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FAQ Lead-acid batteries

Frequently asked questions about lead-acid batteries

What happens when batteries discharge each other? How deeply can you discharge without damaging them? On this page, we’ve gathered answers to the most common questions about lead-acid batteries in boats – from charging susceptibility to lifespan, peak charging and how to avoid unnecessary wear and tear. Perfect for those who want to understand more and take care of their batteries properly.

It is a measure of how well the batteries receive power. Larger battery banks give higher charge receptivity. Older batteries have lower receptivity.

No, as long as you have healthy batteries, only small currents will flow, the effect of which takes a very long time. However, a defective battery will also drain the healthy batteries in the same circuit, and eventually damage them.

No, the starter motor lowers the voltage more than the discharged batteries and will suck all the power. If you have a diesel that needs to be glowed, there will be a small current from the starter battery to the consumer bank for a few seconds, but it will never be over 1 Ah.

After three years, many have only half of their battery capacity left. Then it may be time to change.

Yes, it does. Extending the battery bank increases charge receptivity and reduces deep discharge, which reduces wear on lead-acid batteries. Handling them when not in use also affects their lifetime.

To avoid drastically shortening the life of your lead-acid batteries, marine and leisure batteries should rarely be discharged to 50 per cent. In normal use, you should ideally stay above 70-75 per cent of the battery’s capacity. Gel and AGM batteries are more durable.

If charging continues for a number of hours at 14.4 V, lead-acid batteries become overcharged. In the past, lead batteries gassed a lot. Nowadays, much of the gassing in lead batteries has been removed. Therefore, few boats run on the engine for so long that gassing becomes a problem.

You cannot find out how much electricity your lead-acid batteries really contain when they are fully charged by measuring the voltage. If your lead-acid batteries have lost capacity, you can find out by carrying out a load test.

Yes, because the durability of the batteries increases if they are top-charged occasionally. A solar panel can last for weeks while the boat is not in use.

Of course, but the disadvantage is that you have to run cables across the docks and look for electrical outlets. It’s easier with a solar panel.

Yes, if land soil is not separated from soil in the boat.

Avoid old transformer chargers and opt for a modern charger instead. Large chargers charge faster than small ones, but are more expensive. However, you rarely need a charger that can handle more than 10 amps.