LiFePO4 and absorption charging

[Chotu]

and just for a moment, adding to the age of some of the components, my battery monitor is about 20 years old now amazingly enough. i got it many boats ago and carried it from boat to custom built RV to boat and finally to this boat. So i’m pretty used to it

[Bearkeeper]

So, Litime batteries sent a spec sheet with their battery and recommends a float voltage of 13.8 v and a charge voltage of 14.6.
I emailed them and asked about constant floating the batteries at 13.8 and they replied it is recommended without damage to the battery,

[Chotu]

Originally Posted by Bearkeeper

So, Litime batteries sent a spec sheet with their battery and recommends a float voltage of 13.8 v and a charge voltage of 14.6.
I emailed them and asked about constant floating the batteries at 13.8 and they replied it is recommended without damage to the battery,

Yep. my instruction sheet from 2 years ago says the same.

i used slightly lower 14.2 and 13.6 at the direction of a lot of people online who said even 14.2 and 13.6 were too high.

initially i was at 14.4 for a couple months

my bms seems to very much treat 14.6 as a ceiling. it cuts out when you reach it. (or maybe at 14.7) Doesn’t cut out for a long period of time, just for a fraction of a second to back the charger off. it does that repeatedly if i charge that high

here’s a blog post from the litime site that covers all the general guidel for voltages and explains them too.

https://www.litime.com/blogs/blogs/l...GnlvG84dkfE6iY

[Bearkeeper]

I guess I’ll go with the people that made the battery instead of the online experts!

[s/v Jedi]

Originally Posted by Chotu

is this post directed at me?

No, it is in general. I read something about balancing and when you charge slow you may not reach the voltage where the balancer kicks in, or you spend very little time at that voltage before finishing the charge.

Also, for boats who don’t have enough solar to fully charge daily, I wrote that a periodic full charge is needed “to reset the battery monitor to full accuracy”. While this is correct, the main reason is simply to fully recharge the battery, which must happen periodically, let’s say once every 1-2 weeks.

[Chotu]

Originally Posted by s/v Jedi

No, it is in general. I read something about balancing and when you charge slow you may not reach the voltage where the balancer kicks in, or you spend very little time at that voltage before finishing the charge.

Also, for boats who don’t have enough solar to fully charge daily, I wrote that a periodic full charge is needed “to reset the battery monitor to full accuracy”. While this is correct, the main reason is simply to fully recharge the battery, which must happen periodically, let’s say once every 1-2 weeks.

whew! i was very confused. ha ha ha.

[barcoMeCasa]

Originally Posted by s/v Jedi

While this is correct, the main reason is simply to fully recharge the battery, which must happen periodically, let’s say once every 1-2 weeks.

Why do LiFePo4 need to be fully charged evry week or 2?
Mine lasted just fine for about 6 months over winter not once getting to the top voltage knee just fine.
No published papers mentioning this.

[s/v Jedi]

Originally Posted by barcoMeCasa

Why do LiFePo4 need to be fully charged evry week or 2?
Mine lasted just fine for about 6 months over winter not once getting to the top voltage knee just fine.
No published papers mentioning this.

You mean while using them or in storage? In storage it’s fine as long as they don’t discharge too far, but when in use a periodic full charge extends lifespan. This is so for all battery chemistries.

Manufacturers want you to fully charge each and every cycle, which is why they don’t mention a periodic requirement except when in storage for which they do specify a charge interval.

Edit: attached the relevant parts from LiTime 24V battery as an example: full charge when in normal use and a cycle every 3 months when in storage. Remember the internal BMS consumes energy while in storage.

[sailorboy1]

Originally Posted by Chotu

somewhere I read that the absorption stage is good for balancing cells. Is that true? Do I need it?

maybe it's true, or probably is true, and maybe not true at all

In this case you only need it if you can not just be happy and need something to help you

AND if you really are going to be unhappy not knowing why ask a bunch of people on a forum who don't have the same batteries as you instead of asking the manufacturer of yours??????????

[Chotu]

Originally Posted by sailorboy1

maybe it's true, or probably is true, and maybe not true at all

In this case you only need it if you can not just be happy and need something to help you

AND if you really are going to be unhappy not knowing why ask a bunch of people on a forum who don't have the same batteries as you instead of asking the manufacturer of yours??????????

struggling to understand the language here but it’s enjoyable to have a conversation about topics like this.

it’s nice to read the posts, nice to see different perspectives and THAT makes me happy

[sailorboy1]

Originally Posted by Chotu

struggling to understand the language here but it’s enjoyable to have a conversation about topics like this.

it’s nice to read the posts, nice to see different perspectives and THAT makes me happy

it's that you only need to chase your question if you can not just be happy because it is a useless hair splitting item. And that if you really felt you need to know the answer why didn't you ask the manufacturer of your batteries instead of starting a thread that has already been done dozens of times?

[Chotu]

Originally Posted by sailorboy1

it's that you only need to chase your question if you can not just be happy because it is a useless hair splitting item. And that if you really felt you need to know the answer why didn't you ask the manufacturer of your batteries instead of starting a thread that has already been done dozens of times?

thanks for your input. Enjoy your afternoon in Jacksonville.

[00X]

Originally Posted by sailorboy1

it's that you only need to chase your question if you can not just be happy because it is a useless hair splitting item. And that if you really felt you need to know the answer why didn't you ask the manufacturer of your batteries instead of starting a thread that has already been done dozens of times?

Sailors were not the main intended consumer for many of these batteries. The way we use and treat/charge them can be very different than a guy using them for a gold cart or trolling motor. Some of the companies that produce these batteries recommend settings that are not ideal for us and may be problematic. It should be obvious that charging a battery at max voltage and letting the BMS disconnect and determine full charge is not a wise thing to do on a boat, yet many manufacturers recommend voltages that will do just that. Chotu is not the only one reading this forum. His question may answer questions for many other readers who are new to the technology not to mention that the enthusiast community has done an incredible amount to advance our understanding of the tech and how to treat it.

[Chotu]

Originally Posted by 00X

The way we use and treat/charge them can be very different than a guy using them for a gold cart or trolling motor. This can have an impact on how we treat and charge them. Some of the companies that produce these batteries recommend settings that are not ideal for sailors and may be problematic. It should be obvious that charging a battery at max voltage and letting the BMS disconnect and determine full charge is not a wise thing to do on a boat, yet many manufacturers recommend voltages that will do just that.

a very accurate post in general. Mine do disconnect if I go all the way up to the suggested voltage and that’s not ideal.

the guy you’re responding to has probably one of the biggest trolling motors on the whole forum powered by a 150,000 watt battery bank ha ha

[00X]

Originally Posted by Chotu

a very accurate post in general. Mine do disconnect if I go all the way up to the suggested voltage and that’s not ideal.

the guy you’re responding to has probably one of the biggest trolling motors on the whole forum powered by a 150,000 watt battery bank ha ha

:P,

Mine as well if i charge at the manufacturer recommended voltage (14.6). The manufacturer of my batteries (epoch) have a very good reputation amoung the boating community and yet, even they recommend 14.6 volts charging and expect the BMS to trip at high voltage to discontinue charging. Luckily their batteries are really well made and can handle this without issue, but their main consumer base was/is golf cars, electric vehicles and for trolling motors. RV'rs and boaters have noticed and adopted their batteries because they are very good, but if i called them up for advice, they would tell me to charge at 14.6 volts and not understand why thats a problem for me. The enthusiast crowd and internet forums have been instrumental in refining HOW to define best practice for us.