Charging one battery with another thru and inverter
Submitted: Friday, Apr 11, 2008 at 15:33
ThreadID:
56541
Views:
5276
Replies:
8
FollowUps:
21
This Thread has been Archived
porl
Hi
This is because I am facing an unusual situation where the principal battery will only be used occasionally and reduced only say 10-15% from full. It is situated in a place where there is no mains electricity. Rather than crank up a gennie and so I don't have to leave solar panels lying around and I can do something else, would it be effective to charge it by leaving a fully charged battery with it, wacking on an inverter and running a 240V battery charger to the slightly discharged battery? Then i would of couse taking the draining battery
home to be fully recharged on 240v.
Reply By: Member - Phil G (SA) - Saturday, Apr 12, 2008 at 22:03
Saturday, Apr 12, 2008 at 22:03
There are other 12V powered battery chargers that are used by the Electric model plane/helicopter/model car people and are very flashy, relatively cheap and will probably do the job you require.
I have one thats about 8 years old, called a SuperNova 250S. I use it to charge all manner of NiMh rechargables, but it also charges Lead acid up to 50Ah capacity.
I've just been playing with it in the shed. I've powered it from a small 7Ah gel cell, and used it to recharge my twin N70 batteries (160Ah) to see what would happen, and whether it would work.
Well it worked very
well - even though my car batteries were already
well charged, it still upsized the voltage to 14.12V and was putting 4.2 amps into my car batteries. The voltage on the small gel cell was 12.37V while the charger was going.
I don't think the SuperNova are still around, but they have been replaced by fancier models. An example is the
Swallow battery charger from Model Flight. For $99, its a bargain, but you can spend a heap more money for the flashy German built chargers listed on that site.
This has the ability to charge almost any type of battery (NiCAD, NiMH, Lithium and SLA), but as far as sealed lead acid batteries go, it will also charge them at up to 5 amps. Input voltage is 11-15V.
I will add a disclaimer that I haven't used a Swallow Charger but its specs are the same as my SuperNova, so I can't see why it wouldn't work.
Cheers
Phil
AnswerID:
298170
Follow Up By: Nomadic Navara - Saturday, Apr 12, 2008 at 23:51
Saturday, Apr 12, 2008 at 23:51
Phil
These are similar to the Arrid Twincharge. They do not seem to incorporate any automatic switching down to trickle charging rates like the RanOx does. They are also low current devices with limited applications for the size batteries we use in our vans.
PeterD
FollowupID:
564291
Reply By: Robin Miller - Monday, Apr 14, 2008 at 13:11
Monday, Apr 14, 2008 at 13:11
No Problem Porl from the electronics point of view.
Thats what I do with my $39 laptop supply invertor with the output set on 15v and a small resistor is series to limit peak current.
I use an 18ah gel cell to run the laptop converter and its fairly portable and is great to top up bigger batteries.
Saves me some time as I have a tractor left unattended for weeks some times, and the boost gets her started without having to remove the main battery.
If you were to leave such a device connected and unmonitored for hours then you need to add a series power diode to drop charge volts to 14.4
AnswerID:
298433
Follow Up By: porl - Monday, Apr 14, 2008 at 13:13
Monday, Apr 14, 2008 at 13:13
Great, that sounds the go.
FollowupID:
564524
Follow Up By: Robin Miller - Monday, Apr 14, 2008 at 13:40
Monday, Apr 14, 2008 at 13:40
These laptop chargers mostly come in 3 and 6 amp versions all under $50 from Altronics/Jaycar/D Smith etc
Unlike the much more expensive Arrid types they drop a fuse pretty quickly if overloaded say by attempting to charge a flat battery and a resistor is some protection.
A common 1 ohm 10 watt resistor is usually a good starting point.
The charger I use has a visible inline car blade fuse and its easy to change or see if it is blown.
FollowupID:
564527