05-30-2019, 06:29 AM
Gurus,
I am adding to this thread as I learn things about the new lithium’s.
As you may know, lithium batteries are really, really good at providing their rated voltage until nearly depleated of charge. The red line is regular batteries and the black line is lithium. Notice how much more horizontal the red lines stay.
That is really good.
But..... (and with me you always know there is a but coming)
How does the charger (in my case a Magnum 2812) know when to start charging the batteries?
I ran the batteries overnight with about a 12-25 amp draw. When I went to bed I had a DC voltage of 13.1 volts and when I woke up I had a DCV of 13.1. It was hot and I cranked the generator. The display on the Magnum says Float Charging, but 0 AMPS! This means there is no current going into the batts. What gives?
It turns out that the Magnum was built expecting to see a gentle roll off of voltage (red line) and when it gets below 12.8VDC it starts the four step charging process (Bulk, Absorb, Float, Full).
Since I am at 13.1VDC the charger thinks that I don’t need to charge and it is right.
Here is the thing with lithium technology. It gives that nice flat voltage right til the end (black line). Then it falls like a knife! It seems as though I will not be able to charge the batteries unless they are almost fully discharged. I am not sure how I feel about that.
I have a State of Charge accessory from Magnum that I will hook up this week, but the charger does not use SOC as part of its algorithm...it only uses voltage. (According to the manual).
I am gonna run the generator today. Tonight, I will turn off genny and monitor battery voltages.
Cheers,
Bill
I am adding to this thread as I learn things about the new lithium’s.
As you may know, lithium batteries are really, really good at providing their rated voltage until nearly depleated of charge. The red line is regular batteries and the black line is lithium. Notice how much more horizontal the red lines stay.
That is really good.
But..... (and with me you always know there is a but coming)
How does the charger (in my case a Magnum 2812) know when to start charging the batteries?
I ran the batteries overnight with about a 12-25 amp draw. When I went to bed I had a DC voltage of 13.1 volts and when I woke up I had a DCV of 13.1. It was hot and I cranked the generator. The display on the Magnum says Float Charging, but 0 AMPS! This means there is no current going into the batts. What gives?
It turns out that the Magnum was built expecting to see a gentle roll off of voltage (red line) and when it gets below 12.8VDC it starts the four step charging process (Bulk, Absorb, Float, Full).
Since I am at 13.1VDC the charger thinks that I don’t need to charge and it is right.
Here is the thing with lithium technology. It gives that nice flat voltage right til the end (black line). Then it falls like a knife! It seems as though I will not be able to charge the batteries unless they are almost fully discharged. I am not sure how I feel about that.
I have a State of Charge accessory from Magnum that I will hook up this week, but the charger does not use SOC as part of its algorithm...it only uses voltage. (According to the manual).
I am gonna run the generator today. Tonight, I will turn off genny and monitor battery voltages.
Cheers,
Bill
Bill Johnson
Birmingham, Alabama