Using a lead acid or marine battery DC-DC charger for lithium batteries?

[jeffc2021]

Hi guys, for those of you who are familiar with battery chargers, can I get away with using a DC-DC charger meant for lead acid or marine batteries on my lithium battery?

So I have ~1200w solar panel array and a 24v 230ah LiFePo4 custom DIY battery bank with BMS in my campervan conversion. Everything has been running fine for the last three weeks for full time living, but this Seattle weather I'm in is starting to get very cloudy and rainy for extended days, which is a big concern for power. Normally under a sunny day I would be able to get ~600-1000w of charge but on heavy cloudy or rainy days I only get between ~20-100w(my solar panels are also in parallel).

I'm full time city camping and would like to be as self sufficient off grid as possible, so I'm considering ways to charge up my battery more such as using a DC-DC charge from my van's 12v alternator/lead acid batteries to my 24v lithium battery bank. I found a used 12v to 24v, 10a DC-DC charger by Yacht that seems like a good deal for $100, but it doesn't seem to be meant for lithium batteries.

Now I know that lead acid and lithium batteries have different charge profiles, and the biggest difference is that lead acid battery chargers have an equalization mode which overcharges to remove sulfate crystals, and this stage can damage a lithium battery. However, according to the state diagram for this charger, equalization stage has a 28.8 charging voltage, which seems to be within a safe voltage for lithium batteries.


So, am I safe to hook up this 12v-24v, 10a DC-DC charger between my truck's 12v alternator and flooded batteries and 24v lithium battery? Will anything be significantly damaged?

 

[DIYrich]

Use a Victron Orion TR Smart 12/24. That is what it is designed for. The TR without smart is constant voltage. The smart adds battery charging (absorption, float).

Expensive way to charge your batteries. Find the max output of your alternator at idle, and get to 80% (?) of that to minimize time running your engine.

 

[jeffc2021]

Use a Victron Orion TR Smart 12/24. That is what it is designed for. The TR without smart is constant voltage. The smart adds battery charging (absorption, float).

Expensive way to charge your batteries. Find the max output of your alternator at idle, and get to 80% (?) of that to minimize time running your engine.

I appreciate the suggestion and I've been aware of top of the line expensive chargers such as the Victron one out there. Instead of other suggestions, I'd like to know specifically about what the risks and consequences of using a charger like the one I mentioned, and what I can do to minimize any negative outcomes.

 

[DIYrich]

28.8v is 3.60v per cell. Pretty close to the 3.65v max. Will suggests 27.2v for float.

 

[mikefitz]

Minimal risk, not ideal but will only be operating infrequently. You have the battery BMS as protection.
It's not clear on the absorbtion duration of the charger, so manually ending the charge process when the battery reaches 'full', ( any volts over 24.0 could be considered full), to prevent the fully charged battery being held at highvolts.

 

[Aussieguy]

does the camper have shorepower connection and an onboard charger?
If yes ... run a small 2000w inverter generator .... much less wear and tear on your large gasoline/diesel engine..

moochdock... any house / building close by that you could run a extension cord to?

I have my trailer parked at my house
to keep the converter on I use a 100 ft 12g extension (contractor grade) from Lowes. + a 30amp adapter for shorepower inlet.
I even run my air conditioner to deal with Flodida's humidity

 

[pollenface]

I'd like to know specifically about what the risks and consequences of using a charger like the one I mentioned, and what I can do to minimize any negative outcomes.

The risk/consequence of incorrect charging is shorter battery life. If you're okay with that then that's cool ?