Will converter recharge house battery from 0.0 v while on shore power?

[ShelleyManes]

We are in a 2020 Porto Class C, have been full timing 10-1/2 months, almost always with shore power or very short (1-2 overnights) with no shore power, and we have not needed the generator for our purposes. So far, the inverter has kept fridge and freezer perfectly cold for 48 hours between plugging in, but for the past week we were mooch docking (no shore power, but 2 solar panels kept house batteries charged successfully for lights, USB charge, minimal needs), and we ran inverter without shore power 72+ hours this time, and it appears to have done in a battery or more.

Today we drove a couple hours with inverter on, and arrived to camp where we have shore power. Fridge cooled completely on drive; all appears well, though the solar charge controller panel shows one item at 0.0, and the one new thing is the converter fan is running continually. We don't recall hearing this fan ever running before, but we have never before run batteries down so far.

From other forum threads I THINK I have learned that the converter is trying to recharge the battery while we are on shore power. Here are my questions, and thanks in advance for guidance:

1) Do we just leave everything as-is overnight (very nice temps, no need for furnace or AC overnight) and see if battery charge is improved by tomorrow?
2) Is there any harm in letting the converter fan run and run? It does not sound overworked or anything. Just a quiet fan hum.
3) Should we anticipate taking action at some point to give up on the battery(ies) and replace?

Our plan is to be at this camp with shore power for about a week. Then we may be mooch docking again without shore power but we'll defrost the fridge right away this time!

Here are photos of the 3 current readings given at the Solar Charge Controller. Not sure why there are 3 readings since we have 2 batteries ... Can you tell we are kind of newbies?

[Morich]

Maybe a bit of basics to help clear things?
There readings you show are actually different if I understand an read clearly!
The big 0 and A would look like you are using 0 Amps. No lights, etc and amps is one way we speak of the amount of current (power) we are using at that time. Gallons if we were speaking of water?

If the second which is small to read is 16.1 AH, that should be AMP HOURs and that is what is left in the storage obr if we speak in water, how many gallons you have left! That gives you a sort of estimate that you can use 1 amp for 16 hours or 2 amps for 8 hours?

Using those two together, you can kind of adjust what you want to use and how long you want to use it before it gets totally gone. Don't run it too close as it is an ESTIMATE!

The last is a voltage reading. Voltage is sometimes called how much the elctricity "wants" to do something? Kind of wierd to speak of mechanical stuff wanting anything but maybe it makes some sense. We do know that 110 volts " wants" to do a lot more work than 24 volts?????

But what it really tells us right now is there is charging going on as a normal lead acid battery will never hold more than about 12.8 volts and you can't stuff any more in, so you get the reading of what the charger is putting out, so don't be surprised when youstop the charging and that reading goes down, even if you are not using anything. Called "surface charge".

Some question about the inverter, if it is not actually an inverter charger as inverter use battery to make 110 AC in our RV. That means if you are not wanting to use an item requiring AC, the inverter is just excess if there is a switch to turn it off---until you want to watch TV, dry hair, etc. which requires the higher AC current!

While driving, there is normally equipment to connect your coach and start batteries together as the engine runs so you can get a small amount of charge back into the coach batteries as we move.

Fan is likely normal as it is working the coverter (charger?) section to charge the battery and it can warm up. It likely will shut off when things get less stress for it. Designed to handle it, though.

[ShelleyManes]

Thanks, Richard - you kind of confirm most of what I guessed or understood. And your explanation of the 3 Solar Charge Controller readings is better, by far, than anything in the manual! We'll just see where everything is in the morning. As for our inverter, as I understand it, its primary purpose is to convert battery power to AC/110 for the fridge to run while we drive between shore power connections, and for occasional overnights with no shore power. And it has done a great job at that, until we ran it longer than the batteries lasted! I appreciate your help and info!

[Bones2003]

I interpret the information on your Zamp ZS-30A controller a little differently than Morich.
When you took the three photos, it looks like you were plugged into shore power. If that is correct:
1) In your third photo, the solar charger thinks your batteries are at 13.4V. The solar charger thinks your batteries are charged and is not trying to charge them.

2) If you look at the top of your display, there is a bar graph that indicates the solar charger thinks your batteries are fully charged. It reads 100%.

3) In the first photo, the display says 0.0Amps. That means the solar charger is not putting any charge current into your batteries (because it thinks they are fully charged).

4) Since the fan in your converter has been running, that means your converter has been working hard to charge your batteries (and provide any other 12V power you are using) so it is getting warm. The fan provides cooling for the converter electronics. No harm in letting it run.

5) Your second photo just indicates that over some period of time, your solar charge controller put 16.1 Amp Hours (AH) into your battery. It does not tell you how charged your batteries really are.

A key point to remember is that the Zamp solar charge controller doesn't really know if your batteries are charged or not! It only looks at the voltage and then decides what to do. If you are plugged into shore power (or generator) and your converter is putting out 13.4 V to the batteries, the Zamp solar charge controller thinks everything is charged.

Also if you have the engine running, the alternator will probably charge your batteries and fool the solar charge controller as well.

So for the solar charge controller to do its thing, you need to have the engine off, the generator off, be unplugged from shore power, and have sunlight hitting your solar panels.

It looks like your converter is working as it should while plugged in to shore power. I think you are probably okay. The only way to know for sure is to disconnect everything from the batteries and take a voltage reading. Then several hours later, take another voltage reading and see how they compare.

[ShelleyManes]

Bones 2003 - thanks! Yes, we are plugged into shore power when those 3 photos were taken. Converter fan is still running smoothly and quietly, 5 hours after plugging into shore power. I think we were just a bit alarmed never having noticed that fan running before, and the only real difference in our experience being that we ran the inverter off the house batteries so long while mooch docking that we depleted a battery or both. Solar charge did bring some juice back to run lights and USB chargers while we remained without shore power and did not want to run generator. I am encouraged by your info, especially how to read the controller panel. Many thanks!

[Bones2003]

I re-read your original post again and discovered I missed the point that you ran the inverter for 72+ hours without shore power. That could have damaged your batteries so your converter is trying to charge damaged batteries and it is working very hard. Your batteries might not be damaged too badly though. If you had good solar during the day while you were boondocking that would help especially with two solar panels. It is possible your batteries will come back after being plugged in to shore power over night.

[ShelleyManes]

wow that makes so much sense as we piece it all together. Fingers crossed that we didn't damage the battery, but if so, this is one of those mistakes we'll make only once. If batteries don't gain charge overnight and converter is still running, should we disconnect something to give converter a break?

[lenore]

One other thing have you checked your batteries water level. When charging we have found the level needs to be filled quite often, Many are mislead that the batteries are AGM but they arent. There is a sticker over the top of the cells that confuses people and the batteries die when there is low water. Please make sure you use distilled water to complete this task. If batteries are shot, highly recommend replacing with AGM eliminating further water maintenance. The fan running continuously on converter could mean the batteries are very discharged. Anything below 12.0 volts is not good on Lead Acid batteries.

[ShelleyManes]

our battery water level remains good, and we check them every couple weeks. I am pretty sure the reason they ran out is due to extended running of inverter. But your advice is welcome!

[lenore]

Usually inverter shuts down below 12volts, but maybe you could get battery condition checked out with hydrometer samples. The group 31 batteries are ok, but probably not for extended inverter time to run Refrigerator. I switched to Lithium 280AH and love the longer run times. Also lithium can be discharged to 10% without destroying battery condition.

[ShelleyManes]

Thanks Lenore - that seems like really sound advice!

[Morich]

Go with the Bones explanation as he has the experience with that item which I do not!
Looking at reading the labels and guessing at what it was meant to tell us.
Solar has never been my thing to work with and the newer Rv charging is different!

I love the idea of solar and have looked at it for the house but the way Texas is setup, I would have to pay so much more to use solar as the state limits which companies can provide it, that the total cost for me to go solar would be more than without!!
ERCOT which controls Texas electrical are oil and gas execs in many cases!

[Bones2003]

ShelleyManes, if you plan to do more boondocking, you may want to install a true battery monitor system. As I understand it, they give you a much better idea of the condition of your batteries. A quick search online shows that there are a lot of them available with varying prices and features. I have never used one since we rarely boondock but I'm sure they each come with their own idiosyncrasies and learning curve.

Also, if you ever are searching the forums for advice and see a posting by Morich, be sure to check it out. He is a great source of information on most subjects.

[Seymour2Lane]

Bones has given a very good summary of what's going on with your Zamp solar charge controller.

His advice on installing a battery monitor is also excellent, especially for people who aren't plugged in every day or two.

I have had a Victron monitor for a couple of years now and combined with the Zamp SCC, have gotten pretty good at estimating our battery use (amps in vs. amps out) without even looking at it... kind of a game for me.

Hopefully your batteries will recover... I have accidentally drained the house and chassis batteries one time and mine did recover.

Regards, Mike

[Pianotuna]

When the battery goes to zero volts there is always some damage. Depending on what type of battery it may just be a loss of some capacity. I'd let it charge for 72 hours and see what is what.


You may wish to load test the batteries.

[al1florida]

The next time you plan on mooch docking, get an 10 gauge extension cord (50' or 100') at the hardware store (or Amazon) and run it from your RV to a standard 120V house outlet. You will also need a 30amp to 15 amp dogbone adapter to go from your RV power cord to the extension cord. This may not run your air conditioner, but it will keep your batteries charged and run most things in your RV like lights, TV, fridge, etc. Here is link to the dogbone adapter you will need: https://www.amazon.com/s?k=rv+dogbon...s_ts-doa-p_3_9