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Another 12 volt thread!!!
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SpacedMarine
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January 7, 2020 - 6:30 pm
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Ok so I've rigged up my D14 to 12v.Just made a simple negative earth wiring loom fitted a rec/reg from Mr Caunt.Fitted a 12 volt 7ah sealed battery and everything seemed ok till today.Went for a 70 mile round trip Sunday and everything was working perfectly Nick even commented how bright my main beam was as I mistakenly had it on instead of dip for a few miles.

Today the battery died.Was ok one minute the next 0 volts.Now it could just be a dud battery as it wasnt an expensive one but that's 3 batteries in a year now 2x6 volt and 1x12volt.

I did have an issue with the alternator wiring which I'm pretty sure ive fixed but I will check tomorrow if I get chance.Also as its had a new rectifier I'm assuming the charging side is good although when I took a reading across the battery a while ago was reading 14.5 volts which seems a little high.

I can deal with that the question is what amp hour battery do you reckon would be adequate.

Headlamp is 48w

Tail lamp is 21/5w

So that leaves about 5w for the speedo lamp

?horn

?engine electrics (coil etc)

Round it up to 100w for argument sake.

Is the alternator on a d14 even up to that?and if so by my rough calls I would need a battery with

100w/12volts=8.33333 amps.

Maybe why the battery gave up as it was only 7ah?

Trouble is I'm struggling to find a battery that will fit.I managed to squeezed the current one in 113mm long(but it's a squeeze)  all the ones with higher ratings are 135mm plus and I dont reckon they'd fit.I want a sealed one preferably any ideas?

What's 7/16 in mm again?

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not henpecked
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January 7, 2020 - 7:27 pm
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Hi SpacedMarine

You have given us the electrical loads on your Bantam but haven't told us if you have fitted an up-rated alternator. The factory fitted alternator to the D14 has an output of 60 watts.

Could be a shortfall in alternator output versus load?

B175, on the road. Honda XBR 500, and ....... Suzuki Burgman 200 scoot! Nicknamed "The hair dryer" - by me I hasten to add; & great storage under the seat when you get to your destination.

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SpacedMarine
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January 7, 2020 - 7:29 pm
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Is that 60watts @12 volts or 6?Its just a standard one with the two output wires connected together.

It could just be a duff battery it has been stood a while without trickle charging as I didn't connect the optimiser leads and being quite busy it kind of gets overlooked.Still the ignition has been switched off while it's been parked up so shouldn't be anything draining it as I've wired the lights so they only work when you turn the ignition on.

What's 7/16 in mm again?

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mikef
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January 7, 2020 - 7:49 pm
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Hi SM.
    The D14 alternator is rated at 60W at 6v. Someone on the forum said that it was good for over 100W at 12V. I have never checked this so will assume it's correct. You have probably connected the yellow and orange wires from the generator together to get the full output from the generator.
You said that you had a voltage reading of 14.5V That is about right for a battery on charge.
It is unusual for a battery to fail in the way that yours has, one minute OK and the next 0V but suppose that it could happen especially if it was a cheap battery. The test would be to try to charge it from a battery charger and see if it recovers if not then you know it's no good.
I like Motobatt batteries, I have one in my electric start Honda and it's 100% reliable, holds a charge even if I don't run the bike for months.
7 AH should be more that adequate for a Bantam. I have had a quick look on the Motobatt website and think that the one in the link below would be suitable if you need a good battery. It should fit the battery bracket.

** Please log in to view **

Mike.

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cocorico
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January 7, 2020 - 7:52 pm
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It's the same for both. W = V x A, if you run 12v you halve the current drawn for equivalent wattage with 6v

Modern batteries are fairly robust (in my experience) and do not fail quickly due to neglect, as long as the recharging in service is adequate. Your alternator should supply enough power for normal running (horn can be ignored for most people) with enough left over to recharge the battery. Prolonged draining of the battery without recharge will kill it though.

To be effective the regulator should be putting out above 12 up to about 14 volts to top up the battery.

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not henpecked
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January 7, 2020 - 7:53 pm
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Watts is electrical power i.e. - Watts =Volts x Amps

If you are on 6 volts the amperage will be  - 60 Watts = 6 Volts x 10 Amps

If you are on 12 volts the amperage will be  - 60 Watts = 12 Volts x 5 Amps

Therefore if your load is greater than the alternator output of 60 Watts dim lights and flattened battery.

One question is the alternator the original or have changed it?

B175, on the road. Honda XBR 500, and ....... Suzuki Burgman 200 scoot! Nicknamed "The hair dryer" - by me I hasten to add; & great storage under the seat when you get to your destination.

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SpacedMarine
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January 7, 2020 - 8:04 pm
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As I say it's the original alternator just wired for 12 volts.

Looking at it then I need to get an led tail light as with main beam on I'm gonna be using way more than 60 watts.

Sailing a bit close to the wind 🤣🤣🤣

What's 7/16 in mm again?

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mike p5xbx
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January 7, 2020 - 11:07 pm
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You can get around 100watts out of the wipac alternator at 14volts
I dont use a battery on my 12volt Bantams but this is what it puts out
42watts coil 45watts headlamp 5watts rear lamp
and my home made regulator cuts in at 14.2volt and is dropping a measured 5watts at 3000rpm
around 97 watts in total

the fact that your battery ended up at to 0volts would indicate it had an internal short or you have leakage to earth from something

D? - D10- D14 Bantams 350 AJS -500 Triumph http://bsanotru.....lfire.com/

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SpacedMarine
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January 7, 2020 - 11:28 pm
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Ta Mike so you reckon I can do away with the battery completely then?

Dont suppose you did a wiring diagram?I'd be quite happy getting rid of it to be honest.

What's 7/16 in mm again?

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mike p5xbx
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January 8, 2020 - 12:17 am
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Well there is a gotcha
I use a battery eliminator ie a big capacitor you just replace the battery with it
but at kickover speed you are only generating around 6Volts into a 12volt coil you can probably see the problem with that
and of course you will have no lights unless the engine is running
so bike needs to be in perfect condition I dont have any problem starting but so many people complain they cant start a bantam even with a good fully charged battery

D? - D10- D14 Bantams 350 AJS -500 Triumph http://bsanotru.....lfire.com/

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SpacedMarine
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January 8, 2020 - 12:26 am
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I was gonna ask about starting it.Just looking at the bumf for the rectifier I have and it says for battery systems only.

Seem to remember when we were kids wiring an old cg125 field bike up directly from the alternator to the coil once cant remember exactly how we did it but it used to work sort of .No lights of course.

I'm assuming your rectifier is  some kind of diode?

The bike starts and runs great so no issues there.

What sort of capacitor do you use?

What's 7/16 in mm again?

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mike p5xbx
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January 8, 2020 - 4:43 pm
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you can get the capacitor already wired up
** Please log in to view **

or much cheaper and better the one I use, need to solder the wires on
** Please log in to view **

but you would also need a rectifier/regulator that can use them
** Please log in to view **

I also fit the coil, regulator, and capacitor under the fuel tank with no on/off switch to minimise voltage drop in the wiring for starting
you only need a kill switch without the battery

D? - D10- D14 Bantams 350 AJS -500 Triumph http://bsanotru.....lfire.com/

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SpacedMarine
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January 8, 2020 - 5:48 pm
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Thanks Mike,interesting. 

The only thing like you say is the lack of lights when the engine isn't running but I'm guessing it's pretty much maintenance free once setup.🤔

What's 7/16 in mm again?

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SpacedMarine
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January 10, 2020 - 6:24 pm
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nickjaxe said
The spots in my vision are you about gone now Jame...«censored» bright that headlamp.
Nick.  

Talking of spots in front of your eyes there were a couple of times on the A50 on the way back with the lights on they suddenly flashed really bright for a second I wonder if that was a sign of impending doom.I thought the bulbs might blow but they didn't.Plus I have a 10 amp fuse in it and that didn't blow either .It was the first thing I checked when it died so makes you wonder.

I finally got the battery to read something.11.5 volts but when I put the charger on it it reads 15! So its definitely goosed.Duff battery???I'm guessing £21 is at the cheap end for a sealed 12volt motorcycle battery?🤣🤣🤣

What's 7/16 in mm again?

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SpacedMarine
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January 10, 2020 - 9:23 pm
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nic2kjaxe said
Is it a gel or AGM or wet acid batt James.  

Sealed lead acid type 

What's 7/16 in mm again?

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mike p5xbx
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January 10, 2020 - 11:31 pm
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SpacedMarine said
couple of times on the A50 on the way back with the lights on they suddenly flashed really bright for a second  

well that could be why the battery has failed
dodgy regulator or wiring
is it one of Rex 5wire jobs?
Gel and Agm batterys are great but over voltage will kill them whereas a big wet battery can gas and boil out the vent pipe

D? - D10- D14 Bantams 350 AJS -500 Triumph http://bsanotru.....lfire.com/

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SpacedMarine
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January 10, 2020 - 11:42 pm
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mike p5xbx said

SpacedMarine said
couple of times on the A50 on the way back with the lights on they suddenly flashed really bright for a second  

well that could be why the battery has failed
dodgy regulator or wiring
is it one of Rex 5wire jobs?
Gel and Agm batterys are great but over voltage will kill them whereas a big wet battery can gas and boil out the vent pipe  

Yes it's one of Rex's, I was hoping it wasnt that as I wanted to give it the benefit of the doubt.As I say it was putting out 14.5v at the battery when running which is a little high for my liking.The wiring "should" be good as I made sure I did a proper job and soldered all the connections together.

To me it looks like all the other Chinese ones on Ebay whether theres any difference I wouldn't like to say .🤔

I'll email him I'm assuming he's still up and running at the minute.

What's 7/16 in mm again?

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mike p5xbx
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January 11, 2020 - 12:05 am
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SpacedMarine said
Yes it's one of Rex's, 

but does it have 5 output wires
if so, one of them is a Voltage sense wire and should really be connected to ignition sw so not powered all the time
if that connection is dodgy the voltage output can jump all over the place
if its a 4 wire type ignore the above

D? - D10- D14 Bantams 350 AJS -500 Triumph http://bsanotru.....lfire.com/

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SpacedMarine
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January 11, 2020 - 12:29 am
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mike p5xbx said

SpacedMarine said
Yes it's one of Rex's, 

but does it have 5 output wires
if so, one of them is a Voltage sense wire and should really be connected to ignition sw so not powered all the time
if that connection is dodgy the voltage output can jump all over the place
if its a 4 wire type ignore the above  

Yes it's a 5 wire.I recall splicing two of the wires together.pretty sure one was the ignition live.I remember having a conversation with him about it.Not sure I have the wiring diagram handy either it was a few months ago now.

I'm guessing that could be the problem if it senses the voltage in the system after the ignition.

Otherwise it will be full charge all the time no matter what hence the 14.5 volts?

Will have to wire it up and hope it's not cooked the rectifier.See if it fixes it.Luckily I'm off next week.

What's 7/16 in mm again?

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SpacedMarine
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January 11, 2020 - 9:06 am
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For the record in contact with Rex and he reckons the charging rate is about right.Helpfull as ever I'm sure we'll get to the bottom of it.

What's 7/16 in mm again?

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