How long was this last one left by itself?
There are 3 "hits" on the LiFePO4 technology
1) it costs a lot relative to AGM
2) it has the well known poor performance in colder weather
3) they are rated as an "amp/hour equivalent" and not at their actual amp hour storage rating.
What that means is that a LiFePO4 battery only has about 33% of the true storage of their AH rating.
A lead-acid chemistry battery (wet-cell, Gel-cell or AGM) will have 1,000 milliamps of storage per AH.
So, a 14AH AGM has 14,000 milliamps,
A 14AH Equivalent LiFePO4 has only about 4620 milliamps.
So it will go dead in only 1/3 the time due to any parasitic draw.
And if they are allowed to drop below 12.86V they are often not recoverable using a smart charger.
The smart charger will get back a reading that the battery is totally dead and will not attempt to recover it.
The workaround is to put the battery on a dumb charger of maybe 1 AH rating or less and monitor it *very* carefully.
Put it on the dumb charger and after 30-45 minutes put it on the smart charger and see if the charger goes into it's normal charge routine.
A dumb charger just puts out current and forces it into the battery. It does not measure anything and will overcharge a battery if left on all the time.
If it doesn’t go another 30-45 minutes with the dumb charger. Repeat until it "takes".
Most of the time the dumb charger will eventually get enough charge into it for the smart charger to get a message that the battery will now take a charge and you are back in business.
The Shorai business model is to put the Battery Management system in the charger whereas many of the other LiFePO4 makers include it in each battery (and that's why they often cost more).
So if you have a Shorai it is a very good ideat to use their charger to balance the cells.
Their thinking (I'm assuming) is that if you have 4 batteries you have only had to buy 1 BMS.
Hope This Helps.
M./
While some of that is helpful, there are a few things to note. I'll point out a few things, and provide links with data supporting what Im saying.
The idea that the charger is a BMS is completely false. The only people who suggest this, are those selling these products. Its really unfortunate. What has now happened, is that there is an entire industry- along with many riders- who are completely confused about battery ratings in the real world.
In fact, I wrote a long, well sourced post about this exact issue in...2012. There are a ton of links to primary sources in there:
https://www.fullspectrumpower.com/b...harger-or-bms-for-lightweight-lithium-battery
As I point out in that post, the whole point of a BMS (Battery Management System) is to...manage the battery *while in use*. The Shorai charger does not do this, since *it is not a BMS*. What it is, is a balance charger. That's fine, and Im sure it works well at charging and balancing...but it is not a BMS. If nothing else, a BMS should be *internal to the battery* and should provide basic functions that manage and protect the cells.
I point this out because it is a really important distinction. The external charger does nothing to protect or manage the battery while in use, nor is it part of the battery.
Now, the rating of LA batteries vs lithium is also a murky swamp of BS. Years ago, Motorcyclist Magazine actually tested the AH ratings of the available batteries. They used a 55w headlight bulb to drain the batteries down to 10v (which I feel is too low) and determined a real world AH rating.
https://www.motorcyclistonline.com/news/lighten-lithium-ion-battery-gear#page-2
Excerpt: a Yuasa YTX12-BS had an actual rating of 4.2ah. A Shorai LFX14A2 with a
PBEQ of 14 actually yielded 3.2ah- the lowest in the test.
In truth, the measurement should be 1amp for 1 hour = 1ah, and so on. That is the only way to really be accurate about these things. Just my opinion.
The real question is
why does capacity matter in a bike with a charging system? I would argue that it should not make a bit of difference, so long as there is enough capacity for easy starts. As the Motorcyclist Magazine test revealed, even a 12ah Yuasa had only slightly more capacity that the lowest ranked battery in the test. 4.2ah vs 3.2ah.
So, if that is the case, what is the advantage of lead acid at all?
As you point out above- better cold weather performance and lower cost. I would suggest that a Yuasa is the best LA battery available, and one of those is between $100-$200. In a Harley, it can be over $250.
In 2018, there are high quality lithium options that are well within that range, and they offer significant performance advantages over LA batteries that easily justify an increase in price.
Lastly- cold weather performance can be an issue with lithium. No question. If you leave your bike out all night in temps under 40f, you will likely have to "wake the battery up" in the morning. That is an inconvenience.
