theoldwizard1 wrote:
otrfun wrote:
theoldwizard1 wrote:
You will never get a 100% charge without a DC-DC charger.
Why would you need or want a 100% charge (14.6v) to begin with? Unlike lead-cell batteries, lifepo4's subjected to 100% SOC (14.6v) on a constant, short-term basis experience reduced cycle life. 13.6v will still net 99% SOC (and a higher cycle life), although at a slower charge rate.
Long-term float at =>14.6v can permanently damage a lifepo4.
I never said anything about long term float at that voltage. The point of a DC-DC charger is to give the correct voltage at the correct time during the charging cycle.
No, you didn't. I mentioned it because it's one of the potential consequences of charging a lifepo4 to 100% SOC with a single-stage converter. Something you failed to mention.
In your previous post, you stated 1) "
You will never get a 100% charge without a DC-DC charger. Above you state 2) the primary point (or mission) of a dc2dc charger is to provide the "
correct voltage at the correct time during the charge cycle".
1) Ref charging a lifepo4 to 100% SOC, many folks make the false assumption that a lifepo4 must/should be charged to 100% SOC (14.6v) like a lead-cell battery. The fact is, a lifepo4 experiences a reduction in cycle life the longer it sits at 100% SOC (14.6v). If it floats at 14.6v long enough it can be permanently damaged.
2) Ref your comment about "
correct voltage", the correct voltage is ultimately up to the user---as it should be. Renogy dc2dc chargers are one of the most widely used dc2dc chargers because of their low-cost. It allows the user to choose various absorption/float charge voltages ranging from 12.6 to 14.7v. Surprisingly, if you choose the "lithium" mode, it will only operate as a single-stage charger. As a single-stage charger set to charge to 14.6v (100% SOC), it will charge at 14.6v indefinitely---the worst possible way to charge a lifepo4. This is why I mentioned the dangers of long-term float at 14.6v while a lifepo4 is at 100% SOC. This is precisely what may occur if you leave it up to the Renogy dc2dc charger to provide the "
correct voltage at the correct time during the charge cycle" while charging in lithium mode.
Fortunately, Renogy provides a 2-stage absorption/float mode in their dc2dc chargers which can be used to charge a lifepo4, safely and fully. I find it ironic it's a recommended setting for lead-cell batteries. Progressive Dynamic's first generation of lithium converter/chargers were/are single-stage units. It's telling that they are now transitioning to multi-stage lithium converters.
I also find it ironic (and sad), that so many folks spend their hard-earned money upgrading to so-called "lithium approved" converter/chargers when in many cases their existing 3-stage lead-cell converter/charger will actually do a safer and better job of charging their lifepo4.
