Is specialized charger really needed for commissioning LiFePO4 batteries?

[Fenachrone]

I'm in the process of buying two 12v 200 kwh LifePO4 batteries. My vendor states they must be charged after they arrive and have recommended this
IOTA DLS-45 charger. It's a bit pricey for what seems like almost a one-time use, though I could use it as well for additional batteries as the need may arise.

Nevertheless I was reading a previous related post here which commented that vendors will encourage buying these specialized chargers (which they sell, of course), but that there are less expensive alternatives -- just that they have to be constant current/constant voltage.

Would appreciate anyone's thoughts on this, and other charger recommendations.

 

[Tomthumb62]

That’sa 45A charger. You can get by with a slower one (less expensive), 10A would be fine. A grid charger like this is a good idea to have on hand in case your solar setup isn’t charging ideally.

 

[Ampster]

there are less expensive alternatives -- just that they have to be constant current/constant voltage.

Would appreciate anyone's thoughts on this, and other charger recommendations.

Almost every power supply and charger out there has Constant Current and Constant Voltage stages. For one time use I have had luck with Meanwell power supplies. It is best to buy models that are current limited. The key is finding one with an adjustable voltage in the range that you want to charge your batteries. You do not need to pay the high price for a specialized charger.

 

[Steve_S]

LFP only requires CC/CV Charging, nothing else.
A 12V/100AH Battery can typically take a MAX of 0.5C or 50A Charge for 2 hours. This WILL heat up the cells but not badly... Of course you can charge at a lower rate and that is perfectly fine to do. Chargers can get quite expensive, so it is best to get something that has multiple uses if/when needed.

I assume these batteries are New Prebuilt units, they are probably around 50% SOC (12.8V for 12V pack), if both batteries are at the same voltage then you should be able to install them and have your Inverter/Charger & SCC charge them as normal.

If they are NOT at the same voltage, you can put Both Batteries in PARALLEL and let them balance between themselves prior to connecting them to your system.

TIP: LFP does charge much faster than old Lead Acid BUT it has a very flat voltage curve which mirrors the Working Voltage Range from 3.000-3.400 Volts per cell. This often throws off people because it may seem the batteries are not taking charge until you reach the last 10% capacity, at which time the Amps Taken starts to decrease as the resistance increases. That last 10% can go by quite quickly.

FYI: Your EndAmps / TailCurrent (which is when to switch charging from Absorb/Bulk to Float) and be sure to set that in your gear if possible.
It is calculated as 100AH X 0.05 = 5A. If you have two 12V/100AH batteries in Parallel, it is still 5A.

I run a 24V Battery Bank with several packs which I build myself. Because I build from scratch I charge cells in Parallel (Top Balance Charge) prior to assembling them in series to make a pack. I use a TekPower TP1545E which produces 15V up to 45A with CC/CV charging built-in. It's not cheap but it's a good power supply and works quite well. In your case, this could be used to just charge the 12V Battery Packs without much trouble.
REF: https://www.ebay.com/itm/164972289976

Set your Charging for Bulk/Absorb to 13.7V (3.425Volts per cell)
Set Float to 13.6V (3.400Volts per cell)
EndAmps/TailCurrent 5A
LFP "Allowable range" that does not harm cells is from 2.500-3.650 volts per cell.
LFP Working Range is from 3.000-3.400 which is where the rated Amp-Hours comes from.
Set Low Volt Disconnect to 10.8V (2.700 Volts per cell) Recovery to 11.0V (2.750Vpc) - this allows for low volt disconnect & easy recovery to allow for charging. If the low volt disconnect is too low it may not recover to teh point of accepting charge. If low volts drop below 2.500Vpc there is damage occuring.

See links in my signature for more info like Voltage Charts & More.
Hope it helps, Good Luck.

 

[DIYrich]

I'm building a 48v LiFePO4 battery bank, and could use the Inverter for the pre-charge. If the cells need balancing, then the options are: 1) Let the BMS do it over time; or 2) Top Balance with a bench power supply. You may be able to use a car battery charger for the top balance.

 

[Ampster]

You may be able to use a car battery charger for the top balance.

If he does that he needs to be careful when the cells reach 3.5 or 3.6 volts since the battery charger will keep supplying full Amps to try to take cells to 14 Volts.

 

[Fenachrone]

I appreciate these responses and good information. Thanks!

 

[Mia]

If he does that he needs to be careful when the cells reach 3.5 or 3.6 volts since the battery charger will keep supplying full Amps to try to take cells to 14 Volts.

So what is the sweet spot for charging our LiFePO4s? 14? 14.2? 14.4? I was having issues with the regular battery charger and wasn’t getting much above 3.33 per cell. But when we were hooked to the dcdc charger we were getting up to 3.5 and 3.6 per cell. Or should we never be charging up to 14.4volts?

 

[time2roll]

I appreciate these responses and good information. Thanks!

The IOTA is not specifically required. At least verify it comes with the lithium control module.

What charging system are you looking at?

 

[Tomthumb62]

So what is the sweet spot for charging our LiFePO4s? 14? 14.2? 14.4?

lol, I’m learning now that this is a type of religion. Some never charge past 13.8, some never less than 14.6.

What I’m gathering is: it doesn’t really matter.

 

[Ampster]

Or should we never be charging up to 14.4volts?

As @Tomthumb62 mentioned, it is a matter of personal preference. I take mine to 3.45 per cell which I a bit under 14 volts for 4 cells.

 

[time2roll]

lol, I’m learning now that this is a type of religion. Some never charge past 13.8, some never less than 14.6.

What I’m gathering is: it doesn’t really matter.

Depends on use, expectations, and set up. If maximum cycle life is the goal, a lower voltage is used. If speed charging on generator power, often the higher voltages are used.

Balance parameters and absorption time may also be adjusted to accommodate these voltage differences.

14.6 is generally considered the absolute maximum. Most try not to run equipment at the absolute maximum all the time.

 

[Hank Waconda]

I'm in the process of buying two 12v 200 kwh LifePO4 batteries. My vendor states they must be charged after they arrive and have recommended this
IOTA DLS-45 charger. It's a bit pricey for what seems like almost a one-time use, though I could use it as well for additional batteries as the need may arise.

Nevertheless I was reading a previous related post here which commented that vendors will encourage buying these specialized chargers (which they sell, of course), but that there are less expensive alternatives -- just that they have to be constant current/constant voltage.

Would appreciate anyone's thoughts on this, and other charger recommendations.

I use the DLS 45 and have 3 dongles...The IQ-4, Turbo and Equalize. I use with small inverter generator to help top off batteries on cloudy or stormy days for a couple hours and it works well.

 

[Fenachrone]

The IOTA is not specifically required. At least verify it comes with the lithium control module.

What charging system are you looking at?

I chose a NOCO Genius10. It got my batteries up to exactly 14.1, which is what the manufacturer recommended. At 10 amps it took a bit longer,
but I saved a few $$$ in the process. The batteries are now commissioned and doing a great job in my off-grid system.