Hi, Matt and Kirk.
Good points, in fact great points (that I totally missed!) re the volts modification and the frame insulation.
My understanding was/is that an unregulated 12 volt alternator can put out around 90 volts with a vehicle engine on fast idle, and I read or was told somewhere in the 'old days' when the regulator was not always built into the alternator, that this alternating current can successfully run a regular universal motor such as a power drill hand tool.
Good points, in fact great points (that I totally missed!) re the volts modification and the frame insulation.
My understanding was/is that an unregulated 12 volt alternator can put out around 90 volts with a vehicle engine on fast idle, and I read or was told somewhere in the 'old days' when the regulator was not always built into the alternator, that this alternating current can successfully run a regular universal motor such as a power drill hand tool.
I just never connected this to the 48 v issue discussed! So simple, although there might be a need to carry a spare regulator/diode unit as with any non-standard parts.
This would still leave the marine certification problem if brushes are used. Whether the sparks are small or large or even not really visible, they can still theoretically ignite propane or gasoline fumes that might be in the bilge, or unvented hydrogen higher up.
And authority figures tend to (correctly) err on the safe side for themselves as well as the situation, thus avoiding making a decision that misses something that could be dangerous. But marine certification is another subject that I will post.
Thanks,
John
1.1. Re: 48v diesel telecommunications standby gen?
Posted by: "matt elder" mattelderca@yahoo.ca mattelderca
Date: Tue Sep 18, 2012 5:11 am ((PDT))
Just a few notes on automotive alternators.
They can be easily configured to put out any voltage from 12 to 240 volts. This is simply done by bypassing the regulator, either internally or externally depending on the make. Once 12 volts is fed to the field windings the voltage output is speed regulated.
The brushes in these units carry only the small field current and sparks and wear are of little concern.
As to live frames, automotive alternators produce three phase AC which is then rectified into DC. By removing the internal rectifiers you delete the negative connection to their frame. The rectifiers can be setup externally so as to avoid the connection.
For 48 volt charging there is no need for multiple units, just a single unit with the appropriate regulator.
Newer units are small and efficient although they will not stand up to continues heavy use. Alternatives are available in either older more robust designs, or newer specialty items. Check into the aftermarket car modification market for some really heavy duty units.
All of this being said, I believe there are far better choices out there and there is no need to reinvent the wheel.
This would still leave the marine certification problem if brushes are used. Whether the sparks are small or large or even not really visible, they can still theoretically ignite propane or gasoline fumes that might be in the bilge, or unvented hydrogen higher up.
And authority figures tend to (correctly) err on the safe side for themselves as well as the situation, thus avoiding making a decision that misses something that could be dangerous. But marine certification is another subject that I will post.
Thanks,
John
1.1. Re: 48v diesel telecommunications standby gen?
Posted by: "matt elder" mattelderca@yahoo.ca mattelderca
Date: Tue Sep 18, 2012 5:11 am ((PDT))
Just a few notes on automotive alternators.
They can be easily configured to put out any voltage from 12 to 240 volts. This is simply done by bypassing the regulator, either internally or externally depending on the make. Once 12 volts is fed to the field windings the voltage output is speed regulated.
The brushes in these units carry only the small field current and sparks and wear are of little concern.
As to live frames, automotive alternators produce three phase AC which is then rectified into DC. By removing the internal rectifiers you delete the negative connection to their frame. The rectifiers can be setup externally so as to avoid the connection.
For 48 volt charging there is no need for multiple units, just a single unit with the appropriate regulator.
Newer units are small and efficient although they will not stand up to continues heavy use. Alternatives are available in either older more robust designs, or newer specialty items. Check into the aftermarket car modification market for some really heavy duty units.
All of this being said, I believe there are far better choices out there and there is no need to reinvent the wheel.
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