Using a standard 3 stage RV charger for charging lithium.

[Checkthisout]

Why can't these be used or can they? Battery manufacturer specifies 14.6-14.6 charging voltage and float at 13.8.

I can set my MPPT solar controller to this no problem.

My RV Battery charger is only used for rebulking the batteries when I am there using the cabin or when it's too cloudy to keep the system topped up.

In my situation, shouldn't my little progressive dynamics 3 stage charger 14.4, 13.8 and 13.1 volt charger be just fine?

 

[chrisski]

As long as there is no equalize or boost for the battery charger, and I turned on only when needed and shut off when I’m done, I’d consider it on the lithium charge profile you mentioned.

I would not use it on my lithiums where I charge at 13.8 volts.

 

[Checkthisout]

As long as there is no equalize or boost for the battery charger, and I turned on only when needed and shut off when I’m done, I’d consider it on the lithium charge profile you mentioned.

I would not use it on my lithiums where I charge at 13.8 volts.

Is there anything special about lithium chargers other than the voltage?

 

[time2roll]

Is there anything special about lithium chargers other than the voltage?

I would generally stay away from the lithium converters at this point. The standard Progressive Dynamics profile is fine.

 

[chrisski]

Is there anything special about lithium chargers other than the voltage?

No. I don’t think there’s anything wrong if you shut the FLA converter off when the battery is close to charged.

The problem comes to the charging to 3.65 per cell which is 14.6 on the 12 volt battery and the chance of an overvoltage can cause the BMS to trip or oven a runaway.

Yours converter does 14.4. There is so little energy left between 14.4 and 14.6 because of the knee. That’s what an unofficial charge of around “3.45 per cell, or 13.8 volts” is recommended so much on the forum. Charging at 3.45, you still get about 95% of the batteries capacity. I charge slightly higher than that at 3.475 per cell, or 13.9 volts. The advantage is less of a risk of BMS cutoffs or runaway cells. Occasionally you see a post that goes like, I have been charging my Lithium batteries at 3.65 for months and they’ve started to cutout. They got slightly out of balanced.

I have a lithium setting on an AC to DC converter. It chargers at 14.4, and I actually set it to Gel which charges at 14 volts.

If your manufacture says 14.4 volts, than that will be fine. A couple of my SCCs and Chargers will go into an equalize mode if I leave it connected all the time. One cheaper one has a boost mode that I don’t know what it does but I suspect it is eother five or ten minutes at a much higher amperage or higher voltage for a few minutes. Boy I wish the manual said it did that. Most don’t.

When I did my 24 volt conversion, I pulled out my 12 volt converter and to my surprise it was a 50 amp converter. I never saw more than 10 amps out of it, but wish I knew about that when I had the 4 golf cart batteries in there. I would of found the way to boost up the output.

 

[Checkthisout]

No. I don’t think there’s anything wrong if you shut the FLA converter off when the battery is close to charged.

The problem comes to the charging to 3.65 per cell which is 14.6 on the 12 volt battery and the chance of an overvoltage can cause the BMS to trip or oven a runaway.

Yours converter does 14.4. There is so little energy left between 14.4 and 14.6 because of the knee. That’s what an unofficial charge of around “3.45 per cell, or 13.8 volts” is recommended so much on the forum. Charging at 3.45, you still get about 95% of the batteries capacity. I charge slightly higher than that at 3.475 per cell, or 13.9 volts. The advantage is less of a risk of BMS cutoffs or runaway cells. Occasionally you see a post that goes like, I have been charging my Lithium batteries at 3.65 for months and they’ve started to cutout. They got slightly out of balanced.

I have a lithium setting on an AC to DC converter. It chargers at 14.4, and I actually set it to Gel which charges at 14 volts.

If your manufacture says 14.4 volts, than that will be fine. A couple of my SCCs and Chargers will go into an equalize mode if I leave it connected all the time. One cheaper one has a boost mode that I don’t know what it does but I suspect it is eother five or ten minutes at a much higher amperage or higher voltage for a few minutes. Boy I wish the manual said it did that. Most don’t.

When I did my 24 volt conversion, I pulled out my 12 volt converter and to my surprise it was a 50 amp converter. I never saw more than 10 amps out of it, but wish I knew about that when I had the 4 golf cart batteries in there. I would of found the way to boost up the output.

It will be two 300AH batteries. My little 70 amp charger even when it's trying to hit 14.4 volts, won't be able to as I think the charger will be hitting the current limit long before it can generate 14.4 at the battery terminals when the batteries are low.

No. I don’t think there’s anything wrong if you shut the FLA converter off when the battery is close to charged.

The problem comes to the charging to 3.65 per cell which is 14.6 on the 12 volt battery and the chance of an overvoltage can cause the BMS to trip or oven a runaway.

Yours converter does 14.4. There is so little energy left between 14.4 and 14.6 because of the knee. That’s what an unofficial charge of around “3.45 per cell, or 13.8 volts” is recommended so much on the forum. Charging at 3.45, you still get about 95% of the batteries capacity. I charge slightly higher than that at 3.475 per cell, or 13.9 volts. The advantage is less of a risk of BMS cutoffs or runaway cells. Occasionally you see a post that goes like, I have been charging my Lithium batteries at 3.65 for months and they’ve started to cutout. They got slightly out of balanced.

I have a lithium setting on an AC to DC converter. It chargers at 14.4, and I actually set it to Gel which charges at 14 volts.

If your manufacture says 14.4 volts, than that will be fine. A couple of my SCCs and Chargers will go into an equalize mode if I leave it connected all the time. One cheaper one has a boost mode that I don’t know what it does but I suspect it is eother five or ten minutes at a much higher amperage or higher voltage for a few minutes. Boy I wish the manual said it did that. Most don’t.

When I did my 24 volt conversion, I pulled out my 12 volt converter and to my surprise it was a 50 amp converter. I never saw more than 10 amps out of it, but wish I knew about that when I had the 4 golf cart batteries in there. I would of found the way to boost up the output.

Well, Thanks!

So, with converter/charger at 14.4, as a lithium battery approaches full charge, what happens to the amperage?

I assume it tapers off as the commanded voltage from the charger and battery get closer together? In what way does it look different over lead acid? I can control my charging time based on amps flowing out of the charger as I do now.

 

[chrisski]

So, with converter/charger at 14.4, as a lithium battery approaches full charge, what happens to the amperage?

I assume it tapers off as the commanded voltage from the charger and battery get closer together? In what way does it look different over lead acid? I can control my charging time based on amps flowing out of the charger as I do now.

You’re right the amps max out until 14.4 volts is reached and then it tapers back. You will be able to monitor the amps. Once the amps tapers back with lithium, much less time is spent in absorbtion prior to entering float.

I have only tested my AC to DC converter charger once on my 560 ah bank, and with about 20 amps needed and the current set to 37.5 amps, the battery bank spent around 30 minutes in bulk, and then was in absorb mode for about three miutes, and then switched to float. The time spent in absorption was so much quicker than it had with lead acid. Lead acid took a bit more time in absorption mode before switching to float.