battery charger question?

[jekyl]

I have a new refigerator on my 265 express which is on a trailer at home most of the time.
QUESTION? if i want to cool the fridge down a couple of days before taking the boat out and don't want to run my house batteries down too much .....how should i hook up a trickle charger to the house batteries, running off my domestic supply which is 240v in OZ
Thankyou in anticipation of a thoughtful and sensible answer.

 

[catch22]

If you have shorepower and an onboard charger, you could get a voltage step down transformer, and simply plug in to your shorepower.
example- http://www.alldual.com/trans/VolTRANS/S ... lation.htm
(I don't know what cycles Aussy uses, but in the US, it is 60.)

If not, can you get a battery charger that's 240 volt? If so, just connect that directly to your house battery.

 

[BobP]

I would expect to find battery chargers down under to come proper AC voltage rating.

 

[jekyl]

Maybe i wasn't specific enough....I have a domestic trickle charger.....should i disconnect the house batteries (to recharge) after running the fridge or can i run the fridge and be recharging the house batteries at the same time from the trickle charger?

 

[BobP]

That's not how chargers work.

If your trickle charger ampere rating equals the refrig load, then it will keep up with it but won't do any charging, shoud you battery not be fully charged to begin with, it will stay the same or get worse.

You can have the battery supplying the frig with the harger on all at once.

Much larger chargers (than load) may overcharge the battery if left on all the time simultaneously while load is on. I apply my charger for increments of time, never always on, when load is working.

I'll only leave my 3 stage charger on all the time if all load is disconnected or otherwise off.

 

[Tuna Man]

Jekyl,
In theory if your trickle charger produces as much or more amperage than your refrigerater consumes (about five amps I guess), you can essentially charge the batteries while you are running the refrigerator. If the trickle charger is truly just a low output charger that is designed primarily to keep the batteries from totally discharging when not being uses for long periods of time, you could actually end up with dead batteries after a few days with the chrger on and the refrigerator operating. This assumes that the trickle charger only puts out one or two amps. On the other hand, the refrigerator will probably only run non-stop for the first hour or so, after that the refrigerator will cycle (more off than on) for the next few days once it is cooled down. So for the first hour the batteries may discharge slightly, after the first hour they will recharge.

In short, leave the trickle charger on and connected to the batterys and turn the refrigerator on, I am almost certain the batteries will stay fully charged and ready when needed to start the boat.

Hope this makes a little sese. :?

 

[Tuna Man]

Bob can type much faster than I can. I was typing as his post showed up. I agree with what he suggests, hopefully we do not confuse you too much.

 

[BobP]

Tuna, i don't know if the member will be satisfied, he may tend to prefer a yes / no answer.

Don't we all !

 

[jekyl]

Thanks guys , excellent reply. My charger puts out 6amps continous, so I figure it should be fine.
I can't seem to find how much power the fridge uses. It has a bd35f danfoss compressor, But it is only 45ltrs , so your guess is probably on the mark.
Our weather here is similar to Florida so refrigeration is critical.