XPost: uk.rec.driving, alt.home.repair, uk.d-i-y
From: CFKinsey@military.org.jp
On Mon, 24 Jun 2019 16:33:08 +0100, TMS320 wrote:
> On 23/06/2019 23:55, Commander Kinsey wrote:
>> On Sun, 23 Jun 2019 17:27:09 +0100, TMS320 wrote:
>>
>>> On 22/06/2019 22:58, Commander Kinsey wrote:
>>>> On Sat, 22 Jun 2019 17:03:08 +0100, TMS320 wrote:
>>>>> On 21/06/2019 21:19, Commander Kinsey wrote:
>>>
>>>>>> How does a lead acid battery charger (or car alternator) know when to
>>>>>> switch to trickle charge?
>>>>>
>>>>> It doesn't.
>>>>
>>>> Mine does, if I start my car when the battery is say 80% full, the
>>>> voltage will be 14.4V. After a while, something causes that voltage to
>>>> drop to 13.8, because something knows the battery is full and should no
>>>> longer be charged at a high rate.
>>> >
>>>>>> I can understand it noticing a drop in
>>>>>> charging current if the battery is on its own, but what if a random
>>>>>> changing load is connected, as there is in a running car?
>>>>>
>>>>> Ohm's law.
>>>>
>>>> Explain how an alternator or charger can use ohm's law to distinguish
>>>> between:
>>>
>>> To determine current, measure the voltage across a series resistor, duh.
>>
>> Why didn't you wait until I'd finished?
>
> You asked.
No, I said "explain.... distinguish between:" and before I'd listed the two
things, you interrupted.
>>>> 1) A car battery which is full, with a load of 10 amps connected to it,
>>>> like two headlights.
>>>> 2) A car battery with no load, which is not full yet and draws 10 amps
>>>> for the charge.
>>>
>>> Two resistors?
>>
>> Yes that would work, but not if it has no external sensors (as in
>> external to the alternator).
>
> An alternator is not simply two wire power output. The electronics on
> the alternator would be to keep everything within acceptable parameters
> but fine control comes from the ECU.
So there are external sensors.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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