alternators don't need external controllers

[Guest]

Re: alternators don\'t need external controllers

[ QUOTE ]
My point is that the current and voltage drop settle to a point where enough current flows but not enough to reduce the voltage below that threshold.


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So you admit the current falls. But that is the whole point. Inefficient charging occurs because the battery does not see the full voltage because the voltage is set at a single point which is the Alternator.

So either the current falls or the voltage falls (depends on if the voltage is sensed at battery or the alternator) either way the battery does not get charged as intended.

So raise the Alternator regulator to 14.2v. Wonderful. It charges fine.

BUT after 4 hours of motoring the batteries are taking less current. So as you say the voltage drop is lowered. So the battery now sees 14.2v and starts to gas and get hot. After 4 hours a gel cell will be destroyed as it starts venting. A wet cell will just be making hydrogen and oxygen mixture. I know this, as I destroyed a new gel cell in just 7 hours of motoring through a canal when I first started.

In 1998 I thought some one had been murdered in an MDL Marina. Blood everywhere. Actually it was just head injuries from a hydrogen oxygen explosion on a boat due to over charging.

0.1Ohms is a lot. Normally 40' boats will see 0.005Ohms round trip. So at good charging currents that is 0.25v. Which is the difference between bad and good charging rates.

 

[halcyon]

Re: alternators don\'t need external controllers

[ QUOTE ]
So raise the Alternator regulator to 14.2v. Wonderful. It charges fine.

BUT after 4 hours of motoring the batteries are taking less current. So as you say the voltage drop is lowered. So the battery now sees 14.2v and starts to gas and get hot. After 4 hours a gel cell will be destroyed as it starts venting.

[/ QUOTE ]

Where are you getting your voltages from ?

Squadron batteries recommend 14.7 volt constant voltage charging for there gell batteries, and no float charge.

Brian

 

[VicS]

Re: alternators don\'t need external controllers

[ QUOTE ]
Alistair Garrod in his excellent book shows you can connect a diode across the alternator regulator

[/ QUOTE ] You said this before, post #1359102 on 22/02/07, I complained then and I will do so again. Garrod does indeed show how to fit a diode into a standard alternator, but is not "connected across the regulator" It is fitted in the sensing connection between the rectifier pack and the regulator.

You did in fact subsequently post a photo of the relevant pages of Garrods book showing how it is done! (Which I saved along with the entire thread) Unfortunately he does not give any indication of what diode to use or what rating is required.

The statement "across the regulator" is a very misleading one to make and would end in failure if any one attempted to try it. Depending which way the diode was connected it would either burn out immediately or do nothing!

 

[stevebirch2002]

Re: alternators don\'t need external controllers

Me neither... Nigl must of started early on the Latvian Liquor!!!

 

[Guest]

Re: alternators don\'t need external controllers

From Sonnenschein part of Exide. A small battery company.

They say you can not float them at 14.7 even at -20 degrees.

At a normal battery box temperature after 8 hours of charging not a hope.

Temperature does make a difference to the absolute value. (eg. UK vs. Panama) but the principle of having staged charging is quite well recognised in battery charging technology.

 

[davidbains]

Re: alternators don\'t need external controllers

Thnx Will for the clarity. I fitted a VSR this year 'tween a combined engine/service battery and a seperate windlass battery (further fwd in the boat). The windlass battery was definitely being charged and whipped up the anchor chain again. However the starter battery gradually became less enthusiastic about spinning a 2GM20. In fact I have an Adverc regulator on a nominal 70 alternator (although I have never seen more than 19amps on the monitor for very short periods). Also solar panels and I've never been sure whether I should disconnect the panels when running the engine, in case the solar panel charging voltage confused the Adverc.
Normally I leave everything connected and rely on the fridge to use it up!

 

[Gumpy]

Re: alternators don\'t need external controllers

Does this help?
http://www.smartgauge.co.uk/alt_mod.html

Julian

 

[gandy]

Re: alternators don\'t need external controllers

[ QUOTE ]
Mr Mercedes seems to have permanently parked an ad right over the first paragraph of your post. It seems no way I can get it gone. I am using Linux/ Mozilla Firefox.
olewill

[/ QUOTE ] You want the "Adblock" or "Adblock Plus" add-on for Firefox, assuming the add-in works on Linux.

 

[halcyon]

Re: alternators don\'t need external controllers

[ QUOTE ]
From Sonnenschein part of Exide.

but the principle of having staged charging is quite well recognised in battery charging technology.

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Thanks I'll add them to my file.

Yes I do understand staged charging, I was designing and building them in 1984.
For interest the output voltage was regulated at the battery terminal voltage, but the sensing was done at the battery charger, thus avoiding the volt drop problem.

Brian