BATTERY ADVICE AND WISDOM NEEDED.

[MaxyMax]

Hey legends.

looking for a little bit of advice/help here in understanding batteries , AH in particular .

Im trying to upgrade my old old battery, and ideally wanting to move to something as small as possible . As working on a Cafe, and looking to re-mount the battery under the seat.

The Original battery is estimated to have a CCA of around 67
https://wiki.gstwins.com/index.php?n=Main.Battery

Which has not been hard to find at all in some smaller alternatives. But the original had 11 AH and a lot of these smaller batteries are much less than that.             For example I can find a great fit for what i need (size wise) CCA of 140, but only 3 AH.

Wondering if will be possible/cause issues etc

Thanks in advance
Matthew

[MaxyMax]

I noticed even a lot of Lithiums have smaller AH

looking at this one companies range. Their cheap led batteries are much higher in that department , than their more expensive Lithiums. Which leaves me a little confused/ surprised

[mr72]

CCA is basically a measure of how much current the battery can deliver when cold. If that number is too small, it can't turn the starter. The amp hours is how long it can deliver that current when fully charged.

I can tell you from direct experience that a 3ah battery will not reliably start a GS. It will be dead before it can turn the starter long enough to start it, especially after a short trip. If you are making a show bike that can be jump started easily and lives on a battery tender, it can work. Real life, no way.

[Bluesmudge]

From experience, I used a Shorai LFX14L2-BS12 that is roughly 1/2 the volume of the stock battery. It has 210 CCA and 14 ah.

In warm weather I was impressed by the battery and its small size and weight but after a couple years I still eventually went back to a more traditional battery because I didn't like how Lithium Iron batteries deal with cold weather.

3 ah seem like a joke. You want the stats to be similar to or better than a standard battery for a GS500.

[mr72]

No kidding about cold weather. A 3Ah batt will not start the bike at all if it's under 50F. It will start it if it's already warmed up and the battery is fully charged if it's over 60F. It will start it about half the time starting the bike cold even with a full battery. If you ride to some place just a couple of miles away, a 3Ah battery likely will not have enough juice to start the bike and get you back home.

[MaxyMax]

Thanks to everyone taking time to respond.

firstly Cold weather aint too much of a concern here on the Gold Coast of Australia. BUT i could also get a Dry Cell AGM that would work. as can mount on their back, changing the width into the height.

But either way sounds like everyone is saying 3AH just aint gonna be quite enough.

So what about 5-6 AH ??
This is a dry cell i can pick up cheap/close to me, no need to order from overseas. and will fit snug under my seat compartment.  https://www.mxstore.com.au/p/SSB-V-Spec-VB5L-B-High-Performance-12V-AGM-Battery/4-VB5L-B



I know a lot of well recognised, highly recommended lithiums (for mods) are still quite quite low AH
The Dry cell i have seen so many ppl puttting in mods online, is only a 6.

https://antigravitybatteries.com/products/starter-batteries/small-case/ag-401/

(they hard to find here in Aus eitherway)

[Bluesmudge]

If cold weather is not an issue then you will like the Lithium Iron batteries.

Is the Shorai I posted still too big? Its tiny compared to stock and puts out similar stats (14 ah). If you can't buy the Shorai there must be locally available companies that make a similar battery.

[mr72]

Thanks to everyone taking time to respond.

firstly Cold weather aint too much of a concern here on the Gold Coast of Australia. BUT i could also get a Dry Cell AGM that would work. as can mount on their back, changing the width into the height.

But either way sounds like everyone is saying 3AH just aint gonna be quite enough.

So what about 5-6 AH ??

Well, not trying to be dumb, but ... about twice as good as 3Ah?

Which in my case would not be good enough.

FYI if you search "gs500 starter current draw" on Google you know my blog comes up first!

So in my own personal experience, I couldn't reliably start the bike more than two times with a 3Ah battery. So you might be able to get it to start reliably three or four times between charges with a 5-6Ah battery. Not getting into the weeds, I think if this is enough for you, then go for it. I personally would not use less than a 10Ah battery in my GS500. Just too much stuff on an old carbureted motorcycle to cause it to be occasionally hard to start, and in those cases, it may not start at all if the battery goes flat too fast.

[MaxyMax]

unfortunately its just so hard to find a small enough battery with AH of 10.

im trying to to a cafe build and streamline everything , cut out all the bulk.

So need something small as possible for this under the seat tray.   So gonna come down to cosmetics vs battery reliability.

but at the moment, i currently have a busted led-bat in there that wont hard charge, but even that a little bump start and she is off and purring again. no idle issue .  no issues anywhere unless i switch it off.

So worst case scenario i can always give it a bump start if its not starting one day.  but given i use it every second say and live in hot area.... i it should be ok, no?

[MaxyMax]

Sorry im a bit of a novice, so this confused me "So you might be able to get it to start reliably three or four times between charges with a 5-6Ah battery."

isn't it going to get charged every time i ride the bike anyway. So as long as it turns over once, gets the bike going. id assume it would charge the battery enough for it to turn over on the next ride (unless i left it unattended for a month or something )

am i off ?

[Bluesmudge]

So as long as it turns over once, gets the bike going.

In theory: yes.
But that is a lot to ask out of a carbureted bike with an anemic charging system.

All these things can pop up out of nowhere and mean you need to crank the bike a few times to get it started:
Cold weather, old gas, bad gas, rust in the tank, wrong choke position

Then the GS500 has a bad charging system so all these things could mean you don't replenish the electrons you used to start the bike:
Short trip, stop and go traffic, low rpm cruising, heated grips or clothing, auxiliary lighting

The GS doesn't charge much below 5,000 rpm so when you are sitting at a stop light you are actually drawing on the battery.

If this will be a show bike or a track bike none of that stuff matters. If you ever plan on relying on the GS as transportation you want the best battery you can afford. Even then, I still leave mine on a battery tender so I know I have a full and healthy battery to work with when I swing a leg over. I don't ever trust the GS to start on one press of the button.

[mr72]

Bluesmudge is right on.

It takes some miles at over 3K rpm to charge the battery. It gets drained by starting, a few of the Amp-hours are depleted, and it must be recharged. If you take a short trip in the neighborhood, the battery will not charge during that trip. It will be drained further by the ignition and lights while the bike is running.

You have to be running the alternator fast enough for it to produce more current than the bike's ignition and lighting draws in order to charge, and even if you exceed the drain current with charge current, only the excess is available to charge the battery. A fresh new GS500 alternator can produce 200 watts at 5K rpm. The regulator/rectifier is far from lossless. So let's say the max output of the reg/rect is maybe 10A? a 55W headlight draws 5A by itself. I've never put a meter on it but I would guess the bike probably draws 7+ amps of current while running. So even if everything is perfect, you might only have 3A available to charge. And a 3Ah battery takes an hour to charge at 3A. So you'd have to ride above 5K rpm for an entire hour to recharge even that tiny battery. So that's why you need a 10+ Ah battery to successively start the bike between either longer rides or plug-in charging.

[SK Racing]

I'm afraid that I can't agree with some of the things that are being said about Lithium Iron batteries. Sure, in cold weather, rather stay clear of them. But in warm weather they work fine.

I've built my own Lithium Iron battery (LiFEPO4) out of 3.8Ah cells. In fact, I soldered together two 2S packs to make one 4S battery (4S is 4 cells in series). It works fine and can start the engine a number of times in a row, provided there are no problems with the engine and carbs. I did have to add a BMS (battery management system) in order to keep the cells balanced while charging - which is most of the time while riding. AFAIK commercial Lithium Iron batteries for motorcycles come with built in BMS.

The GS doesn't charge much below 5,000 rpm so when you are sitting at a stop light you are actually drawing on the battery.

I don't agree with that statement. Maybe it depends on the year model and the condition of the charging system, i.e. R/R and alternator. My 2004 GS500 charges the battery even while idling. I know this because when I first installed the Lithium Iron battery, I connected measuring and monitoring equipment and could see exactly when it was charging the battery.

I've had no issues so far. One thing to be aware of though, is that the headlight can drain the battery pretty fast if the engine is not running and the ignition is switched on. A standard incandescent headlight draws around 9A (GS500F on brights), but I installed an LED headlight that draws 2.5A on dims and 4A on brights.

Once the cells were soldered together, I wrapped it in heavy duty heatshrink for some much needed protection. The BMS is the electronic gadget below.
Link to the cells I used: https://www.onbopower.com/m_product/62-ONBO-25C-3800mAh-2S-LiFePO4-battery.html

Here is a picture for motivation.



Size comparison to a standard battery.

[Frank]

I was also going to advocate for making your own lithium.  Another advantage is much less weight.  My own experience with lithium iron phosphate starting batteries was a Battery Tender battery that I used in my Hayabusa for two seasons (in Maine, USA).  It was getting weak so I replaced it with a standard sealed lead-acid and use the lithium battery as an aux. battery in another project.

Most people weld their packs but if you're careful you can solder.  There's a lot of resources out there for this type of thing.

[SK Racing]

I was also going to advocate for making your own lithium.  Another advantage is much less weight.

Plus their lifetime is like 10 years. 

And one can also join the two packs side-by-side for a very flat battery. My stacked battery is 37mm high. Side-by-side it would be half of that - say about 19mm. That would fit in a very tiny space.

[mr72]

QUOTE]The GS doesn't charge much below 5,000 rpm so when you are sitting at a stop light you are actually drawing on the battery.

I don't agree with that statement. Maybe it depends on the year model and the condition of the charging system, i.e. R/R and alternator. My 2004 GS500 charges the battery even while idling. I know this because when I first installed the Lithium Iron battery, I connected measuring and monitoring equipment and could see exactly when it was charging the battery.

[/quote]

my stock reg/rect would not output enough voltage to charge the battery below about 2500 rpm. The mosfet r/r charges at idle. Current or how quickly it can charge is another matter, but I have not measured that.

BTW my Triumph was the same way, I swapped the same mosfet unit into it.

[SK Racing]

my stock reg/rect would not output enough voltage to charge the battery below about 2500 rpm. The mosfet r/r charges at idle.

Doesn't that mean the alternator supplies enough voltage at idle and that the R/R is to blame if it doesn't charge? Maybe a suspect R/R?

[mr72]

Doesn't that mean the alternator supplies enough voltage at idle and that the R/R is to blame if it doesn't charge? Maybe a suspect R/R?

The alternator always produces enough voltage, just the stock r/r is a very lossy design. Mosfet are better but still very lossy. Only on a motorcycle would it be difficult to make 14.5VDC out of 80+VAC.

[SK Racing]

What makes it difficult is that the voltage varies from about 15V or 16V to 80V due to engine speed changes. A constant high voltage is easy to bring down efficiently with a transformer.

[mr72]

What makes it difficult is that the voltage varies from about 15V or 16V to 80V due to engine speed changes. A constant high voltage is easy to bring down efficiently with a transformer.

It should be readily done efficiently with a switching regulator.