Lead Acid vs Lithium Converter

[Shane826]

I think my 3326 needs a new converter since it seems to enjoy cooking my battery. I’m not ready to make the jump to lithium batteries just yet it want to be future proof. I’ve read less than stellar reviews on the auto-detecting converters that switch between lithium and lead acid charge strategies. So here’s my question: Is there a reason you can’t use a lithium charger in a lead acid battery until I can convince myself to take the lithium plunge? I get lithium charges at a higher voltage but it’s pretty much the same voltage a car alternator charges the battery. Thoughts?

[rickst29]

You absolutely don't want a "lithium only" converter cooking your current lead-acid batteries to death, most will overcharge until your current batteries have been killed. That's a matter of days or even hours.

LFP battery cells need to be "pushed" to full only once, and the desired 3.60 volts per cell that job is only 14.4 volts on the pack. Lithium chargers that do were anything more 14.4 volts will harm the lifespan of those cells, the widely implemented 14.6 volts value 3.65 volts) is really not OK.

Power converters, except for costly Victron models, are not directly programmable. I have my own Progressive Converter set to handle my Lithium cells as AGM. The do not reach 'balancing voltage' from the PD in normal operating mode, the PD switches to "float stage" much earlier than desired for balancing.

But PD Converters have an optional push-button wired "remote controller", which I use to force bulk/boost charging whenever I want to push the batteries close to 100%. (That's mounted on lower bathroom wall.). I also have my Solar charge controller set to "float" at an abnormally high voltage 13.9 volts which does get into balancing mode with the BMS settings.

PD alone could also be set to sealed lead acid, because their "equalize" voltage is only 14.4 volts (and not higher).

A programmable Victron is better, but super costly for all the models which can provide enough power. A PD is probably your next best choice, and you can buy it before changing batteries. You should, in fact, continue to use one of the lead-acid modes SLA or AGM/GEL) even after you switch to LFP battery packs.

[rickst29]

Originally Posted by Shane826

I’ve read less than stellar reviews on the auto-detecting converters that switch between lithium and lead acid charge strategies.

Auto-detecting your "battery type" from voltage in the working ranges of these cells (LFP and lead-acid) is complete hogwash, they overlap - a lot. Auto-detecting from current versus voltage curves might be possible, but very unreliable.

[Shane826]

Ironically there is a decent article in the April 2023 issue of RV magazine that talks about charging strategies etc.

Originally Posted by rickst29

Auto-detecting your "battery type" from voltage in the working ranges of these cells (LFP and lead-acid) is complete hogwash, they overlap - a lot. Auto-detecting from current versus voltage curves might be possible, but very unreliable.

I don’t know. Apparently WFCO claims to have one. Todd couldn’t get it to work either.

https://youtu.be/_Tt1U3-kiJU