Battery eliminators

[geck0]

Who in here has used battery eliminators or is still using one. I eBay-ed one years ago but it was encased in aluminium box tube. It works well as a stand alone device or as a capasitor in parell with my battery. Like I said It was in a tube so I couldent tell what the voltage rating was or the uf. I have a few Mallory caps that are 50vdc @ 10000 uf. They are quite large. I would say if it were a can of beer it would hold about 6oz (4" H x 2" dia)

[GT500Andy]

I used one for awhile on my GT500 worked ok, apart from blowing some bulbs in the gauges.
Andy

[Phil C]

I have seen a lot of rubbish suggested for battery eliminators. Lets list a few facts about replacing the battery and we can then derive a sensible design that will work properly.

1. An eliminator will not provide any of the energy that the battery supplies. All of the electrical energy must come from the
Alternator so it must be in good condition. This means:-
a. No lights with the engine stopped
b. A suitable ignition system that will operate purely from the energy from the Alternator during kick- starting
An example of this is a Boyer analogue system on a T500 (I have one and it starts without a battery!)
c. An eliminator must provide the inherent regulating effect of the battery which prevents the terminal voltage from rising
above 14-15 volts under charge conditions. This ensures that the lamps do not blow and other electrical components are not subjected too excessive working voltage.
d. Normally this is achieved when the electrical energy from the alternator is turned into chemical energy ( charges the battery)
e. The eliminator must dissipate the excess energy from the alternator that would normally be used to charge the battery. It must do this maintaining the system voltage to the same level as it was when the battery was in place. One way of doing this is by dissipating the energy as heat.
f. The eliminator must store electrical charge in the same way as the battery does.

So what do we need? …… A storage device (to satisfy ‘f’ above)
A regulating effect (to satisfy ‘c’ above)
A heat sink (to satisfy ‘e’ above )

Storage Device
2. A capacitor is necessary to store the pulsed DC output from the rectifier. As an idea of size of capacitor you can use an old rule of thumb that worked well in the design of mains power supplies which is 1000uF/Amp of charging current to achieve sufficient smoothing of the pulsed DC output from the rectifier. The T500 alternator gives upto about 3A so a cap of 3300uF to 4700uF electrolytic type is adequate. A larger one can be used but there is little benefit in going above 10,000uF. those with screw terminals are most suited but 'wire-ended' types are also acceptable. The capacitor must be of adequate working voltage. You have to be sure that the maximum working voltage (dcwv) is not exceeded. This can be very high without a load on the alternator (up to 70v! you will damage the cap if this is allowed to happen) but with the wiring as stock , a 35Vdc or higher will be OK. Note that the capacitor size is proportional to the working voltage. Another consideration is the peak repetitive pulse current handling of the capacitor(needs to be 3A under worst case conditions). Smaller caps tend to have lower pulse capability so check the specification. Note also that capacitors of this type are almost always polarity sensitive (polarised) and will be destroyed if connected the with the wrong polarity. Running even for a few seconds can cause permanent damage on most ‘polarised’ capacitors.

3. OK so thats the end of the story right? ......... wrong!

The Regulator
4. A capacitor will give results but it will not have the required regulating effect to stop the lamps blowing etc. A simple electronic circuit will be suitable to provide the regulator function.

The Heat Sink
5. A suitable commercially available can be used successfully here

I have a simple design that works if anyone (Robert Bond?) wants to try my idea?

Please note that there is little charge available from the alternator at tickover and headlamp or stop lamps coming on may cause the system voltage to fall and the engine to stall. I have this problem but I have tried and LED stop lamp that fixes the problem. I plan to replace the headlamp with a 4W LED. (about 50W conventional lamp equivalent)

Phil C

[rbond]

Hi Phil! Glad to see you back on the board. As to the eliminator, not my cup of tea. I really prefer a battery in my bike. I can understand wanting to remove the maintenance hassle, but I feel better at having a battery. Since I have a GT500, I get the 'best' of both worlds since my ignition runs off of the alternator separate from the charging part. I do have an experimental regulator for the GT, have not had the time to try it yet.

[geck0]

[quote="Phil C"]
I have a simple design that works if anyone (Robert Bond?) wants to try my idea?
Phil C[/quote

I would be interested in your design. How much heat does a cap generate.

[Phil C]

The CAP generates no significant heat.The heat is generated by the 'shunt regulator' that dissipates the excess energy that was used to charge the battery. The heat is generated within the power transistor that is in the circuit. Its quite manageable and not excessive. Its about watts (~1.5A Amps x ~14v) = 20W.

PM me and I will send a circuit diagram to you. If you wanst to build one, I will helpwith a component layout and parts list etc.

br- Phil C

[jabcb]

Another option worth considering is switching to a modern regulator/rectifier & a maintenance free battery. You get no maintenance, no acid spills & a little more alternator output.

AGM & Gel batteries are less tolerant of overvoltage than the conventional batteries, so its worth upgrading to a regulator/rectifier.

For my T500, I'm using a Tympanium regulator/rectifier that available for around $50 on eBay & a Scorpion AGM battery that costs $47. The battery was delivered via the mail & was ready to install.


Scorpion battery: http://www.scorpionbattery.com/powerspo ... ytx7e.html
Info on my Tympanium install: viewtopic.php?f=2&t=4858&p=109480&hilit ... um#p109480