Forums » Ask a Question

Use this forum to post your questions to our experts – you need to be logged on to do it (you can register here ), then scroll down to the bottom of this page and click the blue Post Thread words

If you can help answer the question, feel free to post a reply – you need to be logged on to do it (you can register here ), then hit the reply button on the thread.

 

To go back to the experts page click here>>

AuthorMessage
tojohnson
tojohnson

Posted: Thu Sep 04, 2008 2:56pm

Post Subject: Electrical Charging

My n/b has a mains land line with RCD but no charger. What amp rate of charger do I need to keep my batteries topped up? I have a 95amp starter battery, 3 x 110amp domestic batteries and 2 x 95amp bow thruster batteries. Do chargers have a trickle setting or do they all have automatic shut-off when the batteries are fully charged. Do I need a galvanic isolator? Many thanks. Tony

Tony-B
Tony-B

Posted: Thu Sep 04, 2008 6:37pm

Post Subject: Electrical Charging

Tony, If your shoreline feeds 13 amp plugs fitted to the boat and it is correctly earthed then you should protect the hull from the possibility of stray currents in the mains earth line causing hull corrosion. In my view an isolation transformer is more satisfactory than a galvanic isolator, but they are far more expensive. Once you have run for half an hour or so the engine battery will be all but fully charged so it may not be worth the expense of buying a three output charger, but depending upon how the boat is wired, you probably need a separate output to charge the bow thruster batteries. Unless you are living on the boat and using the charger as a sort of 12 volt power supply I suspect a two output, 20 amp charger will do the job being left on 24/7. Any decent modern multi-stage marine charger will "step down" to a maintenance charging voltage once it senses the battery bank is near fully charged - even cheapy "Argos" car ones now do this. Tony Brooks

tojohnson
tojohnson

Posted: Fri Sep 05, 2008 10:48am

Post Subject: Electrical Charging

Tony, many thanks for the quick and informative response. The charger would really only be for winter use as the 70amp alternator keeps the battery banks topped up on summer runs. I shall look for a suitable 20amp charger as per your advice. Regards, Tony.

Tony-B
Tony-B

Posted: Fri Sep 05, 2008 11:14am

Post Subject: Electrical Charging

Tony, unless you are doing very long runs each and every day even a modern alternator is unlikely to get the batteries more than about 85% charged. This will inevitable lead to loss of capacity due to sulphation. Some with far more knowledge of the subject than me even question the effectiveness of advanced alternator controllers in this respect (although I use one. If you have a multistage charger I think using it when the boat is left in its berth in the summer will pay dividends with battery life as long as you keep an eye on the electrolyte level. If you have been persuaded to use AGM batteries it is vital that you get a definitive maximum charging voltage because one type may need the charger setting at a lower than normal figure. If, by some chance, you are using gel batteries you must ensure the charger can be set for them. Tony Brooks

tojohnson
tojohnson

Posted: Tue Oct 21, 2008 5:23pm

Post Subject: Electrical Charging

Tony, further to your useful replies of earlier, I have decided to buy a three output charger. My question now is as follows. The online technical instructions for the three brands that I have researched all tell you to wire the outputs to the relevant battery terminal. I have a Victron FET isolator enabling my single alternator to charge all three battery banks (starter, domestic, bow thruster). Can I safely wire the charger 12v positive outputs direct to the FET battery terminals and the charger negative outputs to the single FET negative terminal. I'm sorry if this is an obviously stupid question but my priority if electrical safety and no fire risk. Many thanks for your time Tony.

Tony-B
Tony-B

Posted: Tue Oct 21, 2008 5:41pm

Post Subject: Electrical Charging

Dear Tony If its a three output (as opposed to a three stage) charger why bother with the FET wotsit (FET stands for Field Effect Transistor)I very much doubt connecting the charge to the Battery side of the charge splitter will do any harm, but you need to check with Victron I suspect its a based on an electronic form of a voltage sensitive rely so it might disconnect when the charger drops down to float voltage. If you connect to the battery side its possible, but not probable that the charger might produce a voltage high enough to back feed into the splitter so phone Victron and ask. It is not a stupid question if you need to know. The stupid ones are the ones that say My boat wont go, what's wrong? Tony Brooks

Most Read

Like us on Facebook



Follow us on Twitter

Cache: Disabled for this object  Total Queries: 43.  Total Objects: 162.  Total Unserialized: 3. Total Runtime: 0.25 seconds.