Thursday, October 22, 2020

Setup and Charging of My New LiFePO4 Batteries.

Once my new "drop-in" lithium-ion batteries were dropped in, hooked up,

and buttoned down, there was still some work to do before I could call this project finished. - More work than I thought as it turned out.

Of course, the new LiFeP04 batteries have a different profile, electrical and performance wise, than the lead-acids I had in there before, so the next step in the installation of them was to go into my Xantrex LinkPRO battery monitor and re-program it with the new profile.

This involved changing some of both the Battery and System Properties as well as a number of alarm set points to reflect the characteristics of the new batteries.

Three of these settings, the float voltage, float current, and auto-sync time, work together to perform an auto-sync on the monitoring system. This is just a fancy way of saying that when all three of those parameters are met the monitor resets itself to 100% full and 0-Ah drained. This helps offset internal losses and inaccuracies of the sensors in recording the drain and charge of the batteries.

In reality this only worked about 10% of the time with my lead-acid batteries, but that was way more than the 0% of the time that I'm getting out of it with the LiFeP04 batteries. I've spent way too much time trying to manipulate these three settings to trick it into auto-syncing, but with no luck.

With these new batteries I find that the LinkPRO is off by about 1.5 to 2 amp hours every charge/discharge cycle, and always on the discharge side, so after about a week a full charge on the batteries shows as being about 10 to 15 amp-hours low.  Fortunately I can easily perform a manual sync on the meter, so if it gets far enough out of sync to bother me I just wait until later in the day when the batteries have charged up and gone to float and then perform the manual sync.

The final step here in the LinkPRO was to perform a Battery Status Reset which zeros out the history so I can start tracking the performance of the new batteries long term.

Despite how it looks, that's Marine Vinyl flooring and not carpet.

I have three separate ways of charging my house batteries. (Redundancy is King!)

In addition to the primary charging method, the solar system which I will address in it's own separate post, I have two other ways to charge my batteries, even though I rarely use them.

One is my little 15 amp Iota that I can use when plugged into shore power - if I also plug in the Iota to The Van's 120V system as well that is.

The IOTA is equipped with the internal IQ/4 smart-charge module for lead-acids that makes it a four-stage charger. The four stages are bulk (14.8 which is fine), absorption (14.2 which is a little low), float (13.6 which is spot on), and equalize (15.5 No Way!).

Iota does have 9 different plug-and-play smart-charge modules that change the charging profile of their units, including one for LiFePO4 batteries. Unfortunately they are external modules only and are not compatible with my internal IQ/4 equipped charger.

But as long as I don't screw up and let this charger sit in float for 7 uninterrupted days, which is what it takes to trigger the equalize function, it will treat my lithium's just fine for occasional use.

Since I very rarely plug The Van into shore power, and even more rarely also plug the IOTA in and use it, and never leave it plugged in for more than a day, I see no need to pay the money to swap it out for a LiFePO4 savey, charger at this point.

My third charging method is through a 300 amp disconnect switch (This $10 switch takes the place of the $100 automatic isolator that failed 5 years ago.) By inserting the "key" and twisting it I can connect The Van's alternator directly to the house batteries. (Or the house batteries to the chassis battery if I need to self-jump, like when this happened.)  No muss, no fuss.

Supposedly, with only 200 Ah of lithium battery installed I don't really need one of those fancy automatic isolators that alternates 15 minutes of connect time with 20 minutes of disconnect time to prevent overheating the alternator because of how efficient the LiFeP04s are at accepting charge-current. But to be honest, until I actually see it work (On someone else's rig!) I'm not completely convinced that my 200 Ah's of battery won't overwhelm The Van's alternator.

I certainly don't want to risk damaging my alternator, but because of the cost and hassle of installing one of those fancy isolators, plus a second, dedicated, manual disconnect because I also certainly don't want that automatic isolator operating all the time because engine alternators are great for running your headlights and charging starting batteries, but, beyond giving them a good healthy bulk charge, pretty much suck when it comes to charging deep-cycle batteries. For now, if and when I need it, I'll set the timer on my phone and manually control the duty-cycle with the key, which I can reach while driving, until I see how things work out.

If, and that's a capital If in my case, I was contemplating using the engine alternator as a primary charging source for my LiFePO4's I would use something like this DC to DC charger rather than relying on an alternator's internal regulator. (But don't just run out and buy this on my say-so. I have done absolutely no research on it!) This is a typical 3-stage charger just like my little Iota, the only difference being that instead of 115V input power this uses 12V input power off the alternator to produce a managed three-stage charge on the output side.

Next post: Solar charging and an unanticipated adjustment to my system.

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