Transformer to build 12 volt battery charger

[rovmike]

Looking to build 12 volt battery charger for a project. Having trouble finding a transformer with 120 vac in and 15 vac 10 amp output. Anyone have a place to recommend.

 

[davenn]

Hi there
welcome to the forums

that should be a reasonably common in and out voltage at that current capability

Any decent electronics parts supplier should be able to supply
you could try Digi-key in the USA

Dave

 

[rovmike]

Thanks dave

 

[duke37]

I presume that you will need DC. If so why not get a simple battery charger?
This will give you mains insulation, fuses, rectifier, ammeter and case.
Cost will be similar.

 

[rovmike]

Well I am trying to build my own to make four bank charger for my boat. I found everything but trying to find the right transformer. I the output to the battery to be 14 to 14.5 volts to supply to the board that will operate the trickle charge on e battery is full. I have purchased the on on board chargers and they rarely last over 2 years. At $400 a pop it is kind of hard to go buy another. Corrosion is the usual problem. These units are air tight sealed to go in a boat but the problem is the condensation. They are desiccant pads in them but they get saturated and spill out all in the unit. My plan is to build a sealed unit and fill it with shell diala. This would not allow the condensation and would help with the cooling. Plus I plan to build this so I can replace parts. The one on the market are sealed and you can not access the internal parts. Just thought I would let you guys know what my plan is. Just need what type and size transformer i need to charge the batteries at 10 amp per battery. Thanks for all the help!

 

[davenn]

so I assume you do the battery charging when the boat is tied up at dock ?
or maybe when its at home ?
ie ... the 2 places you will have access to 120VAC

Dave

 

[rovmike]

Yes it will be charged at home. The charger will be mounted in boat with 120 vac cord coming out to plug into wall

 

[duke37]

I do not think that any filling will stop condesation unlass the box is hermetically sealed. You could change the desiccant regularly.

You could keep the chargers in your house and connect to the boat with a multiway cable.

 

[rovmike]

Really want keep charger in boat. We oil fill our transformer where we work and we check for water once a year, and change it out every three years. I have yet to see any water condensate in it. How could condensation build when there is no air. It will be completely full of fluid with small compensator to adjust for oil expansion due to heat.

 

[rovmike]

Still need info on the transformer size.

 

[kellys_eye]

Using a 'simple' transformer/charger unit is a sure way to shorten battery life. You need a properly regulated and conditioning charger and it doesn't need to be 'multiple amps' either. Since you're alongside and the vessel is being unused for long periods the rate of charge can be relatively low as 'there is no hurry' (is there?).

Accordingly a simple car battery charger with the required maintenance function (float/trickle) will more than suffice.

Mains transformers aren't cheap - you'll find that a small commercial charger is cheaper than a transformer......

 

[Martaine2005]

@kellys_eye
I think that boat sank nearly 9 yrs ago.
No problem though, I relayed this message in a bottle.

Martin

 

[kellys_eye]

I think that boat sank nearly 9 yrs ago.

:lol: - I have no idea why that showed up on the list of 'new posts' I usually click on. I didn't even notice the date!

 

[Martaine2005]

Happens to us all
hope they’re ok though!.

Martin