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Old 04-05-2011, 02:01 PM   #1
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GEN SET - vs - DOCK POWER

KOHLER GEN SET - vs - DOCK POWER

Heres a little question - - > 7.5 KW Kohler gasoline gen set / Professional Mariner battery charger / 120 AC dock power... and their power supplies available during use of multiple electric items

USING GEN SET:

- Battery charger turned on alone displays charging at approx 13.45 across the battery bank
- Soon as another item such as the hot water heater or stove are also turned on while battery charger is still turned on the charging DROPS BELOW 12.55 across the battery bank

USING DOCK POWER:

- Battery charger turned on alone displays charging at approx 13.45 across the battery bank
- While another item such as the hot water heater or stove are also turned on while battery charger is still turned on the charging STAYS AT 13.45 across the battery bank

QUESTION:

When powered by the gen set and other items are turned on while battery charger is on... is the reduced charging number simply due to the gen sets natural inability to handle both power draws simultaneously; so called spreading the load? Therefore, does that mean reduced power is also provided to the other items that are on if more than any one item is used at the same time with the gen set? Is that the natural course of events with a gen set? BTW, the gen set is well tuned, always starts immediately, and runs perfectly smooth; including initially lowered rpm upon new item loads being turned on and then it basically resumes rpm.

Or... does it mean there is some type of oncoming gen set electric output problem I should begin to keep my eyes open for?

Your input is always appreciated!

Thanks, Art
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Old 04-05-2011, 02:35 PM   #2
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RE: GEN SET - vs - DOCK POWER

The AVR (automatic voltage regulator) on your genset may be suspect.* It should hold within 2%. * In addition to what David suggested testing, I would also check your frequency with*and without a load.* It should hold at 60 hertz.
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Old 04-05-2011, 03:07 PM   #3
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RE: GEN SET - vs - DOCK POWER

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DavidM wrote:Art:

Do you have an AC voltmeter installed or can you hook up a handheld meter. If so try the load test with the genset to see its output voltage is dropping with load. Depending on the size of your Promariner battery charger it will draw maybe 10 amps AC. Your water heater will draw about 10-15. Niether one or both should have any significant effect on the output voltage of a 7.5 KW genset.

But check its output voltage. That might give a clue why the battery charger output voltage is dropping.

David
David - In master state room, I*have a*hand*meter wired to a cig lighter and*set up to test general level of battery bank*charge when nothing is on.* That way*I can start the morning*feeling confident that*battery bank charge is ample to withstand that day's use.* I just ran accross this (to me unusual) situation at end of last weekend's outing, upon docking at our berth and going from gen set power*to shore power while watching (playing with) the hand meter.* Just seemed odd to me that with gen set the meter dropped and with shore power it didn't when other items were on*at same time as the*battery charger.* I've not yet*taken opportunity to check the guages on main control pannel in salon during both power source uses and in respect to various items turned on and drawing.* We plan to go out again in a*couple weekends and I will*further research this item. - TY for quick input! - Art

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Old 04-05-2011, 03:09 PM   #4
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RE: GEN SET - vs - DOCK POWER

Quote:
Larry M wrote:The AVR (automatic voltage regulator) on your genset may be suspect.* It should hold within 2%. * In addition to what David suggested testing, I would also check your frequency with*and without a load.* It should hold at 60 hertz.
*Larry - Good advice!* I will surely check that out. - TY, Art

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Old 04-06-2011, 04:56 AM   #5
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RE: GEN SET - vs - DOCK POWER

A second hassle is the voltage (even if full voltage) does not have the same power as power hose current , ordinarily till the noisemaker is over 10 KW .

This is why a cruiser that lives off a battery bank will get far quicker house bank re charge times from a dedicated alternator and 3 stage V reg.
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Old 04-06-2011, 08:26 AM   #6
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RE: GEN SET - vs - DOCK POWER

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FF wrote:A second hassle is the voltage (even if full voltage) does not have the same power as power hose current , ordinarily till the noisemaker is over 10 KW .

This is why a cruiser that lives off a battery bank will get far quicker house bank re charge times from a dedicated alternator and 3 stage V reg.
*FF -*TY for input.* If I understand you correctly??

Genset full voltage*(if*genset*is below*10 KW, such as our 7.5 KW genset is) does not have equal power (i.e. voltage)*capability as*shore power current.**Therefore,*by simultanously utilizing more than one high voltage item could reduce voltage output*capability of the 7.5 KW genset*to each individual*item.* Do I understand correctly?

Happy Boating - Art*

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Old 04-06-2011, 09:59 AM   #7
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RE: GEN SET - vs - DOCK POWER

The poorer power output (its the area of voltage under the sine wave) not just the peak voltage causes performance of heavily loaded items.

A house fridge will never notice , but a hard working air cond will.

The HW heater might be a bit slower , but the SCUBA compressor will be really working harder.

Some batt chargers do notice and are not able to maintain output voltage.

This is a common problem on non sine wave inverters too.
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Old 04-06-2011, 12:47 PM   #8
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RE: GEN SET - vs - DOCK POWER

Quote:
FF wrote:The poorer power output (its the area of voltage under the sine wave) not just the peak voltage causes performance of heavily loaded items.

A house fridge will never notice , but a hard working air cond will.

The HW heater might be a bit slower , but the SCUBA compressor will be really working harder.

Some batt chargers do notice and are not able to maintain output voltage.

This is a common problem on non sine wave inverters too.
*TY - FF!* Always learning!*- Art

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