Using shore power instead of solar - question(s) regarding BMV-712

J

J D

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E. Washington
Some background info. This is for a 2021 Granby shell model with heater. When I got the camper in November 2021 I installed a NOCO AC pigtail like this to the battery compartment https://www.etrailer.com/Accessories-and-Parts/NOCO/329-GCP1.html I had one on my last camper and found it very useful. Very recently I've added one (so far) 180 watt solar panel, a Victron 100/30 MPPT, and a Victron BMV-712. There are two 6V batteries.

Sometimes being on shore power is desired. One scenario is where I park the truck and camper at home under a carport. Another might be staying at a campground with little solar exposure.

My thought is to place a AC to DC charger in the setup. I could plug it into the pigtail inside the battery compartment then run + to + on battery and - to the shunt. When hooking up the charger, do I still run the negative from the charger to side of the shunt where everything but my battery goes?

When I added the Victron stuff and panel I also added a two pole DC circuit breaker as the first thing solar power meets inside the camper. Can I assume it would be best practice to turn the solar off at the breaker before plugging into shore power?

Will there be any negative reaction from the MPPT or BMV-712?

Thanks in advance to any help or insight you folks might have. I hope I've explained things well enough.

J D

When hooking up the charger, do I still run the negative from the charger to side of the shunt where everything but my battery goes?
 
J D,

The link you posted leads to a bad page. I think you are referring to one of these NOCO 15 amp port plugs::

https://www.amazon.com/NOCO-GCP1-16-Inch-Integrated-Extension/dp/B009ANV81S

Are you thinking about adding an smart ac-dc charger such as a Victron BlueSmart IP67 Charger?

https://www.victronenergy.com/upload/documents/Datasheet-Blue-Smart-IP67-Charger-120VAC-EN.pdf

1) The batteries don't care where the charging current comes from
2) The Victron 100/30 is fuse protected and senses what the batteries need
3) If you use a smart charger there should not be any problem with the Solar and the charger operating at the same time (particularly if they are both smart Victron devices
4) It is reasonable to assume that the shore power supply is fused (but you never know unless you check)

I have a solar system on my boat which employs a Victron blue solar 75/15 Solar Controller. The boat also has a BlueSmart charger connected to the battery for use when I have access to shore power. Both remain connected to the battery at all times. I have not had a problem with that.

I hope this is helpful,

Craig
 
I second everything Craig said plus yes all negatives go to the shunt. Otherwise the BMV will not see what the chargers are contributing to the batteries. As Craig suggested, stick with the Victron family for the charger and everything will play together nicely.

Dean
 
Craig, Dean, thank you.

Sorry about the bad link. Yes, Craig, the link you provided is indeed the NOCO pigtail I use.

Currently I have a NOCO charger (have had it for years but it's just 4 amps). I've been looking at the Victron IP22 Blue Smart Charger, 12/30, 120V, with three outputs. I'll take a look at the IP67.

thanks again
 
Was thinking the IP22 would be multi use. I like the IP67 however and if I got that I'd dedicate it to the camper.

Thanks
 
Craig,

Since you're a boater you might be a great person to answer this puzzle.

I have a fishing boat with a 12V bow mount electric motor. I want to go on extended multi-day fishing trips likely using the electric motor a lot. My thought is to have a second 12V battery (currently I'm using AGM). While my truck is parked at the boat launch the camper solar could be re-charging the second battery while I'm out fishing. Seems simple enough. But would it be best to situate a switch (Blue Sea Battery Switch 1-2-OFF 350 Amp) in line? The BMV-712 has the second battery sensor lead. How would one set up a system to charge two independent 12V batteries? If I use the 1-2-OFF switch, is there a problem placing the switch to 1+2 and charging both 12V batteries at same time?

The only other alternative I can think of would be to use an inverter to convert to AC then use a plug in charger to the backup trolling motor battery. That inverter option seems inefficient though.
 
I have a version of that NOCO pigtail, but with *two* AC receptacles. (more or less this one: https://www.amazon.com/dp/B083NLXVGN/ref=cm_sw_em_r_mt_dp_N6T7CXARPTPC37MXAQSC?_encoding=UTF8&psc=1
)
That is, I plug my IOTA battery charger in one and the other is dangling there for me to use as an AC source when I'm plugged into 110. Aside from the amount of current I'm asking the 110 to supply (enough for whatever I'm doing which is mostly likely a tiny but likely current hungry space heater) and the requirements of the IOTA charger, is this a terrible idea?
 
UmkaAndHawk said:
I have a version of that NOCO pigtail, but with *two* AC receptacles. (more or less this one: https://www.amazon.com/dp/B083NLXVGN/ref=cm_sw_em_r_mt_dp_N6T7CXARPTPC37MXAQSC?_encoding=UTF8&psc=1
)
That is, I plug my IOTA battery charger in one and the other is dangling there for me to use as an AC source when I'm plugged into 110. Aside from the amount of current I'm asking the 110 to supply (enough for whatever I'm doing which is mostly likely a tiny but likely current hungry space heater) and the requirements of the IOTA charger, is this a terrible idea?
Click to expand...
I took a look at that splitter. The reviews of that item indicate it might not be a great product. At least one report of shorts, and another saying the wiring is done incorrectly, with the "positive" - wire (black or red I suspect this reviewer meant) is wired to the neutral pin.

I'd check the continuity of the wires, making sure that each pin is correctly wired.

As for using both ends at the same time, that IS kind of the implied intent of the splitter. AND, you don't want to exceed 15A of total draw. The iOTA puts out 30A DC at 14V or so, which would take roughly 5A of AC to produce. So you should be good with a heater that draws about 10A or less = 1200W heater.
 
J D said:
Craig,

Since you're a boater you might be a great person to answer this puzzle.

I have a fishing boat with a 12V bow mount electric motor. I want to go on extended multi-day fishing trips likely using the electric motor a lot. My thought is to have a second 12V battery (currently I'm using AGM). While my truck is parked at the boat launch the camper solar could be re-charging the second battery while I'm out fishing. Seems simple enough. But would it be best to situate a switch (Blue Sea Battery Switch 1-2-OFF 350 Amp) in line? The BMV-712 has the second battery sensor lead. How would one set up a system to charge two independent 12V batteries? If I use the 1-2-OFF switch, is there a problem placing the switch to 1+2 and charging both 12V batteries at same time?

The only other alternative I can think of would be to use an inverter to convert to AC then use a plug in charger to the backup trolling motor battery. That inverter option seems inefficient though.
Click to expand...
JD, you are correct that converting back and forth would be inefficient.

I would put the spare trolling motor battery in parallel with your existing camper battery. Doing so WILL completely confuse the BMV though, so you will have to resynch more often to get accurate SOC readings. The chargers will not care if you have one or two batteries in parallel.
 
J D said:
Craig, Dean, thank you.

Sorry about the bad link. Yes, Craig, the link you provided is indeed the NOCO pigtail I use.

Currently I have a NOCO charger (have had it for years but it's just 4 amps). I've been looking at the Victron IP22 Blue Smart Charger, 12/30, 120V, with three outputs. I'll take a look at the IP67.

thanks again
Click to expand...
I have the 12/25 version of that IP67. It works well. Bluetooth range is short though... like standing next to the camper short.

And to +1 to those who said that EVERY -ve DC wire has to terminate at the shunt in order for the BMV to be accurate. That said, hooking up your spare trolling battery will make the BMV wildly inaccurate anyway. To get the BMV to read correctly again, you will have to charge the house battery until you are VERY sure it is fully charged, and then use the "synchronize" feature to set it to 100%

Unless your BMV is setup to auto synchronize?
 
Thanks!

I don't recall setting to auto sync. I'll read up on that.

So putting the spare 12V AGM trolling motor battery in parallel with my two 6V AGM camper batteries could be as simple as just using jumpers from the 6V batts (in series) to the 12V?

Would unplugging the BMV display be of any benefit? I suspect it's just a display and the actual workings of the BMV are part of the shunt but I never thought about that.
 
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