What's Ignition Switch Got To Do With It?

[Gordon1152]

Had some wierd electrical stuff happening this week that I'd like some feedback on:

1) Dry camping in Durham, NC and started the generator around 7pm and shut it off around 11pm;
2) Next morning, first cup of coffee brewed without incident but the coffee maker would not turn on for the second and the fridge had no power;
3) Started the generator, no change; and
4) Started the engine; all 120v power returned

[Mwoodofd]

Did your low battery function kick off. That coffee maker will take quite a bit of battery power and may have caused a quick drain below the low battery cut off. Mine did the same thin in Quartzsite early morning before generator time. Let it sit, and the batteries recovered enough to go back above cut off setting, and switched back on. (I then started the gen).

[YC1]

I too suspect low batteries and fiddling around may have caused a connection somewhere to come alive. Could be from the simple vibration of things.

Running the generator that long should have fully charged the batteries generally but bad connections or bad batteries can give you all kinds of grief.

You need to start at the heart of your RV and look at the batteries and connections. Loose or corroded connections are a recipe for failure.

Without a look at your heart, it is a guessing game and in some cases, it is easier to do proper maintenance than trying to duplicate the problem

To start, take pictures of your batteries and cables. Print them out. Next, take voltage measurements on each battery by pressing the probes into the centers of the posts versus the cables. Write those on the picture. Then ground your meter and take measurements everywhere.

Once done, remove cables from one post at a time and make a mental note of any that are finger-tight. Twelve volts has very little push/pressure and cannot overcome any loose or dirty connections.

Pay particular attention to cables that disappear from your ground posts/negative posts. Follow them and then remove and clean them as well.

Once your cardiac rehab is done, take your measurements again and compare.

Now either start your generator/and or put it on shoreline and measure again. You need to know IF your batteries are getting a proper charge.

[voltdoc]

So then that means 8, 9, 10 hours running on the battery then firing up the coffee maker?

With the batteries down a good amount from the overnight period, then hitting them with a massive load like a coffee maker, as mentioned, your battery voltage probably dipped below the low battery cutoff setting on the charger/inverter (it would be good to know on your coach what that is set to).

Suggestion for lead acid batteries is to always fire up the generator for high load devices like coffee maker and microwave.

If the coffee maker draws 12 amps @ 120 volts, your 12 volt batteries are going to need to supply roughly 120 amps to power it. At high loads like that, battery capacity for lead acid is severely diminished (Peukert effect). Very typical for the battery voltage to dip way down temporarily at those kind of loads.

Instead of stressing the batteries like that try to get into a dry camping routine where you run the generator during the times when you have the highest electrical demand - perhaps dinnertime and in the morning when you are likely to need high power things like the cooktop, coffee maker, microwave, etc.

After the inverter shutdown, running the generator would have eventually let the charger kick in and the batteries recover - how long did you let it run before starting the engine? It was probably just coincidence that the reset occurred after starting the engine.

[kcmusa]

Lead acid battery’s will drop voltage under load more than lithium. What kind do you have?
Voltage measurement would be best troubleshooting steps under load and not under load.

[twinboat]

Your inverter/ charger isn't charging on generator power, check it's breakers. If good check the inverter breakers, on the inverter.

Once you started the engine, the house batteries merged and the chassis batteries and were powering your house system along with charging your run down batteries.

[Persistent]

1) Dry camping in Durham, NC and started the generator around 7pm and shut it off around 11pm;

Good amount of charging time. Batteries should be at least 80%.

2) Next morning, first cup of coffee brewed without incident but the coffee maker would not turn on for the second and the fridge had no power;

Batteries below minimum voltage for inverter.

3) Started the generator, no change; and

Inverter/charger not charging batteries or supplying 12 volt power to RV.

Possible:

• Circuit breaker for inverter charger 120 volt input maybe tripped. It may have been tripped the evening before while the generator was running.
• Generator circuit breaker tripped
• Inverter/charger malfunction
• Generator malfunction
• Transfer switch malfunction
• Loose or corroded wire

4) Started the engine; all 120v power returned.

Alternator working OK
Bridge circuit to house battery working OK
Battery connections OK
Inverter 12 volt input OK

[RayandWendy]

These is a limit as to the minimum battery voltage that it will start charging. They will not charge a dead battery but I don't know what the minimum voltage is.
Later...
Ray

[Gary.Jones]

The fact that your refrig was off in the morning tells me that your house battery bank was critically low AND SHUT DOWN THE WHOLE SYSTEM.

Also, your system for dry camping is not a good one. I do a lot of dry camping as host/wagonmaster of the Quartzsite Gathering in Arizona every year and my recommendation to everyone who attends is to run their genny for 2 hours each morning (first thing after heading to the potty) and again for 2 hours each evening immediately before going to bed (many camp areas on BLM land have strict rules of no genny or noise after 10:00 pm quiet hours, so you have to consider that), plus run the genny any/every time during the daytime when using the microwave, oven, or any other high current draw appliance.

Following that procedure, everyone is able to "live" just fine off the grid for weeks.

There is no way that you can run a very high current draw appliance like a coffee maker in the morning on battery only ....

Gary

[Gordon1152]

Thanks for all of the input guys! I clearly have some more investigating / studying to do as these are all helpful comments. I don't want to think about new house batteries for a three year old coach, but stuff happens. For what it's worth, the low battery cut out is set at 10.7v on this rig and I don't think we got there but I wouldn't swear to it ...

[oneknight]

The current draw from the coffee machine will pull the voltage down that low, temporarily. It's normal with lead acid batteries, even AGMs.

The inverter will have a premature low voltage shutdown.

As Gary said, the inverter gets fussy once it shuts down, needs to see the voltage up before it will start charging again.

Start the generator before using anything with a heavy draw.

If/when you get a low voltage shutdown, start the Genny with the boost switch or start the big motor and just wait

Sent from my moto z3 using iRV2 - RV Forum mobile app

[Gordon1152]

Originally Posted by oneknight

The current draw from the coffee machine will pull the voltage down that low, temporarily. It's normal with lead acid batteries, even AGMs.

The inverter will have a premature low voltage shutdown.

As Gary said, the inverter gets fussy once it shuts down, needs to see the voltage up before it will start charging again.

Start the generator before using anything with a heavy draw.

If/when you get a low voltage shutdown, start the Genny with the boost switch or start the big motor and just wait

Sent from my moto z3 using iRV2 - RV Forum mobile app

Thanks oneknight! I'll try that when we get back on the road in the spring ...

Have fun!