Hi all and Merry Christmas. I have a question for those with much more knowledge on this than I have. I am preparing to install a Hengshan volt/amp meter to monitor my 2 - SOK 100 amp batteries in a motor home. I am also thinking about adding more storage capacity but since we have an on board 8k gen and are 90+5 of the time connected to shore power I want to make sure it is necessary. Will a shunt based monitor be able to tell me what my average real life usage is for say a 24hr period if I run just off the batteries? If not, is there an easier way? I have gone the calculation route (adding up all the watt ratings of various appliances at a guesstimated usage) but now that I have LFO batteries and a way to monitor SOC I figure measuring actual usage in real life setting would be more accurate.
Battery usage monitoring - How best to test before adding more battery capacity
- Thread starter 1holaguy
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sunshine_eggo
Happy Breffast!
Do you mean the AiLi battery monitor with the 350A shunt?
Yes.
It won't tell you Wh, but it will tell you Ah and % SoC based on the net current flow through the battery.
Yes, tis the AiLi monitor. I know it tell you amps and % state of charge. I am not sure if it will give you total amps over time. Since I am usually on shore power when not driving so general reliance on the batteries is limited to when I am driving and occasionally boon docking for a few days. I do not want to invest in unneeded capacity as that is not cost effective but also probably not good for the batteries. In our coach, in addition to 12v demand, all 110 outlets are served as pass through the inverter so the I/C stays on most of the time.
My reason in metering/monitoring is to evaluate real world usage in amps in these instances when not connected. With that I can calculate about how may amps I am consuming in a day. That will help me to better know if I need to add additional capacity.
As an example: If I can meter usage over 24 hours and lets say I find I use on average 150-175 amps a day then I know I can comfortable use the existing 200 amp of LFP with a planned daily run of the generator for an hour or two. If I am using 225-250 amps a day I either need to definitely run the generator more often, maybe every 12 hours or add more storage capacity, say another 100 amp battery. If however I find I am using 300 or more amps I may be better off adding something like an EG4 server rack battery, a more economic way to add storage if adding several hundred amps.
I am leaning to the latter as I am also thinking of replacing our 16 year old Norcold 1200 with a 12v compressor fridge. That in itself will likely require an extra 100 Amps per day.
My reason in metering/monitoring is to evaluate real world usage in amps in these instances when not connected. With that I can calculate about how may amps I am consuming in a day. That will help me to better know if I need to add additional capacity.
As an example: If I can meter usage over 24 hours and lets say I find I use on average 150-175 amps a day then I know I can comfortable use the existing 200 amp of LFP with a planned daily run of the generator for an hour or two. If I am using 225-250 amps a day I either need to definitely run the generator more often, maybe every 12 hours or add more storage capacity, say another 100 amp battery. If however I find I am using 300 or more amps I may be better off adding something like an EG4 server rack battery, a more economic way to add storage if adding several hundred amps.
I am leaning to the latter as I am also thinking of replacing our 16 year old Norcold 1200 with a 12v compressor fridge. That in itself will likely require an extra 100 Amps per day.
chrisski
Solar Boondocker
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No easy way to tell your shore power usage in an RV. A shunt will only the 12 volt side. That can be only 2% of the usage in extreme conditions.
I think my 50 amp RV is capable of using 30 kwh a day of I leave both ACs running, use electric hot water, and the microwave. Those don’t get measured by the shunt on shore power.
that is 2500 ah at 12 volts. I have no idea how much is used but it’s anywhere short of that.
Boondocing, I use between 40 ah and 167 ah depending on how cold it is.
I think my 50 amp RV is capable of using 30 kwh a day of I leave both ACs running, use electric hot water, and the microwave. Those don’t get measured by the shunt on shore power.
that is 2500 ah at 12 volts. I have no idea how much is used but it’s anywhere short of that.
Boondocing, I use between 40 ah and 167 ah depending on how cold it is.
sunshine_eggo
Happy Breffast!
You would need to keep track of the time component, i.e., take readings at a 24 hour interval.
An absorption fridge on AC power will kill you. In a mild climate, a 7.6 cu-ft will use 4.5kWh/day (375Ah @ 12V). The doubles can use 9-10kWh.
They use 5-6X more electricity than a typical compressor fridge of the same size.
An absorption fridge on AC power will kill you. In a mild climate, a 7.6 cu-ft will use 4.5kWh/day (375Ah @ 12V). The doubles can use 9-10kWh.
They use 5-6X more electricity than a typical compressor fridge of the same size.
Chrisski, I am not looking to monitor use on shore power, just 110v and 12v provided by batteries when disconnected from shore or generator. I would think the shunt will measure amps used by the inverter (12 to 110) as the shunt in in line for all negative return to the batteries. I guess the AiLi does not have a way of keeping history for a period of time to show usage over time.
chrisski
Solar Boondocker
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Depending on how you want to measure it, a kilowatt meter may work.
WhIke Boondocking, I run a 15 amp extension cord from the inverter to the RV shore power entry. If you have a 15 amp connection, this may work. If I were to do that, I’d probably place a generator under the RV and hook the kilawatt meter to that. I’d add a inverter inefficiency of 15 amps to whatever I get.
This is a chart I did of amps used per device in my RV fro both 12 volt and 24 volt:
Common sense would say that the 24 volt amps would be hold the amps of the 12 amps since it should be using the some voltage (100% efficiency inn my calculations), but some are more efficient of 24 volts(>100%), and others are less efficient on 24 volts (<100%). Anyway, that gives amperage consumption from the battery for everything in my RV except the electric water heater and the A/C units. Haven’t turned those on yet.
