LifePo4 Charge Performance
Thinking seriously about replacing our two GC2's with a pair of 100ah LifePo4's. Hearing a lot of chatter about how lithiums accept a charge much quicker than lead cells. Very familiar with how ou...
Forum Discussion
Hi BFL,
No fight here either.
I’l do my best to explain what I, as a layman, have seen, learned and experienced after 7 years of Lifepo4 ownership and use. If my terms and spellings are incorrect bear with me.
As mentioned Lithium have extremely little internal resistance. Therefore Peukert’s Effect does not apply. Which results in almost every bit of amps fed to them being used. This is one of the reasons that common alternators can burn up. The average alternator does not sense any resistance and therefore outputs high amperage over a longer time than they are designed for.
As I understand things a depleted Flooded Lead will accept a charge with little resistance, but as the SOC climbs the resistance continues to climb, hence the need for an absorb voltage with diminishing amperage over time to work with the climbing resistance.
With lithium there is really no absorb. For example my solar controllers are currently set at 100amps charge rate, the coach takes about 15 and the remaining 85 go into the battery consistently without wavering in full sun until the target voltage is met. Once the target voltage is met it does technically go into absorb, yet all it really does is quickly drop the amps until the batt. voltage matches my programmed float voltage. This “absorb” lasts no longer than 5 minutes.
The real world effect of all this is that the lithiums will charge up in shorter time. For example friends have a very similar coach drawing the same amperage and a similar solar array. My Po4’s are full by noon and theirs take several more hours to reach capacity. They were razzing me about my Lithium’s and how I had wasted money, well that was all good while the sun was shining for a week. Then the clouds moved in for several days and they couldn’t fill their Leads. We all laughed together the next day when they woke up and realized I had moved away. I told them, “I was tired of listening to their generator, so I left.”
To each their own.
No fight here either.
I’l do my best to explain what I, as a layman, have seen, learned and experienced after 7 years of Lifepo4 ownership and use. If my terms and spellings are incorrect bear with me.
As mentioned Lithium have extremely little internal resistance. Therefore Peukert’s Effect does not apply. Which results in almost every bit of amps fed to them being used. This is one of the reasons that common alternators can burn up. The average alternator does not sense any resistance and therefore outputs high amperage over a longer time than they are designed for.
As I understand things a depleted Flooded Lead will accept a charge with little resistance, but as the SOC climbs the resistance continues to climb, hence the need for an absorb voltage with diminishing amperage over time to work with the climbing resistance.
With lithium there is really no absorb. For example my solar controllers are currently set at 100amps charge rate, the coach takes about 15 and the remaining 85 go into the battery consistently without wavering in full sun until the target voltage is met. Once the target voltage is met it does technically go into absorb, yet all it really does is quickly drop the amps until the batt. voltage matches my programmed float voltage. This “absorb” lasts no longer than 5 minutes.
The real world effect of all this is that the lithiums will charge up in shorter time. For example friends have a very similar coach drawing the same amperage and a similar solar array. My Po4’s are full by noon and theirs take several more hours to reach capacity. They were razzing me about my Lithium’s and how I had wasted money, well that was all good while the sun was shining for a week. Then the clouds moved in for several days and they couldn’t fill their Leads. We all laughed together the next day when they woke up and realized I had moved away. I told them, “I was tired of listening to their generator, so I left.”
To each their own.
