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BFL13

Victoria, BC

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Posted: 06/28/22 11:12am Link  |  Quote  |  Print  |  Notify Moderator

Some "sales" statements here, but also some possibly good info of interest.

One thing is they found longest life (most cycles) was to charge at 14.4v but at lower amps at 0.3C.

Some LFP owners on here ISTR have taken to charging at lower voltages hoping for longer battery life. Perhaps it needs to be established which is correct--lower amps or lower voltage?

They say 14.4 vs 14.6 to reduce stress, and recommend their own charger (of course!) which is single stage 14.4--BUT they say shut charging down-disconnect- once the charger says the batt is full. (light comes on---what makes that light come on? oh well)

They are strongly against floating! see why.

Anyway, it covers some of what has come up on here lately.

https://dakotalithium.com/2021/09/22/how........ge-dakota-lithium-and-lifepo4-batteries/


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Itinerant1

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Posted: 06/28/22 11:48am Link  |  Quote  |  Print  |  Notify Moderator

Their info reads the same as others. It looks like they need 14.4 for 3hours to balance the cells with what ever their bms is inside.


12v 500ah, 20 cells_ 4s5p (GBS LFMP battery system). 8 CTI 160 watt panels (1,280 watts)2s4p,Panels mounted flat. Magnum PT100 SCC, Magnum 3012 hybrid inverter, ME-ARC 50. Installed 4/2016 been on 24/7/365, daily 35-45% DOD 2,000+ partial cycles.

time2roll

Southern California

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Posted: 06/28/22 12:03pm Link  |  Quote  |  Print  |  Notify Moderator

Yes this would have you believe lithium is very finicky and unforgiving. I can see their point to control the charging with the cacophony of various chargers on the market. Hard to comment exactly unless all the BMS parameters are published. All the more reason to build your own and have far more flexibility.


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BFL13

Victoria, BC

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Posted: 06/28/22 12:18pm Link  |  Quote  |  Print  |  Notify Moderator

A guy here was selling his Dakota 200AH for $500 (Can) so I was looking into it. Could not find the BMS specs for cut off voltages. Some specs info only.

(I got nervous about buying used because how can you tell if it has been "damaged" by whatever usage? Didn't need it anyway, but tempting price. Somebody got it, so good luck to him.)

It does seem LFP advice can be "brand specific" even if they all have similar type cells.

pianotuna

Regina, SK, Canada

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Posted: 06/28/22 01:35pm Link  |  Quote  |  Print  |  Notify Moderator

At 0.3 C the "rapid charging" feature disappears compared to my favorite chemistry.

I think it is great that folks can "roll their own".

Can the bms be set to limit current to 0.3 C for charging?

Li are excellent except in the cold.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

time2roll

Southern California

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Posted: 06/28/22 01:59pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

At 0.3 C the "rapid charging" feature disappears compared to my favorite chemistry.

I think it is great that folks can "roll their own".

Can the bms be set to limit current to 0.3 C for charging?

Li are excellent except in the cold.
166 amps is too slow?

BMS does not throttle. On or Off only.

Only if the Li is allowed to get cold.

Durb

NW

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Posted: 06/28/22 03:57pm Link  |  Quote  |  Print  |  Notify Moderator

What does "C" mean when referring to current?

jaycocreek

Idaho

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Posted: 06/28/22 04:20pm Link  |  Quote  |  Print  |  Notify Moderator

Quote:

They are strongly against floating! see why.


I've read that before and from others but I don't understand why someone like Victron would have float in there charge controllers for lithium with no way to disable it..So is it really bad or lol
Lifepo4 parameters seems to be liking asking 10 different doctors what's wrong with me with 10 different answers...lol


Lifepo4-380ah/Lithium NMC-140ah/Solar-400 watts/Wagan & Giandel PSW/Engel & Iceco 3-1 compressor fridge freezer/5K Window AC/Honda 2K

BFL13

Victoria, BC

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Posted: 06/28/22 05:08pm Link  |  Quote  |  Print  |  Notify Moderator

Durb wrote:

What does "C" mean when referring to current?


Relates to the Capacity of the battery bank in AH and how much of that figure to use as your initial charging current (which holds at that until it tapers)

Edit--this all does not apply very much to solar, where the amps rise in the morning and taper in the afternoon.

So for a 100AH bank 0.3C is 30 amps.

Many LFPs will say they can take 1C as "max" but prefer you keep it at 0.5C or less. Some specify max of 0.5C if say their BMS wiring is too thin to take more amps. (That would also affect their max discharge amps I guess---not sure--anybody know? )

FLAs and AGMs can also handle 0.3C, but 0.25C is preferred, so "fast charging" comparisons at that level turn on when amps start to taper in each case, not on the amount of initial charging amps. LFPs supposedly taper later giving them more time at the higher amps.

Still no info on when amps start to taper with LFPs if you use a reduced charging voltage from the 14.6 max. Looks like charging/generator run time comparisons will need to specify what voltage was used as well as what initial amps were, but still no good info on that.

Of course to take advantage of the LFP high acceptance rate in amps for "fast charging" claims by "Sales" you need a charger that can do that many amps, plus a 120v source that has enough watts (VA) to run the charger without dropping too far in 120 voltage, or a generator that has enough watts/VA to run that big (in amps) of a charger.

It is all good fun if you don't weaken! [emoticon]

* This post was last edited 06/28/22 05:39pm by BFL13 *   View edit history

Durb

NW

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Posted: 06/28/22 06:48pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

Durb wrote:

What does "C" mean when referring to current?


Relates to the Capacity of the battery bank in AH and how much of that figure to use as your initial charging current (which holds at that until it tapers)

Edit--this all does not apply very much to solar, where the amps rise in the morning and taper in the afternoon.

So for a 100AH bank 0.3C is 30 amps.

Many LFPs will say they can take 1C as "max" but prefer you keep it at 0.5C or less. Some specify max of 0.5C if say their BMS wiring is too thin to take more amps. (That would also affect their max discharge amps I guess---not sure--anybody know? )

FLAs and AGMs can also handle 0.3C, but 0.25C is preferred, so "fast charging" comparisons at that level turn on when amps start to taper in each case, not on the amount of initial charging amps. LFPs supposedly taper later giving them more time at the higher amps.

Still no info on when amps start to taper with LFPs if you use a reduced charging voltage from the 14.6 max. Looks like charging/generator run time comparisons will need to specify what voltage was used as well as what initial amps were, but still no good info on that.

Of course to take advantage of the LFP high acceptance rate in amps for "fast charging" claims by "Sales" you need a charger that can do that many amps, plus a 120v source that has enough watts (VA) to run the charger without dropping too far in 120 voltage, or a generator that has enough watts/VA to run that big (in amps) of a charger.

It is all good fun if you don't weaken! [emoticon]


Thank you for the information. I have a Battle Born 100AH battery and a Progressive Dynamics 60amp convertor, so I guess .6C. The combo has been working well for two years now. I do unplug the PD once the battery is charged.

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