Is it a good or bad idea to leave your RV connected to shore power?

[gatorb8]

Can you clarify:
Fridge runs on DC in one post
Fridge uses 2.2 amps
Is the 2.2 amps ac or dc?
I suspect ac, which could be 20 amps on dc
If that is the case, I think solar would heavily cycle the batteries daily day to night

My fridge on dc will cycle my batteries heavily in that mode so I choose to use propane or plug in RV to shore power when using fridge in storage
Wether to use shore power or solar is a function of your daily energy usage, small usage will be fine for solar with respect to battery cycling and larger usage would be better for shore power with respect to battery cycling. Or, disconnect the batteries and let them sleep for a month at a time if you don’t need energy usage while in storage

Just my thoughts, I’m no expert

[KanzKran]

Originally Posted by gatorb8

Can you clarify:
Fridge runs on DC in one post
Fridge uses 2.2 amps
Is the 2.2 amps ac or dc?
I suspect ac, which could be 20 amps on dc
If that is the case, I think solar would heavily cycle the batteries daily day to night

I think it would be important for the OP to relate the actual make/model fridge. My Norcold 7 cubic foot AC/DC unit shows 3.2A on 12VDC and 0.4A on 120VAC, though I haven't tested those figures for myself.

https://norcold.com/product/norcold-...-refrigerator/

Oh, never mind. The OP stated earlier it's a 12VDC unit.

Originally Posted by MWeiner

My inverter is turned off..... the refrigerator is 12 volt.... doesn't need to be on the inverter...

[gatorb8]

Originally Posted by KanzKran

I think it would be important for the OP to relate the actual make/model fridge. My Norcold 7 cubic foot AC/DC unit shows 3.2A on 12VDC and 0.4A on 120VAC, though I haven't tested those figures for myself.


https://norcold.com/product/norcold-...-refrigerator/

Good point!

[MWeiner]

Originally Posted by gatorb8

Good point!

It's a Nova Kool R3800, that is 3 and 1/2 cubic feet.
It uses a Danfoss Compressor and is AC/DC.

The 12 DC current draw is 2.2 amps per hour when it's running which I have observed is mostly during the day. At night it would cycle on an off.

Even if it ran for 24 hours that would be only 2.2 amps times 24 or 52.8 amps. Probably not likely.

My batteries if working properly have a 50 percent capacity of 112 amps. I purchased two new AGMs from Full River who will warranty the batteries for two years and have advised me that it's perfectly OK to discharge them to 80 percent at 11.8 volts; which is the maximum discharge for warranty coverage.


To maximize the life of the batteries, I'm going to set my Victron BMV 712 to notify me if it goes down to 12 volts. The system has a low battery warning and can alert me on my cellphone or chirp in the coach.
At that point I can either run the generator or start the engine.

I discovered that Centennial Batteries are just a "house brand" battery ; you really don't know who made them. They are NOT a manufacturer.

https://www.fullriverbattery.com/

Lifeline is a division of Concorde Batteries.

Concorde Battery - AGM Aircraft Batteries

Once my RV shop does all the load testing on the current batteries in the RV, I suspect that they will confirm that my old cells are just worn down.

[gatorb8]

Looking at the life cycles vs depth of discharge graph, if you take them down 50-80% on a daily basis you should see 500-1000 cycles. So, your 30 months sounds like it is in that ballpark, about 900 cycles

[MWeiner]

Originally Posted by gatorb8

Looking at the life cycles vs depth of discharge graph, if you take them down 50-80% on a daily basis you should see 500-1000 cycles. So, your 30 months sounds like it is in that ballpark, about 900 cycles

We don't live in our Class B, although it's very nice and I suppose you could.
It's just too small for us on a 24/7 basis.

I'm old enough to NOT BE SURPRISED by anything and so, I would not argue this point, you're probably right.

When we purchased it the sales guy said "yeah, batteries need to be replaced every 2 to 3 years", what do you know, I'm right there now.

And, you know, even though you might hear of people going 6 years , I think it's only possible if you are always plugged into shore power, maybe?
And, doesn't that defeat the purpose of being self contained and able to be off the grid?

With all the stuff I've had to do with my rig, my RV shop says, yeah, it's all normal.

I guess I'm just so new to the RV experience I don't know what "normal" is.
RV's take a lot of care and feeding which translates to a lot of money and it seems that we're always upgrading something on the rig that wasn't up to my expectations. I wonder if that will ever stop or maybe I should just consider selling it a year or two.

It's a lot more expensive to have this kind of experience than I ever thought.

Here's a picture of my power with the RV unplugged during the daytime. Once the sun goes down, the batteries start losing power. Also, power loss occurs quickly if there is anything else running like my fantastic fan or heater fan.

If I were to go out and turn on the propane heater and blower, the batteries would drop to below 12 volts in around 10 minutes...

[hclarkx]

Originally Posted by MWeiner

. . . . . . .

My batteries if working properly have a 50 percent capacity of 112 amps.
. . . . .

My 160 watt Zamp Solar Panel system keeps the batteries topped off and I just got the new 12 volt DC refrigerator in the last 4 months....up until recently I didn't have any issues...

The above pieces of information are helpful.

First, the four months of new fridge use seems to coincide with a faster downhill trend on the batteries.

Further, with 112 Ampere-hours (AH) available, your fridge may be using nearly half of a 50% discharge. That's a lot unless you don't use much electrical energy for other tasks.

Finally, you may not have been topping off the batteries with solar during that four months. Doing so is generally not possible even with a large solar array. Since it seems you were taking the batteries down to at least 75%, you needed both some bulk charging and a lot of absorption charging (as is always the case). In the absorption stage the charge current is initially the bulk charge current but drops rapidly (exponentially) to only a few amperes over the last hour. Even in mid-summer you may not be completing the absorption stage.

If you are not completing the absorption stage, your SOC meter is likely accumulating error (reading higher than actual). As such, seeing 100% does not necessarily mean you are topped off. SOC monitoring is not an exact science and is never perfect.

So IMHO it seems that you may have had week batteries when you got the fridge, but likely did finish them off over that four months. I'd give new batteries a year under such operating conditions. The manufacturer's cycle spec sheet assumes a new battery under ideal conditions. In the RV world we rarely get close to lab conditions for myriad reasons.

You can confirm or refute my take on your situation by using your SOC monitor to closely monitor a typical charge cycle with your new batteries. First confirm that the monitor is actually reading out battery current (no load is connected to the battery side of the monitor shunt). Then watch charging current closely through a full charge cycle from 75% or lower to full charge. Do not assume a full charge has been reached until the battery voltage has been sitting at 14.4V for some hours and the battery current has dropped exponentially from the bulk charge level (or whatever your solar panels can provide at the end of the bulk stage) down to 1 ampere. If your solar isn't able to hold 14.4V until charge current drops to 1 ampere, you are not topping off.

Note: Above I suggest "75% or lower." The lower the SOC when the sun comes up, the less likely it is that you will top off because more of your solar time will be used for the bulk stage. So if you routinely discharge to less than 75%, running this test starting from a lower SOC would be advisable.

Note: I use 14.4V above, but replace this with the actual absorb voltage if your new battery spec calls for a higher or lower absorb voltage.

Note: In the charge test I outline above, I did not mention the SOC percentage read-out. Keep an eye on it, but do not use it to judge SOC during this exercise. If the SOC percentage readout hits 100% before the battery absorption charge current drops to an amp at 14.4V, then it was reading high before this test. After a string of days of not topping off fully, the SOC readout may have drifted up (in spite of having peukert's law correction).

Note: I would also suggest randomly running this exercise. If in fact you are not topping off most days, you may want to make some changes so that you are.

Note: Seeing 14.4V until charge current reaches 1 ampere is not really topped off, but it is close, probably 99% or more.

I know, I'm anal about this kind of thing.

[MWeiner]

Originally Posted by hclarkx

The above pieces of information are helpful.

First, the four months of new fridge use seems to coincide with a faster downhill trend on the batteries.

Further, with 112 Ampere-hours (AH) available, your fridge may be using nearly half of a 50% discharge. That's a lot unless you don't use much electrical energy for other tasks.

Finally, you may not have been topping off the batteries with solar during that four months. Doing so is generally not possible even with a large solar array. Since it seems you were taking the batteries down to at least 75%, you needed both some bulk charging and a lot of absorption charging (as is always the case). In the absorption stage the charge current is initially the bulk charge current but drops rapidly (exponentially) to only a few amperes over the last hour. Even in mid-summer you may not be completing the absorption stage.

If you are not completing the absorption stage, your SOC meter is likely accumulating error (reading higher than actual). As such, seeing 100% does not necessarily mean you are topped off. SOC monitoring is not an exact science and is never perfect.

So IMHO it seems that you may have had week batteries when you got the fridge, but likely did finish them off over that four months. I'd give new batteries a year under such operating conditions. The manufacturer's cycle spec sheet assumes a new battery under ideal conditions. In the RV world we rarely get close to lab conditions for myriad reasons.

You can confirm or refute my take on your situation by using your SOC monitor to closely monitor a typical charge cycle with your new batteries. First confirm that the monitor is actually reading out battery current (no load is connected to the battery side of the monitor shunt). Then watch charging current closely through a full charge cycle from 75% or lower to full charge. Do not assume a full charge has been reached until the battery voltage has been sitting at 14.4V for some hours and the battery current has dropped exponentially from the bulk charge level (or whatever your solar panels can provide at the end of the bulk stage) down to 1 ampere. If your solar isn't able to hold 14.4V until charge current drops to 1 ampere, you are not topping off.

Note: Above I suggest "75% or lower." The lower the SOC when the sun comes up, the less likely it is that you will top off because more of your solar time will be used for the bulk stage. So if you routinely discharge to less than 75%, running this test starting from a lower SOC would be advisable.

Note: I use 14.4V above, but replace this with the actual absorb voltage if your new battery spec calls for a higher or lower absorb voltage.

Note: In the charge test I outline above, I did not mention the SOC percentage read-out. Keep an eye on it, but do not use it to judge SOC during this exercise. If the SOC percentage readout hits 100% before the battery absorption charge current drops to an amp at 14.4V, then it was reading high before this test. After a string of days of not topping off fully, the SOC readout may have drifted up (in spite of having peukert's law correction).

Note: I would also suggest randomly running this exercise. If in fact you are not topping off most days, you may want to make some changes so that you are.

Note: Seeing 14.4V until charge current reaches 1 ampere is not really topped off, but it is close, probably 99% or more.

I know, I'm anal about this kind of thing.

OK, I'm going to presume you know way more about this than I do. And, I discovered yesterday from Full River batteries that while my engine might charge my batteries "temporarily quickly", it's not as effective and absorption voltage as running the generator.... I'm just going to accept this fact.

Now, here's my questions;

1. Some people have suggested that it's better for the batteries to go down to 50 percent and then recharge based on the cycling..so they are not "short cycled".... do you agree?

2. You know, I'm producing at least 20 amp hours per day when the sun is shining and it is being stored in the two 6 volt deep cycle AGM batteries, so, even if I were using 50 amps per day total, the net amount of actual battery usage is a net 30.... correct?

3. And, most of the refrigerator cycle is during the day at the 2.2 Amps per hour....at night, when the temperature is at 50 or 55 degrees, the refrigerator is not cycling on an off every hour..... also correct?

SO far, my contacts at Zamp Solar told me that I could go for about 2 or 3 days on battery power.... I don't think I'm going to rely on this, but I think I can rely on overnight....

Again, as soon as the sun is shining my solar panel system is powering up and the refrigerator is running off of this right now as a test on the old batteries. It's keeping up with that now, but, I think once the sun sets I believe it will start dropping again on the voltage. I can't rely on this situation once the sun sets otherwise I would not have any power for the lights, toilet or pumps.... that is not good.

Both Full River and Zamp Solar systems said yeah I have enough power as is. You're absolutely right, it's probably under optimal conditions....... and losing power after the sun sets indicates to me that the batteries are dying and weak......

[hclarkx]

Originally Posted by MWeiner

OK, I'm going to presume you know way more about this than I do. And, I discovered yesterday from Full River batteries that while my engine might charge my batteries "temporarily quickly", it's not as effective and absorption voltage as running the generator.... I'm just going to accept this fact.

Now, here's my questions;

1. Some people have suggested that it's better for the batteries to go down to 50 percent and then recharge based on the cycling..so they are not "short cycled".... do you agree?

2. You know, I'm producing at least 20 amp hours per day when the sun is shining and it is being stored in the two 6 volt deep cycle AGM batteries, so, even if I were using 50 amps per day total, the net amount of actual battery usage is a net 30.... correct?

3. And, most of the refrigerator cycle is during the day at the 2.2 Amps per hour....at night, when the temperature is at 50 or 55 degrees, the refrigerator is not cycling on an off every hour..... also correct?

SO far, my contacts at Zamp Solar told me that I could go for about 2 or 3 days on battery power.... I don't think I'm going to rely on this, but I think I can rely on overnight....

Again, as soon as the sun is shining my solar panel system is powering up and the refrigerator is running off of this right now as a test on the old batteries. It's keeping up with that now, but, I think once the sun sets I believe it will start dropping again on the voltage. I can't rely on this situation once the sun sets otherwise I would not have any power for the lights, toilet or pumps.... that is not good.

Both Full River and Zamp Solar systems said yeah I have enough power as is. You're absolutely right, it's probably under optimal conditions....... and losing power after the sun sets indicates to me that the batteries are dying and weak......

Re: #1 ... short cycling


Absolutely not. I saw mention of short-cycling but I read it as cycling without getting to 100%. I.e., cycling 50-80% instead of 70-100%. This might happen if the SOC meter is reading high or if 100% is not being reached during charging.


Re: #2 ..... 20 in and 50 out


True. But there's more to it than that. There are losses in lead-acid batteries during both charging and discharging. As a result, when you discharge, you are taking out more than your monitoring shows. Some AH is going into heat in the battery. Likewise, during charging, some of the AH you put in does not go to SOC, it goes into heat. This is as much as 15% each way in wet cells. It's less in AGM and less yet if you take energy out and put it back at low rates (low amperes) but generally not insignificant. If your solar is generating 20 AH and your battery isn't dead after the third day (falling behind more than 30 AH each day (30+losses)) then you are generating more than 20 AH or using a lot less than 50 AH.


Re: #3 ...... fridge night vs day


Right. Do you know if the 20 AH from the solar is split between charging and the fridge or is that net of load .. the amount going into the battery? You have a different monitoring system for the solar, right? See my footnote on this.



Re: 2 or 3 days on battery


Interesting. Depends on what they meant. I'm guessing they were thinking what you noted in #2. I.e., you are losing some ground every day with solar not getting you back to 100%. 20AH of solar and 50AH of load would draw the battery down 30 AH per day (or more with losses) so with 112 AH, you are down to around 20% charge after three days. They might have been thinking that.


Re: overnight ..


Yes. If you end the day fully charged with 112 AH, and use 50AH overnight, you are definitely good for one night with only normal battery life usage (drawing down to 55%).



Re: solar running the fridge...


You are correct. If most of the solar goes to power the fridge during the day, you haven't made much progress with charging and after two or three nights the battery will be dead.


Re: conclusion ........

Right again. Your setup is okay for two nights. Three might be pushing it. You know the solar does about 20 AH but I think a better calibration on usage is needed. I think you have the metering to work that out. If daily usage is over 50AH, call it two nights max. 40 AH usage and you might be okay at three nights.


Footnote:


Back when I had 200W of solar and two 232 AH 6V batteries (116AH usable) the system was not keeping up. Without much research I went to 400W of solar. That was better, but I was still running the batteries down too frequently. Only then did I dig deeper and figure out that my solar wasn't being used very well. The solar was flat out during the bulk stage but an hour into the absorption stage the charge current was well below what the panels could deliver. Adding panels got me through the bulk stage more quickly, but the solar was still loafing during the absorption stage. You are ahead of the game in that some of the solar I was wasting will, in your case, be used for the fridge. I.e., if at 4 pm your solar is good for 6 amps and the battery charge is being limited to 3 amps, you may be using over 5 amps when the fridge is running. In my case, with no daytime load to speak of, I was using 3 amps from my 200W of solar and later 3 amps from my 400W of solar. So doubling my solar did nothing for the long absorption stage.

[Mark_K5LXP]

Originally Posted by MWeiner

I think you might be absolutely correct when you said that you were "guessing". I don't guess . I hire professionals to check things out....
What makes you think I won't get this as you stated below, I don't know what would make you so skeptical?

I intentionally use the word guess, and I make no assumptions because I'm not standing there looking at your system. We're just having a dialog here to try and establish the facts and data to come to a conclusion.

The batteries are 30 months old, and, I haven't cycled them as many times as you think.... doesn't matter.

I didn't think or assume anything, I didn't know. And yeah, it does matter.

They are not holding a charge after they are not on shore power; and under load.

If it's not cycling and not age then all indicators point to charge profile or trauma.

My 160 watt Zamp Solar Panel system keeps the batteries topped off

An unknown here is just what profile this controller and whatever shore power converter you have is using. I don't trust any of them until I measure them myself because often they're either hard wired or use default parameters for lowest common denominator limits, and err on the side of "caution". Which translates to out of the box they won't burn up a bank but long term are not optimum to what batteries they may be connected to. Even among like topologies there can be slight variations for ideal profiles and while the differences may appear subtle, can have impact long term.

and I just got the new 12 volt DC refrigerator in the last 4 months....up until recently I didn't have any issues...

The thing about battery degradation is that unless you do periodic capacity tests you don't realize it until you've crossed the line. It very well could be (just a guess) that the set was in decline already then when you suddenly modify the use cycle, you push them downhill even faster. Another thing to review is the actual Ah used and replenished, and factor that into your use cycle. What is 30% DOD on a new set of batteries increases to over 50% DOD as the pack ages and degrades, which pushes them over the edge that much faster even though your use cycle hasn't changed.

As per "short cycling", the battery people told me that keeping them as charged as possible is always preferred....

Which is correct, but especially with solar you may not be reaching 100% ('real' 100% as in going through a complete absorption phase, not just '100%' that may appear on a controller display) as described by hclarkx above. So for numerous cycles in a row (daily, if used daily) you run down over night, then replenish most but not all Ah before the sun goes down then discharge overnight again. This doesn't "kill" a battery outright but months of cycling like this will take a toll.

Yeah, a few years ago early on I did run the system too low for a an hour or so...my error...

Once won't kill it, or even 50 times provided you replenish the charge promptly.

I'm going to get it all checked out.

If you trust the facility and they're competent then you stand to learn something you can adjust or change going forward. I don't believe many are equipped to really analyze at a system level to know why a particular issue or failure mode occurs, system engineering isn't a repair shops' line of work. They may be able to tell you if your battery is bad or not but not why. One way to find out is to have them review it and see what they suggest.

Mark B.
Albuquerque, NM

[MWeiner]

Originally Posted by Mark_K5LXP

I intentionally use the word guess, and I make no assumptions because I'm not standing there looking at your system. We're just having a dialog here to try and establish the facts and data to come to a conclusion.



I didn't think or assume anything, I didn't know. And yeah, it does matter.



If it's not cycling and not age then all indicators point to charge profile or trauma.



An unknown here is just what profile this controller and whatever shore power converter you have is using. I don't trust any of them until I measure them myself because often they're either hard wired or use default parameters for lowest common denominator limits, and err on the side of "caution". Which translates to out of the box they won't burn up a bank but long term are not optimum to what batteries they may be connected to. Even among like topologies there can be slight variations for ideal profiles and while the differences may appear subtle, can have impact long term.



The thing about battery degradation is that unless you do periodic capacity tests you don't realize it until you've crossed the line. It very well could be (just a guess) that the set was in decline already then when you suddenly modify the use cycle, you push them downhill even faster. Another thing to review is the actual Ah used and replenished, and factor that into your use cycle. What is 30% DOD on a new set of batteries increases to over 50% DOD as the pack ages and degrades, which pushes them over the edge that much faster even though your use cycle hasn't changed.


Which is correct, but especially with solar you may not be reaching 100% ('real' 100% as in going through a complete absorption phase, not just '100%' that may appear on a controller display) as described by hclarkx above. So for numerous cycles in a row (daily, if used daily) you run down over night, then replenish most but not all Ah before the sun goes down then discharge overnight again. This doesn't "kill" a battery outright but months of cycling like this will take a toll.



Once won't kill it, or even 50 times provided you replenish the charge promptly.



If you trust the facility and they're competent then you stand to learn something you can adjust or change going forward. I don't believe many are equipped to really analyze at a system level to know why a particular issue or failure mode occurs, system engineering isn't a repair shops' line of work. They may be able to tell you if your battery is bad or not but not why. One way to find out is to have them review it and see what they suggest.

Mark B.
Albuquerque, NM

Mark, I sincerely appreciate your time and help; especially your responses here. I'm glad to hear that just depleting the batteries now and then won't "outright kill them", but I'm trying not to let that happen again... especially if I install new batteries...

My batteries are 6 volt AGM'S, deep cycle... and I'm replacing the current Centennial batteries with the Full River batteries. I know a lot of people swear by the Lifeline batteries, but, Full River batteries were the original ones in the RV and I think that they lasted about 5 or 6 years.... I'm the 2nd owner.... first owner must have plugged in a lot.... because, there was only 11 hours on the generator when I purchased the rig..... Turned out, that was not a good thing..... I was way too green behind the ears to understand that.... it's been a huge learning curve.....

My generator is brand new... and now I'm using it very regularly.....

Back to the batteries.....as you know, they are a completely sealed system..... I don't have the tools to do the capacitive testing you mentioned... I'm just using the system.... someone from the battery technical department said, yeah, to do the test correctly, just remove the batteries from the vehicle... hahaha...
These batteries are sitting right up front in my engine compartment.. they each weigh about 70 pounds and my vehicle is probably close to 4 feet tall where the hood is... which means that it's lifting those straight up and out... I know that you can't do that easily without being on a ladder...... I'm 68 years old... I wouldn't even try and do that....I would likely lose my balance, drop the batteries or injure myself....no thanks.

That's why I hire professionals....

I don't know if you are familiar with Zamp Solar Systems, they have a 5 stage charging system and the entire thing is integrated into the my charging platform. Here's their website;

https://www.zampsolar.com/

The rooftop system is warranted for 25 years, trust me, I won't have the RV this long... and at my age ... I'll be lucky to get 25 years....if you know what I mean...

According to Zamp, and they have a great support team, I should be able to go at least two days.... even using some other things in my rig, lights ( mostly LED's), water pump and toilet.... fantastic fan and propane heater fan.....

Again, the refrigerator is only 3.5 cubic feet, it's very small. And, supposed to be extremely efficient. I don't know what size refrigerator you have on your RV...

You mentioned you went to additional solar panels... I actually thought about that.... and when I contacted Zamp Solar to find out additional information for adding to my existing system... guess what.... they told me I didn't need it.... amazing... isn't it? Now, that's a refreshing thing, someone who more interested in helping me than just selling something....... here's exactly what they said....

They told me that... the only benefit I would get with additional panels is a faster recharge of my batteries... and without the additional batteries to store this energy... would be pointless.....

I don't have any additional space for more batteries and can't use larger ones..... after all, it's a Class B....

Plus, I can't use Lithium batteries because the battery bay is in the engine compartment under the hood....too hot...

Now, finally, and I don't know if remember that I mentioned this.... Full River told me that with their batteries, they will honor the warranty and it's completely acceptable to discharge their battery to 80 percent.... that's 30 percent deeper than a lot of other batteries.... I don't know where the notion of only discharge to 50 percent came from..
Someone said only go down to 55 percent, I think I recall that somewhere?

Here's the thing... if the battery manufacturer is telling me that it's perfectly OK to drop to 80 percent....why shouldn't I believe that.....

We're mostly just camping a few nights at one location and moving on. The whole reason I got a Class B was the mobility.

And, I have a generator. I can always use that for power. It has to be exercised anyway......

I know about the power cord at campsites, I have an adapter to show me that the power is clean..... paid a lot of money for this.... one of the first things I got.... I don't think this is or has caused me any problems. My system will light up with green lights showing me it's OK....if I ever saw something different, I wouldn't plug in. And, frankly, most places we go are quality clean power... I've never had a problem...... the only place I don't use it is at home...

Here's a picture of my current charging condition as of this morning.... I think that the batteries are dying and that is evident by the low voltage even after being plugged in all night.....

My RV shop is excellent. They installed the Victron BMV 712 for me and the refrigerator, plus a few other things....

Finally, are you familiar with the Victron system... Zamp Solar has a panel as well, but, they are telling their clients to trust the Victron system..... Zamp is going to eliminate the voltage readout on their panels.....

The Victron system is linked via Bluetooth to my cellphone, I do get low voltage alarms on the phone, but I haven't heard them...I have to check my phone notifications setting or change it??? I do get an audible beeping in the RV if the batteries drop to low.....

Full River said it's fine to go to 11.8 volts on their 6 volt batteries... but, I will probably set the alarm for either 12.0 or 11.9.. sounds better to me...... I would rather be careful.....

[hclarkx]

Good advice from Mark. I'll add this ...

That screen shot is curious. 5AH is 4.5% (or closer to 5% with peukert's law applied). The 12.46 V is a bit low for a 95% charged battery indicating the battery did not start at 100% or taking out 5AH took out a lot more than 5% (i.e., the battery capacity is well below 112 AH). But, that 100% is very strange. If the battery was truly topped off before the 5AH came out, the percentage reading should be 95.5% or lower. Much lower if the monitor has been tracking capacity. I don't know if this model does. I have to wonder if the BMV712 is properly installed and the battery parameters in it are correct.

BTW, you do have what you need to estimate capacity if the BMV712 is properly installed and set. Watch voltage and AH. Look at AH used to take voltage down to around 12.1 (battery sitting idle for a while with no load and no charging). If you take the AH out fairly slowly, you can ignore Peukert's Law.

If the BMV712 tracks capacity, then you can look at AH taken out when the meter reads 50%. The manual should tell you whether it does. Also, if the AH to get down to 12.1 Volts is less than 66AH (it surely will be), compare the AH to the percentage reading. This will tell you whether the BMV 712 is tracking capacity.

I don't know what the Zamp fellow was thinking (or smoking). Mark, what do you think? He should have said more solar will help, but not greatly because the absorption stage is likely not using all of the solar you have (presuming he did not know about the fridge). That said, as I've noted previously, more solar will get you through the bulk charge more quickly and provide more solar time for the absorption stage even if some of the solar is wasted during the absorption stage. And, with your fridge, not that much will be wasted. You will definitely benefit from more solar capacity. I would double it if you boondock a lot. If you double up your batteries, quadruple your current solar. Or run the generator more.

I probably mentioned, I used to run my generator first thing in the morning go get through the bulk stage so the solar would have most of the day to work on the absorption stage. My solar was mostly loafing after the first hour of absorption, but at least it was quiet and didn't stink or require baby sitting.

[MWeiner]

Originally Posted by hclarkx

Good advice from Mark. I'll add this ...

That screen shot is curious. 5AH is 4.5% (or closer to 5% with peukert's law applied). The 12.46 V is a bit low for a 95% charged battery indicating the battery did not start at 100% or taking out 5AH took out a lot more than 5% (i.e., the battery capacity is well below 112 AH). But, that 100% is very strange. If the battery was truly topped off before the 5AH came out, the percentage reading should be 95.5% or lower. Much lower if the monitor has been tracking capacity. I don't know if this model does. I have to wonder if the BMV712 is properly installed and the battery parameters in it are correct.

BTW, you do have what you need to estimate capacity if the BMV712 is properly installed and set. Watch voltage and AH. Look at AH used to take voltage down to around 12.1 (battery sitting idle for a while with no load and no charging). If you take the AH out fairly slowly, you can ignore Peukert's Law.

If the BMV712 tracks capacity, then you can look at AH taken out when the meter reads 50%. The manual should tell you whether it does. Also, if the AH to get down to 12.1 Volts is less than 66AH (it surely will be), compare the AH to the percentage reading. This will tell you whether the BMV 712 is tracking capacity.

I don't know what the Zamp fellow was thinking (or smoking). Mark, what do you think? He should have said more solar will help, but not greatly because the absorption stage is likely not using all of the solar you have (presuming he did not know about the fridge). That said, as I've noted previously, more solar will get you through the bulk charge more quickly and provide more solar time for the absorption stage even if some of the solar is wasted during the absorption stage. And, with your fridge, not that much will be wasted. You will definitely benefit from more solar capacity. I would double it if you boondock a lot. If you double up your batteries, quadruple your current solar. Or run the generator more.

I probably mentioned, I used to run my generator first thing in the morning go get through the bulk stage so the solar would have most of the day to work on the absorption stage. My solar was mostly loafing after the first hour of absorption, but at least it was quiet and didn't stink or require baby sitting.

Here's a picture of the recent history.... what do you think?

Why do you think that the Victron BMV battery monitoring system is not installed correctly? Are you making assumptions?

Again, they're 2 AGM'S deep cycle 6 volt batteries in series for a total of 12 volts.

[MWeiner]

See this trend....