Lithium Batteries

01tundra wrote:

pnichols wrote:

pianotuna wrote:

msmith1199 wrote:


What is the advantage to them over Lithium? Is it just cost? Do they provide as much power?

As far as power goes 100 amp-hours is 100 amp-hours. However SiO2 may do larger discharge rates than LI. LI appear to be limited to about 1 C.

Similar to LI in that partial charging is just fine--though best practise is to do a full charge on a monthly basis.

advantages
1. can be used and charged at -40
2. can be run stone bone dead 620 times
3. can do 50% discharge 2800 times
4. no need to stop charging at 90% which LI prefer (for storage)
5. can do 80% discharge 1500 times

disadvantages:
1. heavier and larger foot print than Li
2. charge rate 4/c however if one has 300 amp-hours that hardly matters as convert size may not be able to get to 75 amps--without upgrading.

In addition to the silicon dioxide battery characteristics that Don lists above, they have one more advantage over lithium batteries that is important to me:

Lithium RV batteries hold their output voltage "high" right to the end before recharging ... their output voltage does not taper off a bit as they discharge .... unlike what the output voltage of lead acid batteries and that of silicon dioxide batteries does. To me the output not tapering off - like lithiums do - as they discharge IS NOT preferred ... it's a "disadvantage". It's nice to know when you're getting near the point where recharging is necessary by merely periodically checking the voltage on your RV's battery powered circuit - when that voltage reads around 12 volts, recharge them. As I understand it, silicon dioxide RV batteries act about the same way ... making it very simple to know about when to recharge them.

To get around this when switching to lithium RV batteries - in addition to their higher cost - you must spend even more money on what is technically known as an "integrating ammeter". This is a battery monitor that tracks how many amps are removed from the battery bank over time - thus showing how many amp hours have been used out of the battery bank.

To me, the above is just another gadget to buy in addition to the high lithium battery initial cost. Why have to purchase an amp hour consumption monitor - when silicon dioxide RV batteries have just about the same performance characteristics (they weigh more than lithium, but they recharge and operate at lower temperatures than lithium) as lithium RV batteries.

P.S. For example, I have a lot of lithium battery powered flashlights, remotes, and small tools ... AND IT'S VERY IRRITATING when they surprise you by suddenly dying with very little get-dim/slow-down type discharged warnings.

Having a battery monitor "gadget" is an accurate way to monitor the SOC of any type of battery chemistry, including lead acid.

Measuring with a volt meter is often misleading and very inaccurate, unless you let the battery sit for a hours at rest. But if you're really stuck on using this inaccurate method, the same can be done with LiFePO4 batteries.....they don't all of the sudden die as you describe. They discharge and have a voltage vs SOC curve just like any other battery.

LiFePO4 batteries are a complete different chemistry from Li batteries in flashlights and such.

How much personal experience do you have with LiFePO4 batteries in an RV?

An integrating ammeter type battery monitor for an LiFePO4 based RV system can be an expensive kindof toy, like so many things that we think we need nowadays. These type ammeters need to be calibrated relative to the actual battery(ies) that you're expecting it to monitor SOC accurately, and they should be recalibrated every once in a while to maintain their SOC accuracy as the capacity of the battery bank declines over time.

Lithium iron phosphate based RV/vehicle batteries are advertised to taper their output voltage less obviously than lead acid batteries -> and my lithium ion based small household batteries act that same way relative to the small amount that their output voltage tapers as they discharge and die on me. I know because I measure my lithium ion AA/AAA batteries with a four-place voltmeter. If one believes the performance curves published for LiFePO4 RV batteries, then my point was that this can be a very irritating characteristic because to know SOC one should add a special monitor to one's RV equipment in order to use LiFePO4 batteries in it. To me, it's just another thing to buy, install, and mess with.

Regarding my "zero experience" with LiFePO4 RV batteries ... experience is not the only way for one to know all they need to about something. Sometimes all the necessary knowledge can be gained a lot less expensively through what others report on regarding their experimentation and experience.

If my current bank of deep cycle Group 31 AGM RV batteries dies before I do, I'll seriously consider several factors before jumping on the hottest RV battery bandwagon. My rig currently has gobs of excess CCCC - so at this point in time based on published specifications only - the new silicon dioxide batteries in drop-in RV sizes read like they have real promise.