Charging lithium

[motion30]

I have installed 900 amps of drop in lithium batteries. At what ampage should I stop charging? Refering to my 1740 watts os solar charging.

 

[SteveK]

I have installed 900 amps of drop in lithium batteries. At what ampage should I stop charging? Refering to my 1740 watts os solar charging.

I continue to study lithium and now have read that they can accept up to 50% of rated Ah but many talk about 30%. You should look at the battery brand website. There does not seem to be a constant.
Ie: One 200 Ah said can do 100A re change in two hours but 40A over 5 preferred.

 

[motion30]

I continue to study lithium and now have read that they can accept up to 50% of rated Ah but many talk about 30%. You should look at the battery brand website. There does not seem to be a constant.
Ie: One 200 Ah said can do 100A re change in two hours but 40A over 5 preferred.

I may have misworded my post. My question is at what Ampage should I end the charge? That is a parameter that I can program into my outback solar chargers. Right now I am just charging by time

 

[Simi 60]

What did the manual for the batteries tell you?
And please tell me they are lifepo4.

I and I imagine the rest of the worlds lifepo4 users hate it when people call them lithium.

Lithium is what catches fire, it's what has insurers scared
Lifepo4 is a different chemistry that does not have these issues.

 

[twistedtree]

Return amps really don't matter. Set the charger for the target voltage called for by the battery vendor, and absorption time that call for. If they say nothing, then I'd charge to 3.45 volts per cell, so 13.8V for a 12V nominal battery, and set absorb to 10-20 minutes. They really need little to no absorb at all unless the internal balancer needs it, which many do.


Perhaps more important is to set float to 3.35 to 3.40 vpc, and not any more. So 13.4V to 13.6V.

 

[motion30]

What did the manual for the batteries tell you?
And please tell me they are lifepo4.

I and I imagine the rest of the worlds lifepo4 users hate it when people call them lithium.

Lithium is what catches fire, it's what has insurers scared
Lifepo4 is a different chemistry that does not have these issues.

Yes they are lifepo4. The manual only suggest charging voltage of 14.4-14.6

 

[twistedtree]

Yes they are lifepo4. The manual only suggest charging voltage of 14.4-14.6

That seems very high. The max for LFP is 3.60 vpc which is 14.4V for a 12V battery. Not charging to the very max is the best way to avoid unexpected shutdowns.

 

[motion30]

That seems very high. The max for LFP is 3.60 vpc which is 14.4V for a 12V battery. Not charging to the very max is the best way to avoid unexpected shutdowns.

I thought it was 3.65 ? No matter As you suggested I'm using a more conservative voltage
Unlike battle born. Many of the Chinese batteries have information that is sorely lacking.

 

[pjtemplin]

I and I imagine the rest of the worlds lifepo4 users hate it when people call them lithium.

Lithium is what catches fire, it's what has insurers scared
Lifepo4 is a different chemistry that does not have these issues.

I'm just going to say wow and move on.

 

[Comodave]

Marinehowto.com has a great article on lithium batteries. Rod Collins does excellent work.

 

[motion30]

Marinehowto.com has a great article on lithium batteries. Rod Collins does excellent work.

Thank you for that article. The author suggests a much more conservative charging profile. I have changed my solar chargers to reflect that. Like everyone else I hope these batteries last a long time.

 

[Comodave]

He has a lot of good articles. Very knowledgeable guy.

 

[Simi 60]

Our batteries came with this info if any help

 

[Iggy]

Return amps really don't matter. Set the charger for the target voltage called for by the battery vendor, and absorption time thay call for. If they say nothing, then I'd charge to 3.45 volts per cell, so 13.8V for a 12V nominal battery, and set absorb to 10-20 minutes. They really need little to no absorb at all unless the internal balancer needs it, which many do.

Yep!

Plus you can look at what Max Charge Current of your batteries. At 1740 Watts off the top of my head, thats just under 150A. Which I am sure your fine. But it is a number you want to look at.

In your settings, I am sure the manual states to turn Equalization off.

If you can't turn off Equalization, than Bulk and Absorption should be set to the same voltage.

 

[CharlieJ]

All Victron charging and monitoring equipment recommends a tail current of 0.04C, at the charging voltage held for three minutes. When these three criteria are meant, charging is considered complete and the battery monitor resets SOC to 100% and sources drop to float. Note that in the spec sheet in #14 above, that manufacture recommends a "termination current" of 0.05C so we are in the right ballpark.

 

[Barking Sands]

Our batteries came with this info if any help

Thanks for that. Very clear concise and helpful

 

[SteveK]

All Victron charging and monitoring equipment recommends a tail current of 0.04C, at the charging voltage held for three minutes. When these three criteria are meant, charging is considered complete and the battery monitor resets SOC to 100% and sources drop to float. Note that in the spec sheet in #14 above, that manufacture recommends a "termination current" of 0.05C so we are in the right ballpark.

This (tail current of 0.04C) is new to me, what is it?

 

[twistedtree]

One of the advantages of LFP is that it's fine if you don't 100% fully charge the battery. The voltage pops up really fast at the end of charge, and as a result there is very little additional energy (Ah) stored between charging to 3.45vpc and 3.6vpc. So many people (me included) feel that best practice is to charge to a more modest level and call it a day. The worst that happens is you give up a percent or two of battery capacity, and it creates a safety buffer to keep you away from overcharging which can be destructive to the batteries. So if it's dangerous over there, then don't go there. Others have described it as a breakdown lane and guard rail before you go over the cliff.

 

[Delfin]

One of the advantages of LFP is that it's fine if you don't 100% fully charge the battery. The voltage pops up really fast at the end of charge, and as a result there is very little additional energy (Ah) stored between charging to 3.45vpc and 3.6vpc. So many people (me included) feel that best practice is to charge to a more modest level and call it a day. The worst that happens is you give up a percent or two of battery capacity, and it creates a safety buffer to keep you away from overcharging which can be destructive to the batteries. So if it's dangerous over there, then don't go there. Others have described it as a breakdown lane and guard rail before you go over the cliff.

Ditto, with one comment. Depending on the BMS, cell balancing may not occur until cell voltage reaches 3.6 or 14.4 v. On my Lithionics, they recommend 14.6 volts for a few minutes occasionally to balance. I'll usually allow voltage to rise to 14.6, then disconnect charging as the battery is full, and balanced at that point.

 

[motion30]

The marine how too article was very informative and helpful. I did see one contradiction though. They of course recommended a more conservative charging voltage of 13.8v. But then in the next paragraph it stated it was important To get the batteries to full charge,3.6 per cell To activate the cell balancing feature...

 

[Delfin]

The marine how too article was very informative and helpful. I did see one contradiction though. They of course recommended a more conservative charging voltage of 13.8v. But then in the next paragraph it stated it was important To get the batteries to full charge,3.6 per cell To activate the cell balancing feature...

Is there an echo in here?

 

[CMS]

The marine how too article was very informative and helpful. I did see one contradiction though. They of course recommended a more conservative charging voltage of 13.8v. But then in the next paragraph it stated it was important To get the batteries to full charge,3.6 per cell To activate the cell balancing feature...

13.8V is for a DIY bank you built yourself with very well matched cells. The next part was talking about drop in batteries where you have no idea what the cells are doing...

"*If you have drop-in batteries, or cells you don’t know match extremely well, you will want to charge into the BMS's “balancing range” with each cycle and hold this for the manufacturers specified duration."

 

[Delfin]

13.8V is for a DIY bank you built yourself with very well matched cells. The next part was talking about drop in batteries where you have no idea what the cells are doing...
"*If you have drop-in batteries, or cells you don’t know match extremely well, you will want to charge into the BMS's “balancing range” with each cycle and hold this for the manufacturers specified duration."

Your contributions to mariners privileged enough to know about your work are so much appreciated, so thank you Rod! Talk about giving back - you're in a class of your own!

 

[CharlieJ]

@SteveK #17: Tail current is usually expressed as a portion of the battery's C rating; e.g., 0.04C equates to a current of 4% of the C rating.

As the battery is charged, the amount of current being accepted by the battery decreases. Once the charging current decreases below the tail current limit, the battery voltage is below a charged voltage limit and both of these variables are held for a certain amount of time (3 or 4 minutes), the battery is considered full. The charging source takes appropriate action and any Coulomb counting battery monitor resets SOC as 100%.t

 

[Neil Ramsey]

Have you switched to just LFP or do you still have some lead for backup?

 

[motion30]

Have you switched to just LFP or do you still have some lead for backup?

I have 2 group 31 la as start batteries

 

[Don L]

I have installed 900 amps of drop in lithium batteries. At what ampage should I stop charging? Refering to my 1740 watts os solar charging.

I have mine set up to stop charging at 2% acceptance at 14.4V or after 30 minutes of hitting 14.4V

Both of these for me are not an everyday thing and only happen on days of motoring plus good solar as I have my alternators dropping to float if it does 14.0v for 12 minutes.

 

[av8tr]

I'm just going to say wow and move on.

Exactly, I'm with you.

 

[Iggy]

Exactly, I'm with you.

Please do....