Renogy LiFePo4 battery monitor

[IanHall]

So I now have a Renogy 20Amp. DC-DC Charger; a Rover MPPT 20Amp Solar Controller; two 80Ah LiFePo4 batteries in parallel; older WFCO 8955PEC Distribution Centre in my 17 ft. Escape trailer. So I am adding a Renogy battery monitor and I'm a little confused about the wiring.
I plan to connect the neg. terminal to the Shunt; then on the other side of the shunt connect my DC-DC neg. wire and my main neg. ground wire to the frame. Some posted info on internet suggests I have to connect all neg. grounds from everything to the shunt. Is this correct??? (like the WFCO Dist. Centre) Would appreciate any input. Thanks.

[gordon2]

IDK what all you are doing but the simple answer is that the shunt will only measure current which goes through it. So whatever device / load / charger etc you want to monitor must be on the shunt. Do you have a schematic diagram?

[IanHall]

So are you saying that having my neg DC-DC charger wire and main neg ground wire to frame on the P- C- terminal on shunt is not enough. That I need to bring all ground wires to this P- C- shunt terminal??
The only wires on my battery neg terminal would be the shunt connection and my neg wire from battery #1 to the neg pole of battery #2.(in parallel).
Thanks for helping.

[gordon2]

Im sorry but what you are saying sounds like "greek" to me. P-C is political correctness, of which I am not a fan. A diagram would help, but I can offer this in the meantime... if you want to monitor a battery in an RV, then the shunt is placed between the battery neg post and everything else. If two or more batteries then between them and everything else. So on one side of the shunt is the battery neg post. On the other side is every other negative or ground or frame connection. The monitor thereby monitors the current into and out of the battery from every charging source (converter, solar, etc), and every load (lights, pump, inverter, etc.). If you wanted the shunt to measure the solar input and output o the entire system then the shunt would be between the solar system and everything else (but there should be no solar input.. solar should only output current).

[CarlD]

Here is a diagram showing how to connect the shunt in a victron system. I would assume yours shunt installation is similar. Red is the positive, black is the negative. The only problem with this diagram is that the positive wire that feeds the shunt should come directly from the battery to eliminate any voltage drop on the positive wire from the battery to the junction block. Also, the gray junction block is where you make your frame connection.

[IanHall]

Got it... thanks for all the input. Ian

[Amazinghank]

I just installed a similar device in my Casita. I have 2-Lion 1300’s (105ah each) hooked up in parallel. I have a short 4/0 cable coming off the neg post, than the shunt, than another 4/0 cable to the inline 500 amp fuse, than 4/0 cable to the negative post on the never text. 1-18ga wire goes from positive post to the shunt so the monitor can light up. I have pictures if you want me to txt or email. Not sure how to send to cloud & get a url?

[IanHall]

Thanks, I've had lots of useful feedback and have it sorted. Ian

[Ballman1]

You that can help always give great feedback and we all appreciate your time and information
Bob in Sisters, Oregon

[Mike_L]

Now that we have that sorted out, what do you think of the lithium batteries as a replacement for lead acid and/or AGM batteries? Are they worth the cost?

[Amazinghank]

Well, the thing that is impressive is that you can take them down to 0 volts with no harm, they are very light. The Lion 1300 is guaranteed for life but........ there not cheap, although the prices are coming down. From what I see, the community can make an argument for both. AGM’s seem to be a fair compromise. HW

[gordon2]

Originally Posted by Mike_L

Now that we have that sorted out, what do you think of the lithium batteries as a replacement for lead acid and/or AGM batteries? Are they worth the cost?

If they are used in a camper on a regular or frequent basis for over five years or so, they will save you money. But not everyone uses their camper that often, or keeps their camper for more than five or so years. If you only go camping a few times a year then they are not worth the cost. If you use your camper more frequently but sell it in a few years, then they are not worth the cost. If you use your camper at least two full months out of each year or more, and keep your camper for more than five years, they they are worth it. If you can also use the battery for other purposes such as a ham radio portable station, then they might very well be worth it even if the camper use alone is not enough justification for the initial cost. It all comes down to this.. does the usage justify the higher initial cost.

[Jon Vermilye]

Originally Posted by Mike_L

Now that we have that sorted out, what do you think of the lithium batteries as a replacement for lead acid and/or AGM batteries? Are they worth the cost?

For most they are still not worth the cost. That said, I've had a pair of Battleborn lithium batteries in my Escape for 2 years & love them. I dry camp all winter in the southwest desert, as long as 91 days in a row. The combination of the batteries & 480 watts of solar let me use my trailer (with the exception of thee air conditioner) as if I had hookups. Microwave, toaster, all kinds of electronics, etc.

It was not an inexpensive conversion - while the batteries are described as "drop in", to do them right there is more involved. Here is a link to my conversion.

[kramg]

Ian,


I am looing at the same DC-DC charger. Did you wire it directly to your 7-pin trailer connector or did you run a separate set of heavier leads and use an anderson type connector?


Thanks,


- gustav

[Mike_L]

Thanks Jon, appreciated. I've used flooded lead/acid batteries for 40 years, charging them at home in the garage and taking them down to 50 - 60% before recharging. I was getting 5 - 7 years out of batteries at about 20 cycles per season by they are getting heavier to carry each year. Solar panels allowed me to charge my batteries in place however I was concerned about leaving my batteries on the tongue of my unit in the back country when I wasn't there for security reasons. I don't want to put lead/acid batteries inside my unit as they can off gas hydrogen and I've seem them explode twice. I've installed an AGM inside my unit but come replacement time I'm leaning towards Lithium, if I can afford it. Cheers!

[sokhapkin]

Originally Posted by Mike_L

Now that we have that sorted out, what do you think of the lithium batteries as a replacement for lead acid and/or AGM batteries? Are they worth the cost?

Actually high capacity Lifepo4 batteries (in the 200-300AH) range are cheaper now than AGM batteries if you build them yourself. Cells and BMS are available for cheap on aliexpress. 280AH Li battery weight will be half of the weight of 100AH AGM battery.

[IanHall]

The question above re: wiring DC-DC 20 amp charger. Ran 8Awg wire with 40amp. fuse from battery in my 4 runner to an anderson type connector by my hitch. Grounded the negative wire to the frame then to connector. Continued with 8Awg wire to DC-DC charger inside the front of my trailer. On the output side ran 10 Awg wire back to batteries with 30 amp fuse. The D+ I connected to the input side of the charger and ran it to a switch inside the trailer. The D+ has to come from the tow vehicle positive with the higher voltage. I plan to run my frig. on 12V with the DC-DC charger on (Frig. draws about 12 amps.) while driving.
Hope this helps, Ian