RV FEATURE
High quality battery chargers will have a ‘ recondition ’ or ‘ de-sulfation ’ mode in their charging profiles . This uses a period of pulses of electricity to remove the build-up of lead sulphate before the recharging process takes place . This is good in the short term but , over time , the sulphate powder settles at the bottom of the battery and it can build-up to such levels that it can cause a short circuit between the lead plates , killing the battery .
DETERMINING STATE OF CHARGE
Determining the SOC of a lead-acid battery can be done by measuring the standing voltage . This is without any load or charging occurring . It can be difficult in caravans as there is usually always a charger , solar controller or load on the battery all the time .
It is also only an indication . A proper battery management system that measures charging amps in and load amps out against the known capacity of the battery is far more accurate .
It ’ s easy to see why lithium batteries are becoming much more popular for RVs . Lithium batteries can sustain much deeper discharging than lead-acid batteries . They are generally capable of sustained discharges to 10 per cent SOC .
There is no build-up of sulphates on their internal plates , either , so they can be discharged and recharged many more times than lead-acid batteries .
Further , most commercial lithium batteries have internal battery management systems that protect them from over charging and excessive discharging .
A van ' s lead-acid battery is often mounted under the bed by its manufacturer .
STATE OF CHARGE INDICATOR FOR 12V AUTOMOTIVE LEAD-ACID BATTERIES
Voltage
Approx % State Of Charge
Notes
> 12.6 100
12.5 |
90 |
12.4 |
80 |
12.3 |
70 |
12.2 |
60 |
These voltages are approximate and are influenced by temperature , etc . Batteries just taken off charge will have significantly higher voltage until the surface charge drops over a period of at least 30 mintures .
12.1 50 11.9 40 11.8 30
Repeated discharge to these levels will reduce battery life .
11.6 20 11.3 10 10.5 0
Permanent damage to the batteries will likely occur .
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