LiFePO Batteries ???

[bruceb58]

Do not float charge LIFEPO4 cells / batteries.

You just set the float voltage to 13.5V. Will not harm them at all. Most LiFePO4 battery manufacturers spec that voltage.

 

[tpenfield]

You just set the float voltage to 13.5V. Will not harm them at all. Most LiFePO4 battery manufacturers spec that voltage.

Yes, the solar charging essentially does the float charging, based on its capacity. It does not have enough wattage to do the other stages of charging.

In other news. . .
I installed the new alternator on the starboard engine yesterday . . . lots of 'fun' . . . see my write-up in the Mercruiser forum. The outdrives are off the boat right now for maintenance, so it will be a few days before I can run a test.

 

[tpenfield]

The new alternator works . . . it even likes the DC-DC charger.

 

[bruceb58]

This is something new that you could have used with this project. It's A DC to DC converter that can charge each direction. This would be perfect for motorhomes that go somewhere and sit awhile as long as the house batteries are charged via solar.

EcoFlow 800W Alternator Charger | 800W Alternator Charger | EcoFlow

Please kindly note that the EcoFlow Alternator Charger and the portable power station will be shipped separately. Shipments are expected to begin from early August. Charge while you drive, and stay powered up on the road. 800W turbo alternator, 8× faster than traditional in-vehicle auxiliary...

us.ecoflow.com

 

[bruceb58]

Yes, the solar charging essentially does the float charging, based on its capacity.

The solar controller only goes into float once it has completed bulk and absorption. Once it senses a slight reduction in voltage from the battery, it comes out of float and back into bulk, starting the process over again. Not sure how that really works right going through that ArgoFET isolator. I would likely have designed it without that component.

 

[bruceb58]

Question
A Bat charger reduces the amount of Amps as the need for charge is decreased. The solar charger outputs X amount and is dependent on the sun. What regulates the excess power not needed, and where does it go?

On lithium batteries, the amount of charge they will accept is as much as the charger can source up until it's close to 100% full. I see 90A received on my older 200AH bank until they were up into the 14V region which is basically fully charged...then it has a slight taper. Now that I have 560AH, they behave exactly the same. Lithium bateries have VERY low input resistance compared to a lead acid battery. On a lead acid battery, since resistance is higher, is what they taper compared to lithium.

The way a 3 stage charger works(including solar controllers)is that during bulk, the charger is is constant current mode which means it outputs the max current it can. Once the controller sees the battery hit absorption voltage(I set mine to 14.3V for lithium)the charger output constant voltage until the current drops to less than an amp and then it switches to float. The charge controller takes care of the output. The input from the solar panels is just naturally reduced based on what the controller is outputting. No different than plugging a 120VAC charger into the wall receptacle. The receptacle can source way more current that it is asked to deliver by the charger.

 

[tpenfield]

The solar controller only goes into float once it has completed bulk and absorption. Once it senses a slight reduction in voltage from the battery, it comes out of float and back into bulk, starting the process over again. Not sure how that really works right going through that ArgoFET isolator. I would likely have designed it without that component.

Charging of the LFP batteries does not go through the AgroFET. The LFP batteries are connected directly to the Orion. The ArgoFET is on the lead-acid side.

The best that I'm seeing out of the solar panel is 62 watts . . . mid-day full sun . . . So, that yields about 4.5 amps of charging to the LFP batteries at 13.5 volts. Of course the EPEver does not really tell you what stage of charging it is in. The thing is OK, but it has a mind of its own.

 

[tpenfield]

On another note . . .

I was able to clean up that starboard electrical box using some harsh chemicals . . .
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The floor is pretty well cleaned up, but I need to figure out something to clean up the walls. I was able to clean up the starboard isolation post and put it all back together.
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The other bus bars will also need some TLC or replacement. I'm not a fan of having all of this stuff in a box, particularly on the floor of the box. The engine bay is big enough, they certainly could have used some more wall space. . . . but oh well . . .

 

[bruceb58]

Charging of the LFP batteries does not go through the AgroFET. The LFP batteries are connected directly to the Orion. The ArgoFET is on the lead-acid side.

I never stated what type of batteries get charged from the solar controller through the ArgoFET. Your engine batteries do!!!

 

[tpenfield]

Quick Update. . .

I ran into some engine issues today while waiting for dock space to open up to pick up the crew. The stbd engine started throwing fits the alarm went off, then it died. I got it started, but I wanted to check it out once we got to our anchoring spot for the day.

No codes on the Diacom, but the alarm history had a few voltage warnings. So, I thought about the Victron Orion DC-DC converter. It turned out that I had the activation settings too low and the charger was activating (into bulk charging) when the engines were at idle. So, I raised up the settings to stop charging when the input voltage (i.e. alternator voltage) goes below 13.9 and not to re-activate until the voltage goes above 14.2.

I tested it on the way back at the end of the day and all seems good. Something to keep in mind with these digitally controlled engines.

 

[bruceb58]

That is very odd. You should not be having problems if the voltage stays above even 13.0V. What did you have it set to?

What happens when you have a low battery and the alternator is cranking out the amps at idle?

 

[tpenfield]

Just catching up on a few pictures that I was not able to post previously . . .
New battery isolator . . .

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The new alternator

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The system has been running well over the summer. Happy batteries . . .

 

[tpenfield]

A quick update to this thread. . .

I was at the summer house this weekend, where the boat is located. So, I checked the electrical system/batteries, as they are in 'maintenance mode' for the winter.

The 2 engine batteries (SLA) are sitting nicely @ 14 volts each (trickle charged)

The house battery bank (LiFePO4) was reading '0'. No power at all. My thoughts are that the BMS has kicked out due to the low temperature. I looked for some spec's on the LTCP and this is all I could find off hand.
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Low temperatures in the area have gotten in the mid-low 20˚ F during the past week. So, I suspect that the charging feature has kicked in, but the discharging spec goes much lower in temperature. So, I am thinking why it would be seeing zero volts for the house bank. Naturally, the engine bay hatch runs off the house bank, so I could not check things at the electrical panel.

So, maybe the lack of charging (for a while) has caused the battery voltage to dip below the low voltage cut-off (i.e. over-discharge protection). (maybe )

Or perhaps it is something more severe . I guess I won't be able to tell until spring time.

 

[bruceb58]

If your batteries got down to a point where the low voltage discharge kicked in, you need to charge them up...PRONTO! Even if the low discharge of the BMS disconnects, the cells will still self discharge at a rate of 1% to 3% per month and the cells will be ruined eventually.

 

[tpenfield]

Yes, @bruceb58

That's what I need to figure out . . . M-T-W of this week the temperatures were at/above the "recovery" point (41˚ F) entirely for those 3 days. If the batteries came back to life, then the Xantrex inverter/charger would/should charge them at 20 Amps for a 'while' per the custom profile. (of course the boat is 90 miles away at the summer house, so no way to tell) Maybe I'll have to figure out an IoT gadget that I can use to monitor the boat remotely.

This being the first winter with the LFP batteries, it is a bit of guess-work as to if the batteries can make it through the winter. Lowest temps are typically +5˚ F now & then. But it looks like the problem is the charging cut-off & recovery spec vs. the discharging spec is a problem.

If this does not work out, then I may need to change my winterization routine to include removal of the LFP batteries.

 

[Scott Danforth]

Ted, it was 41 at my house this morning in Florida.

 

[tpenfield]

Ted, it was 41 at my house this morning in Florida.

26˚ F at my house this AM. Cape Cod was about the same.

I'm going to do a wait 'n see on the battery charging. A mid-winter global warming spell would help, as I can take a look at things to see if the charging/recovery kicks in.

As luck would have it, the engine hatch runs off the LFP battery bank, so raising the hatch to get a look at things is a no-go for the moment. I'm not sure manually raising the hatch is an easy task either . . .

 

[airshot]

If your batteries got down to a point where the low voltage discharge kicked in, you need to charge them up...PRONTO! Even if the low discharge of the BMS disconnects, the cells will still self discharge at a rate of 1% to 3% per month and the cells will be ruined eventually.

Only charge back up to the recommended storage voltage unless your gonna be using it within the next 24 hrs. Storing at full charge is not healthy for them either.

 

[tpenfield]

I may have to re-think my winterization routine. . .

Perhaps have a way to pump some warm air into the engine bay via the blower/intake vents.

That way, I can force a temperature rise and see if the batteries wake up. I suspect a self heating battery might be better to keep things 'alive' over the winter.

Not being able to raise the engine bay hatch is a real problem, because all of the batteries and electrical stuff is in there.

Also wondering if I should go with a black or dark colored winter cover to absorb some heat from the sun.

 

[cyclops222]

Can not remember the companies. But their own BMS ran the batteries down to recharge point endlessly.