[modeleng] Topsy - to charge and how to charge, that is the question! - modeleng

[modeleng] Topsy - to charge and how to charge, that is the question!

From: "John Rippengal" <j.rippengal@xxxxxxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Date: Wed, 30 Mar 2005 13:21:00 +0300

From: "John Rippengal" <j.rippengal@xxxxxxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>


> You should have a voltage regulator which controls the field current so 
> that when the battery reaches its proper charged output voltage the 
> alternator is reduced to just a trickle charge. Some alternators have an 
> internal regulator but if not it is easy to fit an external regulator. For 
> 28volts I suppose  you will neeed to source the regulator from an aircraft 
> supplier.
> To prevent any external voltage source damaging the alternator such as 
> regenerative braking you need a heavy current diode in the main alternator 
> output connected so that its normal output current is conducted but any 
> reverse current is inhibited. Just connect the diode +ve terminal to the 
> alternator and the negative terminal to the load. It must be mounted on a 
> good heat sink. Make sure that the voltage regulator input terminal is 
> connected after the diode as you will lose about 0.7volts through the 
> diode.
> Not sure of the load but it is easy and cheap to buy diodes that will 
> carry say 70 amps.
> This would be a standard sort of setup and will solve any problems of 
> overcharging and reverse current through the alternator. The charge will 
> also automatically increase to take up the load of the motor.
>
> John Rippengal.
>
> From: "Peter Sheppard" <peter.sheppard@xxxxxxxxxx>
>

.........................................................
slightly).  With the engine running and the field on (apart from slowing
>> the
>> petrol engine quite markedly - and this was with no load on the battery!) 
>> the
>> battery volts rose to around 28v.
>>
>> So, it looks like the alternator works.
>>
>> So my question remains, what is better, weaken the field (which is 
>> intrusive to
>> the alternator) and leave the engine running all the time, or leave the 
>> field
>> as is and switch the charge to a dummy load whenever power is taken by 
>> the
>> motor?  I am still concerned by regenerative braking taking the volts up 
>> to 36
>> and damaging the alternator.
>........................................... 

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[modeleng] Topsy - to charge and how to charge, that is the question!

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