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Re: [EVDL] LED Taillights - a money saver in gas cars?->rangeextenderin EV's? - an an

The difference between a 60Hz and a HF transformer is simple:
- 60 Hz transformer has iron sheet metal laminations and is bulky
because the magnetic field changes so slow, that it has to store a
lot of energy each cycle.
The laminations usually look like adjacent E and I, with the
windings around the middle leg of the E and the I closing the
loop of all 3 legs on the E. The E and I may alternate in the
layers of the transformer core to avoid too large air gaps.
(other types of core do exist, one of the high end variants
is the toroid transformer, which is not wound on a bobbin but
around the circular ferrite core. It is still bulky though.)
- HF (High Frequent, usually around 100,000 Hz or even higher)
tranformer has a grey ceramic (ferrite) core and is small
because the cycles are so short that only a small amount of
energy needs to be stored in the transformer each cycle.
The core often looks like two c or E glued together with a
small (air) gap between the legs of the c or E, to get a
well-defined energy storage.
(It is in the air gap that most magnetic energy gets stored.)
There are variations of winding style, often HF transformers have
litze wire (many thin gauge wires parallel) to avoid eddy currents
although I have seen solid flat-strip wire for high current
secondary windings. The 60 Hz transformers usually have a single
round magnet-wire style winding for primary and secondary.

Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Danny Miller
Sent: Sunday, September 30, 2007 11:20 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] LED Taillights - a money saver in gas cars?->rangeextenderin EV's? - an analysis PC Power Supply

I don't know of any commercial charger that doesn't have a transformer, the shock hazard is too great.

There's ones with a 60Hz transformer (which won't work on DC) and then there's ones with a rectifier and DC cap feeding a high freq "switch mode" inverter feeding a high freq transformer. The high freq transformers are far smaller, lighter, and cheaper. That type will generally work fine on DC input. These are really really common.

The point being that either way it's gonna have a transformer. It'll look like a transformer either way too, although someone familiar with them can easily tell the high freq one from the 60Hz one.

Danny

Mike Willmon wrote:

>If it doesn't have a tranformer then it is a switch mode charger, or
>switcher. The forst thing it does is rectify the AC power coming in to
>make a DC signal that is then puls width modulated to get the correct
>average voltage the charger calls for. If it has a full wave recitifer
>on the front end it will conduct your DC pack in either direction. (I
>believe most smart chargers employ full wave bridge rectifiers - but I
>can't promise its always the case). If by chance they skimped on the
>parts and used a half wave rectifier it will work in one direction but not the other. You can test it by putting in a small 5-10 amp fuse coming from the pack voltage when hooking it to your charger. You can look on the data plate and see if it lists it as a 90VAC to 240VAC input. If so then you would be safe with a pack big enough not to sag below 90VDC or with a max charge voltage greater 240V DC.
>
>Mike,
>Anchorage, Ak.
>
>
>
>>-----Original Message-----
>>From: [email protected] [mailto:[email protected]]On
>>Behalf Of storm connors
>>Sent: Sunday, September 30, 2007 6:50 PM
>>To: Electric Vehicle Discussion List
>>Subject: Re: [EVDL] LED Taillights - a money saver in gas
>>cars?->rangeextenderin EV's? - an analysis PC Power Supply
>>
>>
>>How do you tell if a charger will work on DC? I have a 2-6-10amp
>>Vector charger which does a great job charging 12v batteries. I am not
>>brave enough to plug it into my 144v pack. I hate electronic smoke. It
>>doesn't use a transformer - it only weighs a couple pounds- so I'm guessing it might work.
>>But how does one tell?
>>
>>On 9/30/07, Mike Willmon <[email protected]> wrote:
>>
>>
>>>I've been using one of the Guest 6 amp 12V auto tender chargers for
>>>my Dc-to-Dc. My Aux battery was kinda smallish, it was the starting
>>>battery out of the truck I converted. After 1.5 years it finally
>>>gave up. Now I have about a 75AH battery out of some medical
>>>equipment cart. The 6A Guest recharges it after my daily commute in
>>>less than an hour. It can also plug right into the 120V pack to
>>>charge while driving. I relied on this a little when the old aux
>>>battery couldn't keep the headlights for a 10 minute drive. But the
>>>Guest charger is potted and I don't worrry about it getting damp.
>>>I've had this charger for near 10 years now.
>>>
>>>Mike,
>>>Anchorage, Ak.
>>>
>>>
>>>
>>>>-----Original Message-----
>>>>From: [email protected] [mailto:[email protected]]On
>>>>Behalf Of Lee Hart
>>>>Sent: Sunday, September 30, 2007 7:04 AM
>>>>To: Electric Vehicle Discussion List
>>>>Subject: Re: [EVDL] LED Taillights - a money saver in gas cars?
>>>>->rangeextenderin EV's? - an analysis PC Power Supply
>>>>
>>>>
>>>>[email protected] wrote:
>>>>
>>>>
>>>>>Has anyone used a cheap pc-power supply rather than a DC/DC
>>>>>converter
>>>>>
>>>>>
>>>- to
>>>
>>>
>>>>>recharge their 12-volt aux battery?
>>>>>Do you think it would hold up?
>>>>>
>>>>>
>>>>You get what you pay for. The quality is low, the specs wildly
>>>>exaggerate their real performance, and there are performance issues.
>>>>There's been a lot of discussion on this on the EV list in the past
>>>>(see the archives).
>>>>--
>>>>Ring the bells that still can ring
>>>>Forget the perfect offering
>>>>There is a crack in everything
>>>>That's how the light gets in -- Leonard Cohen
>>>>--
>>>>Lee A. Hart, 814 8th Ave N, Sartell MN 56377,
>>>>leeahart_at_earthlink.net
>>>>
>>>>_______________________________________________
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>>>>
>>>>
>>>>
>>>_______________________________________________
>>>For subscription options, see
>>>http://lists.sjsu.edu/mailman/listinfo/ev
>>>
>>>
>>>
>>
>>--
>>http://www.austinev.org/evalbum/1059
>>http://stormselectric.blogspot.com/
>>Storm
>>_______________________________________________
>>For subscription options, see
>>http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>>
>
>_______________________________________________
>For subscription options, see
>http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>

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