New Battery

One thing that people might not know about non-acid batteries is that their amps an hour are much, much, much lower.

Example: YTX20-BS is 18Ah. The lithium I think go to 6Ah max and mostly 3-4Ah. When you hold the lithium battery, you think, "Oh my God, it's so light. The new technology must be marvelous." On the other hand, for some reason, they just don't include as much energy capacity in those batteries. So if they added all 18 amps an hour there, the battery probably would have been very, very expensive and also heavy, and it probably would burn really, really well. Therefore, there are always all kinds of trade-offs, and new batteries, unfortunately, are not a magic solution for everything.

So if you, for example, turned off your engine and kept the lights on, it means your lithium battery can drain really quickly. If you had, for example, an acid battery instead, that would not be a danger for a long time of having accessories on while the engine is off.

While I understand that maybe not many people run the accessories while the battery is off, all I'm saying is that 18 A/h provides a really good safety margin for energy supply compared with those newer batteries.

I think the idea here for this post is that sometimes people think a newer battery is better because it's newer, but they forget that it just doesn't hold as much energy in the first place.

A1A Rider, you’re right about the raw label numbers, but quoting 3Ah to 6Ah lithium batteries is a bit disingenuous for big bikes. Those tiny capacities are meant for 250cc dirt bikes or small commuter twins, not a Gen 2 Rocket 3. No one should be throwing a 4Ah battery into a 2.5-litre triple engine IMO, you're just asking for trouble.
For a 2.5L engine of the Rocket 3, you need proper sizing. For example, I run the Motobatt Pro Lithium MLX16UHD-HP. It’s a 10Ah battery that pushes 600 Cranking Amps (CA).
When you scale up to a properly sized 10Ah LFP battery, the original argument about missing a 'safety margin' completely falls apart because of usable capacity vs. nominal capacity:

• The AGM Reality: While a standard YTX20-BS is rated at 18Ah, lead-acid batteries shouldn't be discharged past 50% if you want them to live. Because of severe voltage sag under load, you only get about 8–9 usable Ah out of that AGM before the voltage drops too low to crank a massive engine like ours.
• The LFP Reality: Lithium Iron Phosphate (LFP) can safely utilize nearly 100% of its rated capacity while maintaining a perfectly flat, stable voltage curve right until it's empty. The 10Ah Motobatt actually gives you a true 9.5 to 10Ah of usable energy. There are other brands too that are suitable, Antigravity for example.

So, in the real world on a Rocket 3, a proper 10Ah LFP starting battery actually gives you more usable capacity and a better safety margin than an 18Ah AGM, all while dumping 600 Cranking Amps instantly.

The flaw in your argument is treating the AGM's 50% discharge guideline as a hard limit while assuming lithium remains usable down to nearly 100% (actually around 80%).

The 50% recommendation is about extending AGM battery lifespan over a long time use, not the point at which it stops working or should never approach.

Likewise, a lithium battery discharged to nearly 100% has little or no reserve left to start the engine.

Motobatt explicitly warns that lithium starting batteries have relatively limited amp-hour capacity and are unsuitable for applications involving substantial accessory loads. Motobatt positions itself as a racing battery, and race bikes would not have all these accessories it needs to power. Information - LifePO4 Lithium

There is no argument in my post above, there is science and fact. But, there is a lot 'misguided information' in your posts on this subject. You say, and I quote "The lithium I think go to 6Ah max and mostly 3-4Ah. " You think??? You think? when did you think before posting that? It's rubbish mate, sorry, but it is. You say a Lithium battery discharged to nearly 100% has little reserve left? Yeah? Really? if it's discharged to nearly 100% flat, of course it has very little left, if the AGM was discharged to nearly 100% how much would that have left?? Jeez, what is this?
But what could be of interest to other users is if a lithium battery is discharged to 80% gone, chances are there is still enough left in it to start a big bike like ours, discharge an AGM to 80% and you'll be lucky to hear a click let alone turn the engine over. This is because the voltage curve is so flat / stable using lithium. As for Motobat it explicitly states the below battery is an direct replacement for our AGM variant (YTX20CH-BS), you can't tell me a racing bike is going to use a
YTX20CH-BS.

Motobatt Pro Lithium Battery MLX16UHD-HP​

Specs etc:

Description​

Motobatt Pro Lithium batteries are around 3x lighter than conventional lead-acid batteries, yet they produce even greater cranking performance ideal in competitive environments. This additional power translates into the ability to provide strong starting currents that are required for reliable, repeated starts at a wider range of temperatures than lead-acid batteries. Due to their very low idle discharge, Motobatt Pro Lithium batteries can retain charge after more than a year of inactivity. Pro Lithium batteries have a high life expectancy with over 2000 cycles compared to around 500 for a lead-acid battery, while also boasting a short recharge time, supplying up to 90% charge after.
Specifications:

• Capacity: 10 Ah
• CA: 600
• Box quantity: 4
• Size: (LxWxH) 151 x 87 x 145, 151 x 87 x 161 (EVA 5)
• Quadflex: MBYZ16U/HD, MBTX20U/HD
• Replaces:
  • GYZ16HL, GYZ16H, YTX14, YTX14BS, YTX14H, YTX14HBS, YTX14L, YTX14LBS, KMX14BS
  • YTX16, YTX16BS, YTX16H-BS, YTX16BS1 YTX20A-BS, YTX20CH, YTX20CHBS

You can not like LFP batteries, that's completely your choice, but for heavens sake, learn about the things before spouting falsehoods and misinformation.


Happy riding, take care.

Kiwicol said:

A1A Rider, you’re right about the raw label numbers, but quoting 3Ah to 6Ah lithium batteries is a bit disingenuous for big bikes. Those tiny capacities are meant for 250cc dirt bikes or small commuter twins, not a Gen 2 Rocket 3. No one should be throwing a 4Ah battery into a 2.5-litre triple engine IMO, you're just asking for trouble.
For a 2.5L engine of the Rocket 3, you need proper sizing. For example, I run the Motobatt Pro Lithium MLX16UHD-HP. It’s a 10Ah battery that pushes 600 Cranking Amps (CA).
When you scale up to a properly sized 10Ah LFP battery, the original argument about missing a 'safety margin' completely falls apart because of usable capacity vs. nominal capacity:

• The AGM Reality: While a standard YTX20-BS is rated at 18Ah, lead-acid batteries shouldn't be discharged past 50% if you want them to live. Because of severe voltage sag under load, you only get about 8–9 usable Ah out of that AGM before the voltage drops too low to crank a massive engine like ours.
• The LFP Reality: Lithium Iron Phosphate (LFP) can safely utilize nearly 100% of its rated capacity while maintaining a perfectly flat, stable voltage curve right until it's empty. The 10Ah Motobatt actually gives you a true 9.5 to 10Ah of usable energy. There are other brands too that are suitable, Antigravity for example.

So, in the real world on a Rocket 3, a proper 10Ah LFP starting battery actually gives you more usable capacity and a better safety margin than an 18Ah AGM, all while dumping 600 Cranking Amps instantly.

Click to expand...

I agree that 10ah is much better than some and most likely as good with reserve as the stock battery.
The only thing I didn't like about the MotoBlatt is that according to their site, when low voltage cuttoff is activated, you're done. No more starts. Other brands (Antigravity specifically) have a low voltage cutoff that is just high enough so that when you reset it, you most likely have enough for one last start. That feature has come in really handy on multiple bikes over the years.

Well, as it happens, I've been making a workaround for a 0v situation, when away from home, which to be fair, is an extremely rare occurrence and is 99.9% of the time operator error, but, you still need to get a fix if it happens.
Understanding: What has happened when a multi meter shows 0v, is the battery bms has disconnected the cells to protect them, they are not dead, just disconnected. An ordinary LFP battery charger will not charge a 0v battery simply because it can not see there is a battery there, 0v remember. For the battery charger to start working it needs to see some volts, usually 9v+ as a minimum, but it depends on the charger. What you need to do is wake up the bms so it connects again.
The bms isn't dead in a 0v situation, it's waiting for some voltage to be applied to it, then it goes, oh, there's voltage there now, it snaps shut and the connection is restored. How to get power into the bms when the charger can't see it? This is what I have been working on.

The remedy: An A23 battery, it's tiny, easy to carry on tour, and more specifically, it's 12v.

The method: Keep the bike electrics turned off, what we're trying to do is wake the battery, not start the bike (yet)
Touch the A23 battery to the bike's terminals (using some 2 strand wire) for 2 or 3 seconds, this 12v pulse tricks the bms into thinking there is a charger there now and snaps closed. Check with a multi meter there is now power showing and the bms has indeed snapped shut. if not and it's still 0v, try again. It will wake up. If you have trouble waking it, remove it from the bike or just isolate it from the bikes wiring, so the A23 is only powering the bms circuit on the battery.
Now either connect a charger and charge the battery, or jumper leads off a mates bike, or connect a portable jump pack and start the bike.

Alternative method: Another way to 'wake up' a 0v LFP is to use an old analogue charger on it, the type that just puts out 12v as soon as you plug it in, it doesn't care if a battery is there or not, the clamps are live and have 12v at them. One of these (if you still have one - I do) will wake and slightly charge the battery . Don't leave it on there a long time though, these old types can get to 15+v and that causes the LFP to disconnect again because of over voltage. Wake it using this, wee bit of charge, then start the bike or use a proper LFP charger.
Another way is to just use jumper cables from a non running car battery or off a running motorbike, this will wake the bms and provide some charging current and of course start the bike.

The work around (touring) will work for a battery that has disconnected because of leaving the lights on (say) and it got too low and shut down. It will not fix a battery that has been left for months in a 0v condition due to parasitic draw by the bms itself. The bike is disconnected from the cells but the bms is still connected and needs a tiny bit of power to stay alive, hence the continued draw, albeit a tiny amount.

Looks like i'm on the cusp of needing a new battery.

6 years old is probably a fairly expected lifespan for a bike battery on a modern bike, with all the electrical draining stuff that's on them, but I can't help being slightly disappointed with how long it's lasted. I've had many other vehicles where the battery has lasted significantly longer than 6 years.

.......hmm.......I can't decide which way to go. Stock or lithium.

I just had a chat with the guy who services my bike at my local Triumph dealership and he mentioned that some of the latest Triumph models come new with lithium batteries.

That was news to me.

I already have a Nobo battery tender that can maintain 12v lithium batteries, so that makes the process of going lithium a bit easier.

The bike is still going to be a heavy bike with a lithium battery fitted and it's not like I require a physically smaller battery, as the battery box is still the same.

At the moment with the old battery, I can tell that it's getting weaker so I have some time to sort out it's replacement, but I have the impression that with a lithium battery, it either has the power output or it doesn't, so no tell tale indication of it getting weaker, which isn't an ideal characteristic.

Lithium is more expensive, so that's not selling the idea to me either, yet for some reason i'm not decided on which way to go.....hmm...

Jagster said:

Looks like i'm on the cusp of needing a new battery.

6 years old is probably a fairly expected lifespan for a bike battery on a modern bike, with all the electrical draining stuff that's on them, but I can't help being slightly disappointed with how long it's lasted. I've had many other vehicles where the battery has lasted significantly longer than 6 years.

.......hmm.......I can't decide which way to go. Stock or lithium.

I just had a chat with the guy who services my bike at my local Triumph dealership and he mentioned that some of the latest Triumph models come new with lithium batteries.

That was news to me.

I already have a Nobo battery tender that can maintain 12v lithium batteries, so that makes the process of going lithium a bit easier.

The bike is still going to be a heavy bike with a lithium battery fitted and it's not like I require a physically smaller battery, as the battery box is still the same.

At the moment with the old battery, I can tell that it's getting weaker so I have some time to sort out it's replacement, but I have the impression that with a lithium battery, it either has the power output or it doesn't, so no tell tale indication of it getting weaker, which isn't an ideal characteristic.

Lithium is more expensive, so that's not selling the idea to me either, yet for some reason i'm not decided on which way to go.....hmm...

Click to expand...

my rocket battery is in my Polaris sportsman. the lithium I put in spins the starter a lot faster than stock. I guess the shipping to the UK might be cost prohibitive. this place had the best prices though.

rick danger said:

my rocket battery is in my Polaris sportsman. the lithium I put in spins the starter a lot faster than stock. I guess the shipping to the UK might be cost prohibitive. this place had the best prices though.[/URL]

Click to expand...

Thanks Rick.

I've just had a quick look for a UK supplier and found this:

£420 ....yep feels uncomfortable on the wallet, so next i'll have a look and compare prices for a conventional battery.......Might focus my thinking a bit...

Antigravity batteries are superb and have that failsafe re-start button, I'd have one in a heartbeat. But for us down under the cost is astronomical like $1200 or so, so it's a no go from me.