battery voltage 2019 I5 30fw with residential refer

[Dick Skeers]

Hi again,
I've added 2 group 31 Crown group 31 AGM batteries to the two the came with it.
I've also added a solar panel so that I've got 300 watts total.
We were plugged into 50 amp outlet for 8 nights. A few minutes after disconnecting from shore power, 12.6 volts were showing on the Magnum readout. We drove 130 miles under sunny skies yesterday immediately after disconnecting and when we stopped, it still showed 12.6 volts. After dry camping last night, the readout showed 12.2. After electric brewing of 4 cups of coffee readout was 12.1 to 11.9.
Any ideas as to what voltage I should be expecting under the above scenario?
Thanks in advance

PS: it is now 11:49 and solar has increased readout to 12.3

[houstonstroker]

What voltage do you show when hooked to shore power? Are all your batteries same brand and size?

[Dick Skeers]

I can't recall the readout when plugged in, but it shows floating.
I think the original batteries were group 27 or 29 and the two added were 31. I've been told by experts that the batteries are reservoirs so that in this application they don't have to match.

[Dick Skeers]

i added the 2 additional batteries within a couple of months of the mh being new.
I agree with your comments regarding matching batteries for starting batteries but have been told that the same doesn't apply to storage batteries?

[formerFR]

it looks like you are doing just fine

when you are plugged into shore power(120v to your charger), you should be seeing in the range of 13+..14volts while charging is happening, or float, or absorb

when you are under solar charger, after unplugging from shore power(120v), or your generator, you are only going to see the 'current' Volts of the batteries, NOT the Charging volts at 120v input, since your Solar is not a high enough amperage to give you anything other than a 'trickle' charge. 12.6 is a great number, basically 'FULL', or close to it.
If you are at 11.9 to 12.0 after all of your usage, as you state, you are doing just great.

[formerFR]

also, if your Magnum Inverter/Charger has a remote readout panel, make sure the setting for Battery Type is set to your battery bank's type, AGM, which has it's own set of charging time and variables as compared to the typical FLA flooded acid batteries, which come with most motorhomes.

[FOURWHL]

If you want to get detailed in your battery analysis I'd recommend a battery monitor. It measures the actual amps going in/out of the battery bank and thus can give you true state of charge. Voltage is a decent indicator but can also be affected by several other factors.

https://www.victronenergy.com/upload...-series-EN.pdf

[sseaner]

Originally Posted by FOURWHL

If you want to get detailed in your battery analysis I'd recommend a battery monitor. It measures the actual amps going in/out of the battery bank and thus can give you true state of charge. Voltage is a decent indicator but can also be affected by several other factors.

https://www.victronenergy.com/upload...-series-EN.pdf

I am installing one this week and will have some pics of the install and a review from our trip next week.

[Dick Skeers]

thanks, everyone for your responses.
However, I forgot one fact, that I ran the generator for one hour both nights. Last night I turned it off at 8:00 it showed 12.7 volts. this morning at 7:30 it's at 12.1 which I think is too low to perk coffee or run the microwave, and camp rules state to not run the generator before 10. Am I expecting too much from 4 batteries with the res refer, or do I have a problem?
Dick

[formerFR]

nope, it sounds like you are doing just fine - perk your coffee!

remember, too, that those with only one or two House batteries, will see these 'number' drop so much faster - but since you have FOUR, you are going to have higher numbers for much longer time periods, so seeing a 12.1 is not any problem - you could fall all the way to 11.5 before I would 'worry', though starting your generator at about 11.9 would be a good idea, but 11.5 is not a deal breaker for the 'every now and then' scenario when you are in a campground that limits generator usage times. Go with it!

[Webefine]

What I have found is, looking at the voltage of my batteries while they are under load is not accurate to there actual state of charge. The voltage will read lower while under load. I have seen my batteries showing 12.1 volts with the refrigerator running and an hour after I turn everything off it will read 12.3.

[Chuck_S]

Battery voltage as an indicator of charge level is only valid if the battery has been at rest (neither charging nor discharging) for several hours. Readings immediately after a charge or heavy discharge will skew the voltage to a misleading figure as only the surface charge is detected.

The common error is in charging when someone charges their nearly dead battery for an hour and then finds it at 12.7 volts -- fully charged. They are then astounded when the battery is dead the next morning after sitting all night.

The chemical reaction inside the battery is why they bounce back to a higher voltage if left sitting a while after a high amp discharge.

-- Chuck

[Webefine]

Going back to the original question, to me I think 4 group 31s should be doing a little better than described. 4 group 31s should give 200 amp hours of usable battery (not going below 50% or 12.2 volts). I have 4 - 6 volt 135 amp hour batteries which gives me 135 useable amp hours and I have run the refrigerator and furnace for 10 hours along with misc lights and water pump in the evening and still had 12.4 volts in the morning.

[FishinGuy]

Batteries hooked together in parallel configurations do have charging challenges. You will fill the batteries to the level of acceptance of the weakest/ smallest capacity battery. That is why people advise to buy the same brand/size/ and age batteries. Someone told you otherwise.
A full battery is 12.8 volts, an empty battery is 12.0 volts. FLA batteries should not be taken below 50 %, doing so hurts the batteries ability to come back to a full charge voltage. Also as stated, voltage is not an accurate measurement unless the battery has been allowed to "rest" ( no loads ) for several hours.
The conversion of 120 volts to 12 volts consumes a lot of battery power. If you were living in the 12 volt world ( not able to plug in to 120 volt ) you would not
have a 120 volt refer.
AGM have specified charging voltage figures, you need to find those figures. FLA bulk charge between 14.2 to 14.4 volts, and the floating charge rate is between 13.2 to 13.4 volts. If you disconnect the charger at that point, let it "rest" the battery will settle to about 12.7 or 12.8 volts. It should be able to sit at that figure for several days without dropping any further. If it begins dropping, you have a battery problem.

[tomkatb]

Just for interest sake, check the wattage of the residential fridge.

That wattage plus 15% to 20%. Additional loss for the inverter. That is the use per hour worst case. Divide that by 12.5 gives amps used. 200 Watts can empty a battery in two or three hours. 18.2 per hour.

Depending on outside weather, a large not terribly efficient fridge is hard on batteries.

Also what was said about mismatched different batteries is a real concern.

Next time around, six volt batteries are a good choice.

[babock]

Originally Posted by formerFR

you could fall all the way to 11.5 before I would 'worry', though starting your generator at about 11.9 would be a good idea, but 11.5 is not a deal breaker for the 'every now and then' scenario when you are in a campground that limits generator usage times. Go with it!

11.5V is around a 10% SOC. You are damaging the batteries when they get that low.

[babock]

Originally Posted by tomkatb

JNext time around, six volt batteries are a good choice.

12V Crown AGMs are an excellent choice already. The batteries are not the issue here.

[babock]

Originally Posted by Dick Skeers

Hi again,
I've added 2 group 31 Crown group 31 AGM batteries to the two the came with it.
I've also added a solar panel so that I've got 300 watts total.

You need way more than 300W of solar, as you already know. The bare minimum would be 600W and that is only if you can aim them.


You really need a battery monitor like the Victron 712. That will help a lot keeping track of your batteries.

[Tom48]

Originally Posted by Dick Skeers

Hi again,
I've added 2 group 31 Crown group 31 AGM batteries to the two the came with it.
I've also added a solar panel so that I've got 300 watts total.
We were plugged into 50 amp outlet for 8 nights. A few minutes after disconnecting from shore power, 12.6 volts were showing on the Magnum readout. We drove 130 miles under sunny skies yesterday immediately after disconnecting and when we stopped, it still showed 12.6 volts. After dry camping last night, the readout showed 12.2. After electric brewing of 4 cups of coffee readout was 12.1 to 11.9.
Any ideas as to what voltage I should be expecting under the above scenario?
Thanks in advance

PS: it is now 11:49 and solar has increased readout to 12.3

A lot of accurate information has been shared here and maybe some bad. Any time a lead acid battery, wet or AGM is run down below 50%, there is some damage. This thread is correct that we should look at a resting voltage with no recent load and no charging for several hours, but your scenario sounds as though MAYBE, those original batteries had suffered and are now pulling the new ones down.


Also, though I may had missed what charge controller you have but my GoPower PWM, does not seem to charge as well as my cheaper, but similar WindyNation PWM did. It just does not seem to charge quite full.


Finally, panels laid flat are not nearly at their best with low winter sun, and if you don't get up there and clean the panels with a mop or other wiper ( not just hose em off) their output is significantly impaired.


Good luck

[babock]

It sounds like your solar controller is not working correctly. Even with half of your 300W output, depending on if you have a PWM or MPPT controller, you will have over 7A of charge current and the charge voltage should be close to 14V.