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Old 07-28-2017, 08:24 AM   #81
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I think Lithium wins that contest, at least it will if the lifetime cycles reported are close to correct. Maine Sail seems to think that based on his testing, 2,000 cycles looks attainable, and I suspect that if the batteries are not discharged to 80% 100% of the time, that number can be stretched.
I think 2000 will turn out to be low, only time will tell, and of course only babied banks.

But that babying can include going a lot deeper than 20% SoC, just need to stay away from where the voltage drop steepens. Lower amp discharge rates help.

And avoiding full charging (at over 14V, or even lower V left going too long) is apparently just as important.

Another piece is temperatures, no charging when it gets freezing cold.
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Old 07-28-2017, 08:39 AM   #82
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Carl & Rod
Does Balmar have the edge on sensing and load management devices or is there meaningful marine oriented competition to consider?

Peter
Has Nordhavn used battery weight as a stability factor thus necessitating some re-ballasting if lead removed and Li put in its place?
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Old 07-28-2017, 08:45 AM   #83
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I think 2000 will turn out to be low, only time will tell, and of course only babied banks.

But that babying can include going a lot deeper than 20% SoC, just need to stay away from where the voltage drop steepens. Lower amp discharge rates help.

And avoiding full charging (at over 14V, or even lower V left going too long) is apparently just as important.

Another piece is temperatures, no charging when it gets freezing cold.
Your comment opens another area that seems a bit unknown, although Maine Sail's testing seems to point to some possible conclusions. Specifically, what is the best "exercise regime" for these banks that will keep them "fit" the longest? Lithionics calculates that you can get 35,000 cycles at 5 - 10% DoD. Maybe so, but what is the capacity of the bank if that is only how you use them? And who lives long enough to use 35,000 cycles?

I'm guessing without knowing that running these down 60 - 70% with the occasional DoD to 90%, keeping peak voltage <=28 volts and no floating will result in more cycles than I will ever use.
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Old 07-28-2017, 08:47 AM   #84
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Carl & Rod
Does Balmar have the edge on sensing and load management devices or is there meaningful marine oriented competition to consider?

Peter
Has Nordhavn used battery weight as a stability factor thus necessitating some re-ballasting if lead removed and Li put in its place?
I wish Ample Power was still around, as they had some kick ass equipment a few years back, or so I thought. I used one of their regulators on my sail boat for 20 years without a hiccup. Beyond that observation, I am relying on alleged familiarity of the Balmar, and its ability to set a whole lot of variables that very few people seem to actually understand until they feel they have to.
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Old 07-28-2017, 09:41 AM   #85
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Your comment opens another area that seems a bit unknown, although Maine Sail's testing seems to point to some possible conclusions. Specifically, what is the best "exercise regime" for these banks that will keep them "fit" the longest? Lithionics calculates that you can get 35,000 cycles at 5 - 10% DoD. Maybe so, but what is the capacity of the bank if that is only how you use them? And who lives long enough to use 35,000 cycles?

I'm guessing without knowing that running these down 60 - 70% with the occasional DoD to 90%, keeping peak voltage <=28 volts and no floating will result in more cycles than I will ever use.
IMO size for what you need, stay away from extremes, but don't be afraid to exercise the bank much as you like when needed.

When not cycling, store at low SoC and cool.

Other than that enjoy being on the water!
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Old 07-28-2017, 02:56 PM   #86
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This is an actual discharge curve at 2 min intervals...
Yes your charts are always very informative. In this case, 30A is pretty high for me, but shows effective capacity of 90% is doable, at lower discharge rates will get even more without pushing the shoulders.

For LVD protection, I think I will shoot for 12V as a floor, in addition to derived SoC, actually AH out since full. IOW either condition will isolate the bank from the Loads Buss, and/or turn on the genny if that functionality is in place.

Feedback? (from anyone is welcome)
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Old 07-28-2017, 06:09 PM   #87
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Correct and why I often refer to bulk as the "constant potential" with solar wind or an alternator. With these devices bulk current will be determined by such things as engine RPM, alternator temp, irradiance, wind etc. but it is still bulk or the maximum the charge source can produce, based on things such as RPM etc. up until the CV transition point.

If we were talking about an AC charge source the current will continue flat or at the same current until the CV set point is reached. Bulk is simply not a constant voltage stage but rather the most the charge source can deliver to the battery... It means the regulator has not been limited by target voltage..
Another way to describe it is that when in "bulk" mode, the charging source is Current Limited. It is putting out as much current as it can, irrespective of the voltage. And as you point out, "as much as it can" depends on a number of factors, so the actual current can vary. But the device is running balls to the wall and putting out as much as it can.

And in "Absorb" mode, the charger is Voltage Limited. It is putting out as much current as is required to maintain the desired voltage set point.

In reality these devices are all just voltage regulated. It just happens that during bulk charge, the device can't put out enough current to attain the desired voltage, so it's stuck current limited until the target voltage is reached, and which point it can begin actively regulating the current.
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Old 07-28-2017, 06:16 PM   #88
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In reality these devices are all just voltage regulated.
Many let you set a maximum current limit.

This is to me a critical feature, when

wiring or downstream devices can't handle high current safely

upstream supply doesn't handle being overloaded well

you just want to reserve some total capacity for other purposes (e.g. engine propulsion)

or you just want to be gentler with your bank, say respecting the mfg max charging spec
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Old 07-28-2017, 06:17 PM   #89
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Peter
Has Nordhavn used battery weight as a stability factor thus necessitating some re-ballasting if lead removed and Li put in its place?
Not for stability, no. 1000 lbs of batteries in a 130,000 lb boat just isn't significant. I can't imagine any building using an accessory like batteries as part of it's stability calculations.

But swapping them for LiFePO will likely affect trim and require some adjusting of weight distribution. But it's frankly not much more than the difference between a full and empty black water tank.
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Old 07-28-2017, 06:22 PM   #90
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Many let you set a maximum current limit.

This is to me a critical feature, when

wiring or downstream devices can't handle high current safely

upstream supply doesn't handle being overloaded well

you just want to reserve some total capacity for other purposes (e.g. engine propulsion)

or you just want to be gentler with your bank, say respecting the mfg max charging spec

Point taken. But in my experience such things are usually accommodated in the initial system sizing. In practice people are usually looking for more change current, not less.

The only cases I've seen for dialing back charge current are 1) to not overload an alternator that is not rated for continuous duty (this is what Balmar's feature is for), and 2) to limit shore power draw when you are stuck with less than you normally want/use.
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Old 07-28-2017, 06:30 PM   #91
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The 624 I have is delivering .2 volt more than it thinks it is, and while Balmar has kindly offered to replace it, for now in order to get a final bulk target of 28 volts I've applied the following settings, all shown in Balmar's cryptic abbreviations:

dLc: 30 (delay before ramp up of current)
CL: 28.2 (temperature compensation limit)
bv: 27.8 (bulk voltage set point target)
b1c: 2 (duration at bulk after set point is reached. 12 minutes)
Av: 27.6 (absorption voltage after 12 minutes at bulk set point)
A1c: 2 (duration at absorption set point is reached. 12 minutes)
Fv: 26.4 (float voltage, set below resting voltage so they don't float)
F1c: 2 (minimum time at float, 12 minutes)
AP: 78% (max output of alternator)
FbA: 74% (percentage of alternator output that triggers shift to absorption voltage, after the minimum of 12 minutes. I may have this one set too high, but I am not sure about that....)
FFL: 74% (percentage of alternator output that triggers shift from float back to absorption voltage. Same comment....)

This is based on my understanding of how this device functions, so any corrections from more knowledgeable users would be much appreciated. Engineers should not write documentation....

Just curious...

Why not run bulk mode (using Balmar's meaning for bulk) until the target voltage it reached, then stop completely? I think there is an immovable 6 min time that it will spend there, but set the programmed value to zero. Then set the absorb (again using Balmar's meaning) to the same voltage as float, and set the time to zero?

The reasoning is that as I understand LiFePO, you risk over charging if you linger at a higher charge voltage for too long. Between bulk and absorb, you are lingering for 24 minutes, and perhaps 36 if my recollection is correct about the built-in extra 6 minutes that you can't control.

Or, does charge acceptance current simply drop to zero once the battery reaches the bulk/absorb voltages, and it doesn't matter?
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Old 07-28-2017, 07:06 PM   #92
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In practice people are usually looking for more change current, not less.
I use the same (very expensive) charger for a very wide range of different AH sized batteries in multiple contexts and locations.

But even on one boat, just switching from House to the Nav/Engine bank may require different current rates.
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Old 07-28-2017, 07:35 PM   #93
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Just curious...

Why not run bulk mode (using Balmar's meaning for bulk) until the target voltage it reached, then stop completely? I think there is an immovable 6 min time that it will spend there, but set the programmed value to zero. Then set the absorb (again using Balmar's meaning) to the same voltage as float, and set the time to zero?

The reasoning is that as I understand LiFePO, you risk over charging if you linger at a higher charge voltage for too long. Between bulk and absorb, you are lingering for 24 minutes, and perhaps 36 if my recollection is correct about the built-in extra 6 minutes that you can't control.

Or, does charge acceptance current simply drop to zero once the battery reaches the bulk/absorb voltages, and it doesn't matter?
At least with the 624 unit I have, the minimum time setting is 12 minutes, so zero isn't an option. I don't think the 12 minutes more charge time when the bulk set point voltage is reached is going to be material. My plan is to set the absorption time period to the time it takes for the current acceptance to drop to around 20-30 amps. At that point, further charging is probably pointless.
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Old 07-28-2017, 08:10 PM   #94
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Well at 600AH, voltage 3.45pc, you could go until 6-10A without hurting longevity.

But there is nothing to be gained by doing so other than a fractional % gain in effective AH capacity.

Better to err on the low side than high.
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Old 07-28-2017, 09:30 PM   #95
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What happens to everything on your DC bus when the voltage transient, caused by an open circuit load dump, shoots your DC bus through the roof?


I know of no regulation circuitry that can react fast enough, with a charge source at full bore, to eliminate the possibility of a voltage transient causing damage to your gear. This includes alt regulators, inverters and other charge sources.
Transorbs can do the job.
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Old 07-31-2017, 12:06 PM   #96
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Transorbs can do the job.
But why would you wire a system to rely on a Band-Aid approach, or what should really be a secondary or tertiary design addition, as your primary line of defense?? TVS diodes are also not 100% reliable, especially after a high current transient, so they must be properly sized.
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Old 08-01-2017, 08:26 PM   #97
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Had our first few days out with our new batteries and I am thrilled. The voltage changes so slowly as you draw off current it is just amazing. After full charge, 27.2 volts. After a day of rest 26.8 volts. After 100 amps used about 26.6 volts. At -300 amps, 26.4 volts.

I think we stumbled on the best way to use this bank, given our style of cruising, and I think this may be applicable to others with similar equipment. As always, comments and corrections are welcomed....

We have a Blue Seas Combiner designed to connect a lead acid starter bank with the house bank when the house bank reaches around 27 volts. I wired it with a three position switch for Manual Combine/Auto Combine/No Combine. This is a typical installation. The LiFe batteries have a Lithionics BMS with an on/off switch. Our usage will be as follows:

Sitting at the dock on shore power: BMS off, so Li batteries are "off line". Combiner on manual combine so they can be re-charged via the Trace 4000 charger/inverter that is wired to the output buss of the Li batteries. Since the BMS is off, they are disconnected from that buss, so the charge current is only going to the FLA starter bank to supply shoreside 24 vdc loads.

Underway, the BMS is also likely off unless I want the Li batteries recharged. Since they don't much care whether they sit partially charged or not, and since they re-charge so fast I imagine I will mostly just keep them offline when underway. This would especially be the case on long voyages where we were motoring for days. In this state, the Combiner is in the Auto position.

At anchor, the BMS is on, the Combiner is in the Auto position and we are using the Li batteries for all loads. Recharging, at least for now, will be done at around 240 amps or 40% of the capacity of the bank via the engine alternator and the Trace charger powered by the genset. About and hour and 15 minutes to fully recharge after a day's usage.

In other words, the Li bank is the "at anchor" bank. If you are at the dock, or underway, let them sit - you don't need them. At anchor, they provide rock steady voltages, delivering up to 450 amps without a hiccup. We'll draw them down to around 75%, then re-charge.

Under this scenario, combining chemistries of FLA and Li isn't an issue since they are never combined unless you are charging both, and then the charging requirements of the Li batteries are fine for the FLA.

So far, so good.
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Old 08-01-2017, 09:27 PM   #98
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I'd love to see details on the switch's "no combine" wiring.

And note this isn't what I'd call "drop-in" LFP, which to me means the protective circuitry is built in, unable to bypass. Therefore for example unsuitable as the only batt fed by an alt.
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Old 08-01-2017, 10:16 PM   #99
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I'd love to see details on the switch's "no combine" wiring.

And note this isn't what I'd call "drop-in" LFP, which to me means the protective circuitry is built in, unable to bypass. Therefore for example unsuitable as the only batt fed by an alt.
It's a latching relay with a solenoid. No combine kills the solenoid, manual combine activates it and auto activates it based on house bank voltage.
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Old 08-01-2017, 10:35 PM   #100
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But why would you wire a system to rely on a Band-Aid approach, or what should really be a secondary or tertiary design addition, as your primary line of defense?? TVS diodes are also not 100% reliable, especially after a high current transient, so they must be properly sized.
Band aid approach? Quite the contrary, but obviously it isnt something you would prefer. As for not being reliable you may be confusing transorbs with varistors, transorbs are quite predictable after a transient unlike varistors.

Refer to figure 6...
www.st.com/resource/en/application_note/cd00005042.pdf

P.S. I wasnt suggesting to design in anything, I was simply rebutting your comment about knowing of nothing that could do the job. TVS diodes can and do.
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