Forum

[Barry N]

I am dealing with an electrical fault on my Sixty5 in another thread, but out of interest, now that I have converted my bike to kicksart-only and will sooner or later have to replace the battery, would it be ok to get a lighter-duty (smaller) battery, say, as fitted to non-E/S Bullets? I ask this because both the alternator, and rectifier/regulator units are different part numbers on E/S and non-E/S models.

[simon]

Yes if you don't have an electric start you won't need nearly so much cranking power so a small battery will be fine.

[Dennis C]

A smaller battery may well be fine, just be careful that the amperage output from the alternator is not higher than the maximum charge rate of the battery, exploding batteries are not fun.

[Alan (Lancashire)]

this is where a regulator/rectifier is used.

no harm will come if you fit a smaller battery , or indeed use a boyer "powerbox" , with no battery fitted

[Barry N]

Thanks gents - but the point Dennis made is what I am really concerned about, because both the alternator and the rectifier/regulator units have different part numbers for the two models (ie. electric start v. non-electric start) and I have retained the Sixty5 equipment. But it turns out I don't need a new battery yet, because I have established that the fault I am dealing with lies elsewhere. But the question is still relevent for future reference!

[Alan (Lancashire)]

the regulator/rectifier sorts out the charging rate dependent on the battery status , it sets out the voltage to go to the battery , and when the battery reaches this , the "regulator" cuts in

just like your automatic battery charger that turns off when your battery is full , the ampage , is a bit like saying the "speed" to charge the battery

[Barry N]

Got it - thanks!

[PeteF]

Mmmmmm......
I'm no battery expert but I always understood that you shouldn't charge a battery at more than 10% of its capacity.
Hence a 10amp/hr battery shouldn't get more than an amp to avoid damage.
Could it be that the E/S machines allow more current than would be healthy for the smaller battery?
I ask for my own information as much as Barry's.

[Alan (Lancashire)]

umm, lets look back to the std "lucas" parts , of which the indian carp are copies , the std lucas altenator is 120w @ 12v = 10 amps , and brit bikes used to have little 5hr batteries( kick start) EVERY older enfield charging sys I have checked has been capable of giving far less than 10 amps .

in the old days a zenner diode was used , over "x" volts = down to earth = electric fire element , but power being sapped from the engine as the altenator was under load all the time .

a modern reg/rect (and we must inc the enfield crap) uses electronics to regulate the flow

A battery (a good one) will only accept currant if needed at a set voltage (max 14.4?)

many people in the classic world use sub minicture fire alarm sealed batteries or even boyer black boxes without batteries

you are correct that when bench charging from what is no more than a transformer (not a smart charger) 10% is a good figure to work from .

[Dennis C]

Alan

What you say is mostly correct, A good regulated 12v charging system will cut off when around 13.8 - 14.4 volts is reached, this is all OK if the battery is not allowed to become discharged as it will only be charged for a very short time until the voltage is reached, a flat or partially discharged battery however will be given the full amperage that is available for a long period of time, if this is for instance "by your sums ten amps" and the battery is only rated at 5 amp hour the result is a very hot and overstressed battery the result can easily be a destroyed/exploded battery.

A vented type lead acid battery will most likely just blow all the acid out the vent and boil dry, but if a sealed battery is fitted the bang can be very disturbing when right under you Bum.