Battery disconnect vs a shunt and Bluetooth monitors

[Kirk E]

Hey there,
I’m investigating battery disconnect switches and battery monitors.
So far I’m looking at this monitor:
https://www.amazon.com/gp/aw/d/B0824...XTOGXF1I&psc=1

If I go with this one I want to tie it into the cables coming straight from the battery but near the converter instead of at the battery so I don’t need to run a cable through the shell of the camper out to the battery box. Then I’ll run the cable around inside and mount the monitor in the doorway. I’m thinking in this mounting location I can open the door without opening the camper to check on charging status after a trip.

Questions:

should the shunt be between the disconnect switch and the battery so the monitor is always powered and doesn’t loose settings? In sleep mode this monitor pulls next to nothing. Or should it be after the disconnect and I’ll have to reset the max capacity each time?

Charging through the converter the monitor will see the charging current but if I hook up the monitor the way I’m suggesting and use a separate charger at the battery it will not see the charging current.

The Bluetooth monitors connecting to an app on the phone are interesting. Just set it up in the battery box. No wiring no mounting and the shunt can be local to the battery. One member said it was educational to have the power usage history graph over the course of a trip. Does anyone have a recommendation for a Bluetooth monitor with a shunt?

[PhilFromMaine]

Originally Posted by Kirk E

Hey there,
I’m investigating battery disconnect switches and battery monitors.
So far I’m looking at this monitor:
https://www.amazon.com/gp/aw/d/B0824...XTOGXF1I&psc=1

If I go with this one I want to tie it into the cables coming straight from the battery but near the converter instead of at the battery so I don’t need to run a cable through the shell of the camper out to the battery box. Then I’ll run the cable around inside and mount the monitor in the doorway. I’m thinking in this mounting location I can open the door without opening the camper to check on charging status after a trip.

Questions:

should the shunt be between the disconnect switch and the battery so the monitor is always powered and doesn’t loose settings? In sleep mode this monitor pulls next to nothing. Or should it be after the disconnect and I’ll have to reset the max capacity each time?

Charging through the converter the monitor will see the charging current but if I hook up the monitor the way I’m suggesting and use a separate charger at the battery it will not see the charging current.

The Bluetooth monitors connecting to an app on the phone are interesting. Just set it up in the battery box. No wiring no mounting and the shunt can be local to the battery. One member said it was educational to have the power usage history graph over the course of a trip. Does anyone have a recommendation for a Bluetooth monitor with a shunt?

The shunt needs to be installed at (very near) the battery negative, period. Your monitor can be easily installed with one or two drill holes into the cabin area.

[TitanMike]

The shunt should be installed between battery's negative terminal and the cable that carries ALL current returning to the battery. Since almost all RV batteries have the negative connected to the nearest point on the frame and not all devices are connected to the power center/ converter's negative bus, connecting the shunt near the converter will not monitor all current.

You can really install the shunt anywhere you want but unless it's installed where it will read ALL current accuracy will suffer depending on loads that are grounded directly to the frame (slide, power awning, etc).

[chriscowles]

Originally Posted by Kirk E

... Should the shunt be between the disconnect switch and the battery so the monitor is always powered and doesn’t lose settings? ...

I installed the QWork in the link and it works fine.

Any shunt should be connected directly to the negative pole of the battery. Nothing else should connect to that pole and all current should pass through the shunt. A small wire goes from the shunt directly to the positive pole to power the shunt itself. The disconnect switch should not affect that power source. Current draw is negligible.

If charging with an external battery charger, put the negative clamp on the far side of the shunt, not directly on the battery's negative pole. All current, in and out, should pass through the shunt. Otherwise it will be horribly inaccurate and pointless.

If not cost-prohibitive, I recommend the Victron SmartShunt. Not only is it easier to install (no wires), but it takes Peukert's factor into account. That improves accuracy for lead-acid batteries but is (I believe) less important for LFP. While I don't have one, I think the BT display on your phone may show more information, too.

[Giboneys]

As others have said the Shunt goes on the negative side of the system and the negative battery terminal is only connected to the battery side of the Shunt all other negatives go on the load side of the shunt. You may want to look at the Victron Smart shunt that does not need a control panel you access it via Bluetooth and an app on your phone or tablets

[yukongold]

^^^^^^
x2
A bluetooth shunt doesn't need a control panel.
No wires to run. Just hook it up to the battery and use its app and a phone.
The current draw on a Victron Smart Shunt is less than 1 milliamp - not enought to worry about, IMO. A fully charged battery would last months (and months) before you needed to worry/wonder about it.

[TacomaJoe]

I had a shunt like that mounted on the battery out front. I extended the display cable wires so that I could mount the display inside my trailer. The monitor doesn't use very much power so there's no need to disconnect it. It is also handy to see what is happening when you do have the battery disconnected by the switch to determine what those parasites add up to.

Victron has a bluetooth shunt. I've heard complaints about the range.

Currently I have lithium batteries with bluetooth and I can monitor them from inside my house 50ft away from the trailer.

Putting the shunt inside near the converter may not work because the frame is used as a current path and I don't think you will capture all the charge/discharge paths. If your shunt misses any it won't be accurate.

[TitanMike]

Originally Posted by TacomaJoe

Victron has a bluetooth shunt. I've heard complaints about the range.

Many don't realize that two factors affect Bluetooth. One is distance with most companies incorporating Bluetooth tech in their products only claiming ~30 feet. Second is the amount of interference from others using the same frequency spectrum (2.4 Ghz). This can be a cordless phone, RC toy, Wifi router, etc.

Wonder what they expect for a system that limits transmit power to 2.5 milliwatts?


For longer range devices will usually employ Wifi (like my MicroAir EzTouch Thermostat) but it needs access to a WiFi signal/router.

[nvs4602]

I bought that shunt as well. For $44

https://a.co/d/5ymwtzN

It works good for me. As others have said it needs to be connected to the negative side of the battery, then to the chassis so everthing goes through it.

Here are my installed photos.

[Kirk E]

Thanks for the pictures. Nice job on the wooden housing for the read out.
Can you tell me more about what Im seeing in the photo of the shunt?
Battery type? All of the wires?
Your battery is inside the camper?

[Aussieguy]

Originally Posted by Kirk E

Thanks for the pictures. Nice job on the wooden housing for the read out.
Can you tell me more about what Im seeing in the photo of the shunt?
Battery type? All of the wires?
Your battery is inside the camper?

That battery is a DIY assembled from 4 x 3.2 Lifepo4 cells and a BMS
cells are available in many sizes ... RV trailers and solar peoples are using 100ah or greater

Its a moderate skill DIY and is cost effective + you learn stuff + if it breaks you can swap out parts

4 x 280ah cells = $450-600
150amp BMS = $120.00
MISC stuff (if just starting ) = $50.00

You get almost a 300ah battery (280ah)......... for around $600.00
haven't looked at prices for the 100ah version in a while


more info if you want to learn about this
https://www.google.com/search?client...iy++lifep%5Bo4


.

[nvs4602]

That's correct. It's a 280ah lifepo4 battery. The small wires on top are for the red box which is a BMS (battery management system) and reads the voltage of each cell. I added a balancer board as well which adds another set of sense wires to keep the cells balanced or at equal voltage. There is also a temperature sensor and the Bluetooth dongle. They make a plastic box to mount everything in but it was $120 more + shipping. So I just made my own.

I moved the battery inside under the dinette because lifepo4 batteries don't like temperature extremes.

The shunt is on the wall and the negative battery blue wire from the bms connects to it. Then the black wire runs to chassis ground. I put a 200amp resetable breaker on the positive side of the battery.

I installed a 40amp DC-DC charger on the alternator and a new lifepo4 compatible converter.

[NavyLCDR]

I installed basically the same battery monitor just in the top of my plastic battery box. Used a hole saw to cut a 2 1/8" hole (I think), dropped the battery monitor into the hole, put a bead of silicone sealant around it. 10 minutes to install it. But, yes, it is outside and I have to go outside to read it.

[Aussieguy]

Originally Posted by nvs4602

That's correct. It's a 280ah lifepo4 battery. The small wires on top are for the red box which is a BMS (battery management system) and reads the voltage of each cell. I added a balancer board as well which adds another set of sense wires to keep the cells balanced or at equal voltage. There is also a temperature sensor and the Bluetooth dongle. They make a plastic box to mount everything in but it was $120 more + shipping. So I just made my own.

I moved the battery inside under the dinette because lifepo4 batteries don't like temperature extremes.

The shunt is on the wall and the negative battery blue wire from the bms connects to it. Then the black wire runs to chassis ground. I put a 200amp resetable breaker on the positive side of the battery.

I installed a 40amp DC-DC charger on the alternator and a new lifepo4 compatible converter.

how long have you had battery..
and how has it performed ?

[Kirk E]

Originally Posted by Aussieguy

how long have you had battery..
and how has it performed ?

I just bought the Camper from an RV dealership. They installed a new 12 v 81ah RV/marine battery. Big enough to power the electric brakes if my truck and camper go their separate ways... I have not been camping with the new rig yet. I will be buying larger capacity batteries to support boondocking for 4 nights. The next step after that will be to buy a generator so I can recharge while camping. We like the NH State parks. clean nice but no hook ups.

[chriscowles]

Originally Posted by Kirk E

... The next step after that will be to buy a generator so I can recharge while camping. ...

Do your camping neighbors a favor by not using an open-frame generator.

I bought a Honda EU2000i inverter generator because, at the time, it was the only brand offering authorized service locally and the cheaper brands of inverters like those sold at Costco weren't common yet. While happy with my purchase and decision, I wouldn't pay that much again. The second-tier brands have proven reliable and are cheaper.

[Kirk E]

Thanks. Several people have recommended the Champion 2500 w unit.
It’s small and “quiet” 53 dB at ~20 ft. My Thoughts on further noise control: build a wooden box with a top and three sides. When using the generator but the box over it with the open side directed away from my camper and away from other camp sites. Need to think about it WRT where the exhaust is located, heat build up etc.

[Aussieguy]

Originally Posted by Kirk E

Thanks. Several people have recommended the Champion 2500 w unit.
It’s small and “quiet” 53 dB at ~20 ft. My Thoughts on further noise control: build a wooden box with a top and three sides. When using the generator but the box over it with the open side directed away from my camper and away from other camp sites. Need to think about it WRT where the exhaust is located, heat build up etc.

Careful with a box design.....
may need to have sound deadening material in a box otherwise you risk making an echo chamber / vibration amplifier .

use that peaked foam deadener on the walls or something.
and the box needs good good sized ventilation holes
which then tends to make it easy for the noise to get out!

you certainly don't want to make a 3 sided version that will aim / reflect the sound.
anyone on the OPEN side of the box may get annoyed.
-------------------------------------------------

maybe a soft sided generator tent ?
for weather and some noise protection may be a better option
------------------------------------------------------------[-
keeping the generator properly maintained will keep it nice and quiet.
no loose covers or nuts/bolts , don't remove side covers

[chriscowles]

Originally Posted by Kirk E

... Need to think about it WRT where the exhaust is located, heat build up etc.

And fresh air intake.

[TitanMike]

Originally Posted by Kirk E

Thanks. Several people have recommended the Champion 2500 w unit.
It’s small and “quiet” 53 dB at ~20 ft. My Thoughts on further noise control: build a wooden box with a top and three sides. When using the generator but the box over it with the open side directed away from my camper and away from other camp sites. Need to think about it WRT where the exhaust is located, heat build up etc.

My Champion 2500w Inverter generator is quiet enough there is really no need for extra sound abatement.

It's no louder than normal conversation or background music. Mine sits on a rear bumper mounted platform and when sitting outside with trailer between me and generator it's very comfortable.

Any other campers thinking it's loud are too close, especially considering generators are mostly used in boondocking locations.

Only cover really needed is weather protection. For rain I purchased a "Genshed". Sets up in 3 min's or less, folds flat for storage, and has side flaps that can be opened or closed as necessary for control access, rain protection, exhaust, and cooling.

Amazon has them, just search for "Genshed".

Someone here asked about these last year and I checked to see where company was located. Turned out their warehouse/distribution center was here in the greater Seattle area. Contacted them to look at it in person. Liked it a lot and wrote a check so I could take it home with me.

Comes in two sizes but smaller one fits most <4000w inverter generators. Large size is more for contractor types.