LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[mitiempo]

Originally Posted by rgleason

Yes, I do because:
Cruising: We enter and leave harbors about .5 - 1 hour per day.
Solar: now (2) 50w on dodger, future (2) 100w on stern with (2) Victron 75/15 controllers.
Alternator: Faster charging with modified Delco Remy 12vdc 28SI 160amps belt managed down to 80-100 amps. (almost finished modification).
Regulator: ARS-5 has alt & batt temp sensors, belt manager LFP advance programming. Early WS500 VSR Alt Regulator available.
Want faster charging for at sea. DC-DC requires two or three 30amp. and very little room for that that I have found so far.
Absolutely no room for any generator and I don't want that complication.
Where do you put it when running? On deck? That's insane while at sea

With what you have that makes sense.

Personally I do want to charge when using the engine to move but not at anchor or sailing.

[newhaul]

Originally Posted by mitiempo

Actually, whatever the price of the generator ($100?), a 75 amp quality charger that can be set properly would be more expensive than the Victron Orion DC to DC charger.

My trace 2512 has the charger built in as do most units we use so the cost is just a cheap generator from harbor freight. But solar is the way to go.

[newhaul]

Originally Posted by rgleason

Yes, I do because:
Cruising: We enter and leave harbors about .5 - 1 hour per day.
Solar: now (2) 50w on dodger, future (2) 100w on stern with (2) Victron 75/15 controllers.
Alternator: Faster charging with modified Delco Remy 12vdc 28SI 160amps belt managed down to 80-100 amps. (almost finished modification).
Regulator: ARS-5 has alt & batt temp sensors, belt manager LFP advance programming. Early WS500 VSR Alt Regulator available.
Want faster charging for at sea. DC-DC requires two or three 30amp. and very little room for that that I have found so far.
Absolutely no room for any generator and I don't want that complication.
Where do you put it when running? On deck? That's insane while at sea.


I had some questions below.

Renogy has a 60 amp b2b with integrated mppt for at last sale it was 250 USD

[fxykty]

Originally Posted by newhaul

But solar is the way to go.

If and only if you cruise only in areas and seasons with good solar conditions. There are lots of cruising areas where solar on its own is not enough.

On our boat we removed the built-in 3KW generator and tripled our solar capacity (now 2.6KW). We still had to get a portable generator to charge when there are multiple grey/rainy days in a row. Our planned engines’ alternators upgrade will hopefully allow us to get rid of the portable generator. I am OK with running a propulsion engine to charge while anchored if needed because solar is not sufficient - two diesel engines is better than three diesel engines.

In our case the alternators charge the lithium battery directly - best for charge acceptance and precisely controlling the charging. We use Balmar DuoChargers to charge the starting batteries from the lithium battery to ensure they have proper charging. This design requires time and money spent to ensure a BMS charge stop command doesn’t damage the alternator.

[newhaul]

Originally Posted by fxykty

If and only if you cruise only in areas and seasons with good solar conditions. There are lots of cruising areas where solar on its own is not enough.

On our boat we removed the built-in 3KW generator and tripled our solar capacity (now 2.6KW). We still had to get a portable generator to charge when there are multiple grey/rainy days in a row. Our planned engines’ alternators upgrade will hopefully allow us to get rid of the portable generator. I am OK with running a propulsion engine to charge while anchored if needed because solar is not sufficient - two diesel engines is better than three diesel engines.

In our case the alternators charge the lithium battery directly - best for charge acceptance and precisely controlling the charging. We use Balmar DuoChargers to charge the starting batteries from the lithium battery to ensure they have proper charging. This design requires time and money spent to ensure a BMS charge stop command doesn’t damage the alternator.

I have 200 watts mono solar running through an epever trace mppt to charge my lfp and it does just fine 8 months out of the year. Need my air 400 wind generator from mid November to mid March here then it is just a backup . And I cruise above the 45th parallel North. Home is at 47°32' 23.7" N in late May till late August I am always fully charged by solar noon . Even on overcast days. So if your solar is not doing the job I suggest a better mppt controller be installed.

[rgleason]

This design requires time and money spent to ensure a BMS charge stop command doesn’t damage the alternator.

I guess this is not the place to try to come up with a nice simple BMS system which will protect the alternator. I had some thoughts/suggestions about that in my double garbled post below.

Newhaul, I have the Renogy 60amp DC-DC with solar MPPT bookmarked, but would like to try to utilize more of the Alternator capacity (say 80 amps, about 1/2 of the rated output). Also these DC-DC have about 15% loss in efficiency which is converted to heat. Additionally I don't believe it is capable of 60 amp output continuously, it is probably 50 amps.

Charging at 80 amps at .3C house bank should be 80/.3 = C = 266 amps.

Charging at 80amps at .25C house bank should be 320 amps.

Charging at 60 amps at .3C house bank should be 200 amps.

Charging at 60 amps at .25C house bank should be 240 amps.

Charging at .3C would be occasionally when use dictated it. The more likely target rate would be .25C for greater battery longevity. This rate would be adjusted by the regulator charging parameters. I have been considering 200 - 240a LFP batteries.

I think I had 80-100 amps as the daily load and more like 140 amps at sea.
With about 100w - 300w (future) of solar (providing 20a - 60a daily) reducing the alternator load to something achievable.

[newhaul]

Originally Posted by rgleason

I guess this is not the place to try to come up with a nice simple BMS system which will protect the alternator. I had some thoughts/suggestions about that in my double garbled post below.

Newhaul, I have the Renogy 60amp DC-DC with solar MPPT bookmarked, but would like to try to utilize more of the Alternator capacity (say 80 amps, about 1/2 of the rated output). Also these DC-DC have about 15% loss in efficiency which is converted to heat. Additionally I don't believe it is capable of 60 amp output continuously, it is probably 50 amps.

Charging at 80 amps at .3C house bank should be 80/.3 = C = 266 amps.

Charging at 80amps at .25C house bank should be 320 amps.

Charging at 60 amps at .3C house bank should be 200 amps.

Charging at 60 amps at .25C house bank should be 240 amps.

Charging at .3C would be occasionally when use dictated it. The more likely target rate would be .25C for greater battery longevity. This rate would be adjusted by the regulator charging parameters. I have been considering 200 - 240a LFP batteries.

I think I had 80-100 amps as the daily load and more like 140 amps at sea.
With about 100w - 300w (future) of solar (providing 20a - 60a daily) reducing the alternator load to something achievable.

It will do the rated 60 all day long according to the renogy tech I asked. Also they are stackable if you really want to go 120 amps into your bank .
For me the 60 in from my 75 amp chevy alternator to top up when leaving or entering an anchorage but my daily usage is a lot less than yours . If I fall asleep watching a movie it can go as high as 40ah used from dark to daylight . ( which has only happened 3 times )
And I don't watch TV at all underway .

[newhaul]

Originally Posted by mitiempo

Actually, whatever the price of the generator ($100?), a 75 amp quality charger that can be set properly would be more expensive than the Victron Orion DC to DC charger.

But your Victron is max rated at 30 amps . Unless you use the ip20 rated for 70 amps and $150 . But it utilizes a 24 volt alternator so more cost for th alternator.

[mitiempo]

Originally Posted by newhaul

.....the ip20 rated for 70 amps and $150 . But it utilizes a 24 volt alternator so more cost for the alternator.

What are you referring to?

[fxykty]

Originally Posted by newhaul

I have 200 watts mono solar running through an epever trace mppt to charge my lfp and it does just fine 8 months out of the year. Need my air 400 wind generator from mid November to mid March here then it is just a backup . And I cruise above the 45th parallel North. Home is at 47°32' 23.7" N in late May till late August I am always fully charged by solar noon . Even on overcast days. So if your solar is not doing the job I suggest a better mppt controller be installed.

OK, you better talk to Victron Energy about our SmartSolar MPPT controllers that they aren’t working well. That wasn’t my point at all - I’m just saying that your wonderful solar experience in your part of the world cannot necessarily be replicated in other parts of the world, or in winter time in your area. Hence the need to diversify charge sources if one isn’t planning to cruise solely when the sun shines.

Our solar keeps up with our consumption and charges to 80% (which we consider full) most days that there is full or partial sun. This is in the middle of winter at 27* S, while the sun is at 23.5* N. It doesn’t keep up when cloud cover is solid and/or if it’s raining steadily for all or part of the day. After a couple of those kinds of days we need an alternative charging source.

[newhaul]

Originally Posted by mitiempo

What are you referring to?

The Victron Energy Orion IP20 24/12-Volt 70 amp DC-DC Converter Non-Isolated, High Power

https://www.amazon.com/Victron-Orion...84104616&psc=1

Most of the rest are low power Units.

[newhaul]

Originally Posted by fxykty

OK, you better talk to Victron Energy about our SmartSolar MPPT controllers that they aren’t working well. That wasn’t my point at all - I’m just saying that your wonderful solar experience in your part of the world cannot necessarily be replicated in other parts of the world, or in winter time in your area. Hence the need to diversify charge sources if one isn’t planning to cruise solely when the sun shines.

Our solar keeps up with our consumption and charges to 80% (which we consider full) most days that there is full or partial sun. This is in the middle of winter at 27* S, while the sun is at 23.5* N. It doesn’t keep up when cloud cover is solid and/or if it’s raining steadily for all or part of the day. After a couple of those kinds of days we need an alternative charging source.

You must really have some serious usage . Your solar would almost charge my entire bank from 20% to 80% in an hour . That is about 5 days usage on my defender.

[mitiempo]

Originally Posted by newhaul

The Victron Energy Orion IP20 24/12-Volt 70 amp DC-DC Converter Non-Isolated, High Power

https://www.amazon.com/Victron-Orion...84104616&psc=1

Most of the rest are low power Units.

First I am 12 volts.

Second that is not a charger, just a 24 to 12 converter.

[newhaul]

Originally Posted by mitiempo

First I am 12 volts.

Second that is not a charger, just a 24 to 12 converter.

But it is a charger insofar as it converts the 24v output to what ever voltage you program to allow 70 amps charging .read the specs. Settable from 10 to 15 volts so set at 14.2 it will do its job as a cc/cv charger.

[rgleason]

Newhaul:

my daily usage is a lot less than yours .

I looked at my spreadsheet

• Cruising: 85 ah but ref 52ah, may be high, no TV, no SSB.
• Sea: 129 ah, ref 52ah, no SSB

Simple Alternator Charged LFP System

Thanks to CarlF and hzcruiser, I think I've found the answer to a nice Simple Alternator charged LFP system.

House Battery: LFP 200-240ah with built in BMS
Starter Battery: FLA 12vdc 200cca Motorcycle Battery 6"lx3.5"wx5.5"h $70
Alternator to LFP: 28SI Delco Remey with

• Balmar ARS-5 160a with belt manage to 80amps, temp sense for alt & batt, programmed for LFP
• or VSR Smart Alternator Regulator with similar conditions.

DC-DC Charger 30a: LFP to FLA


Alternator Protection:

• DC-DC Charger to ".. absorb a spike from a BMS shutdown into the start battery protecting the alternator"
• Balmar APM to provide a second level of protection for the diodes.

My Earlier Question:

Question: How important is it to have this level of protection (advance shutdown communication between the LFP BMS and the Regulator) if you have the FLA battery and Balmar APM?

This actually then turns into the question, Can I reliably use Closed LFP BMS Batteries with no external signal for the alternator?

Answer: Not very important. Yes you can use closed LFP BMS batteries reliably.