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Charging difference between …
generator and shore power.
We spent a week in the Flamingo campground in the Everglades National Park. Great place to spend some quiet time. It was our 2nd visit and we will probably go back in the future. One thing of note is that the park entrance and Flamingo campground are 39 miles apart! There is only 1 road in and out. So if you forgot something, it could be a 78 miles roundtrip.
Anyway … There are just a few electric, 30A sites. No water or sewer on any site. We decided to dry camp since we had done this here before.
I noticed something that I am still wondering about and would like to learn about.
While we dry camped, I ran the generator about 1-2 hours in the AM and again 1-2 hours in the PM. While the generator was running it put in a constant 20A charge and this number did not change. When I shut the generator off, I was usually at around 25.5 volts which did quickly go down to about 24.6/24.8 volts.
It was in the low 50’s in the morning these past couple of days, so I switched on the Aquahot to heat up the bus and water. At that time, the voltage had dropped overnight to about 23.5 volts and twice during our stay, with the Aquahot running, it dropped below 23 volts and all systems shut down.
At that point, I started the generator, regained AC and all was well for the time being.
Now, we are at the Aztec RV Resort in Margate, FL (Fort Lauderdale) and plugged into 50A shore power.
When I plugged into shore power, the charger input was 20A but in a very short time, it started to drop and after a couple of hours, the charger amp input is at 3A and battery readout at 27 volts.
My inital question is why is shore power so much better at recharging our batteries and what could be wrong, if anything, with the generator charging output?
Your thoughts?
Cheers,
Ronald
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2 Replies
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Ronald,
If I am understanding your description what occurred was that when you were dry camping you never charged long enough or at a high enough setting to get the house batteries in float. The reason the voltage appeared to drop off fast was because as batteries become discharged the amperage on the devices being used goes up as the voltage goes down so they are going to discharge faster at lower voltages than at higher voltages, such as when fully charged.
Tom, do you have any curves on how the rate of partially discharged batteries lose their charge compared to fully charged?
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You didn’t charge long enough Ronald. You don’t want to shut down until the batteries are at float. Mine takes 2 -3 hours to bring six 4D’s back up to float from a discharge of around 50%, or 12 -12.2. You want the bulk/absorption charge to be at least 28.6 and float 13.3, assuming you have AGM Lifelines.
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