Choosing LFP batteries for my conversion from AGM

[PierreR]

Currently wired as the port engine charges the house bank and the house bank is used to start the port engine. The starboard engine charges the starboard start battery that is also used to start the generator and power the windlass.

 

[tiltrider1]

Everyone is different, I do not like combining house and start but not knowing your boat I can’t say it’s not appropriate for the boat. Now is a good time to think about what the electrical system should look like and plan the whole system.

 

[HeadedToTexas]

I asked Balmar for the spec for their port (which I understand does something similar) but they declined to provide it.

Thanks, DDW. Great stuff.

Love the initiative on the app development. So if I were to be able to pry an answer out of Balmar, you could add that input option to your app?

 

[Marco Flamingo]

Not only are the FLAB's shot, I have 7 months with the boat in heated storage to do it.

7 months is about the right amount of time! Might be cutting it a little close. That's assuming you have an external regulator for your alternator. And the regulator settings are only half of the puzzle. You also get to set parameters on the LFP batteries BMSs.

I'm now looking into the use of the BMS as a more sophisticated replacement for the 1-2-Both switch (which gives great comfort to those who fear draining start batteries and having to use a bank of house batteries to start).

Manufacturers set the BMS low voltage disconnect (LVD) to save the battery (usually at 10 to 10.5V). I'm looking at setting my LVD at about 12.5V (I've never gone below 13.2 in months of cruising). That creates an automatic "reserve" such that if the bank were drained sufficient to disconnect, a couple of Bluetooth clicks brings the batteries back online with sufficient SOC to start and recharge the house/start bank. Nothing to forget to switch and one doesn't need to haul around an expensive block of lead that does 2 seconds of work a day (and sometimes a gaggle of additional gadgets to try to effectively charge a lead start battery in an otherwise LFP system). A "dead battery," should that ever occur, would simply be a reminder to change the BMS setting, start the engine, and charge it.

That would address the amperage anxiety reduced by the old 1-2-Both switch (without the danger of turning to Off and blowing the alternator). No need for a separate house and start banks with the wasted space, weight, cost, maintenance, nuisance, and danger of lead.

 

[DDW]

Thanks, DDW. Great stuff.

Love the initiative on the app development. So if I were to be able to pry an answer out of Balmar, you could add that input option to your app?

I'd could try. It's all object code so pretty easy to add variations. I've still got two Balmar 624 on the sailboat, one for each alternator. Mythology has it that this serial link has been there since at least the 612, there are terminals marked Tx and Rx. But only used for Balmar internal testing. It might even be possible to hook up to them and take a look at what's coming out, and reverse engineer it, but I'm not going to be that ambitious on this one.

One of the reasons to like the Wakespeed is it is much more fully documented than the others. My app allows configuration on the fly as well from the laptop keyboard. I've just got a new WS500 Pro, so I am adding stuff to it for that, plus chasing some bugs that have been reported.

 

[HeadedToTexas]

Programming the 614 took a few passes, but I got all of the values above entered. Starting the main engine went well, but after the 60 second start delay my voltage never came up. The Epoch app and SmartShunt still show the same 13.4 float voltage the LFPs had when I disabled charge on the Xantrex. What am I missing?

 

[HeadedToTexas]

My DC amp meter confirms zero amps going through the positive cable from the alternator to the main positive bus bar.

 

[HeadedToTexas]

The only deviation from the last table of program values I posted on page 8 was the battery temperature compensation slope. I get that it should be zero, but the lowest value my 614 would scroll to was 00.4, so that’s what I gave it. Can’t imagine that’s why the alternator is putting out zero amps.

 

[SteveK]

If the Batts were already on float, why are you expecting any change.
Deplete your batteries and try charge again. The closer to full the less time for getting back to float.

 

[HeadedToTexas]

Well that’s a good point, though one I hadn’t seen yet. Might have just missed it because my systems offered so little information. I thought that a Bulk-Absorption-Float cycle began every time a charger came online? It would be a short cycle if the voltage was already at the float point, but the charger, be it the Xantrex or the Balmar regulated alternator, would still start up with a cycle. Have I been wrong about that?

 

[SteveK]

I have a setting for that on my Magnum inverter, so while available you have to choose the option. Maybe yours is the same. However, I have turned on power and watched the display say bulk and blip it was saying float.
Discharge the batteries about 5% and try again.

 

[HeadedToTexas]

Thinking more about it, I hope I am not wrong about that. I want a charge profile for the alternator that makes sure I arrive at a destination on float, not ready for bulk or nearly so.

I get that if, for instance, my SOC is 50% and I only motor 20 minutes to a destination, the alternator will only put as much back into the bank as it can in that short run time.

My example today is a two hour run out to Put In Bay for a night at anchor. The house bank was on float at 13.4 volts after a week on shore power. The house bank continued to show 13.4 volts after shutting down the charger and shows 13.3 volts and using about 13 amps per o run the MFDs, autopilot, and refrigerator. The SOC will be about 95% when I arrive in another 20 minutes. That’s fine, but is it unreasonable to want to arrive at 100% SOC?

 

[DDW]

I would verify that the power line and ignition line at the regulator are in fact hot. Also that ground is connected. Then look at the field terminal. It is pulse width modulator but should show something on a DVM if you are charging. Next look at the display on the 614. It can be made to show primary values, and with some waves of the magic screwdriver will show more information (though it will only cycle through it once before returning to the normal display, so you may want to video it). The manual explains all of this. Yes, it should go through a whole charge cycle at each key on. So if you have absorb set for a minimum time you should see absorb voltage for at least that time.

 

[Delta Riverat]

Me thinks something is not working properly. Even at float there should be a few amps going in.

Yeah for sure check the field voltage. Also the all the other "must haves" like B+, gnd, sense and ignition. Verify the fuses in the lines that have them.

 

[HeadedToTexas]

I got lazy with those since I changed none of the alternator connections. Other than the 614 profile changes, the only wiring change I made was to the ground cable. The negative bus was wired to the engine block and then on to the AGMs in the lazarette. I left the 2/0 cable from the engine block to the negative bus, but the negative side of the LFP bank is also wired directly to the bus bar. Can’t imagine that is a problem.

I posted earlier that my amp meter read zero, but it was really 0.2 amps DC. SOC is down to just 93% now a few hours later and will be fine until tomorrow when we’re back to shore power.

 

[SteveK]

Do you have a re bulk voltage setting?

 

[Delta Riverat]

Me thinks you are good. Better to under charge than over charge. The only time mine are 100% is when I overnight them at the dock with the charger set to 90A, 13.8 and 13.5. I do this once or twice a month.

The rest of the time I'll let then run down to 50-60, charge them while I'm there, get them up to 80-90 and unplug and go home. Let them run down until next visit.

From what I got from Will, good to top balance often and good to cycle too. Let 'em swing, but do the good soak and balance also.

They keep up a good steady 8% / day drain keeping up 2 refrigerators and the bilge pump sensors, the poop tank bubbler and the shunt monitor.

 

[HeadedToTexas]

Do you have a re bulk voltage setting?

My BU setting is 14.3 volts.

 

[HeadedToTexas]

The rest of the time I'll let then run down to 50-60, charge them while I'm there, get them up to 80-90 and unplug and go home. Let them run down until next visit.

Interesting. So even though you have shore power, you run the boat on batteries knowing that at a consistent 8%/day you’ve got over a week until they need charging? I get it, but I’m not sure I’m ready for that level yet. It’s probably my two hour drive, variable schedule and tendency for schedule conflicts to crop up. I can see that once we are aboard for much longer stretches.

 

[Delta Riverat]

Yeah, one of the differences between Lead and Lithium me thinks. Lead likes to be topped up all the time. I keep the lead acid starters plugged in 24-7. The charger keeps them at 13.5 volts with less than 1 amp per battery. No gassing and not a lot of water needed.

But Will the guru says to USE these batteries. No problem with full charge discharge cycles. Problem with prolonged zero charge, problem with too much heat and problem with no 100% charge for balancing. Another source I read said they also don't like being held at full charge either. They like to swing.

I dunno. I'm just reading the writing on the wall like all us guys -

 

[fryedaze]

Last year Epoch had great Black Friday sales. It lasted a few weeks. We purchased two 460 Epoch Essentials for $999/each. I saved $1000 on my battery install. Normal price $1499.

 

[SteveK]

My BU setting is 14.3 volts.

Ok. But I meant a lower setting like 12.8 or 13v where no charging is done until battery level hit target set. I have that in custom settings.
Same idea as drain batteries and then see if charging starts

 

[HeadedToTexas]

Hmmm, the codes are dizzying and abstract. The lowest voltage I have set is the ALL at 12.8 which appears to be the alarm lamp limit. I don’t have an alarm lamp and the voltage is still well above that this morning. The next lowest voltage setting is 13.4 volts for float.

 

[Randy Morgan]

I went with four of the Li-Time 320 ah blue tooth non heated, low temp & high temp cut outs in parallel of course because I previously had LifeLine GPL-L16T AGMs in the boat I could fine absolutely nothing from any manufacture that would remotely fit my existing battery boxes. I really can not tell you much about the batteries yet as I just got them online a few days ago. I did however have to adjust my charge paramotors a bit - these are the settings for the Mastervolt charger I have settled on, I may tweak them as time goes on, but for now they seem to be working fine and charge to 99% with these settings when I had them set higher the BMS overcharge protection came on.



Set bulk to 14.25 volts, max bulk 480 minutes, minimum bulk time set to 0, start bulk time at 13.25 volts, return to bulk voltage 13.25, bulk return time 5 minutes ... I set minimum bulk time to 0 in an effort to get charger to stop starting in bulk charge mode even if the batteries were full if AC power is removed from the charger & then restored which worked.



Absorption voltage 13.6, Max Absorption time 60 minutes, Minimum 60 minutes, return amps 6% of max – I set the absorption time fairly short as when the batteries hit absorption they are pretty close to full anyway.



As I do not have the option to turn float off on the charger I set float to 13.4 ... needed to set it lower than absorption (13.60) and higher than return to bulk (13.25) so 13.4 is what I landed on for float. So basically once the batteries are charged at this float voltage there is no current going into the batteries and the Mastervolt charger handles the small DC loads we have while on shore power – I turned every small DC load on in the boat I could think of and got current draw up to 20 amps and at that point nothing was being drawn from the batteries and the Mastervolt supplied all the current for the loads – side note on that I have a super capacitor in the system to smooth out any ripple from the charger.



The only bad thing I have to say so far is that the monitoring application is very basic and you can not see individual cell voltage with it instead you get a graphic of some cartoon guy saying your batteries are well balanced – guess I guess have to take cartoon guys word for it



Something else to consider .. what are you using for alternator protection if the BMS shuts down assuming of course you alternator is only feeding the LPF batteries.

 

[Marco Flamingo]

Set bulk to 14.25 volts, max bulk 480 minutes

I still don't understand why charging phases have set times. "You have between 28 and 33 minutes to eat lunch." What if I'm done in 20? What if it takes me 37? What difference does it make? I'm done when I'm full, dammit!!!

The only bad thing I have to say so far is that the monitoring application is very basic and you can not see individual cell voltage with it instead you get a graphic of some cartoon guy saying your batteries are well balanced – guess I guess have to take cartoon guys word for it

Get the Overkill app and be prepared for information overload.

Something else to consider .. what are you using for alternator protection if the BMS shuts down assuming of course you alternator is only feeding the LPF batteries.

I have the Sterling alternator protection module, but with 4 BMSs, the ability to initially monitor them with the Overkill app, and moderation on your charging parameters, you will be unlikely to ever need it.

 

[Delta Riverat]

Yeah, I don't get the times either. With lead it might be a thing but lithium needs only an absorb voltage and a float voltage and the charger sets the current thresholds. Two numbers to input, both voltage.

 

[DDW]

Actually there are some reasons for the times. If something goes wrong with the voltage triggers, setting a max bulk time eliminates the possibility of continuing in bulk forever. Not the greatest for either LA or LFP. Setting a minimum time allows the cell balancers time to work. Many manufacturers recommend a minimum bulk time (or absorb - they are really the same thing) for this reason. Also, since the Balmar is so bad at switching to float early, setting the minimum may be the only way to get a full charge.

 

[SteveK]

I still don't understand why charging phases have set times. "You have between 28 and 33 minutes to eat lunch." What if I'm done in 20? What if it takes me 37? What difference does it make? I'm done when I'm full, dammit!!!

OK, this is new. There has been a lot of talk about limiting the Absorb time, now the bulk time?
If the charger is unable to reach the target volt setting, something is wrong. Setting for 8 hours as suggested is ok I suppose as long as you get the warning that it occurred.
What next?

 

[Delta Riverat]

Now that I think about it, it does make sense. Makes sense for something like a Balmar regulator that has no idea what current is being supplied. That's what I remember all these time settings for.

But a charger certainly does and shouldn't need time settings for lithium, only breakpoints.

 

[Delta Riverat]

Yesterday I left the boat with the batts at 65%. I decided to try my " float in the middle" idea a way to make sure I don't go shutdown low if I don't visit the boat in time. Which I've done twice now. Set the charger for 30 amps, absorb at 13.1 and float at 13. Enough juice to run the bilge pumps if needed, the refers and the rest of the parasitic loads. Winter is coming and my visits will be getting farther apart especially since my fix it projects are diminishing.

Monday will be my next visit and that should tell the results of my "middle settings"