Older "Professional Mariner" 35/20 Amp Battery charger

[StellaBorealis]

Older \"Professional Mariner\" 35/20 Amp Battery charger

This large loud blue steel monster came with my recently acquired Magellan 36' Ketch and the house bank is knackered. There was no water in the cells and after refilling them and testing their SG the following week they were still quite dead. Consequently I am replacing the house bank and intend on getting a significantly higher capacity bank. It occurs to me that the old Battery Charger/DC Power Supply might have contibuted to cooking off the batteries. I have found no detailed specifications for this device but the front of the case indicates a charging rate of 13.8volts and while i know this is a safe rate I thin without proper 3 stage charging the new bank might suffer the same fate.

So, should I replace my charger as well as my bank, if so, what would be a good replacement? Also I am in the US so it has to be something that functions off of 120V AC at 50hz (I believe the US is 50 and the UK is 60 correct me if I am wrong)

I am very glad to have found this forum as my recent experience working toward yachtmaster has convinced me that the UK is the home of the serious sailing.

Cheers,
=====
Fair Winds and
Following seas,
Adam Yuret
s/v Stella Borealis
Magellan 36' Ketch
http://www.stellaborealis.com


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[William_H]

Re: Older \"Professional Mariner\" 35/20 Amp Battery charger

Hello Adam It is amazing how much serious sailing is done in UK with such rotten conditions of weather and tides. I am visiting UK this june but wouldn't dream of trying to sail. I have had it too easy here in West Oz.
Battery chargers. The contradiction is that you need high voltage to get large current into a battery. But when it is charged that high voltage will push high current in to boil destroy the battery. An engine generator is voltage regulated to 13.75 volts which will charge the battery well when it is low but only a little when it is nearly charged in a way that is safe for long term charging. Now am guessing that your battery charger if quoted at 13.8 volts is a regulated type which will perform similar to an engine driven generator (alternator). The chargers usually transform and rectify to a voltage about 18 volts which then passes through a regulator transistor to deliver 13.8 volts regardless of current drain. This should be quite suitable for connection to shore power where it will keep the battery topped while also providing power for your domestic use. Unfortunately a common failure mode for power transistors is to short circuit internally which then delivers 18 volts continually which will cook your batteries.
So what you need is a good multimeter that will measure voltage and current preferably to 20 amps or a separate amp meter. Check the voltage out of the battery charger with no connection or preferably with a 12v light globe connected if it is 13.8 volts then you have no worries. Connect it then to your new batteries and check the current going in. A few amps is good. It may start at 10 or 15 then fall to just a few after 30 mins or so. (this depends on the size of the batteries and how discharged they were at the start.) If the battery charger gives lots of volts and charges at a high current then it may be it has shorted regulator transistors or it may be that it is a crude type without regulation. If it is the latter it is not necessarily useless but definitely can not be left charging indefinitely. I would suggest you limit yourself to 1 hour at 20 amps once per week for 200AH bank. (obviously 2 hrs at 10 amps is ther same) You need to add to this your estimated current use in amp hours. It gets a bit difficult but basically a not quite full charge or a slight overcharge wont hurt but many hours of high current will. So max of 10% of AH battery rating per week and a min of 5% are some ball park figures.
Now if you go for a staged charger the idea is to quickly fill the battery then reduce the current to a rate which is safe for long term charging. Great but not necessary if you are willing to use amp meter voltmeter and clock to monitor yourself.
You implied that you based your estimate of the old batteries as dead on the hydrometer readings. If they were dry and you put in water you will not get any correct SG perhaps you should add a little sulphuric acid as well. I would be measuring voltage after a long slow charge and check for voltage after running lights etc for some time. You should also see how it handles trying to start the engine. These are the critical real life tests that matter. Don't rush to spend money on chargers although you may need new batteries but do get a meter and learn what is happening by looking at this forum and asking questions. PS 50 cycles power in UK 60 in US but it doesn't usually make much difference to chargers maybe a little hotter running but of courser the voltage is critical regards will

 

[dickh]

Re: Older \"Professional Mariner\" 35/20 Amp Battery charger

As william H says, don't dump the charger yet. Not familiar with the pro Mariner range which appear to be a US company - search on Google and you may get more info on them. They certainly seem to be still selling a range of chargers. The latest ones also seem to be multi-voltage.

 

[mcheca]

Re: Older \"Professional Mariner\" 35/20 Amp Battery charger

Adam,
13.8V continuosly applied will cook your batteries. Your charger must "float" the batteries at 13.3V.
Contact ProMariner and ask them for support: http://www.pmariner.com/contact_us.php or call:
Allan Butler
Service Manager
Professional Mariner
603-433-4440
Good luck!
Mike Checa
"Sailors' Choice"
Port Canaveral

 

[john_morris_uk]

Re: Older \"Professional Mariner\" 35/20 Amp Battery charger

With respect you are wrong reference 13.8 volts cooking batteries.

One might note that a standard car alternator is normally set to charge withing the range 13.8-14.3 volts when everything is on. And one doesn't cook a car battery by driving for as many hours as you want!!

There are several factors that will give the maximum voltage that a battery charger must not exceed for long periods, which are too complex for me to explain in the time I have got now.

The voltage that a high impedence multimeter might show when the battery charger is not connected to a battery is almost completely irrelevant. (I know that you say better to connect it to a globe- I assume you mean bulb to provide a load.) For any meaningful reading, the test must be a lot more sophisticated. For instance my Sterling charger shows 0 volts when its not connected to a battery!

 

[halcyon]

Re: Older \"Professional Mariner\" 35/20 Amp Battery charger

If the batteries have been run for a long time at 13.8 volt, this will kill them. They need a periodically running up tp 14.6/8 volt. This may be the reason for the failure.
If you are using the engine on a regular basis, and it charges to around 14.4/6 volt, you could live with what you have. That is assuming it is working correctly, ie 13.8 volt as maintainance charge while in marina.
If you want to change the charger the new range of solid state Newmar charger's are now running OK, and are made your side of the pond, so could be a good option.


Brian