Separate names with a comma.
Discussion in 'The Garage' started by _cy_, Jan 20, 2012.
Actually, it seems to be marked as Li-Po, so not LiFePo, but not "standard" Lithium Ion either.
Since the pack is marked 3s1p it looks like LiIon to me- gets close to 12V, LiFePo4 would be 4s to get to the correct voltage.
So the pack could have suffered a thermal runaway, this could have gotten ugly.
Does 3s1p mean 3 series, 1 parallel?
Li-Ion are 3.7v. Lithium Polymer 3.6v.
Would 3 in series (10.8v) be adequate for a booster to a 12.8 battery? (and a bit more drop from the schottky diodes for polarity protection)
LiFePo are 3.2V, so 4 in series gets you 12.8V. With the 3s in LiIon you get 11.1V- but a very high discharge rate if your starter tries to get the voltage below that.
That way it does not try to charge even a quite empty Pb battery, but still keeps the systems voltage above 10 while cranking to keep the EFI happy.
Would that be this one? The follow up comments didn't look too promising...
my Battery Tender LifePo just passed five yrs old. Still starts the DR200se at 40F after waking it up.
I have a Schumacher SE-1275A battery charger.
Quoth the manual:
"12 AMP setting: The initial charge current should be 12
AMP's gradually tapering throughout the charge cycle to
5 Amp's. Though not indicated, battery voltage will
gradually rise to approximately 15 volts, then hold
constant throughout remainder of charge cycle. When
the battery reaches 15 volts and charge current drops to
5 AMP's the charger will turn off. Initially the battery
voltage will drop from its 15 volt level fairly quickly.
When 13 volts is reached, the charger will again turn on,
until the 15 volt, 5 AMP condition is met. As this action
continues, ON time will decrease to a few seconds while
OFF time increases to a range of several minutes to an
hour. ON/OFF times vary with size, type and condition of
2 AMP setting ON/OFF action is a function of battery
voltage only, otherwise identical to 12 AMP setting."
Is this the completely wrong thing to try and revive the totally drained LiFe battery with?
Yes. Don't even think about it. I also find this charger very aggressive even for AGM batteries. The max charging voltage should't be more than 14.7V. 14.4V is wiser...
So it is a FLA only charger?
Are the Battery Tender Plus/Junior the value standard in quality chargers? Is there a better place to read up on options than picking back through 137 pages of this thread?
Take a look at OptiMate and Ctek. Prefer those with temperature compensation.
If the Li batteries do not work with the regular chargers for lead batteries, how come they will work properly with the charging system on my bike, which was designed for lead batteries?
Lead acid chargers have a desulfation / recovery mode which applies high voltage to break sulfation crystals. That will destroy a LFP battery. Otherwise LFP is 100% compatible with AGM charging systems.
Also note, that LFP batteries with a built in BMS (Battery Management System) that protects the battery from over discharging disconnects the cells to stop further discharging and prevent their destruction. To wake up the BMS and reconnect the cells you’ve to use a LFP charger.
But the desulfation mode on the lead acid charger is effectively constantly topping up the battery, isn't it? If that is bad for LFP batteries (which as most Lithium based batteries prefer to be kept at around 50% SoC) than how are they OK with the charging system on a motorcycle which does exactly that - charges the battery constantly to full charge? The lead acid batteries, on the other hand, prefer just that - to be charged continuously and kept at 100% SoC and that is why the batteries on motorcycles that are being ridden constantly last the longest.
Furthermore, the LFP cells are 3.2v, meaning that a motorcycle battery with 4 cells is 12.8v. That means that maximum charge is reached at 12.8v but most motorcycle charging systems output 14.5-14.7v and maintain that output constantly. Doesn't that mean the LFP batteries will in fact be constantly overcharged?
And finally, even if LFP battery has BMS it does not communicate with the charging system on the bike, meaning that once it reaches certain parameters the only thing it does is to simply disconnects the battery from the charging system. Can you elaborate on how disconnecting the battery from the charging system affects the diodes on the alternator and also the regulator/rectifier? The alternator on the 99.99% of the motorcycles is of the permanent magnet type, meaning that even if the BMS on the LFP had a means to communicate with the electrical system on the motorcycle, there is simply no way to lower the rotor current or switch to a dummy load. So, where does all this heat from the alternator/regulator/rectifier working at full power go and what does it do to these components?
No. Desulfation mode applies a voltage more than 15V and low current. It’s not topping and if not done properly it may harm even a VRLA battery (causes gassing & electrolyte depletion).
Constant charging is not the best for lithium but don’t worry about it they live long enough.
A battery consists by cells in series and parallel to achieve the needed voltage and capacity. It’s 3.2 x 4... On lead acid is 2-something x 6...
_Cy_ may enlighten you about the BMS and the charging system.
Take a look at https://batteryuniversity.com/
@Ste7ios I thought you are the expert and will answer my questions. Apparently not. Thank you for the link - it is well-known to me and probably almost anyone else.
Desulfation mode gives short high voltage shocks that may dissolve the salts that have formed, bringing the battery back to form. The voltage spikes are more than 15V. That is what harms the lithium batteries.
I lately installed a Skyrich battery. It is first installation battery on smaller KTMs. A friend had it installed in the begining of this winter and it performed satisfactorily in temps reaching -17C. I also found it strong starting, except when too cold. I tried 3 crancking cycles when too cold and it worked nicely. Now I need to monitor its longevity.
It took you a week to come up with that snarky retort?
Yes! And 6 days, 23 h, and 59 min. of those I spent riding around Greece )) You, on the other hand, must have spent this time on the forum counting the days waiting for my response?
Can the BMS in the battery not keep up with the short bursts of +15v in desulfation mode?
It's not entirely clear to me that the BMS addresses overcharging at all. EarthX makes it seem like BMS is just a protection against discharging.
As they say, it also voids your warranty although I don't know how they'd know.
I think you were misreading what @Ste7ios said which is that BMS disconnects to stop over-discharging rather than overcharging. FWIW, my understanding is that it's not ideal for a LiFePO battery to get charged constantly but it'll survive. So...
1. No desulfation mode as that kind of voltage spike kills LiFePO batteries.
2. You can leave them on a charger but it's better not to unless you have some parasitic drain.
3. It's also probably better not to have them hooked up to the bike's charging system while you're riding but then what's the point of a battery? It's not ideal, but it's fine. Because your bike doesn't produce crazy voltage spikes like desulfation mode does.