CB550 Battery size w/o starter?

[BNR34RB26DETT]

Im trying to figure out the battery size for my CB550.
No starter, no blinkers, no indicators. Bike is gonna have just headlights and taillights.

Im not trying to get new regulator or rectifier.
How small of a battery can I go?
any specs would be appreciated

 

[mydlyfkryzis]

Why not stay stock? Gives you the longest engine running time, and the charging system is sized right for that battery....

 

[BNR34RB26DETT]

i could, but i do want something more compact. i am converting the bike into cafe/scrambler style and do not want that big battery.
I will also get rid of the starter so i was thinking i wouldnt need such a big battery anymore.

 

[mydlyfkryzis]

Honda bikes without e-start usually dropped the amp/hour rating about a third. So a CB360 has a 12AH battery, the CJ360 (no e-start) a 9 AH battery.

You probably have a 14AH battery stock. So about a 9-10 AH battery would give you performance like stock. Since you aren't using the e-start, even a sealed lead acid (SLA) battery with 1/4 tabs instead of terminals would work. They can be mounted in any position too. Others put even smaller batteries on, but I prefer having some reserve capacity. I have never been stranded, but maybe that's why. I have had charging and electrical issues, but was always able to make it home.

 

[BNR34RB26DETT]

thanks for your input!
sealed lead acid acts like regular acid (OEM Battery) correct?
In another words, i wouldnt need to get new v reg or rectifier for SLA since its still acid based batt?

thank you

 

[mydlyfkryzis]

Yup, SLA is similar electrically to the "regular" batteries. You may want to find an AGM Motorcycle battery in the size you want. My 750 is using a sealed Yuasa battery. Sealed batteries will not cause corrosion on the terminals either./

 

[BNR34RB26DETT]

Thanks!
I am still curious though... as to how low of Ah i can go... I was looking into as low as 6 Ah.
Does anybody have personal experience on cb550 w/o starter on low AH?

 

[mydlyfkryzis]

You can go as low as you want.....but there are 2 times that get shortened. The time it takes for the battery to go dead after you turn on the ignition and how long you can ride if the charging system stops charging. A really small battery will drop voltage quickly enough that you may not have a chance to start. Since you are kick start, if the bike doesn't start in a couple of kicks, the battery could be too low to give a good spark.

The coils draw about 3 amps when the point are closed...that will cause a small battery to drain quickly.

6 AH, to me, seems very low. While the bike will run and start, you will have minimum reserve. When the bike is running, you are not using the battery, it is only for starting (kick or e-start, both need current to get the bike running) and as a reference for the charging system, and if you have a field excited alternator, to bootstrap the alternator to a charging condition.

Think of it like gasoline. If you get 40 MPG, and you need to drive 40 miles, would you put exactly one gallon in? or would you put 2 gallons in case you need to detour. I like having a little extra in there...the battery is the same way....You can go minimum, but if you forget to turn the fuel on, and try to kick start for a couple of minutes before you realize, a small battery will have drained enough to make a start difficult.

Me? I'd stick to 9AH. You can go to 6ah, but 9ah gives you 50% more time to get the bike running, and 50% more time riding if the charging system quits.

 

[BNR34RB26DETT]

thanks for your input. it is extremely informative.
I guess i will stick with 9Ah then. So if coils draw 3 amps would i need 3 amps at absolute minimum to be able to crank the bike?
As a mechinical engineer, im not very good with electronics but I would like to understand what type of calculation takes place in order to reach 9.
6 is too low, 9 can be used but 12 is recommended.
Is there a formula you are using to come up with 9ah? or is it coming from experience.
Sorry to get technical here

 

[mydlyfkryzis]

I am a ME also. Lol. I work with small Cogen plants plus was a diesel mechanic for 9 years before that. It's knowledge, experience plus reading.

A lot of 'builders' get the electrics wrong. Being an engineer and not an artist, I tend to be conservative on issues like these.

I like a little safety margin. 6ah would be, IMHO, the minimum that would work reliably with no real extra reserve.


A few other notes. The batteries on vehicles are sized for cca (cold cranking amps). To get the 120 cca needed for a 360, a 12ah battery is needed. Honda deleted e-start on the cj360 and figured 9ah was the right capacity. Since that is about 25% less than 12, I figured the ratio is pretty relevant. I would not second guess Honda on that.

It is just like the gasoline example I used. How large a tank should be on a bike? There is no right number, but I like having a larger tank. Harley put a 2 all on peanut tank on. That bike you ride gas station to gas station. So pick the capacity that makes you feel comfortable.


Sent from planet Earth using mysterious electronic devices and Tapatalk

 

[BNR34RB26DETT]

Ah i see where 9 Ah is coming from now.
Thanks for your explanation
Its funny that you are a ME as well. I am learning a lot as i tear into these wire harnesses haha.
I will go with 9Ah in that case then. Thanks again for your input. It is very very helpful

 

[mydlyfkryzis]

ME's need to know about electric too...LOL

Between cogen and VFD's on our machines and aux equipment, I know more about electric then some EE's. Not so much much on the circuit design side (Though I can cobble up a nicely regulated voltage supply), but power generation and power handling.

It's good for an ME to get some grease on their hands. too many ME's don't know how to change a tire....I have a career built on making a PE's design work..