BBQ! (Basic Battery Question)

[Urlauber]

Originally Posted by SteveJ

I've used this one for just over a year. It provides the info that makes living with 12 volts a lot easier. No tie in with my Victron stuff but otherwise it has worked well.

The light on it modulates on and off when charging so you may want to install where it won't be an irritation when sleeping. When discharging the light stays on making an excellent low current night light.

Not too difficult to set up, just go through the steps.

Less than $50 at the big A.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Thank you! Yep, along those lines I went with something even cheaper, to figure out how and where something like this could be installed in my setup.
Just seeing the amps going in and out will already be super helpful to understand what is drawing how much and what is charging how much.

My two coach batteries are located in different places underneath the van, so I have to figure out where to cut the negative and insert the shunt. Isn't there a better place closer to the fuse box or main switch maybe?

Once it is working I'll consider something more advanced and expensive. I have some not so great experiences with some of the components, which makes me want to hold off complicating things more. For example, the RV Master app used for the BMPro worked great (on my phone, via BT) ONCE, and since then I have not been able to connect again. Lol. The Android Auto phone display worked also great at first, and then started to disconnect with increasing frequency (causing increasing frustration).

So going very cheap and simple (wired display) seems like a good first step for the beginner here. I appreciate the help and will report back. 🔥🔥🔥

[booster]

Originally Posted by Urlauber

Thank you! Yep, along those lines I went with something even cheaper, to figure out how and where something like this could be installed in my setup.
Just seeing the amps going in and out will already be super helpful to understand what is drawing how much and what is charging how much.

My two coach batteries are located in different places underneath the van, so I have to figure out where to cut the negative and insert the shunt. Isn't there a better place closer to the fuse box or main switch maybe?

Once it is working I'll consider something more advanced and expensive. I have some not so great experiences with some of the components, which makes me want to hold off complicating things more. For example, the RV Master app used for the BMPro worked great (on my phone, via BT) ONCE, and since then I have not been able to connect again. Lol. The Android Auto phone display worked also great at first, and then started to disconnect with increasing frequency (causing increasing frustration).

So going very cheap and simple (wired display) seems like a good first step for the beginner here. I appreciate the help and will report back. 🔥🔥🔥

Be aware that unit you ordered is a one way only, so you can either read charging or discharging, but not both. To do both ways you would need two of them. They also do not auto reset to calibrate on each recharge cycle so they will get less accurate on each charge, discharge cycle until you manually reset them. It is at 100% it is not to bad to do, but they indicate can be reset to zero so would have to discharge the batteries all the way to reset and be accurate again.


It is all dependent on what you are actually trying to do with a battery monitor. If you just want it to check how much any given power use is taking in either amps or amp hours over a time period, then it work if put on the discharge side. If you want to see how much you have charged since a reset, it would work on the charge side but wouldn't tell you how full the battery is unless you looked at the amps the battery is taking during charge. What it won't keep track of accurately is you state of charge of the batteries so you know how full or empty the batteries are, and to many of us that is the most important to know.

[tgregg]

Originally Posted by Urlauber

You probably did not click on my link... the SmartShunt is not cheaper, it's much more expensive than what I was asking about.

I did. And when I click on the link this is what comes up:


$9 more than the smart shunt. No idea how that happened...

[Urlauber]

Originally Posted by tgregg

I did. And when I click on the link this is what comes up:


$9 more than the smart shunt. No idea how that happened...

I see... I posted multiple links... you must have clicked on the one in post #9, but then replied to post #11.

The more expensive one in #9 got disqualified, as Booster noted, it only does up to 60amps which is too little.

[Urlauber]

Originally Posted by booster

Be aware that unit you ordered is a one way only, so you can either read charging or discharging, but not both. To do both ways you would need two of them. They also do not auto reset to calibrate on each recharge cycle so they will get less accurate on each charge, discharge cycle until you manually reset them. It is at 100% it is not to bad to do, but they indicate can be reset to zero so would have to discharge the batteries all the way to reset and be accurate again.


It is all dependent on what you are actually trying to do with a battery monitor. If you just want it to check how much any given power use is taking in either amps or amp hours over a time period, then it work if put on the discharge side. If you want to see how much you have charged since a reset, it would work on the charge side but wouldn't tell you how full the battery is unless you looked at the amps the battery is taking during charge. What it won't keep track of accurately is you state of charge of the batteries so you know how full or empty the batteries are, and to many of us that is the most important to know.

Thanks again! I think I could use a DPDT switch to have it both ways. I'll have to think about the reset issue, I assume this is referring to the "Energy" part of the display. Like I said, may be a good way to play around to learn, and later spend some more money on something more sophisticated.

I hope that the batteries will rarely bottom out. The only constant draw will be the compressor fridge, and if I am parked in a sunny spot, this should be offset by solar charging (or plugging it in). It would just get low when in a shady spot for a few days without hookups nor driving. We'll see.

[booster]

Originally Posted by Urlauber

Thanks again! I think I could use a DPDT switch to have it both ways. I'll have to think about the reset issue, I assume this is referring to the "Energy" part of the display. Like I said, may be a good way to play around to learn, and later spend some more money on something more sophisticated.

I hope that the batteries will rarely bottom out. The only constant draw will be the compressor fridge, and if I am parked in a sunny spot, this should be offset by solar charging (or plugging it in). It would just get low when in a shady spot for a few days without hookups nor driving. We'll see.

I am not sure what it will do if you swap the two wires as the interruption might shut it down or reset it somehow. Most likely it will continue counting from where it was so if you charged 80ah and then swapped wires it would start that way and keep going positive.

[themexicandoctor]

Originally Posted by Urlauber

Thank you, pics are always helpful to learn how things can be set up.
I decided to go with something much cheaper for now and use that to figure out how things can be set up and managed, before I pay some more serious money for a Victron etc.

I am not Smart enough in this arena to choose something inexpensive. And I am probably brainwashed by Victron.

Did you know that if you go on their website there is a Free Book they send you/and or you can download a pdf that is like a Treatise on understanding this entire field.

Illuminating, educational & Free.

I sent you a photo of a couple of screen shots of the Bluetooth
readouts on my phone - plus my electrical compartment but next is a couple more photos below of the actual meter in my truck.

And the device you see in Blue inside the box is my Victron MTTP 30/100 unit for the Solar.

Bottom line; you are in the right place to ask questions from the Basics to the Finest Detail & Minutae of the great mysterious 12, 24 & 48 volt systems.

The Guru's on this forum are more than helpful.

And most all, it's honest, hard earned advice given freely in support of our community & that's priceless ...

[Urlauber]

Originally Posted by booster

I am not sure what it will do if you swap the two wires as the interruption might shut it down or reset it somehow. Most likely it will continue counting from where it was so if you charged 80ah and then swapped wires it would start that way and keep going positive.

Agreed. But like you said, the Ah display is questionable (wrong) anyway since there is no clean starting point... I can see myself switching a lot in the beginning but then settling down to my resting voltage and just showing the discharge and letting the Ah's accumulate.

Need to figure out where to put the shuntshuntshunt first.

[SteveJ]

Originally Posted by Urlauber

Thank you! Yep, along those lines I went with something even cheaper, to figure out how and where something like this could be installed in my setup.
Just seeing the amps going in and out will already be super helpful to understand what is drawing how much and what is charging how much.

My two coach batteries are located in different places underneath the van, so I have to figure out where to cut the negative and insert the shunt. Isn't there a better place closer to the fuse box or main switch maybe?

Once it is working I'll consider something more advanced and expensive. I have some not so great experiences with some of the components, which makes me want to hold off complicating things more. For example, the RV Master app used for the BMPro worked great (on my phone, via BT) ONCE, and since then I have not been able to connect again. Lol. The Android Auto phone display worked also great at first, and then started to disconnect with increasing frequency (causing increasing frustration).

So going very cheap and simple (wired display) seems like a good first step for the beginner here. I appreciate the help and will report back. 🔥🔥🔥

We used a pair of those in the RT. They worked OK for what they are and are a lot better than just a volt meter or the factory joke of a monitor but the one I linked earlier is less brain work and stupidly simple.

[ikanode]

Originally Posted by booster

How far you take the batteries down is a personal choice. Many feel that going only to 50% down SOC is necessary, but I am not one of them. Battery life is shortened a bit by go the 80% regularly, but you gain 60% in capacity, so it seems like a very good trade off to me. .

I'd like to emphasize this point. The 50% rule isn't a big deal! You probably aren't going to use 80% of capacity every day which makes it even less important. However, if you use more than 80%, it can damage the battery.

Even if I used 80% of capacity every day. It just means that I'll have to replace the batteries a little more often but I can buy somewhat smaller/cheaper batteries to get identical daily amp hours of capacity. The lifetime cost per amp hour is pretty close.

The important rule is don't use more than 80% of the capacity of lead acid batteries or you will significantly impact their life.

[Jack1943]

Originally Posted by Urlauber

BBQ AGM ETC

Very basic question - my Thor Rize has two group 31 AGM batteries (that's what the manual says).

What's the consensus about how low you can let voltage go? I've read different things, so what say you, oh experienced RVer, to prevent any serious stress to the batteries?

My BMPro display has shown them at 12.1 - 13.1V. There is no SOC gauge. The solar charger shows them full at around 12.8 fwiw. I want to double-check if the voltage display is correct.

So, when is it time to crank up the generator? And what happens if you don't (to the compressor fridge, for ex)?

********************************************
Bonus question:
I wouldn't by an RV as a power backup, but since it is now parked in front, in case of a power outage in the pueblo, would there be any issue to crank up the generator and plug the fridge, computer screen, aquarium pump into an RV outlet?

My fully charged standing voltage is 12.8 my low is no lower than 12 on my agm

[engnrsrule]

Agree that just tracking voltage is not enough. The Victron with Bluetooth is great. It will also allow you to determine what the specific draws are of various loads, and thereby better manage battery life. Realize too that some things like inverters draw when not being used. As for your batteries, I changed to 6v golf cart batteries and increased my Ampere Hour rating from 90 to 235.

Another point to maximizing battery life is having a properly match multi stage charger.

[Jim86301]

I use the Thornwave Labs PowerMon BTDCPM. Although it only has a 60 Amp built-in shunt it can be used with external shunts of any size; which I added, installed in the negative battery lead (shunts installed in the positive side can be monitored as well). The unit works great and the Bluetooth range is amazing; I can read the SOC from 100 feet away from the van. It works with lead-acid, AGM and Lithium batteries.
Jim

[themexicandoctor]

Originally Posted by Jim86301

I use the Thornwave Labs PowerMon BTDCPM. Although it only has a 60 Amp built-in shunt it can be used with external shunts of any size; which I added, installed in the negative battery lead (shunts installed in the positive side can be monitored as well). The unit works great and the Bluetooth range is amazing; I can read the SOC from 100 feet away from the van. It works with lead-acid, AGM and Lithium batteries.
Jim

I love Victron & will never change but the Bluetooth Range of yours is incredible - in the real World, does being able to access your values 100 feet away make a difference?

The above is not a criticism, just a question.

I have a Hot Spot from Verizon but do not have any of the Victron components connected via wifi but I know some of the very sophisticated technical types here are able to remotely access their rigs from anywhere in the World & make changes.

[Jim86301]

The long BT range of the PowerMon is useful to me as I can check the SOC of the battery from my office while the van is parked in the garage on the other side of the house. The other features of device: second battery monitoring, low/high voltage disconnect, over-current disconnect, timers and data logging I don't use.
Jim

[Urlauber]

So I ended up returning the basic meter I bought, and went with this one.

My problem is that I have no idea which cable to stick through the Hall sensor. It is supposed to be "the positive" cable from the battery, but I have two batteries, and what sprouts from them battery poles looks like a frigin Kraken.

Is there any place where it all meets up somewhere? Like a main fuse? Main power switch? That one probably triggers some relay, right? Maybe I bought the wrong thing again. Or maybe I need to crawl underneath the van and spend a few hours there.

[engnrsrule]

The meter you have will not give you the info you need. Better battery monitors use a shunt that goes off the negative pole of the coach battery in order to capture all loads on the battery. If you have two batteries it goes where the final negative goes to ground. The shunt contains large resistor and some electronics that read current in or out, voltage, temperature, and calculate the state of charge. The Victron I have is very good and will tell you when you need to run generator. Here are pics of the shunt and meter. The SOC is related to both the voltage and the rate of current draw being experienced at the time, more likely remaining Ampere-hours. Zero SOC is not zero voltage, but is more like that 10v or so where items won't function.

[Urlauber]

Thanks, and yep, I am aware of the advantages of more sophisticated monitors. However, at least initially, I am more interested in how much the different components draw and how many amps go into the batteries via driving/generator/solar/plug-in.

So, no way to do this with this contraption.

[engnrsrule]

To do it with the gadget you have you would need to find the positive side feed to each load or power source, clamp onto that line and observe reading.

With the Victron, it gives the instantaneous net current draw. With the Bluetooth version all the info is viewed on your phone. So if everything is off, your turn something on and see -0.2 amps, that is the draw of that device. If you start the engine, it goes to +1.2, that means the engine is charging the system at 1.4 amps (1.4 going in, 0.2 going out). You can then identify higher draw items and better manage their use. If you have an inverter, check to see what it draws just by being on, even with no 120vac loads running (it is not zero). I keep mine off unless I need 120v.

Bear in mind that some items may not always draw the same amount all the time. You have a compressor fridge, it may work harder during startup. Your charging circuit (from engine, or from 120v charger) might likewise deliver different charging rates based on the voltage condition of the batteries.

Having the Victron has greatly reduced the mystery and stress over battery condition. It also shows longevity in days or hours, so you can readily know when you will need a charge. This is very helpful when you are in a place that limits generator hours. With us we typically need to pump waste tanks every 3-5 days. So if the Victron tells me I have 2 days battery left, maybe I just move up the trip to the dump station.

[GeorgeRa]

You can measure energy consumed with this inexpensive meter. There are other ones with higher amerage capacity.

https://www.amazon.com/dp/B079JVGRSL...t_details&th=1