this point I have the egg timer doing stuff and the smart shunt to tell me what it's doing, which is actually significantly better than what I had before, although its a bit of info overload.

Originally Posted by Stu Jackson

This is ONLY critical if you're not being plugged in all the time. That is the ONLY "chronically" thing involved. If you remain plugged in overnight with no loads then you do NOT have a problem.

If you're plugged in all the time and on the boat running loads, then one answer, if you don't have a Link, is to simply switch the charger off and then back on every once in a while. This just cycles the charger through bulk, a short acceptance and then float. It WILL fully charge your bank, it just takes longer AT FLOAT VOLTAGE.

If you're plugged in all the time, you WILL NOT BE CHRONICALLY UNDERCHARGING. Why? Because 13.6 is still higher than a fully charged battery of 12.7 or 12.8V. You are STILL CHARGING at float voltage.

This is extremely helpful. Based on this info and how we use the boat, which is that when we plug in, it's almost always overnight, there shouldn't be an issue fully charging, though it may take a while. However, I need to watch out for plugged in and running loads (the diesel heater and fridge in particular). I didn't consider that the charger would remain in float regardless of our usage unless I force it to cycle. Good to know!

Originally Posted by Stu Jackson

I used to live in San Francisco and sailed up here in 2016. I know what cold water is.

I've been in a couple times, both voluntarily and accidentally, it's cold both ways!

Originally Posted by Stu Jackson

Good luck, you can sleep well now.

Indeed, this thread has been a huge help.

Brian

[goboatingnow]

My experience is too many smart chargers get confused by the presence of tail currents. They stay in absorption mode far too long or even triggered again then stay in absorption mode too long. I’ve had sophisticated mastervolt units damage batteries because of this issue. I’m currently installing tail current shunts to fix this issue once and for all.