Added a new battery monitor...(Aili)
Battery Monitor == Fun!
Plus: How to avoid a common mistake regarding AH total
I have a couple 2015 Thor Majestic 28a RVs. I added a 2nd 12v battery to the coach (they only came with one). My batteries state they have 122AH each, so 244AH total. These are standard lead acid deep cycle marine/RV batteries from Walmart (...great value I feel). I am considering adding solar to one (or both) of the RVs. I'm trying to assess how much solar I actually want to add (100w or 200w). I have already purchased a 200w Windy Nation system. I might add 200w to one RV and try it out, or I might split it and put 100w on each (...I'd just have to buy another charge controller and some wiring).
I have always wondered how much various items in the RV are actually drawing from the batteries. But I was ALSO equally curious to know how well various charging methods actually work (Generator vs Shore Power vs engine alternator). (Anyone else wonder this or is it just me???) Eventually, also would be nice to see how much the solar is adding. I have always wanted to know: When the batteries are at 50% (for example) and need to be charged, how long does it take with the various charging methods to get the batteries back to 80%, 90%, etc. I often let other people use my RVs (family) and I'd like to have it easy for others to figure out also (so they don't drain/damage the batteries).
So I decided to buy the Aili battery monitor (<$45). I installed it in a convenient place. It was a pretty straight forward install and if you are curious there are various youtube videos showing people do it.
I was very pleased to see it working in action! If you aren't familiar with this battery monitor, it shows the following information at the click of a button:
- Battery voltage
- Current amps going in OR leaving your battery
- Remaining AH in your battery bank
- Battery % remaining monitor (Kind of like a "fuel gauge" for your batteries!)
It was very easy to program. Once it was set up, I could see how much each RV item is drawing from the batteries. I ran an overnight test with the furnace on set to about 65 degrees (it got down to 38 degrees overnight) and saw that over a ~16hr time period it used ~40AH. I wanted to do this because I know the furnace is one of the largest battery consumers. I can see that when I have everything OFF in the RV, it is still drawing ~0.1 amp (could be the carbon monoxide/propane detector). I got the batteries down to about 50% and then I got to see how the various ways of charging the batteries did... For example, if I turned on the engine and just idled, approximately 45amps were flowing into the batteries. If I turned off the engine and I turned on the generator, it was pushing 20amps into the batteries. Interesting. I didn't have an opportunity to plug the RV into shore power, but I suspect it would provide a result similar/identical to the generator (since it is the converter that is charging the batteries and I think it should operate the same on generator/shore power). As the batteries started getting more full (80%) the engine at idle was pumping 25amps into the batteries. And at 91% full, the engine at idle was putting only 7amps into the batteries. I suspect this is the correct operation roughly of how batteries get charged (when low they can accept much more amperage and when you are getting closer to full it slows down).
All-in-all very useful info and I am happy that I added this monitor. I will add it to the other RV also.
One thing to point out for anyone using this Aili monitor (or other monitors), I think there are some people out there pushing some false information. We all know that with typical lead acid batteries you are not supposed to let them discharge below 50% before charging them back up. So some have suggested that you should set your Max AH on your battery monitor such that it is only 1/2 of your total AH. I suppose this would be true for any type of battery monitor and not just the Aili monitor. For example, my battery bank is 122AH x 2 batteries - 244AH. Some would suggest that you "tell" the battery monitor that your battery bank is half that amount (122AH). This way, when you are reading your monitor % full when it gets to 0 you would know you must charge your batteries. I understand the motivation some people might have regarding this, but I believe it is misguided. Here's why...
Let's use my battery bank of 244AH as an example. Let's assume that we "told" our monitor that we only have a 122AH battery bank. On the Aili battery monitor, once it gets to 0% full (used 122AH) it cannot go any lower...it cannot go negative. So if you continue using your battery your batteries will in reality be less than 50% charged and the monitor will still say 0% full. To illustrate my point, let's assume that you could actually drain your battery completely all the way down to 0AH (would be a horrible idea, but stay with me...). Then, let's assume that you start charging your batteries. As soon as you start charging, your Aili monitor will start showing your battery % grow. After you have charged your batteries 122AH your monitor would say it is 100% full...BUT the reality is that you are only at 50% of the total battery bank charge! You would incorrectly THINK that your batteries are full but they would not be...they would only be at 50% and needing a lot more charge. That is the flaw! So if you set your monitor to 1/2 your total battery bank AHs you will not truly know if your % full is correct or not. Now let's say you are driving and your monitor got to 100% but you were still hours from reaching your destination. Your monitor would say 100% full and you'd be driving and actually still charging your batteries aggressively via the alternator of your car. When you arrive hours later at your destination, your monitor would say you are at 100% full but your batteries MAY be at 100% or 90% or 80%, and you'd never really know.
So my feeling is that it is important to program your Aili battery monitor (and any other that operates the same way) with your TOTAL battery bank AHs. And anytime you see it reach 50% you need to get those batteries charged back up. With this type of programming, you will always know exactly where your battery charge is. If, for example, you drained them all the way down to 30%, you would see it and when you are charging them back up you would know truly when they are all the way charged back up to 90%, 100%, etc.
Hope that all makes sense!
I wanted to post this to
a) Let people know how informative it is to have such a battery monitor, and
b) Give people my thoughts on programming your AH so that you always know the true state of your batteries.
Hope that helps someone!
-Chris
Question: How many AH/day do YOU use when boondocking??
Plus: How to avoid a common mistake regarding AH total
I have a couple 2015 Thor Majestic 28a RVs. I added a 2nd 12v battery to the coach (they only came with one). My batteries state they have 122AH each, so 244AH total. These are standard lead acid deep cycle marine/RV batteries from Walmart (...great value I feel). I am considering adding solar to one (or both) of the RVs. I'm trying to assess how much solar I actually want to add (100w or 200w). I have already purchased a 200w Windy Nation system. I might add 200w to one RV and try it out, or I might split it and put 100w on each (...I'd just have to buy another charge controller and some wiring).
I have always wondered how much various items in the RV are actually drawing from the batteries. But I was ALSO equally curious to know how well various charging methods actually work (Generator vs Shore Power vs engine alternator). (Anyone else wonder this or is it just me???) Eventually, also would be nice to see how much the solar is adding. I have always wanted to know: When the batteries are at 50% (for example) and need to be charged, how long does it take with the various charging methods to get the batteries back to 80%, 90%, etc. I often let other people use my RVs (family) and I'd like to have it easy for others to figure out also (so they don't drain/damage the batteries).
So I decided to buy the Aili battery monitor (<$45). I installed it in a convenient place. It was a pretty straight forward install and if you are curious there are various youtube videos showing people do it.
I was very pleased to see it working in action! If you aren't familiar with this battery monitor, it shows the following information at the click of a button:
- Battery voltage
- Current amps going in OR leaving your battery
- Remaining AH in your battery bank
- Battery % remaining monitor (Kind of like a "fuel gauge" for your batteries!)
It was very easy to program. Once it was set up, I could see how much each RV item is drawing from the batteries. I ran an overnight test with the furnace on set to about 65 degrees (it got down to 38 degrees overnight) and saw that over a ~16hr time period it used ~40AH. I wanted to do this because I know the furnace is one of the largest battery consumers. I can see that when I have everything OFF in the RV, it is still drawing ~0.1 amp (could be the carbon monoxide/propane detector). I got the batteries down to about 50% and then I got to see how the various ways of charging the batteries did... For example, if I turned on the engine and just idled, approximately 45amps were flowing into the batteries. If I turned off the engine and I turned on the generator, it was pushing 20amps into the batteries. Interesting. I didn't have an opportunity to plug the RV into shore power, but I suspect it would provide a result similar/identical to the generator (since it is the converter that is charging the batteries and I think it should operate the same on generator/shore power). As the batteries started getting more full (80%) the engine at idle was pumping 25amps into the batteries. And at 91% full, the engine at idle was putting only 7amps into the batteries. I suspect this is the correct operation roughly of how batteries get charged (when low they can accept much more amperage and when you are getting closer to full it slows down).
All-in-all very useful info and I am happy that I added this monitor. I will add it to the other RV also.
One thing to point out for anyone using this Aili monitor (or other monitors), I think there are some people out there pushing some false information. We all know that with typical lead acid batteries you are not supposed to let them discharge below 50% before charging them back up. So some have suggested that you should set your Max AH on your battery monitor such that it is only 1/2 of your total AH. I suppose this would be true for any type of battery monitor and not just the Aili monitor. For example, my battery bank is 122AH x 2 batteries - 244AH. Some would suggest that you "tell" the battery monitor that your battery bank is half that amount (122AH). This way, when you are reading your monitor % full when it gets to 0 you would know you must charge your batteries. I understand the motivation some people might have regarding this, but I believe it is misguided. Here's why...
Let's use my battery bank of 244AH as an example. Let's assume that we "told" our monitor that we only have a 122AH battery bank. On the Aili battery monitor, once it gets to 0% full (used 122AH) it cannot go any lower...it cannot go negative. So if you continue using your battery your batteries will in reality be less than 50% charged and the monitor will still say 0% full. To illustrate my point, let's assume that you could actually drain your battery completely all the way down to 0AH (would be a horrible idea, but stay with me...). Then, let's assume that you start charging your batteries. As soon as you start charging, your Aili monitor will start showing your battery % grow. After you have charged your batteries 122AH your monitor would say it is 100% full...BUT the reality is that you are only at 50% of the total battery bank charge! You would incorrectly THINK that your batteries are full but they would not be...they would only be at 50% and needing a lot more charge. That is the flaw! So if you set your monitor to 1/2 your total battery bank AHs you will not truly know if your % full is correct or not. Now let's say you are driving and your monitor got to 100% but you were still hours from reaching your destination. Your monitor would say 100% full and you'd be driving and actually still charging your batteries aggressively via the alternator of your car. When you arrive hours later at your destination, your monitor would say you are at 100% full but your batteries MAY be at 100% or 90% or 80%, and you'd never really know.
So my feeling is that it is important to program your Aili battery monitor (and any other that operates the same way) with your TOTAL battery bank AHs. And anytime you see it reach 50% you need to get those batteries charged back up. With this type of programming, you will always know exactly where your battery charge is. If, for example, you drained them all the way down to 30%, you would see it and when you are charging them back up you would know truly when they are all the way charged back up to 90%, 100%, etc.
Hope that all makes sense!
I wanted to post this to
a) Let people know how informative it is to have such a battery monitor, and
b) Give people my thoughts on programming your AH so that you always know the true state of your batteries.
Hope that helps someone!
-Chris
Question: How many AH/day do YOU use when boondocking??
