Question about Generators and boon docking

I upgraded my converter to a powermaxx converter. When charging the battery with an inverter generator, the furnace causes the generator RPM to increase, RPMs drop when the furnace shuts off

As a side note. It was my first real dry camp with the new converter. Pretty amazing to see it jump right to 14.8 volts. Less than an hour per day of generator run time kept us charged up

Linc

2oldman wrote:
RV electricity 101:

12v side of life.

Sometimes the answers on here are tmi for someone with a simple question.

Great site and good info.

Thanks for posting

goatrancher wrote:
So it would be best then to use a battery charger directly to the battery from generator, and not plug shore plug to the generator. I have a rechargeable power pack for my CPAP machine, and I had planned to plug it directly into the generator anyway.

The answer probably depends a lot on how long you're going to be away from electric hook-ups.

If you still have your 2014 TT, then the converter in that is probably good enough for weekend or week-long trip recharging by generator without worrying about getting all the way to 100% on the batteries.

And if you're running the genny anyway, I'd hook up the TT's shore cable to the generator and leave your CPAP battery charger inside the TT plugged into one of the 115V outlets. You won't get any real advantage hauling it out and connecting it directly to the generator.

dvitale300 wrote:
The more I thought about this the more I thought I should ask.

Just returned from our first boon docking trip on a generator. I know the led lights, bathroom fan, radio, etc. are all 12V and draw from the battery. When you have a generator on do they draw from the generator power, or from the inverter (I think that's the term) which is powered by the generator? If you have a lot of led's and the radio on - would that cause any kind of significant draw on the generator?

thanks

In short no. Before we swapped our traditional light bulbs for LEDs we'd hear the converter's fan come on if we had more than 2 of them turned on at once. Now it doesn't matter how many are on and even if the bathroom fan is running.

The only "significant" draw on the generator is the converter's work to recharge your batteries since you ran it last. Even then, it may not be that much - my Honda stayed at idle in Eco mode over the weekend (after 2 days/nights of dry camping since unplugging from home).

You didn't say how long you were camping, nor if you have more than 1 battery on your TT. We've found that even with using the furnace at night, we can go for more than 2 days on batteries alone. I only ran my genny on this trip since I didn't want to hassle with getting the covers off my batteries to check their voltage (a better measurement than the 4 lights on the TT's info panel).

RV electricity 101:

12v side of life.

Sometimes the answers on here are tmi for someone with a simple question.

So it would be best then to use a battery charger directly to the battery from generator, and not plug shore plug to the generator. I have a rechargeable power pack for my CPAP machine, and I had planned to plug it directly into the generator anyway.

road glide wrote:
I'm sorry, should have looked at your profile. You have a pull trailer, does it have an inverter? Otherwise you have a converter...
Is your generator a stand alone? Like a portable Honda or Generac?

Sorry hit the button twice....

Wondering the same thing - A "Starcraft Ultralight 28BHS" appears to be a TT?
If so, posting in the TT forum will get help from other owners.

Also generator info (for what it will power) would help.


"road glide" - in re, double post - "hit the button twice"

Stuff happens, delete one..;)

.

Look at it this way. If the converter output voltage is greater than the battery voltage, the battery is just a load on the converter and it is absorbing energy from the converter and thus being charged, although very slowly if the voltage difference is small.

If the battery voltage is higher than the converter, then the battery is supplying the power.

Of course, wiring losses due to resistance can confuse things.

i've made the observation while studying prior to my own upgrades, a lot of OEM "converters" don't do that good of a job at charging the battery. 13.2 volts isn't enough to charge a battery that's been run down all night.

to maximize the fuel spent on your generator, you want an aggressive charger that'll output 14+ volts right up until the battery is in the 90% charge range.

here's a simple test. run the battery down till the voltage is 12.1-12.2 volts. now start the generator and plug in. give it a few minutes and then flip the eco switch on the generator. if it idles right on down, that means your converter is not aggressively charging the battery. you'll likely need to run all day to recover the battery at that rate.

i'm not suggesting you get one, but the magnum inverter + charger I use will charge at 90 amps from a 2000 watt yamaha. it doesn't let the generator idle down at all. sure it's louder, but the generator only needs to run for 2-3 hours versus all day... once I hit 95%, generator off, silence the rest of the day and night. repeat the next day if needed. when I get home, house hold power will take it to 100%

The battery is providing (and/or accepting) 12v power. The converter is providing 12v power.

That is like turning on the hot and cold water taps at the same time, then asking which tap your glass of water came out of.

However, that being said, as a rule of thumb, (enough idioms?) the converter is providing 13.2 or more volts, while the battery is providing only 12.6(ish) volts, so the converter is providing the power. UNTIL the number of amps required exceeds the capacity of the converter, then the battery provides the balance.