Shore charging 24v lifepo

[Ampster]

Yes I have used those as well. In fact I have gone through four or five in eight years. They have all blown some internal circuitry and I don't think they are built for long term content use. They are great for powering various device for test purposes. What i don't like is that the display doesn't always show you what the content voltage setting is. They do show you what the voltage going to the device is but unless you push the right buttons that may not be the maximum, so the user goes to bed and wakes up to a puffy cell.

If you are looking for 29 volts then query for that and not 24 volts to get closer. The have a small voltage adjustment that has at least a volt or two range between nominal.

 

[John Frum]

Ah ok, so important not to leave power supply/charger connected for too long after full.
The nice thing about the Yescom I guess would be easy voltage/ current adjustment and display showing whats going on. The current would taper but the voltage would remain at 29.2v. What would be the resting voltage for a 24v battery? 26.6v or so? I know my one 12v lifepo rests13.3-13.4v so double for 24v ?

I would consider 27.6 as full resting voltage for an 8s lifepo4 battery.
You can charge a battery 99% full at that voltage.
It just takes longer.

How to Find Happiness With LiFePO4 (Lithium-Ion) Batteries –...

By: Rob Beckers You have just sold your first-born into slavery, remortgaged the house, and bought yourself a lithium-ion battery! Now you want to know how to take care of your precious new purchase: How to best charge lithium-iron batteries, how to discharge them, and how to get the maximum...

www.solacity.com

 

[MrNatural22]

Yes I have used those as well. In fact I have gone through four or five in eight years. They have all blown some internal circuitry and I don't think they are built for long term content use. They are great for powering various device for test purposes. What i don't like is that the display doesn't always show you what the content voltage setting is. They do show you what the voltage going to the device is but unless you push the right buttons that may not be the maximum, so the user goes to bed and wakes up to a puffy cell.

If you are looking for 29 volts then query for that and not 24 volts to get closer. The have a small voltage adjustment that has at least a volt or two range between nominal.

Yeah i understand the lower priced desktop power supplies aren't durable for lots of use but it would likely only be used for charging occasionally 98% of the time when sunless days and grat skies are upon us. And use for a power supply if needed for other things.
A separate meter on the battery to show voltage battery is at. and maybe set the power supply to 27- 28v since 100% SOC isn't needed for except on occasion for battery health?

on a side note......it’s gonna be freaking hot again it’s only 1:00 Brought the LiFePos inside so they don't bake in the trailer ?

 

[Ampster]

Can you link to an acceptably accurate one please?

Here is the one I have used off and on for eight years. I think it can be adjusted for accuracy because with the wide range an volt is a bigger difference per cell at 12 volts (4 cells) than it is at 116 volts (36 cells)
There are less expensive ones on Amazon but it turn out I have never need another.

Programmable 4 Digit Red LED AC/DC Volt Meter with Dual Control. Good for HHO System

www.lightobject.com

 

[Bob142]

@MrNatural22, what's your budget? There are chargers like this out there for $99.

29.2V, 10A AC-to-DC Charger (Alligator) for 24V LiFePO4 Batteries (BPC-2410C)

Click here to download the Material Safety Data Sheet for LiFePO4 (Lithium Iron Phosphate) batteries. This 29.2VDC, 10A AC-to-DC Charger, Model BPC-2410C is an AC-to-DC charger for use in charging 24V LiFePO4 batteries. The charger comes available with Alligator Clips for easy...

www.bioennopower.com

 

[Ampster]

You provide the charge termination manually.

I should clarify my answer based on subsequent discussion. I always manually terminated charging when using a power supply. If not by voltage then just by unplugging it or leaving it on a timer. A power supply turns into a trickle charger once the Amps have tapered to zero. Then as the voltage settles it cranks up a few MilliAmps to keep the voltage at the set value. The cycle repeats and if left on long enough, certain chemical reactions occur that shorten the life.

 

[John Frum]

I should clarify my answer based on subsequent discussion. I always manually terminated charging when using a power supply. If not by voltage then just by unplugging it or leaving it on a timer. A power supply turns into a trickle charger once the Amps have tapered to zero. Then as the voltage settles it cranks up a few MilliAmps to keep the voltage at the set value. The cycle repeats and if left on long enough, certain chemical reactions occur that shorten the life.

You are talking about micro cycling?

 

[Ampster]

since 100% SOC isn't needed for except on occasion for battery health?

That is a Pb concept that definitely does not apply to Lithium. In fact manufacturers recommend long term storage at 50%.

 

[Ampster]

You are talking about micro cycling?

Yes, but the real damage is done from the higher voltages and states of charge. I have not heard any examples of microcycling hurting a battery at 3.2 volts, but at that voltage the cycles would be a long time apart.

 

[John Frum]

Yes, but the real damage is done from the higher voltages and states of charge. I have not heard any examples of microcycling hurting a battery at 3.2 volts, but at that voltage the cycles would be a long time apart.

Is there something I could/should read on this?

 

[MrNatural22]

@MrNatural22, what's your budget? There are chargers like this out there for $99.

29.2V, 10A AC-to-DC Charger (Alligator) for 24V LiFePO4 Batteries (BPC-2410C)

Click here to download the Material Safety Data Sheet for LiFePO4 (Lithium Iron Phosphate) batteries. This 29.2VDC, 10A AC-to-DC Charger, Model BPC-2410C is an AC-to-DC charger for use in charging 24V LiFePO4 batteries. The charger comes available with Alligator Clips for easy...

www.bioennopower.com

Thanks Bob 142 ? I’m leaning towards the desktop power supply because it can be used for multiple things. Can get for around $60 with the Wikibuy deal ?

 

[Ampster]

Is there something I could/should read on this?

I don't think it is all in one place although Jeff Dahn did a lot of excellent YouTube videos during the ramp up of his consulting gig with Tesla.

Jeff Dahn - Wikipedia

en.wikipedia.org

There maybe subtle differences across the Lithium landscape.

 

[PfloydBham]

Thanks for the link to JD. Very interesting guy!

 

[PfloydBham]

Overall, this has been a very enlightening thread for me. I am relatively new to dc power, solar and lithium storage. This stuff just seems so cool and worthwhile.
I really thank you guys for putting this out there so I can pick up a little bit.
Pink

 

[tictag]

I would not recommend a basic PSU being used as a 'hands off' battery charger. A LiFePO4 cell requires 3.65V in order to fully charge but should not remain at that voltage for any longer than is absolutely necessary e.g. typically no more than 10-15 mins, capacity dependent. If you want to charge a 24V(nominal) battery, buy a 24V(nominal) battery charger with explicit support for LiFePO4 charge profiles, for example, Victron's Blue Smart Charger, or equivalent.

Charging at any less than 3.65V will result in a significant drop-off in stored energy and significant increase in time to fully charge, for example:



And, of course, don't forget to ensure that you are cell balancing during the charge (and discharge) cycle.

 

[Ampster]

Charging at any less than 3.65V will result in a significant drop-off in stored energy and significant increase in time to fully charge, for example:

My interpretation of that graph is that charging at less than 3.4v volts is where the significant drop off occurs.

 

[tictag]

My interpretation of that graph is that charging at less than 3.4v volts is where the significant drop off occurs.

Yes, agreed, though this will be battery dependent - that chart was just one test with one set of cells. My point was more about using a PSU instead of a 'proper' (i.e. staged CC/CV) battery charger.

 

[John Frum]

A LiFePO4 cell requires 3.65V in order to fully charge but should not remain at that voltage for any longer than is absolutely necessary e.g. typically no more than 10-15 mins, capacity dependent.

Thanks for making think about this.
A lifepo4 battery can be fully charged at ~3.5 volts per cell or higher, It just takes longer.

How to Find Happiness With LiFePO4 (Lithium-Ion) Batteries –...

By: Rob Beckers You have just sold your first-born into slavery, remortgaged the house, and bought yourself a lithium-ion battery! Now you want to know how to take care of your precious new purchase: How to best charge lithium-iron batteries, how to discharge them, and how to get the maximum...

www.solacity.com

As for the voltage stress of lingering above the resting full voltage.
In the hierarchy of battery stressors It's low on the list.
It really depends on how long and how high.
Charging at above 3.65 volts per cell is abuse.
I wonder if 3.65 volts is the sweet spot and many of us including me have been overthinking it.

 

[Ampster]

My point was more about using a PSU instead of a 'proper' (i.e. staged CC/CV) battery charger.

And that is an important point. Even though a power supply can provide a CC/CV charge sequence it should only be used where it can be shut off when finished. That can be by timer, amperage or voltage programmable relay, or manually. I have only used them temporarily.