alphaa211
Long post for a simple question but since the devil is always in the details I included them all :).

I have a 2004 13/15 kW NG Guardian Model # 43903 serial # 3923891 with 240 hours on it.

After frying my second Optima Red Top battery with the built in battery charger I performed the recommended charger repair / rewiring per Generac Bulletin PIB11-06-AAC through step 19 or so disabling the old charger in float mode but when the unit runs the built in charger still works (at 13.8 volts and who knows what amps!) Effectively it cuts out the old standby charger and you have to buy a new one from Generac.

I didn't buy their new charger but remote mounted a new sealed AGM battery since it was only an 11' total length run into my garage. I used a 5 amp Deltran Battery Tender Plus charger and ran a generator supplied outlet over from my transfer switch. I put in a 12v outlet and a voltage meter at the battery so I can see the voltage at all times. Like others who have successfully done so, this has all worked great. I have had no issues either with the remote mounted battery or the Deltran charger. I used #4 wire and have fast starts like always. The battery floats at 13.1-13.2, the battery is easy to move if needed, and the Deltran is wired in modularly in case it ever dies. Overall I am very pleased with the project.

My question has to do with airflow & RPMs with the battery missing. After the remote install my RPMs dropped a bit and I had to bump my no load screw and full load screw up a bit to compensate. I have live voltage, frequency, and amperage readouts on both legs at my transfer switch and live & logged data at my computer. There was an approximately 4-5 volt drop and maybe .3-.4 hz drop under load and at idle. I thought moving the battery would have slightly increased the airflow or decreased airflow resistance and would have caused the RPMs to increase if anything.

Am I missing something in this regard? Have others experienced this RPM change when the battery is remote mounted?
Quote
Skip Douglas SkipD
alphaa211;36350 wrote:
There was an approximately 4-5 volt drop and maybe .3-.4 hz drop under load and at idle. I thought moving the battery would have slightly increased the airflow or decreased airflow resistance and would have caused the RPMs to increase if anything.
Could you please be a little more clear about what you're reporting?

Is the voltage drop you are reporting in the DC circuit from the battery or the AC output of the generator?

What does the air flow have to do with anything other than cooling of the engine and generator?

What sort of meter are you using to make the measurements?
Skip Douglas
Quote
alphaa211
The AC output of the unit.

This an older unit so it has a non-electronic governor which is affected by airflow. An example is with the door open and the front cover off you get more airflow and higher RPM which has to do with airflow. The manuals specifically indicate this when checking frequency and voltage, adjusting the gas regulator, etc. I can open the lid of my generator while it's running and hear the change in RPM as well as see it in frequency, voltage, and RPMs = airflow dynamics change.

Meters - At the transfer switch they are simple inexpensive meters that read out in LCD but they are consistent. I checked them against my fluke when I installed them and they are within 2-4% of it on all readings (Volts, Hz, Amps). At the computer they are a combination of a UPS with live data and logging and a Current Cost ENVI Monitor and associated software. Both those are consistent in their readings as well. For the RPMs I'm just using a Tiny Tach at the unit.

Additional - It was just a noticeable but slight lowering in RPMs and subsequently frequency and voltage that showed up at all load ranges and which I had to adjust for with the idle and full load screws both needing to go up. The only thing I could chalk it up to that shows up as affecting RPM, voltage, and frequency is a change in airflow.
Quote
techntrek
As an experiment, try taping a cardboard box in place, approximately the same size as the battery. That will either prove or disprove that is the problem. If it is, leaving the box there may be an easy/cheap solution.
Quote