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

[newhaul]

Originally Posted by s/v Jedi

I fully agree with CNB here… when your batteries are full, why waste solar production by powering the boat from batteries instead of solar.

For us, half of daily solar production goes into the batteries and the other half is consumed directly during the day.

That is when I run my rice cooker to make dinner rice and run fridge extra. ( holding plates are nice that way. Or run watermaker if I need water.

[sparrowhawk1]

Okay I get it 13.5 volt float it's pretty much the same as setting it to your charge voltage. I want to learn I'm not being obnoxious why not set your float to the same voltage as charge? Lithium batteries act differently from lead that's previously bin discussed.

[newhaul]

Originally Posted by sparrowhawk1

Okay I get it 13.5 volt float it's pretty much the same as setting it to your charge voltage. I want to learn I'm not being obnoxious why not set your float to the same voltage as charge? Lithium batteries act differently from lead that's previously bin discussed.

Controller won't allow them to be identical must be set with bulk higher than float
Likely a throwback to fla as the controller can do all common chemistries of battery.

My Bulk is set to 14.1v. And float is 13.6 bulk reconnect is setmto 13.3v

[swampbush]

It is disappointing that people can make a video and it is taken as gospel. He completely misses expert mode on the victron controller that has adjustable rebulk offset voltage that will trigger rebulk when the battery drops below float. This allows a recharge after heavy power consumption.
I charge to 14.2 which is when my cells start to balance. Float is 13.4 volts. After absorption the batteries discharge fairly rapidly, until state of charge is 99%. It is repeatable and holds at 99% for the rest of the day till the sun goes down. I didn't want to hold charge at 100% as from my reading that is bad for longevity. At 13.4 the solar powers the loads, and in the event of a moderate discharge will bring the voltage back up to float level of 13.4 and 99% without going back into bulk as my rebulk offset is 0.2v. At the standard victron 0.1 rebulk offset it went into bulk several times a day as we use an electric kettle and induction cooker.
If float was set at 13.2 my batteries would be discharging half the afternoon. I live aboard and don't want to waste power that I could be using for hot water or making water.

[newhaul]

Originally Posted by swampbush

It is disappointing that people can make a video and it is taken as gospel. He completely misses expert mode on the victron controller that has adjustable rebulk offset voltage that will trigger rebulk when the battery drops below float. This allows a recharge after heavy power consumption.
I charge to 14.2 which is when my cells start to balance. Float is 13.4 volts. After absorption the batteries discharge fairly rapidly, until state of charge is 99%. It is repeatable and holds at 99% for the rest of the day till the sun goes down. I didn't want to hold charge at 100% as from my reading that is bad for longevity. At 13.4 the solar powers the loads, and in the event of a moderate discharge will bring the voltage back up to float level of 13.4 and 99% without going back into bulk as my rebulk offset is 0.2v. At the standard victron 0.1 rebulk offset it went into bulk several times a day as we use an electric kettle and induction cooker.
If float was set at 13.2 my batteries would be discharging half the afternoon. I live aboard and don't want to waste power that I could be using for hot water or making water.

So your bank starts balance at 3.55v. Mine is 3.6v. But full is 3.65. Of 14.6v ( calb aluminum case) . I set the same at 14.2 as I have found balance is in necessary in 3 years of testing and no loss of capacity.

[sparrowhawk1]

https://youtu.be/DQeUYJoTpzg

All hail Lord Andy. Please please that was a joke. The bottom line is all his videos are experimenting . No one has said why it makes sense to put your float lower than your charge . no dogs in the game I have an old school controller and I've stated the drawbacks to it. works with my circumstances but if I could change the parameters life would be perfect LOL

[sparrowhawk1]

And if you want to find out the correct way to keep your batteries in balance watch Andy's videos. I currently have mine set to start balancing at 3.45 is it correct is it too low is it too high only you can decide

[newhaul]

Originally Posted by sparrowhawk1

And if you want to find out the correct way to keep your batteries in balance watch Andy's videos. I currently have mine set to start balancing at 3.45 is it correct is it too low is it too high only you can decide

balancing at a specific point is all up to the end diy user. I had my Daly bms flashed to balance at 3.6vpc as I dont balance except one time a year when I do my capacity check. In 3 years liveaboard use no need to balance and no loss of capacity .

[sparrowhawk1]

I stopped posting because a lot of people on this forum are jerks so I'll be back up because you and other good people on this form have helped me. Back one or two years ago, time flies, I was using a daily bms and thought everything was fine, they are everywhere and it's potted, for those unfamiliar that it just means it's totally sealed in epoxy or some material. I thought how can anything go wrong until it stopped working so I bough a radio b that has Bluetooth and I saw how far out balance my cells were and took me 3 months because it has a small maybe 200 milliamps balancing ability and I would manually put a small load on the highest cell to equalize. you can adjust what voltage you want it to start balance and Andy goes over that too, not with the daily and factory settings of 3.65 you're already pushing boundaries according to vid-gospel. If I had to do it again I would go with with the JK BMS that Andy has done a review on. Thank you new haul and Andy. I have no affiliation with anyone and not giving any advice just saying what works for me and what I would do if I had to repeat my steps

[newhaul]

Originally Posted by sparrowhawk1

I stopped posting because a lot of people on this forum are jerks so I'll be back up because you and other good people on this form have helped me. Back one or two years ago, time flies, I was using a daily bms and thought everything was fine, they are everywhere and it's potted, for those unfamiliar that it just means it's totally sealed in epoxy or some material. I thought how can anything go wrong until it stopped working so I bough a radio b that has Bluetooth and I saw how far out balance my cells were and took me 3 months because it has a small maybe 200 milliamps balancing ability and I would manually put a small load on the highest cell to equalize. you can adjust what voltage you want it to start balance and Andy goes over that too, not with the daily and factory settings of 3.65 you're already pushing boundaries according to vid-gospel. If I had to do it again I would go with with the JK BMS that Andy has done a review on. Thank you new haul and Andy. I have no affiliation with anyone and not giving any advice just saying what works for me and what I would do if I had to repeat my steps

as to the Daly. I am a commercial customer and had them flash to balance at 3.6 at .5amp.
Amazing what you can have done when you talk about multiple units with the factory
I have adjustable 5 amp single cell charger left over from my old remote control flying days .
But in 3 years the worst cell was .05 off from the average of the other 3 so I am happy

[sparrowhawk1]

This is typical for my battery not typical for everyone and Im pretty sure mine are grade b because when they're being charged they are not anywhere near this close but that's why I would like to have a JK controller to keep them top balanced

[sparrowhawk1]

And unfortunately I have to use the word typical again but it is typical For my cells to be completely balanced until they get above three point something let's say 3.5 and I typically LOL charge my batteries past that point so they have time to balance. The only reason I can see charging above 13.8. and I'm still waiting for someone to tell me why it's not a good idea to have the float the same.

[mitiempo]

Originally Posted by sparrowhawk1

The only reason I can see charging above 13.8. and I'm still waiting for someone to tell me why it's not a good idea to have the float the same.

By having float at the same voltage as bulk you effectively have a bulk voltage that never stops unless the BMS shuts it off.

[newhaul]

Originally Posted by mitiempo

By having float at the same voltage as bulk you effectively have a bulk voltage that never stops unless the BMS shuts it off.

Bingo . And that's not good for lfp.

[sparrowhawk1]

Well I guess that's the big question is it more harmful for them to sit full or to needlessly cycle. Also it's clear to me that it's best to either top balance or bottom balance and my BMS has I believe 200 milliamp balancing capability so I believe it's a good thing to keep the battery full for a couple hours every day so the balancer can do its thing.