View Full Version : Generator question

07-30-2015, 07:22 AM
When my 12.5 KW Westerbeke generator is running and the A/C cycles on, my boat's lights dim a bit as the generator is hit with the sudden power demand from the HVAC. Is that normal? If not, how can I improve this condition? I already have the settings on the Marine Airrrr system set to where the compressor kicks on 1st and then the fan system comes on ~10 seconds later to aleviate some of the instant demand. Thanks for your input.

07-30-2015, 08:14 AM
My lights dim when my heat pump compressor kicks in. I have a 15 kva Westerbeke and a dual stage soft start kit on on the heat pump. I think it is just part of it.

07-30-2015, 08:15 AM
No problem. A sudden load momentarily slows the engine until the governor picks it back up. More pronounced when the load on the genny is light.

07-30-2015, 08:22 AM
Well, I feel beter now. Thanks for the info guys!

07-31-2015, 05:17 AM
From one who doesn't have a generator, that would get darned annoying after a while.

Suggestion: I'm guessing the generator also charges your batteries? You could isolate the lighting circuit and put it on an inverter off the batteries. Then they won't be affected by the surges.

Also how long since you changed your fuel filter? Sometimes that will help.

07-31-2015, 08:23 AM
Fuel filter and plugs were changed last summer; oil was done this spring. It's running like a top. I was told the Westerbekes are kinda bad about bogging down when hit with a large demand, like AC. I was further told that the Kohlers don't tend to do that. This comes from my boat's manufacturer, who exclusively uses Kohler generators now.

My current generator can surge so much when the AC kicks on that the tube-style TV in the salon will turn off and the Dish Network DVR will reset itself for ~3 minutes. It's quite annoying indeed, but we don't watch much TV when on the anchor anyway. If I had a volt / amp indicator on my system, I'd check to see total demand before, during, and after the AC kicking on, but I don't have the luxury. I suspect I have too many items pulling too much demand on the 12.5KW generator. I have a full size fridge, 1 beer fridge, a 5 gallon hot / cold water dispensor, ice maker, 37" flat tube TV (heaviest SOB you ever picked up!), incandecent rope lights in cabin and outside on front porch, hot water heater, microwave.....

07-31-2015, 09:03 AM
Mine dim, but only slightly - nothing ever turns off. It is the same dimming effect that I get when on shore power.

Look at a hard start kit for the AC unit. It is basically a capacitor (or set of capacitors if a dual stage kit) that dampen the initial load. They are not that expensive - especially if you know a decent AC guy.


07-31-2015, 09:59 AM
Come to think of it, I had to replace the control box guts for my Marine Airrrr system last Summer. I had someone send me new run and start capacitors for it as well. The new start capacitor burned up on the 1st try to get it working again, so we put the old one back in. I'm betting that capacitor is on its last leg and that's my culprit. Can I buy a stonger start capacitor or do I need the exact replacement for it?

07-31-2015, 10:08 AM
Yes you can get larger capacity capacitors. This is the basis for hard start/booster kits.

If you have an adjustable carb opening the high speed needle slightly may reduce the dip. 1/4 - 1/2 turn

08-03-2015, 06:23 AM
Look at a two stage kit. My terminology will probably be wrong, but it has a high amperage short duration capacitor that fires first, then a lower amperage longer duration capacitor that fires next. They are not specific to any type of A/C unit or electrical load for that matter - they just absorb the initial surge in demand.

08-03-2015, 01:26 PM
Would this do the same thing for roof top units?

08-04-2015, 11:57 AM
I would say yes. Hard start kits are agnostic. They do not really care what causes the surge. They just help mitigate it.