There is an easy and quick way to lighten your bike, lower its center of gravity, and marginally improve its dynamic performance for $200 or less: the starter battery.

Lead-acid, absorbed gas mat, and gel batteries have been around for years now, and while they provide cheap, reliable, and robust performance, they are obtrusively heavy and large.

In terms of packaging and placement, most bikes have them mounted high and away from the center of gravity; basically, it’s like carrying around a brick at arm’s length all day.

Luckily, the market for starter batteries has been moving in the direction of new battery technologies with the latest iterations utilizing lithium iron phosphate chemistries.

These batteries are not plagued with the same issues that lithium ion batteries faced (read: exploding when cycled improperly), and are more environmentally friendly and theoretically last longer than the equivalent lead-acid or AGM battery.

We had two companies send us their most popular models for testing and we came away impressed with the weight savings, performance, and overall value that they had to offer.


Stark Power, a relative newcomer to the powersports battery market, sent us their 18 amp-hour Ultra Start 4 (US4) LiPO4 starter battery, along with a diminutive 8 amp-hour “performance/race” starter battery. The former weighed in at 2.10 lbs and rated at 500 cold-cranking amps (CCA), while the smaller black case battery weighed in at approximately one pound and is rated at 180 CCA.

Both batteries feature internal microprocessors which control cell balancing. The US4 also incorporated an innovative “Ultra Start” feature, which automatically switches the battery off when the voltage reaches a certain threshold. This is to ensure that there is always enough juice left in the battery to restart the bike.

I found that the 8AH small battery to be adequate if you bike does not have high wattage driving lights or other accessories that are going to tax the charging system beyond its limits. The 18AH battery has plenty of juice in case you need to run a few accessories intermittently that are going to draw the battery down.

Yes, it weighs a pound more and is approximately two and a half times the size of the smaller battery, but it also has the added feature of “Ultra Start” which works well enough for its intended usage, but was a tad wonky (sometimes switching the battery on or off and on again and then off). As an added plus, both Stark batteries ship with battery chargers.


Shorai sent us their LFX19A4-BS12, which is a rated at 285 CCA with 19Ah capacity. The Shorai feels a bit better built than the Stark battery with a more high-end feeling case design. Although it has a lower CCA rating than the US4, in my testing it performed just as well as the Stark battery.

At 2.31 lbs, it is just a tad heavier than the US4 and does not have the neat “Ultra Start” feature that the Stark battery does.

In addition, the terminal design of the Shorai is not as versatile or flexible as the four-corner terminal design on the Stark US4 battery. Additionally, the Shorai battery does not ship with a charger.

Overall, both the Stark and Shorai batteries performed the task of starting the bike and running accessories all while coming in at six to nine pounds less in weight. The cold weather starting was a bit anemic but once the battery had warmed it was not a problem.

Prices currently are about 1.5 to 2 times the price of the equivalent flooded lead-acid or AGM battery. The Stark power US4 and the smaller 8Ah powersports battery are $220 and $120 respectively.

The Shorai battery costs around $200. However, what you get is a battery that will last longer and perform as good at an 80% weight savings. So next time your battery gives up the ghost, consider a LiFEPO4 replacement.

Do you have experiences with starter batteries incorporating this chemistry? What have your experiences been? Some die-hard adventure tourers swear-by their 15-20lb 24Ah as proven reliable and higher performing in cold weather.

We would be interested to hear if any tourers out there have adopted a lighter battery and how well it has performed for them, especially when the temperatures have dropped.

Note: As always, Asphalt & Rubber received no compensation for this article, though both Shorai and Stark Power provided demo battery units free of charge for review.

  • Easily the best modification you can make to a sport bike. I’ve got a Shorai in my track bike (Yamaha YZF-R1), and love it.

    I lost probably close to 8 lbs over the stock unit, and the thing has taken a beating with 110 degree track days and below freezing winter storage — never gave me any trouble (I just started the bike in the garage, it’s easily sat for 4 months without a tender…started right up, no fuss).

    There is a reason OEMs are starting to make these stock on production bikes. The days of lead acid starter batteries are over, especially in sport bike applications.

  • Bob

    I tried a 12 cell Ballastix in my HD and it generally worked fine. The biggest issue was taking up the excess space in the battery tray and was enough reason to not bother with LiPo in my tube framed Buell. It would just look stupid.

    Performance wise, the cold weather issue was an issue on the 2 dozen days it dipped below 40 F. 35-40, it was slow cranking and would eventually kick over. Below 32 F, forgetaboutit. Learned later that you need to get the electrons flowing first. Turn on the ignition and let the lights and heated grips run for a couple minutes. Then the bike would start fairly well. However, this was done in a cold garage. At work, the bike is outside and subject to to the temperature directly and windchill. I had the bike not start at all even with the trick I had learned. Had to get a jump.

    My biggest concern still is that the batteries require a unique charging program. The battery I had was basically “dumb.” It needed the appropriate charger. So I got to wondering if I was damaging the battery or shortening it’s life with a charging system that was never designed to use a LiPo battery.

    If the batteries are now being built with intelligent circuitry, great. If not, I will avoid the “dumb” LiPo as a “dumb” AGM will likely be a more reliable choice. If the bike manufacturer’s start building bikes with charging systems that can switch between multiple chemistries or just the LiPo only, then I look forward to a lighter future. Right now, I would love to shave a few pounds off my porky CRF450X.

  • Kirk R

    Yeah, these are not good batteries for year round commuters in areas with any kind of a winter. It was a waste of money for me to put a shorai in my cbr1000rr as it would not start the bike most winter mornings even after warming up the battery.

  • proudAmerican

    I’m lucky enough to live in southern California, and all of my bikes are kept in the garage. My ST1300, VFR1200f, and CBR1000RR’s Shorai batteries are all over two years old, with not a single problem. As a huge bonus, no more extension cords snaked through the garage attached to Battery Tenders. The Shorai’s are well built, and fit very well into the OEM battery box.

  • Earl Shives

    I had a problem with one of my Shorais once. Hands down, one of the best customer service experiences I have ever had with any product ever. Highly recommended product.

  • Old Adv Rider

    The Shorai will be ruined if it is submerged in water, which can happen when riding off road.
    This is not something Shorai will warranty, and it is an undesirable characteristic for an off
    road bike. All it takes is one large puddle, or a river crossing which was deeper than expected,
    and your Shorai battery will be ruined. Also, the Shorai lacks onboard battery management electronics, which are critical for proper charging of these batteries. Other batteries DO have
    such onboard electronics and are also immune to submersion in water. Do your homework before you buy a battery which will leave you stranded like I did ( I learned what I now know the hard way ).

    Antigravity and Earth-X batteries are the best choices in this sort of battery. However, it
    must be added that virtually all the lithium battery vendors rate their batteries in an unrealistic
    manner and you should not trust their claims of cold cranking amps if you intend to ride
    your bike in cold ( sub 40 degree F. ) weather. If you want to ride in cold weather you should
    buy the largest lithium battery which will still fit in the battery box on your bike. It will still be
    dramatically lighter but best of all your bike will start in cold weather instead of requiring a jump start.

    I have no hidden agenda nor am I affiliated with any battery vendor. But I don’t want people to be misled by the questionable marketing practices of various lithium battery sellers.

  • Ken C.

    I have a Shorai in my R6 and it’s been awesome. On cold mornings up here in northern California, when temperatures are around 30-35 F, the bike starts slightly slower than when it’s warmer, but it’s still way faster than the lead acid battery that I replaced. Also, I went away for a few weeks over the holidays, and when I came back, the bike started up like it was freshly charged. So far, it’s been money well spent. No more push starts for me.

  • Norm G.

    re: “Stark Power, a relative newcomer to the powersports battery market”

    but not to the Defence sector and Variable Threat Response Battle Suit trade.

    jokes aside I’ve got a question, actually SEVERAL…

    any of you early adopters ever ask why (even after all this time) established battery companies like Yuasa, Exide, Westco, GS, Unibat, Deka, etc who supply both the OEM’s and the aftermarket, STILL don’t offer this technology with their name on it…? doesn’t it strike you as odd…? or are we too busy “consuming”, “self-ingratiating” to notice…?

    How is it that there can be this sudden proliferation of lightweight batteries, with all these names, and all these so-called experts touting their particular brand (coming out the woodwork this), yet the established 20, 30, perhaps even 50 year old companies (surely staffed by professionals holding Doctorates in Chemical and Electrical Engineering) are still constructing SLA and sucking down H2So4 fumes…?

    clearly with all the names popping up, logic would dictate they are merely assemblers and not manufacturers, and are acquiring these cells from a 3rd party. okay, but what were these guys doing BEFORE they were in the “battery business”. and why are the people who actually have the MANUFACTURING capability and the economies of scale to put all of these guys lights out NOT hopping on the bandwagon as quickly as the laymen and general public seem to be doing…? I dunno, not saying there isn’t an answer…

    but it’s one of things that should make you go hmmmmnnn… (Normstradamus rubs chin)

  • Mitch

    I also have a Shorai in my track 600RR. I accidentally ran it to death at the track once (bad connection from stator to RR), but a little time on a normal tender and it came back to life even after being at a bad volt level for a day. I’m a fan. (Stock battery – 8 lbs, Shorai 1lb)

  • Norm G.

    PS: iirc Yuasa is the company Boeing contracted (or at least one of them) to make the Li batteries for the composite 787’s that grounded JAL last year and more recently again last week. just a factoid, not implying any relationship to the above observation (not yet anyway).

  • taikebo

    The better way to shed the weight is to shed the fat in our body

  • The real question is… How will taking weight out of this part of the bike affect the speed you can accelerate, brake, and turn?

    It is likely that it will actually raise the CG of the bike and rider system, and lower maximum acceleration and braking rates.. thought a relatively high CG is actually good for cornering (I think).

  • JoeD

    I installed the Ballistic 12 cell in the Benelli. Below 60 F the thing sucks. No, that’s too kind. Until cold weather performance improves and spontaneous combustion problems are fixed, I’m out. I ride year round in the SE US and winters are mild.

  • chris

    i bought my shorai battery and it sat on a shelf for a year…. put it in a bike and fired up like new.

    beeler, there’s no need to say “probably close to 8 lbs.” just look up the weights. i used to make a lot of subframes for race bikes, and competitors of mine would claim 10+ lbs in weight reduction… when the oem subframe was only 8 lbs. numbers matter, especially when that’s the point of the article.

  • Kevin White

    Shorai in my FZ6R. It’s been the best battery I’ve had in a motorcycle, starting fast in every weather / temperature condition and enduring extended absences (business travel) with no loss in performance.

  • I’ve tried 2 different light weight batteries in 2 of my bikes with alot of issues (losing charge and not holding a charge) since i have switched all 12 bikes to Shorai without a single issue. Great company excellent product.

  • Switched to a Ballistic battery in our Historic Moto Gran Prix Triumph race bike and started having cold-start issues as well as hot-start issues- which is really frustrating when sitting on the grid after a red flag waiting for a re-start. Went back to a MotoBatt AGM and starting issues went away. Couldn’t show a difference in lap times, either.

  • Scott F

    Two comments from an electrical engineer, albeit one without any great battery experience:
    1) As mentioned, LiFePO4 batteries deliver a significantly lower current at low temperatures. It may be enough to start your bike, or maybe not. Turning on a current drain such as headlight, heated handgrips, etc will warm the battery, as long as you bike’s CanBus (it it has one) allows it.
    2) LiFePO4 full charge is a few tenths of a volt higher than lead acid. This means you need a special charger if you want a full charge. Standard chargers designed for lead acid won’t hurt them, but you will not get a full charge. Similarly, your bike’s charging system, designed for lead acid, won’t fully charge them either. As a result, you will not get the full rated performance from the battery, so go up a little in capacity when you chose a LiFePO4 battery.

  • do you know where your battery cells come from?

    this is essentially the biggest question for any of these batteries, and most of the answers are from a contractor nowhereville backwater china.

    So far the best all around performing batteries I have used are based on a123 system cells. – Back in 2009 we made the switch to a 6 cell MOTY Design that uses these cells. Never had a single issue with them, even sitting for over a month.

    About a year ago when we pulled the pc5 and reflashed the stock ecu we switched out to the 8 cell factory like fit – which is still only 1.52 pounds. have not had a single issue – 2 ballistic batteries went tits up during that time. Revzilla replaced them but the cells are unknowns and seem to be problematic so we sold the second replacement.

    If you want to know what the difference is, remove the battery and tip it back and forth – fairly noticable difference.

  • David Richardson

    I have used the StarkPower for over a year, and it’s fantastic! Super light and powerful.

  • Meaty Beard

    I have a Shorai in my Honda 599. Sometimes I ride it seven days a week, sometimes not for a month. The battery has never missed a beat. Thing is awesome. When I was handed one at the Long Beach International Motorcycle Show I thought it was a joke because it was so light. Surely it was just the case with nothing in it, right? Nope, it’s crazy light. Get one.

  • paulus

    Sounds like there are lots of consistency issues. Some great reports, some terrible.
    I will wait until the technology/source/product quality is stable.
    Once OEM’s fit them as standard, you can be sure that they are tested and at least meet the terms of the warranty.


    Try AntiGravity, i’ve use it for my drz. Super Light and it comes with a 3 year warranty.

  • Norm G.

    re: “I don’t want people to be misled”

    I don’t want people to be injured.

    for example, take the guy with 12 bikes…? that’s 12 opportunities to blow his fuggin’ balls off.

  • There’s an extremely detailed thread on the ADVrider forums on these Lithum Iron Batteries.

    The Shorai comes out extremely poor in all of the test run it compared to the Balistics battery.

    The tester also tests a number of popular AGM batteries.

    I haven’t got the link to hand but a quick search and you should find it.

    Warning it’s amazingly detailed, and you’ll need a week to read through it.

  • Denis L

    Love the compact dimensions and light weight of the Shorai battery, however, low temperatures- any time when the temp is in the 40 degree range, these batteries suffer mightily. Even following the “turn the key on, finish that cup of coffee” ritual does not solve the cold- start conundrum. Shorai has been diligent in working with me on replacement batteries, however, New England weather still has the upper hand. I just bought a 2014 Triumph Thruxton, and have a new Shorai on the shelf, yet I am reluctant to swap out the stock Yuasa, as I know I will have the same issues I have with my Sprint ST. In warm weather, there are no issues whatsoever, quick cranking all the time.