New to lithium battery

[lem55]

Have a question which l hope you can help with. First my charge/converter went out and replaced with a 40 amp OEM unit. I know this unit is not designed to charge the lithium battery.
I needed to replace my batteries, so I invested in a 200 amp lithium
battery with a external charger designed to charge it.
And now for the question, will it hurt the lithium battery to be hooked
to the system when I am plugged into shore power. a long with that I have a old 100 watt solar charging system. Do I need to put in a disconnect switch. I had planned on charging with lithium charger.
I don't want to damage this very pricey battery.
Please help.

[3_tons]

“You will never get a 100% charge without a DC-DC charger.”

Agreed sorta (if not considering solar), but with LFP’s, with the exception of occasional cell re-balancing, there’s not much point in gaining a full 100% SOC - even the high 13’s is enough to at least get you into the low 90% range, and this is what I do (made practicable due to LFP’s deep Depth of available discharge, or ‘DOD’), which seems a fair enough trade-off to extend longevity…At least that’s my own routine…I don’t bother to charge from the vehicle due to having 660w of rooftop solar…Again (unlike Lead batts) there’s no need to routinely achieve a full 100% SOC, in my view it’s better if you don’t..

3 tons

[theoldwizard1]

3 tons wrote:
“Ditch the old converter and wire the battery to the DC distribution panel.…”

I’m not sure what this means?? …Since he merely replaced the previous battery, wouldn’t the LFP still be connected to the distribution panel??

He said he REPLACED the old converter. It needs to be removed.

3 tons wrote:
Goggles 14.6 volt figure merely refers to the upper charge limit before BMS protective cut-off…From my own experience, LFP’s are happy to charge even in the high thirteens

You will never get a 100% charge without a DC-DC charger.

[theoldwizard1]

steveh27 wrote:
While driving the alternator charges it just fine also shutting down when full.

I question that statement !

Modern vehicle charging system do not supply adequate voltage to properly charge LiFePO4 batteries. That is why DC-DC chargers exist !

[steveh27]

I have 2 100AH LiFePo4 batteries and a PD9235 converter-charger. It works just fine. I do have to push in the boost mode button to really get it charging. It cuts off on its own. While driving the alternator charges it just fine also shutting down when full. I have portable solar panels which also work fine.

[3_tons]

A standard PD (Progressive Dynamics) converter-charger (if so equipped?) will do the job fine so long as it’s tethered with the optional Charge Wizard dongle, which allows you to kick it into it’s 14.4v Boost mode - perfect for LFP’s….If this is your scenario (??), then a stand-alone charger may not be needed, except (depending on capacity) to enhance battery charge recovery times - just saying…

3 tons

[Isaac-1]

As others have mentioned, we really need to know the specs on your converter, and batteries. I have 420 AH of LiFePo4 Lithium batteries being powered by a standard (Non-Lithium) Progressive Dynamics PD9260 and it works just fine, though might be slightly slower getting to a full charge than if I were to have one of their Lithium specific converters. On the other hand some standard off the shelf Non-lithium converters are not nearly as Lithium battery friendly as my PD-9260

[AllegroD]

As others have said, you need to do some research. What is max input for your lithium batt? Can your charger be programmed to that max value?

[3_tons]

Goggles 14.6 volt figure merely refers to the upper charge limit before BMS protective cut-off…From my own experience, LFP’s are happy to charge even in the high thirteens…Just saying

3 tons

[3_tons]

“Ditch the old converter and wire the battery to the DC distribution panel.…”

I’m not sure what this means?? …Since he merely replaced the previous battery, wouldn’t the LFP still be connected to the distribution panel??

3 tons

[theoldwizard1]

wa8yxm wrote:
Google says A fully charged 12V LiFePO4 battery will have a charging voltage of around 14.6 volts and a resting voltage of around 13.6 volts.

Why do people over think these things !

That is well within the range of 12VDC appliances.

Ditch the old converter and wire the battery to the DC distribution panel.

[theoldwizard1]

If the charger has reasonable amount of power for your 12V needs (lights and ... ?) Just get rid of the converter and wire the battery directly to the 12V distribution box. Plug your charger into a convenient outlet.

[wa8yxm]

First what OEM converter did you buy.
Second what is the charge/float voltage for your LI battery

As I recall (And I stress that As I recall part for I may recall incorrectly) LI's float and charge a couple points higher than Lead Acid.

Google says A fully charged 12V LiFePO4 battery will have a charging voltage of around 14.6 volts and a resting voltage of around 13.6 volts.

For Lead acid Google says: The typical charging voltage is between 2.15 volts per cell (12.9 volts for a 12V 6 cell battery) and 2.35 volts per cell (14.1 volts for a 12V 6 cell battery)

Which is not what I recall from earlier research. (I recall closer to LiFePO4 specs)

In either case I do not think the LI will be damaged by the OEM converter.

[time2roll]

Best to dig in and find the converter make and model and post for best answers.
Same with the solar. Need to know the charging voltage.

Most are actually quite compatible with drop in lithium batteries. Actually some lithium converters are worse than standard converters.

May as well post what battery was installed.

[3_tons]

When hooked up to shore power, just use one of these (Link):

https://www.amazon.com/Ampper-Battery-Disconnect-Isolator-Vehicles/dp/B07JYDY7FQ/ref=sxts_rp_s_a1_0?crid=1V4RUX6Y2YVRO&cv_ct_cx=battery+knife+switch&keywords=battery+knife+switch&pd_rd_i=B07JYDY7FQ&pd_rd_r=0afd5500-0ede-4cbd-a902-966165ee207e&pd_rd_w=DRC4v&pd_rd_wg=OzLnR&pf_rd_p=ae71c5d9-0355-41f0-ae0d-6fe5c47bc5dd&pf_rd_r=XXFHAMRTKRHDZ8FE0W1W&psc=1&qid=1652481232&sprefix=Battery+knife%2Caps%2C470&sr=1-1-5985efba-8948-4f09-9122-d605505c9d1e

Solar should not cause any difficulties because with Lithium (LFP) there’s no real need to charge it to a full 100% SOC (state of charge) like you would with a lead-battery, except for the ‘occasional’ cell-balancing regime - in fact, except for cell-balancing, it’s far better to avoid maintaining the battery at a full state of charge, and thanks to LFP’s far deeper discharge characteristics, you can just allow the solar to battery just ‘play’ somewheres between the upper and lower SOC span…However, because of LFP’s relatively flat voltage discharge plateau, determining SOC can be problematic, thus I’d recommend a quality lithium compatible SOC meter, something like a Victron ‘Smart-Shunt’ (smart phone compatible), or of equivalent make…

Charging LFP’s is simple, so long as ‘post, cell-balancing’ you don’t overcharge for an extended period of time…

I would also recommend (because of some stray info interlopers), that you endeavor to follow forum advice from those who have ‘actual’ hands-on LFP operational and ownership experience…JMHO Only…

3 tons

[Lwiddis]

I charge my Lithium battery in only two ways…solar (95% of the time) and via a 10 amp Lithium AC to DC charger that I plug in separately from my TT, usually while driving.