Tuesday, September 29, 2009

More inverter charger

More inverter chargerI'm posting more on the inverter charger, simply because I can't get over just how significant this is to Lady Jane and all who sail on her.

First off, it's a Studer XTM-3500-24. An pure sine inverter/charger which I bought from Barden at the boat show. Following some negotiation, I got what I consider was a excellent price for both the inverter charger and it's accompanying remote control/display unit (RCC02). By the way, I'd say the remote control is pretty much essential.

Previously, I'd been planning on buying just a 3kva pure sine inverter. As it works out, it costs about the same for an inverter charger as it does for an inverter, with the advantage that the inverter charger does more.

Again, it was mainly on price that I opted for the Studer inverter charger. This worked out at close on half the price of the inverter I had been considering. Plus the XTM-3500-24 is capable of far more.

The main thing is that the inverter provides 3.5 kva, which is more than the 2.0 kva generator I normally use for most power tools and certainly more power than the 1.0 kva pure sine inverter I bought because of the central heating. More powerful than both of them put together in fact.

Having this power available to me directly from the battery bank means I can pretty much do everything, except welding, without using a generator. All kinds of things now become possible without any special thought to the power likely to be consumed including:

  • Using the microwave
  • Making toast
  • Power tools of all descriptions
  • Patch's hair dryer

For any of the above, I previously had to start up the generator specially.

What had become an issue for me with the previous setup was the automatic switch-over between inverter power and generator power had a small time delay. This was enough to cause a power failure in whatever was running at the time:

  • The central heating system relies on power to cool it after it's been running. This would just shut down, and sometimes play up on a manual restart. I had to resort to waiting for the hot water/central heating system to stop completely before I could switch to/from generator power.
  • The radio I use on deck would shut itself off during switch over. In doing so, annoyingly, it would reset back to it's default settings, so needed fiddling with to get back to the station I was on (I tried using rechargeable batteries, but that was not a big success).
  • If the fridge motor happened to be running during switch-over it would, for some reason, consume a huge amount of power running at full speed when the power went on again.

This new inverter charger acts like an interruptible power supply (UPS), so there is no power failure on switch over. Even the radio carries on as if nothing happened. Now I can start and stop the generator pretty much at will with no problems at all.

With the new inverter/charger, my thinking on generator power is changing. It now more fulfils the role of a battery charger than it does that of a mains power provider. This is mostly because I'm no longer concerned about that switch over from battery to generator power. That automatic generator startup on a defined voltage level really comes into it's own now. I am developing more on this, so will post about it when I'm further down the line.

Sometimes, new visitors to Lady Jane don't grasp the significance of appliances and their power consumption, and just leave things running. I'd have the generator running then sometime after shutting it down would discover the inverter had tripped and that the fridge has been off. Obviously this should no longer happen.

This inverter seems to be vastly more efficient than the last inverter, as evidenced by the higher than usual voltage showing the following morning. I suspect that it's ability to hibernate when there is no power demand is a big part of that.

The remote control shows all kinds of cool stats, this helps me keep a close eye on things like the battery voltage and mains amps being consumed.

I now have two easy to program relays on the unit. One of these will be used for powering a socket, initially only when a generator is running. I could also use this to power my Christmas lights each day between 5.00pm and 11.00pm come December. The other, I have yet to decide what to do with.

The inverter/charger also saves me that valuable space the battery charger took up.


  1. Nice job tim! I have a generator and mainly use it, like you did as needed (as I don`t, yet,have an inverter on this boat) but I cope OK with it as it is, also I charge the batteries as they move down to below 26v.

  2. Anonymous2:27 PM

    I have been struggling with my own inverter-charger setup -- it doesn't like my generator and won't switch over the loads and charge the battery. A real frustration as that was the principle requirement for upgrading to the inverter-charger.

    Anyhow, I think you have yourself a fine piece of kit there and may be deservedly proud of how it performs.

    On the charger side, how powerful is the one in your inverter? Does it get along well with other things (wind, maybe solar one day) also charging the batteries at the same time?

    My old charger used to get confused when there was current coming in from the solar panels, and switch out of bulk charge into trickle. I rather think my new inverter-charger may have the same issues. I may have to create a relay cut-out that disconnects the solar charge controller whilst the generator is running.

  3. Hi Rob

    Ahh, the bliss of having say a PC running without the generator noise in the background):

    You know you need one..



  4. Hi Anonymous

    The charger is capable of 90amps, though I've had to throttle it somewhat for my little generator 2000W = a max of 71 amps at 28.8V.

    I've not had any proper wind about to tell if I have a problem with external charges, but the Studer user guide has pictures of alternate energy feeds in the system, so I'd expect they'd work just fine.

    Only time will tell...



  5. Most of this went over my head, but Hubby is avidly following all technical details and keeps making notes along with muttering something about 'that's interesting'. From a girlie point of view, great that it runs the hairdryer and that the fridge stays on to chill the wine!!!!

  6. Hi Fran

    Sorry for the long, technical, stuff.

    It's just that, so far, I'm very pleased with the result.

    I also feel that if others (eg. yr Hubby) can also benefit from this, then so much the better.



  7. Hi Tim, We are actually learning
    at lot from you.I admire your technical know-how and wished I had a bit more of it. I can only just master the dvd and usually only with the help of a child!! Keep up the good work and the blog - we need you!

  8. Hi Tim, most of what you said went over my head as well, but I am grateful you are posting about it. You don't realize what a convienience it is to plug something in and have it just work magically. When I was on my boat, I had shore power but only 2 20 amp breakers so couldn't use more than one heat producing appliance at a time. I am the worlds biggest energy hog I'm sure, have all kinds of gadgets and lamps that all need plugging in. Most of my rooms have a snake nest of extension cords running everywhere. When I get my place built, I want to factor in being off the grid and I will come back and reread your posts and grill you with questions so I get the best setup for my needs. Keep up the good work, your ship is looking better all the time.

  9. Hi Cyberangel

    Thanks for that.

    I'm learning all the time, so am happy to pass on that knowledge and maybe save folks their time and money.

    This is the fourth inverter I've bought and, as it happens, also the fourth battery charger I've bought!

  10. Hi Fran

    I don't claim to be any kind of expert, and have made plenty of mistakes along the way, so advise people to also do their own research into things.



  11. Thanks for the sharing the updated information. Yes new inverters seems to be vastly more efficient than the older ones and they have the ability to hibernate when there is no power demand.

  12. Hi Power Protection

    Hibernation is not always a good thing!

    I now have the situation where the neon light down below will not turn on if the inverter is hibernating.