30th August 2022
Marine Battery Testing, Get to Grips With Berthon Spain’s Electricians


How To Test A Marine Battery

One of the most common questions our electricians are asked is “Can you test our batteries?”, or just about marine battery testing in general. When not in port and plugged in to shore power, yachts rely entirely on their battery bank to keep them functioning. With the modern day desire for everything to be electrical and linked to the internet, it is more important than ever to keep your batteries in the best condition possible.

Recharging The Marine Batteries

When stepping on-board to check the overall condition of a gel battery, the first thing our marine electricians will do is to charge them up. Once fully charged, they are disconnected and left completely alone for anywhere between 12-24 hours before being tested. We take our specialised battery tester on-board, which will give each battery a CCA rating. This Cold Cranking Amps rating, printed out from the battery tester, will give a result of either “Good” or “Replace”.


From that result, depending on the individual battery specifications, we can advise what action to take. Generally, if 30% need to be replaced, then our advice would be to replace all of them. For example, from a bank of batteries, if one or two are gone, the following discussion with the owners would be on the topic of replacing the whole bank.


In the case recently on board an Azuree 46, after checking through the Mastervolt installations and the configurations of all the devices on the network, our electricians found that despite all functionalities working as they should, the alternator was giving out less than half of its expected capacity. This called for a replacement Mastervolt alternator and a newer model Mastervolt regulator to be installed.


How Long Should A Marine Battery Last?

Batteries have a set life span; they can only be charged and discharged a certain number of times. Ultimately, the lifespan depends on the usage and care. A battery at 0% is very bad, and ideally should not be discharged to less than 50%. Therefore, monitoring your batteries is vital to keep them functioning as they should. Our marine electricians will always recommend the installation of a battery monitor and our guardiennage team include a battery level check on their weekly checklist.


An alternative to the more common gel batteries, are lithium-ion batteries. Whilst they are still a very expensive option, they are definitely a good choice. They come as standard with an inbuilt safety computer. This will monitor the temperature, the charge rate, the discharge rate and keep a look out for any anomalies. If any of this collected information is outside of the safe operating parameters, then the system automatically breaks from the circuit as a safety precaution.


Earlier this year our marine electricians installed a bank of 4 Mastervolt MLi Ultra batteries on a CNB 76. Also fitted alongside these were a new Mastervolt alternator and Masterbus network with Mastervolt Easyview. The addition of a USB interface to the batteries is beneficial to both the captain and our electrical engineers. As long as the yacht has access to internet, it is possible for the owner or captain to plug in a laptop and allow us to log in and check the condition of the batteries from anywhere. A recent battery settings issue on a yacht at anchor in Ibiza was able to be solved from a deck chair in the garden of our marine electrician in Mallorca. What could be better?!

Contact andrew.fairbrass@berthonspain.com.

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