Thread: Problems powering notepad with UPS in cabin

In all honesty Bill, I would go for a small 240v Genset running a "smart" charger, and have all the batteries connected as one bank, batteries are expensive, and I wouldn't risk them with just a car alternator doing the charging, or mucking about with swapping pairs about.

But to answer your last question, not far, and you will have even higher current through the cable from the alternator, so it will not get an accurate "feeling" for the voltage of the batteries.

If I have read your first posts correctly you have 8 pairs of 150Ah batteries, so thats a total of 1200Ah at 12v, so if you have them all connected together as a 12v bank, you are safe to pump 120A into them for at least 10 hours if they were flat!
That's a hell of a lot of current and stored power.

There are some good inverter/charger combined units about at the moment that can charge at 50A, and you would be looking at least 24 hours of straight running to charge the batteries from flat.

Now, a 50A charge at 12v would require a 600w genset (in reality you would want around 1Kva)
at 120A you need 1.4Kw (again probably a 2Kva genset, but you would be hard-pressed to find a 120A 12v charger)

Now as I'm sure you know it's not good practice to use more than the top 10% of charge if you want the batteries to last, so we are looking at 120Ah, so a 50A charger would replace that in only 2.4 hours.
If you had a 25A charger (300w at 12v), it would take 5 hours to charge that 10% and it could be run by a very small genset (a 500W one would do).... (in reality it is longer, but you get the idea..) all of this would allow the genny to be a long way away, and not suffer from voltage drop....

I hope some of that helps.......

Cheers,
Fraser

Thanks very much Fraser, that is all very helpful information.
To be honest, I didn't know that 240/12volt battery chargers were available in such high ratings.
Bill.

Originally Posted by wagoo

Thanks very much Fraser, that is all very helpful information.
To be honest, I didn't know that 240/12volt battery chargers were available in such high ratings.
Bill.

Bill, I have one of these and it's excellent, very efficient too.
I have since noticed these too.... there are others about too...

Just for interest Bill, where did you get your batteries from?
I have a mate who is setting up a shed on his new property to live in, and I'm the guy who's doing it for him......

Cheers,

Fraser

Originally Posted by fraser130

Just for interest Bill, where did you get your batteries from?
I have a mate who is setting up a shed on his new property to live in, and I'm the guy who's doing it for him......

Cheers,

Fraser

Fraser.
The batteries were given to me by a mate and neighbor who used to work for Telecom, who replace batteries on a schedule rather than as needed basis.
My collection is probably getting a bit long in the tooth, and I've been charging them as a single 12 volt bank for the past 2 years with an 80 ah alternator fitted to an additional belt pulley on my 6kva gen set powered by a larger 18 hp petrol engine.The engine failed about 4 weeks ago, and I figured I had more power than was required for battery charging, and the 6kva wasn't really sufficient for welding,(I have a larger genset for those tasks), Hence the fitting of the 65 amp alternator to my 8hp grass slasher.

I'm a little concerned at the amount of power the DC/DC convertor uses.
I made a 4metre long, heavy cable and placed a partially charged {11.6 volt} 12 volt 100Ah deep cyle battery close to the cabin as a trial.
With the PC battery removed and only the Modem and DC convertor connected to the 12 volt battery I only get 2 hours of operation before the PC shuts down due to insufficient power.Unconnected the battery reads 10.03 volts 4 hours after shutdown.
The whole purpose of trying to run everything on 12 volts was so that I could lose the power hungry 1000 watt invertor that i've been using to power everything for the past 2 years, that was costing me a jerry can of fuel a week to keep the battery bank topped up sufficiently to prevent the invertor fom shutting down. So far, and due only to the computer it appears that I'm no better off.
i've just connected up the small 370 cca battery out of my wifes Honda, which currently reads 13 volts when connected.I'll see how long til shutdown.
Bill.

Bill, 11.6 Volts is a flat battery!
Just for interest, is the laptop adapter getting hot? If it's not, then it's working efficiently, as any power it actually uses is given off as heat.
I've attached a little file showing what voltage equals how much charge.....

What brand/model number is your adapter? Mine is fantastic, and barely gets warm during use.




If ever you can get any more batteries, be sure to let me know!!

Cheers,
Fraser

Thanks for the chart Fraser. That is very interesting and I'm very surprised that the % of charge drops so dramatically with barely 1 volt difference between full and flat.
I have 2 brands of DC adaptors. a Power Tech Plus mp3463 one and a Ritmo brand KC195 digital output voltage readout type one.The Power Tech one that has been on for about 5 hours is still room temperature. I haven't tried the other one for more than 2 hours but don't think it got hot. I'll try it later once i know how long the Honda battery lasts until shutdown.
I'll certainly let you know if anymore batteries become available. Somebody told me that it's worth checking with golf courses, as they replace buggy batteries at scheduled periods.I haven't personally done so.
Where is your friends property? I am in the hills of Dixons Creek.
Bill.

That Ritmo one looks like it's got enough zzz's to power anything.

https://secure.vividcluster.crox.net...3&form=KEYWORD

Ritmo Online

How's the cigarette adapter? Maybe losing some at that connection?