Lithium for the love of God

[john61ct]

Sorry but you're wrong.

I'll stop now.

[nebster]

Yes, careful here, other readers...

[mbartosch]

Big red „dangerous idea“ flag.

[john61ct]

Thanks for the confirmations / reinforcements

[Nicholson58]

I have also engaged in the LIPO4 quest.

We may all find this link a great starting point. There are a lot of very specific YES NO answers to a lot of questions and much discussion of how best to shorten the battery life. This is geared mostly for DIY with not much nice to say about drop-in replacements. His main message is do not overcharge. That means no float, charge to high percentage and STOP; unlearn everything we know about lead batteries.

https://marinehowto.com/lifepo4-batt...ts/#comment-66

Battery and component suppliers - here are a couple.

https://www.electriccarpartscompany....ockb_c_12.html
https://www.ev-power.eu/Winston-40Ah-200Ah/


Drop in. https://www.victronenergy.com/batter...-battery-12-8v

I have found that our stuff is mostly re-programmable.
Balmar MC624. Total no problem
Victron charger-inverter. Can be done with a PC and free ware
Solar Morningstar TriStar45. Can be done with PC and free ware.

A BMS is necessary. It has to be smart enough to handle the solar differently. The controller power must NOT be disconnected by the BMS and there needs to be a way to command zero out or disconnect the panels input to the controller. Morningstar has a trick method of forcing the controller off or low using the battery temperature input.

ROXY is on the hard in Trinidad, Power Boat Marine in Chaguaramas. This makes doing anything at least double difficult.

[jbinbi]

Originally Posted by Nicholson58

Drop in. https://www.victronenergy.com/batter...-battery-12-8v

Many thanks for this. I did not know victron made these. No idea about the cost, but I have FLA, 3x 140 Ah that will need replacing soon. Just installed 2 Victron 100/20 controllers for each 285 W panel, and will be installing Victron charger/inverter in the near future. So thinking this might be a very simple way to go? Size and wt is fantastic, the Victron 160s are ~ 12 x 12 x 8".

[Nicholson58]

Originally Posted by Woodland Hills

No, but the blanket statement made previously was incorrect in my experience. I wouldn't want there to be any lithium cells on any boat or airplane I was traveling on. I would expect cheap hoverboards to catch fire randomly, but when Boeings solution to the well known lithium battery fires on the 787 is to armor the compartment, well, you decide......

Lithium LiFePO4 Is safe. You cannot make it burn. Please remember we used to send austronauts into space in capsules of compressed oxygen. There are many lithium chemistries. Things do change

[Nicholson58]

Originally Posted by barnakiel

Thanks John !

Yep. This is what I meant. Going from flooded to agm does not offer similar benefits that going from agt to litium does. The total charge time is largely limited by the last 15%.

This is actually important even more with solar charging, at least in our 100Ah boat - the battery cycles mostly through 80-100%. So we are virtually always charging the 'remaining 15%'.

I have found there is a simple and elegant solution. It is to split into house1 and house2 where 1 is lithium and sized at what the boat normally cycles daily. Bank2 is then a reserve used only if and when the 1 gets depleted in one cycle. Bank 1 (say 35Ah) can be lithium and Bank 2 can remain plain car batteries.

I have made some calcs and this is way faster to charge (and of course) way less expensive than one big lithium bank.

I think I am buying a litium NEC ALM for our next adventure. 35Ah lithium + Bank 2 60Ah Varta flooded sealed car grade.

Thanks!
b.

This is OK is you have separate charging options or equipment. The lithiums and the lead batteries demand different voltages. Two alternators with two differently programmed controllers would do.

[CatNewBee]

Originally Posted by Nicholson58

I have also engaged in the LIPO4 quest.
...
A BMS is necessary. It has to be smart enough to handle the solar differently. The controller power must NOT be disconnected by the BMS and there needs to be a way to command zero out or disconnect the panels input to the controller. Morningstar has a trick method of forcing the controller off or low using the battery temperature input.

.

Victron MPPT does have an input for a remote switch, you can connect the stop charge signal of the bms here to gracefully disable the charger if needed. When using multiple devices on the output, consider using small signal relays to galvanically isolate the signals for each device! Also opto coupler can do the job if there are low current digital inputs, while they are a more elegant solution, you must consider the right polarity, relays are easier for amateurs.

[john61ct]

Originally Posted by Nicholson58

Lithium LiFePO4 Is safe. You cannot make it burn.

Too strong.

Had a poster assembling packs from small cylindricals, DIY Tesla style, say that accidentally puncturing them did cause a brief flash-flareup type fire.

Did not ignite others though.

So, yes, very safe, maybe as safe as lead, safer than gas or propane.

But "You cannot make it burn" is overstating.

"Much less subject to thermal runaway" is how I'd put it.

[john61ct]

Originally Posted by Nicholson58

This is OK is you have separate charging options or equipment. The lithiums and the lead batteries demand different voltages. Two alternators with two differently programmed controllers would do.

DCDC charger accepts any charge source.

[john61ct]

Originally Posted by CatNewBee

you can connect the stop charge signal of the bms here to gracefully disable the charger if needed.

I think it would be more elegant to just isolate the LFP charge buss, and let the source inputs continue carrying loads and charging the lead bank.

The challenge there is re-connecting the LFP loads buss to consumers when current demand rises and starts depleting the lead bank.

[CatNewBee]

Originally Posted by john61ct

Too strong.

Had a poster assembling packs from small cylindricals, DIY Tesla style, say that accidentally puncturing them did cause a brief flash-flareup type fire.

Did not ignite others though.

So, yes, very safe, maybe as safe as lead, safer than gas or propane.

But "You cannot make it burn" is overstating.

"Much less subject to thermal runaway" is how I'd put it.

Electricity induced fires are very common, even without batteries. Energy, especilly in high density, is always dangerous, she had always a big impact if something goes wrong, np matter what kind of energy you chose.

That is the reason, everything in nature is striving to maximize entropy, this is the state of least energy, maximum safety, no impact on anything.

[exMaggieDrum]

Question: My Outback MX60 MPPT solar charger regulator is programmable for bulk/absorption and float voltage levels. It implies, and a charge profile diagram backs this up, that the float is only active when the battery is below the float voltage after it goes through the bulk/absorption phase. I.e. no voltage pressure from it to the battery when at or above the float voltage.


If this is the case, and it might not be, then that would seem to negate the problem of leaving a float charge to the LFP bank. I do understand the importance of not keeping a charge at float level going, or at least that seems to be the consensus of the "best" LFP gurus on CF.



Any one with better info on this?

[CatNewBee]

No problem with float on LFP, especially if you use power during the night, youll cycle the battery. It is only important to set it lower than a full cell would have in rest without charge, so there is no current going into the cells.

The main concern of the folks out there is, they want the LFP at 30% SOC (the recommended storage charge) for longitivity, that is a senseless approach. If you go for LFP, you do it on purpose and want the battery full in the afternoon and cycled during the night and morning. You want the power, and not just the storage 30% energy.

If you set the Float to 13.4...13.6V, the cells remain at 98%,while all current of the Float controller goes straight at the loads. Nothing wrong with that. At some point the voltage drops and the battery provides the missing energy.

Next day you simply re-charge what you have used.

It is not recommended to STORE LFP batteries at full charge, but you are not storing them,you are using them, so it is ok. It makes no sense to install a double size battery to just keep it at 50% SOC for longuitivity. This is a stupid approach. You buy the capacity you need and some extra for safety in cloudy days, you harge to full and use what you need. That is all.