Need help running Wiring behind Bathroom on RT

[engnrsrule]

I am installing a battery monitor with display on the Control panel, and need to run the control line (CAT 5) from the control panel back to the electrical compartment where the shunt is located. I am having trouble finding a path for the cable. I also plan to add solar at some point and will need to run the solar power plus the control line to the remote along the same route.

I am thinking of running down the void where the tank vent is located
to get past the sprinter's main horizontal structural member, then across. Will require potentially cutting a fishing access.

Suggestions welcome.

[hbn7hj]

Put the monitor somewhere else. You need to see it while in bed anyhow to monitor your evenings activities.

[engnrsrule]

I do not want to see it from bed...

The control panel location works best. Plus the original BMV-700 had an issue and I had to return it, so I upgraded to a 712. Added plus it draws less current for its own operation than the 700 or 702.

The routing that worked is from behind the main cabin electrical box (which is easily removed with 4 screws) down the tank vent void to just below the horizontal body structural channel. I cut a 2" hole to make the turn and route it through the bathroom and out another 2" hole I cut through the fiberglass wall behind the sink panel insert. From there it runs down and through existing plumbing openings and into the space containing the water pump. The visible hole was covered with an electrical plate.

The power supply wire attaches to the battery side of the positive feed from the 30a battery fuse. The inline 100ma fuseholder will be replaced with a mounted fuse block in the future.

If/when I add roof solar the wires will drop right down the void and the Solar Controller can go right into the electrical compartment. The Controller I have selected is the EPEVER 30A MPPT Solar Charge Controller Tracer A 3210AN with Remote Meter. The remote will be located by the control panel.

Speaking of solar, I had bought a small solar charger to use with the dinghy, but upgraded to an on board battery tender through the towing connection. I tried using it on the dash of the RT and it produces 1.3 amps. It simply plugs into one of the cabin 12v outlets.

[booster]

As long as you already have a shunt in place, you may want to consider using one of the solar controllers that use shunt current based charging, as it will be much more accurate of a charge, normally harvest more power, and be easier on the batteries than the one you list, which appears to be a straight timer unit. Timer setups are almost guaranteed to over or under charge, unless your solar is very small compared to use and battery capacity as then they will always undercharge.


The shunt based units would be able to share the shunt you have so you save that cost and wiring.

[engnrsrule]

I am not sure I understand your recommendation. I cannot find any reference to shunt based controllers. In charging, Shunts refer to the redirection of excess solar energy to other uses or systems when not required by the battery. The shunt in a battery monitoring system uses a specific known resistance placed at the battery's negative terminal to facilitate precise amperage measurements and calculate projected battery life and remaining charge.

Can you advise a solar controller that works in the manner you suggest?

[booster]

Originally Posted by engnrsrule

I am not sure I understand your recommendation. I cannot find any reference to shunt based controllers. In charging, Shunts refer to the redirection of excess solar energy to other uses or systems when not required by the battery. The shunt in a battery monitoring system uses a specific known resistance placed at the battery's negative terminal to facilitate precise amperage measurements and calculate projected battery life and remaining charge.

Can you advise a solar controller that works in the manner you suggest?

Trimetric (Bogart) and Blue Sky are two of them. The charging in controlled by amps to the batteries instead of time or algorithm.


There are many discussions on this forum on amp based charging control, and it is the preferred method of nearly all lead acid battery manufacturers.

[engnrsrule]

It's been suggested I post some specifics on my system to allow greater specificity on recommendations by the forum.

The vehicle is a 2006 Roadtrek Adventurous. It has an Onan propane generator and Tripp Lite Charger/inverter. I recently upgraded batteries from the original spec single 12v/90aH to two 6v/235aH (lead acid). That change was based on a recent experience at a National Park where generator use was severely limited, where essentially there was not enough time allowed for me to keep the battery up. There was also a separate charging issue that has since been fixed.

That also led me to add a Victron BMV 712 battery monitor.

We typically might dry camp 2-3 days. We are not looking to carry any big inverter (AC) loads while dry camping like air conditioner or microwave. Our most constraining limitation is probably the blackwater tank. So if we need to get underway every 3-4 days anyway to visit a dump site (where running the engine would significantly boost the battery), the ability to sustain batteries for any longer than a week would seem to be an unnecessary investment. Would like to be confident in handling up to a week. So I am considering solar options.

The suggestion to use amperage-based (shunt) solar has my interest, primarily from the perspective of maximizing the life and performance of the batteries. Looking at the Blue Sky MPPT solar controller systems, they could apparently share the Victron shunt, but would essentially duplicate most of the functions of the Victron.

Suggestions welcome, given the constraints above and the conclusion that I am at near max battery storage capacity without finding more space (which is non existent without losing already scarce storage or significantly reconfiguring the electrical system).

[SteveJ]

Originally Posted by engnrsrule

It's been suggested I post some specifics on my system to allow greater specificity on recommendations by the forum.

The vehicle is a 2006 Roadtrek Adventurous. It has an Onan propane generator and Tripp Lite Charger/inverter. I recently upgraded batteries from the original spec single 12v/90aH to two 6v/235aH (lead acid). That change was based on a recent experience at a National Park where generator use was severely limited, where essentially there was not enough time allowed for me to keep the battery up. There was also a separate charging issue that has since been fixed.

That also led me to add a Victron BMV 712 battery monitor.

We typically might dry camp 2-3 days. We are not looking to carry any big inverter (AC) loads while dry camping like air conditioner or microwave. Our most constraining limitation is probably the blackwater tank. So if we need to get underway every 3-4 days anyway to visit a dump site (where running the engine would significantly boost the battery), the ability to sustain batteries for any longer than a week would seem to be an unnecessary investment. Would like to be confident in handling up to a week. So I am considering solar options.

The suggestion to use amperage-based (shunt) solar has my interest, primarily from the perspective of maximizing the life and performance of the batteries. Looking at the Blue Sky MPPT solar controller systems, they could apparently share the Victron shunt, but would essentially duplicate most of the functions of the Victron.

Suggestions welcome, given the constraints above and the conclusion that I am at near max battery storage capacity without finding more space (which is non existent without losing already scarce storage or significantly reconfiguring the electrical system).

It takes several hours to fully charge a LA battery. Don't expect a short driving burst to fully charge the batteries. If every few days you will be doing extended driving, i.e. 6-7 hours, you may be OK, certainly not too bad. Solar is nice cuz it works all day to do a top off on the batteries.

My setup uses 150 watts of portable solar, a single "maintenance free" LA Walmart DC group 29 battery and a Renogy Adventure PWM controller with temperature compensation. The cheapo battery still performs strongly after about 15 months, about 7-8 months was about 75% boondock camping, up to two weeks stationary.

[booster]

Originally Posted by engnrsrule

It's been suggested I post some specifics on my system to allow greater specificity on recommendations by the forum.

The vehicle is a 2006 Roadtrek Adventurous. It has an Onan propane generator and Tripp Lite Charger/inverter. I recently upgraded batteries from the original spec single 12v/90aH to two 6v/235aH (lead acid). That change was based on a recent experience at a National Park where generator use was severely limited, where essentially there was not enough time allowed for me to keep the battery up. There was also a separate charging issue that has since been fixed.

That also led me to add a Victron BMV 712 battery monitor.

We typically might dry camp 2-3 days. We are not looking to carry any big inverter (AC) loads while dry camping like air conditioner or microwave. Our most constraining limitation is probably the blackwater tank. So if we need to get underway every 3-4 days anyway to visit a dump site (where running the engine would significantly boost the battery), the ability to sustain batteries for any longer than a week would seem to be an unnecessary investment. Would like to be confident in handling up to a week. So I am considering solar options.

The suggestion to use amperage-based (shunt) solar has my interest, primarily from the perspective of maximizing the life and performance of the batteries. Looking at the Blue Sky MPPT solar controller systems, they could apparently share the Victron shunt, but would essentially duplicate most of the functions of the Victron.

Suggestions welcome, given the constraints above and the conclusion that I am at near max battery storage capacity without finding more space (which is non existent without losing already scarce storage or significantly reconfiguring the electrical system).

It is too bad about the duplication of monitors, as the Blue Sky would fill the monitor needs just about identically. That said, it does give you a bit of flexibility of being able to set some of the monitor settings differently on the solar to better tweak some of the solar quirks that happen, like intermittent clouds and such messing up the charging, as the setting also controls the charging profile.


You would have the same duplication on the Trimetric setup, too. Downside of the Trimetric is that it is not MPPT so OK for smaller solar systems, not as good for larger ones. Advantage of the Trimetric is that it has a fully charged light that makes use a bit easier for most users. I don't think the Victron has a light or other indicator either, but I didn't look closely.


Two six volt GC2 batteries will likely do what you want pretty easily, especially if you add some solar and keep the propane frig. With LED lighting and efficient TV and DVD if you use them getting by on well under 50 amp hours per day is pretty easy.


As Steve mentioned, it takes a long time to totally fill lead acid batteries, but you don't need to do it every charge cycle. The manufacturers will usually say something like every 7-10 cycles is enough as long as you get totally full when you do get a good charge. Your monitor will show you exactly how long it takes, once you get all the settings in properly and run a few charge cycles.


The important setting will be the amps at float transition which might also be called tail amps, return, amps, or some other term. It will normally be given as a % of amp hour capacity and programmed as amps or % that you would get from the battery manufacturer's data. For AGM, expect .5 to 1 percent of capacity so pretty small number of amps to the batteries when full.


Also, it needs to have the voltage that is needed to be acheived and held until the above amps are reached. This would normally be the absorption voltage you are changing with in the 14.4v range for most.


Third is the hold time needed to indicate full batteries and when the above two criteria are met. 3-5 minutes is normally plenty.


The Victron looks to have very conservative settings in it as shipped, probably because many chargers aren't capable of getting the batteries full, so you will need to reset them. I think the defaults were listed at 4% amps and 13.2v.

[engnrsrule]

Thanks Booster. I am still learning the Victron, but believe I can set it to beep at a bunch of different points including fully charged. Since I plan to have the controller in the compartment with other electrical stuff (next to the shunt in the pic), lights on the SC don't matter as I can't see them anyway. That is why a SC with a remote is preferred (like the blue sky).

And Yes I do run propane fridge. I did add aux cooling fans but they only pull 0.3a and cycle with a thermostatic switch.

[Nic7320]

If you are referring to a Victron BMV, the cable from the shunt is NOT a cat-5 ethernet cable. It looks similar, but it is a 6 conductor RJ11 like a phone cord, but it has all 6 conductors present. I found a short one at Fry's Electronics (6c6p RJ11) so I don't have to use the really long one provided, since my BMV712 is only 4 inches away from the shunt.

And I use the head unit sometimes to look at data, but I prefer the bluetooth app.

So you might not even have to run the cable, if the bluetooth app is to your liking. Just find an old cell-phone and mount it where you need it. The bluetooth app is much friendlier than scrolling through parameters on the head unit, it integrates well with other Victron devices, and it has extra features such as a history page.

I recently became a convert to the Victron product line. I now have a Victron Phoenix inverter, a BMV712 monitor, a 65 amp battery protect device, a 220 amp battery protect device, and two Victron solar controllers. it's all top notch.

[booster]

Originally Posted by Nic7320

I recently became a convert to the Victron product line. I now have a Victron Phoenix inverter, a BMV712 monitor, a 65 amp battery protect device, a 220 amp battery protect device, and two Victron solar controllers. it's all top notch.

Does the monitor control the charging from the solar controllers and the battery charger on your Victron setup?

[Nic7320]

Originally Posted by booster

Does the monitor control the charging from the solar controllers and the battery charger on your Victron setup?

Yes, using the VE.Smart wireless network, the BMV712 broadcasts Battery Voltage and Battery Temperature to the solar controllers, which use the BMV measured voltage instead of their own voltage reading, for a more accurate voltage measured directly at the battery terminals. This eliminates any voltage drop in the wires between the solar controller and the battery, resulting in better topping off of the battery charge.

They also use the temperature reading from the BMV712 to shut down lithium battery charging below a set temperature, which is a necessary safety feature. For additional safety, I used the BMV712 relay contacts to drive two solid state relays to shut off the solar panel inputs. I realize his is somewhat redundant to the smart network shutdown, but felt it it was necessary for safety in case of a network problem and it has additional programmable settings that drive the relay.

Additionally, the BMV712 relay sends a second signal to the 120 VAC charger to shut it down if temperature is below the safe charging range.

My battery is a 24 volt, 5.3 kWh, 444 cell Tesla lithium battery module purchased on ebay, so these safety concerns are very important.

[Nic7320]

Originally Posted by Nic7320

If you are referring to a Victron BMV, the cable from the shunt is NOT a cat-5 ethernet cable. It looks similar, but it is a 6 conductor RJ11 like a phone cord, but it has all 6 conductors present...

On the Victron Website, they call this an RJ12 cable. RJ12 simply means it has all 6 conductors present in the 6 position shell.

[booster]

Originally Posted by Nic7320

Yes, using the VE.Smart wireless network, the BMV712 broadcasts Battery Voltage and Battery Temperature to the solar controllers, which use the BMV measured voltage instead of their own voltage reading, for a more accurate voltage measured directly at the battery terminals. This eliminates any voltage drop in the wires between the solar controller and the battery, resulting in better topping off of the battery charge.

They also use the temperature reading from the BMV712 to shut down lithium battery charging below a set temperature, which is a necessary safety feature. For additional safety, I used the BMV712 relay contacts to drive two solid state relays to shut off the solar panel inputs. I realize his is somewhat redundant to the smart network shutdown, but felt it it was necessary for safety in case of a network problem and it has additional programmable settings that drive the relay.

Additionally, the BMV712 relay sends a second signal to the 120 VAC charger to shut it down if temperature is below the safe charging range.

My battery is a 24 volt, 5.3 kWh, 444 cell Tesla lithium battery module purchased on ebay, so these safety concerns are very important.

I have not been deeply into the Victron control system, but I think it is also capable of controlling the battery charging by using the amps reading off the shunt and the battery state of charge, and full charge parameters in the monitor. Charge control by amps is far and away the best method for lead acid batteries and can also be good for lithium but not as much advantage there. There seem to be very few class b's that are using the complete Victron setup for lead acid, and it would be nice to see just what it takes to do it as a centrally controlled system would be nice compared to controlling three sources independently and trying to get them to play nice together.

[engnrsrule]

Yes I figured that out, initially thought it was cat 5 from pics. But the BT works from the display to the phone, the cable is necessary to connect the display to the shunt.

[Nic7320]

Originally Posted by booster

... Charge control by amps is far and away the best method for lead acid batteries ...

I haven't found any claims to this on their websites. And it doesn't make sense from an engineering point of view, so you may have misinterpreted some poorly worded information, or some marketing hype.

Voltage control is always necessary to prevent overcharging.

Constant current mode, used bulk mode charging (in a charger of any type) is necessary, as it prevents the charger from producing current beyond its capability, and shutting down when the battery demands more current than the source can provide. During bulk mode, once a solar controller achieves Maximum Power Point, there's no reason to further regulate the current to any value other than its constant current setting; you push as much of that current into the battery as you can.

There is also something called a solar shunt controller, but that's a simplified regulation technique that regulates excess solar power by dumping it into a shunt resistor. In doing so, it heats up the controller unnecessarily. Most solar controllers are not this type.

Many Battery Management Systems also estimate State Of Charge, which is another criteria from voltage and current.

This is a good (and rather lengthy) technical discussion on battery charging: https://www.mpoweruk.com/chargers.htm

[booster]

Originally Posted by Nic7320

I haven't found any claims to this on their websites. And it doesn't make sense from an engineering point of view, so you may have misinterpreted some poorly worded information, or some marketing hype.

Voltage control is always necessary to prevent overcharging.

Constant current mode, used bulk mode charging (in a charger of any type) is necessary, as it prevents the charger from producing current beyond its capability, and shutting down when the battery demands more current than the source can provide. During bulk mode, once a solar controller achieves Maximum Power Point, there's no reason to further regulate the current to any value other than its constant current setting; you push as much of that current into the battery as you can.

There is also something called a solar shunt controller, but that's a simplified regulation technique that regulates excess solar power by dumping it into a shunt resistor. In doing so, it heats up the controller unnecessarily. Most solar controllers are not this type.

Many Battery Management Systems also estimate State Of Charge, which is another criteria from voltage and current.

This is a good (and rather lengthy) technical discussion on battery charging: https://www.mpoweruk.com/chargers.htm

IMO, the link and claims that voltage is the way to terminate charging are not correct and don't fulfill the battery manufacturer's requirements for getting a full charge without overcharging. Here is a copy paste from the Lifeline technical manual on how they want their batteries charged. Note the requirement to get to .5%C AMPS at absorption voltage before going to float.

Document No. 6-0101 Rev. F Page 19 of 405.4 ChargingCharging Lifeline® AGM batteries is a matter of replacing the ampere-hours removed during discharge plus a little extra to make up for charging inefficiency. The ampere-hour inputnecessary for a full recharge depends on the depth of discharge, rate of recharge, and temperature. Typically, between 102% and 110% of the discharged ampere-hours must be returned for full recharge. If the recharge is insufficient, the battery’s state of charge will gradually “walk down” as it is cycled, resulting in sulfation and premature failure.The recommended method of charging Lifeline® AGM batteries is to use a 3-stage charging profile. In the first stage, a constant current is applied until the voltage reaches a pre-set limit. The first stage is often called the Bulk charging stage. In the second stage, the voltage is held constant at the same pre-set limit until the charging current tapers to a very low value, at which point the battery is fully charged. The second stage is often called the Absorption charging stage. A voltage setting of 14.3 volts ± 0.1 volts (7.15 ± 0.05 volt for a 6-volt battery) should be used when the battery temperature is 77°F (25°C). The battery is considered to be fully charged when the current drops below 0.5% of the battery’s rated capacity (0.5A for a 100Ah battery). The absorption stage will typically last 2 – 4 hours before the current reaches this level.In the third stage, the charging voltage is reduced to a lower value that minimizes the amount of overcharge, while maintaining the battery at 100% state of charge. This third stage is often called the Float charging stage. A float voltage of 13.3 ± 0.1 volts (6.65 ± 0.05 volts for a 6-volt battery) should be used when the battery temperature is 77°F (25°C). The charging voltages at other temperatures can be determined from the following table

Here is a link to the original document


https://lifelinebatteries.com/knowledge-center/


I think there is very good engineering reason to do it by amps because that will be a much more accurate measurement of how charged the battery is. When the charging current gets to the point of it being going only to outgassing or heat, you know you are full. Voltage will not tell you that.


You will find an amps spec for nearly all high end lead acid batteries as they all know it is best, and several changer and solar controller mfgs have equipment to do the charging that way. The amps at transition to float are called "tail" , "return", "ending" , "float transition" amps by different brands. My guess is that Victron can use the amps reading from the monitor though the central controller to control the charging stages for all the charging sources like shore, solar, motor generator, but I have been able to find specific instructions for that.



There is no need to estimate a fully charged battery as using the amps will tell you nearly exactly. It is also how the Victron battery monitor determines the fully charged point of the process, as do nearly all the other top quality monitors.


There is a lot of discussion on this topic on this forum, so it you may want to take a look at what is here.

[Nic7320]

When you referred to "amp based charging control" I didn't read that as tail current shutdown. My apologies. And this is off-topic to BMV cable routing, so maybe this thread should move elsewhere.

"There is no need to estimate a fully charged battery as using the amps will tell you nearly exactly" isn't always true: A battery has sulfation and leakage issues, particularly at end of life, that can overwhelm the tail current used in the chemical process of charging. A partially shorted cell will burn up lots of power and not put any that current into charge.

But back to your earlier question if the Victron BMV uses a tail current measurement. Here is a good overview about how tail current is timed in the BMV, using a lead acid example:

https://www.victronenergy.com/blog/2...nc-parameters/

And she discusses the how the BMV is synchronized to estimate SOC. SOC is always an estimate.

[booster]

Originally Posted by Nic7320

When you referred to "amp based charging control" I didn't read that as tail current shutdown. My apologies. And this is off-topic to BMV cable routing, so maybe this thread should move elsewhere.

"There is no need to estimate a fully charged battery as using the amps will tell you nearly exactly" isn't always true: A battery has sulfation and leakage issues, particularly at end of life, that can overwhelm the tail current used in the chemical process of charging. A partially shorted cell will burn up lots of power and not put any that current into charge.

But back to your earlier question if the Victron BMV uses a tail current measurement. Here is a good overview about how tail current is timed in the BMV, using a lead acid example:

https://www.victronenergy.com/blog/2...nc-parameters/

And she discusses the how the BMV is synchronized to estimate SOC. SOC is always an estimate.

That explanation is the typical one we see from most brands. I would say, for sure, the 4% is not the right tail current for almost any decent condition battery. Lifeline say 1/2% some TPPLs say 1/10%, and even wet cells say 1-3%. Our Lifelines bottom out on amps at about .3% so the .5% is good and that amp test hasn't changed in over 4 years now. Certainly the tail current will go up with age, but not very quickly from what I have seen, usually in years between changes until end of life. Capacity will change a bit faster than that so the AH setting needs to be confirmed maybe once a year or more often for old batteries. Ours still check at the same capacity as when just broken in.



The charge efficiency messes up the actual SOC almost as much as not using much of the time and often more as it depends on depth of discharge, so really doesn't matter about recommendations as you have to set it to you most common net CE by trial an error. Victron also uses Peukert which can significantly mislead on SOC because it is based on a constant amp draw to 10.5v cutoff. If you discharge the first 50% of the battery at 5hr rate, and then the last 30% to 80% DOD at 100hr rate you will essentially get the AH total you would get at the 100hr rating. Discharging at high rate doesn't make energy disappear, it just gives bigger voltage drop so 10.5v comes sooner in test. If you discharge at a 5hr rate to 10.5v and then let the battery sit, the voltage will recover and you would get a whole bunch more energy out depending on the discharge rate. I have tested this repeatedly and that is what happens, which is so against everything we hear. Trimetric does not use Peukert for that very reason.


Anyway, if you get a full charge to tail amps and reset to 100% SOC and zero AH out, the AH will be right on during discharge if Peukert is at 1.0 and SOC will be also very accurate but when you would actually runout would be affected by the amperage being drawn. If you stop before cutoff the SOC will be correct based on your AH setting which can be for any rating you want based on how heavy your draws might be at the end of discharge. On recharge you will be off by the amount the CE misses the actual net CE of that cycle, and each time you discharge without being to reset at 100% you can get further off on SOC and actual AH down. Getting full is very important but takes time, so probably why Victron uses 4% for the reset as that would save several hours of charge time, I think, but the batteries will also walk down capacity to that point. Going to .5% also will lower your net CE per cycle as the CE is very low for that last 3% of charge.



IMO, the very best thing you can do is have all your charge sources controlled by the tail current so you always get a consistent reset on the meter and also preserve the battery capacity. That is what generated the question of if the Victron system could do that, which it appears it could if setup with all the right stuff, so would make for a very nice system as all the control would be in one place so no surprise conflicts.


One big problem is that when users get a monitor and set the full battery parameters to the battery manufacturer's specs, it is extremely common that they never get a reset on the monitor because the charger is not capable of getting the batteries full, without overcharging. Then it gets to decision time as to whether improve the charging stuff at substantial cost, or accept the lower battery life by leaving it as is and increasing the tail amp setting to get resets for as full as you get, calling that point 100%.