An amp meter is a necessary device as a voltage regulator to monitor the voltage drop of the RV battery bank.
There are many instruments available, the amp meter being one but also the amp hour meter and the volt ohm meter.
The amp hour meter is probably the best choice to measure on a regular basis your amp hour daily consumption while RVing. If you start with a full charge, you will be the person responsible to manage its use.
A fully charged battery has a voltage of 12.63 volts across the two battery terminals while a completely discharged one would have a reading of 10.50 volts.
In order to have an accurate measurement of its voltage, before taking a reading with any amp meter of your choice, a battery has to rest for a period of time without having any charge or load applied.
This rest will allow the voltage to equalize between the cells. A 24 hour period is suggested for full accuracy. We all understand that while you are RVing, it is impractical to wait 24 hours without any load applied.
However, you can be satisfied with sufficient accuracy with a waiting time of 5 to 10 minutes before taking an amp meter reading. If you can wait 2 or 3 hours, even better.
Many manufacturers suggest that in order to prolong the longevity of the RV batteries, they should not be discharged less than 12.06 volts. (50 % voltage drop)
To take a reading, you can either use an amp meter (series or shunt models) or voltage meter.
Here are suggestions of amp meters you may consider:
You can measure the energy consumption of individual appliances which is quite useful.
You can get all the information you need: how much amp hour you have consumed over a period of time, when it is time to recharge your batteries and when you battery has reached a full charge.
Many amp hour meters nowadays are very sophisticated and as well have features found in amp meters and volt meters.
These amp hour meters are accurate and show a negative reading for the cumulative discharge of batteries (ex. - 4.8 Ah for 4.8 Ah of accumulated consumption) and a neutral 000 reading or slightly higher positive number when a full charge is reached.
You should ideally not exceed more than 25 % of discharge of your battery bank before recharging daily.
This means that if your battery bank has a capacity of 200 amps, a negative reading of -50 Ah should be your limit of cumulative amp hours consumed before fully recharging.
Keeping the depth of discharge (DOD) as low as possible will extend the lifespan of the house batteries.
A good advice is not to discharge your batteries more than 50 % of their capacity. This will shorten considerably their lifespan as I mentioned before if it is repeated on a regular basis.
For this reason, it is a lot wiser to invest in a battery bank with higher capacity to handle a daily amp-hour consumption with a lower discharge percentage ( not more than 25%) than over discharging a smaller battery bank.
The batteries of a smaller bank will have to be renewed a lot sooner because you pushed their limit too often.
The common sense stipulates not to discharge your batteries more than what is the daily capability of your charging equipment.
A thing to remember in the recharging process is that you also have to take in consideration a factor of inefficiency .
This inefficiency is found in the fact that for every 1 amp of discharge, you have to provide 1.2 amp of charge to the battery.
The recharging process should be done so the battery bank gets back to its full charge daily.
If you recharge the batteries not to full charge but for example only to 80 % and re-apply other loads on a constant basis without a rest, you will damage the batteries very quickly.
Like I mentioned above, the batteries need to rest and this will make a huge difference.
The goal is then to have the proper equipment to fully recharge every day. (solar panels, wind power, generator).
You will have to spend extra money to renew your batteries more frequently if you do not follow proper methods to discharge and charge your battery bank.
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