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SvLoad test for your battery bank
How to perform a load test on your battery bank
With the right instrument, it is easy to measure the voltage of your batteries. The voltage tells you how charged your batteries are, but not how big your battery bank is. To find out, you need to do a load test.
The size of your battery bank is measured in ampere-hours (Ah). It is a measure of how many hours you can consume a certain number of amps with your batteries. If you have a battery bank of 200 Ah, you can consume 20 A for 10 hours. This is true in theory. How much you can consume without damaging your batteries depends on the type of batteries you have.
A load test is done to check how many Ah your battery bank can hold. Especially if your batteries are a few years old, it can be useful to do this to find out how much capacity is left in them.
How the test works
1. How the test works
The test involves first fully charging your batteries, then switching on the consumers and checking how long it takes for your batteries to be half-discharged.
2. Full discharge and recommendations
It can be measured by fully discharging your batteries, but we recommend that you avoid doing so to avoid unnecessary wear and tear on the batteries.
3. Checking the voltage
To know what voltage corresponds to full and half charge of your batteries, we look at the voltage table on the right. We see that the batteries are fully charged at 12.7 V and half discharged at 12.2 V. So the first step is to make sure that your batteries are fully charged and that the voltage is at least 12.7 V.
4. Switch on the consumers
Once that’s done, it’s time to switch on the consumers. Be sure to check how many A your consumers draw (ideally measure with a clamp-on ammeter).
5. Start the clock and wait
Start the clock. Then you just have to wait. We want to know how long it takes for your meter to read 12.0 V.
6. Adjustment of measured value
No, we have not made a mistake. Remember that during consumption, you must add 0.2 V to the value you read on your meter to get the correct voltage. 12.0 V on the meter thus corresponds to 12.2 V in the batteries if you consume electricity.
7. Measure time and calculate capacity
When the voltage in the batteries is 12.2 V, check the time. Then take the time and multiply by your consumption.
8. Final calculation
Time (h) x Consumption (A) = Ah
Now we know how many Ampere-hours are available if you only want to discharge your batteries by half. Double the figure you have obtained to find out how many hours are available until your batteries are completely discharged.
See the calculation
Time (h) x Consumption (A) = Ah
Belastningstest
Tid X Förbrukning (h x A)
What is the most I can use from my battery bank without destroying my batteries?
