Lithium battery

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Lithium battery

My turn for help now from anyone out there, despite what people think reading these forums I do try out new technology. So last year after reading about them I bought my first Lithium battery  (HJTZ10S-FP) replacing a gel battery that had only lasted 2 years, , I knew there would be problems with the cold but I've been caught out despite my best efforts. I've got 4 bikes but only two chargers, normally in the winter I swap them over after a week, I leave them off in the summer as experience is beginning to show they eat gel batteries? Both are optimate but according to everyone shouldn't be used on lithium anyway. Fair enough I run the bikes every couple of weeks anyway, it didn't hurt to run the Lithium one longer to keep the battery charged, as it wasn't on the charger.

We had a really cold spell and when I tried to start it nothing, won't jump start and in desperation I tried the optimate - nothing doesn't want to know, not even any checks, voltage is 1.7v after being fully charged a fortnight before, there is nothing drawing off current (I know how to check), so it must be the cold. A bit more research has brought me to a new term 'bricking' where voltage is so low it will not charge. I am tempted to buy a lithium charger but if the battery is goosed (and I won't be buying any more Lithium) it will not work anyway.

I gather there is a protection built in that needs to be reset? anyone know how to do this and can I then use my ordinary charger. Can that clever person please also explain how it charges on the normal bike system when running, same as any other battery, but needs a special charger to trickle charge? or is that a myth on behalf of the manufacturers?

Thanks - a puzzled oldboy54

PS my experience over the years for batteries :- Lead acid - 7-10 years, even more if looked after, found Yuasa best Gel batteries - 1-2 years, given up on them, trickle chargers seem to damage them, got one to last 4 years by not leaving on trickle Lithium (see above) - 1 winter Bloke across the road from me just scrapped his Nissan after 23 years, still on original lead acid battery - amazing.

Rechargeable lithium batteries are extremely sensitive to charging conditions, get it very wrong and they will catch alight.  Hence the internal safety measures, I guess. In addition, charging by only a fraction of a volt above the optimal will lead to a reduction in charge / discharge cycles, by which mechanism I have no idea.  I.e. not using a properly-regulated lithium-ion-specific charger will most likely prematurely age the battery. As for the on-board charging not damaging the (any) battery, I don't think that can be guaranteed, especially on bikes with dodgy electronics.   My old man fitted a lithium iron phosphate battery to a Z1300 after a spate of electronics issues that effectively boiled down to: the lead acid battery wouldn't hold charge and the ignitor unit's output power transistors had got so hot as to damage the board they were on... He changed the regulator / rectifier to a modern unit (modern component tolerances, fresh / different semiconductor material) at the same time he fitted the new battery, plus a remanufactured ignitor unit using modern equivalents to the largely discontinued original semiconductor components.  It ran perfectly, but he sold the bike after a summer's worth of use, so no idea how it's held up since then.   A dodgy charging circuit will eat lead acid and gel batteries, too, eventually (which was partly the issue on the above-mentioned Zed).  Measure the terminal voltage with the engine running at mid-revs and check it's within spec (about 14.4 V). Even then you can't guarantee that the rectified generator output isn't some ugly shape - remember it pulses, it's not constant. The regulator part dissipates excess power to earth to maintain a given voltage, and that causes the components to run quite hot. That heat (cycling) ages them over time and may lead to an inability to properly regulate the signal coming from the generator.  This goes doubly if the rectifier portion is running out of spec.  The same would be true of cheap / reject regulator rectifiers.  Pay attention to the age and quality of any high current wires and connectors to / from the regulator, since any voltage drop here may skew the output (some designs use a separate low-current wire to monitor the terminal voltage to avoid this.)  The earth connection is also important. Remember the electronics were probably designed for (supremely hardy) lead acid batteries, which allow a lot of wiggle room.  Some bikes will inevitably take advantage of their hardiness and rely on it.   I can't comment as to how to revive the lithium beastie, though.

Inert thank you, a great answer, the bike has only done 2000 miles, I did check the terminal voltage when I replaced it, running at 2500 rpm which was 14.2v, before it died . Never thought about whether the rectified current was smooth, I'd need an oscilloscope which I don't have, I'll give it some thought, it's a BMW but doesn't mean to say it isn't a cheap one as this is my smallest bike a G650GS, and build quality is not great. I replaced it today with a new lead acid and checked for current draw again but there wasn't any, so it's definitely the cold thats killed it. Now the problem is can I save the (new) Lithium battery and how. I've just come in from the garage and will check wires to and from the regulator tomorrow. It's put me off Lithium as it's the first one I've tried.

I have since read a great deal more about this specific battery type - much of what I thought I knew actually applied to lithium cobalt oxide (LiCoO2, "lithium ion") batteries, and not the lithium iron phosphate (LiFePO4) batteries used in motorcycle applications.  I'm glad I did, since I've been considering one myself for some time, and I'll share what I found.   The reg / rectifier smoothness probably isn't an issue, except to the electronics on the bike.  Even then, it's probably fine in your case as you describe it, so I doubt there's any need to look closer at that. I did come across some talk of modifications to charging circuits on bikes, but I don't  know if it's truly necessary, or even exactly why it was done.   So to voltages, which differ from the cobalt chemistry: Nominal cell voltages are around 3.2 V. Optimal charging voltage (max capacity) is 3.65 V; higher voltages yield no benefit except faster charging, with possible reduction in life (opinions differ here).  Voltages above 4.2 V are sure to damage the cell, though. Minimum cell voltage is 2 V; held below that for some time, the cell could be damaged (unwanted chemical reactions causing shorts etc.).  Constant deep cycling reduces lifetime, but not as badly as a cobalt oxide cell. For a four-cell LiFePO4 battery, that yields 12.8 V nominal, 14.6 V charging and 10 V minimal service voltage.  So a perfectly fine replacement for lead acid, at first glance, unlike a 3-cell LiCoO2 battery (11.1 V nominal, max 12.6 V charging) I mistook this to be.   They charge best at "1C", which means at a current equivalent to the numerical capacity: a 10 Ah battery can charge at a maximum of 10 A; 1 A would still work but obviously take longer.  The battery needs an internal balancer circuit to ensure each cell is charged fully, but no cell is over-charged, but its tolerance to over-volting means it's often not used. A lead-acid battery charger supplies 14.4 V at first, but some drop to 13.8, so may not fully charge a lithium iron phosphate battery, especially in the cold.  In theory, it should only be around 5% short of fully charged, but it seems to depend on the charger.  Such chargers might not even turn on if the battery voltage is too low.  Note that a bike's charging circuit operates at a constant voltage when running above idle, so could in fact charge the battery better.  I also learned that gel batteries don't like voltages over 14 V, so you seem to be onto something there.   In the cold, the LiFePO4 batteries flat out do not work well below about 10 degrees C, or 50 degrees F, so they often cannot drive the starter motor fully straight away.  It is recommended to warm the battery on a low-ish current first, such as a headlight or accessory.  Cranking cold is not recommended as it drains the battery disproportionately quickly and seems to be related to early failure.  AGM lead acid batteries lose cranking ability with temperature in much the same way, but are usually properly sized. Many "replacement" batteries offered by retailers / manufacturers are selected for maximal weight saving, and are arguably too small a capacity for the application.  Heated gear tends to drain the battery too much in use, for instance, and smaller capacities have much lower cold cranking capacity, exacerbating (if not directly causing) the cold start issues. Watch out for "equivalent" capacities and cranking amps; these are generally believed to be nonsense (and may damage the long term prospects of this technology).  Try to find the actual capacity.<

Chopped my reply short.  Above 10 V minimum should be 8 V, obviously.   Finally to the point: A low current can wake an over discharged battery, typically 0.1C or less.  Some chargers have a "slow start", "pre-charge", "boost", "wake up", "conditioning" etc. feature to do just this.  Some chargers will do nothing if the battery voltage is too low.  Charging is even more temperature sensitive than discharging. I'd recommend putting the battery indoors to warm up and re checking the terminal voltage.  If it's close to 8 V, put it back in the garage on charge.  If not, the low current approach could still be tried.   There is more info available on LiCoO2 cells than LiFePO4 cells on this point, so the following applies to the former for certain but may also apply to the latter.   It is potentially dangerous to charge the battery if it is dead, but bespoke chargers are designed for that possibility.  LiFePO4 chargers certainly exist with the over-discharge recovery functionality, but I can't be sure of its exact operation, and whether it's as I describe below for LiCoO2. The internal safety can reportedly be reset with a low current.  If the voltage does not rise significantly within a minute, the battery is dead - it may still charge after several minutes, which is the dangerous part.  It's that initial low voltage and subsequent voltage rise that the special chargers "look" for - no rise within a certain time and the charge is aborted. Some people do it manually with variable power supplies, and others do it with other batteries!  Again, it is said to be dangerous due to heating and short circuit risks.

What a great answer, thank you Inert, I'd read a little about them but missed the cold cranking. I'll try what you said but it looks as if it's going to be ditched before even being used. My conclusions (personal) are that these batteries are ok if you race (weight saving) or live in a warm climate. They otherwise are not suitable for motorcycle applications for everyday use, definitely no use in cold climates. That was an expensive learning curve. You may be onto something with the 14v for gel batteries, my experience is definitely when left on trickle in winter in a cold climate they fail. However it may now be because when used the bikes charging voltage is over 14v, interesting. Anybody out there interested enough to run two new gel batteries, one on a bike where charging is limited to under 14v?

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