Tom T's posts

Hi Patrick,

Thomas is very likely correct that the pump has a capacitor start motor.  That would be the best explanation for more than two wires. 

I have a 3/4 Hp pump and a much shallower well.  I'm running mine at 230 volts.  The line losses start to add up at 115 volts.  I measure 6 Amps running with a 20 Amp surge at startup.  I have it battery backed up with a pair of Xantrex DR1524 inverters.  I use the two inverters stacked to get the 230 volts.  It was a bit of a toss-up as a 1500 va transformer to go from 115 to 230 would cost almost as much as the second inverter.   

The Magnum inverter looks like it will probably do what you want, but at a steep cost.

If you're very serious about powering your pump only from solar, I'd suggest using a DC pump.  In doing so, you remove one layer of inefficiency in the inverter. 

AltE sells a Shurflo, and there are several other brands out there.  Not super cheap, but still less costly than the Magnum. 

Good luck,

Tom T.

Steve,

550AH will power a 5000 Watt inverter.  A 100AH battery bank will power a 5000 Watt inverter.  BUT! You won't be able to get 5000 watts out of it at 12 volts.  And as Dennis said, you wouldn't want to draw that kind of current from your batteries.  It'll destroy them. 

At 12 volts, to get 5000 watts, you'll be drawing over 416 amps.  Even 4-0 wire won't carry that safely. 

To get 5000 watts, you'd be better off wiring them in series to get 48 volts.  5000/48 is a little over 100 amps.  #2 wire can safely carry that. 

Read.  Read.  Read.  Next time, we'll have a quiz on why we should keep the current through our wires as low as possible. 

Good luck,

Tom

I think I've solved the problem. 

Xantrex supplies a stacking cable with only 4 wires.  It's has a telco style modular connector at each end.  I replaced it with a similar cable but with 6 wires.  The extra two wires connect to the outer two contacts in the connectors on the inverters.  Both outer contacts are grounds and they add shielding to the communications signals between the two inverters.  Without those two extra wires, the inverters would lose communication with each other and shut down. 

I discussed the different cable with the Xantrex support tech.  He said there'd be no problem using the 6 wire cable instead of the 4 wire. 

The system ran for over three weeks and was still working when we had a power outage yesterday.  It supplied power when I needed it and charged the batteries when the power came back on. 

Thanks to all who offered suggestions. 

Hi Tom,

When I power each unit up they both go through their self test and the fans briefly run at that point, but they're not running before the units shut down. 

No luck.

One of the two inverters shut down some time last night. 

Any other suggestions?

Hi Ron,

1 I noticed all of the battery wiring schematics in the manual were drawn as you described.  So that's how I put my system together.  I got the sense that they were trying to balance wire length so that the longest positive lead connected to the battery with the shortest negative lead and vice versa. 

2 and 3 My AC neutral is only bonded at one place.  At the moment I'm grounding everything to the AC ground.  Would it be advantageous to sink another ground rod outside the wall were my inverters are and ground my inverters to that?  I do understand the importance of a single neutral bond, so this would only ground the battery negatives and the inverters.  I also set up the system with Xantrex's DC disconnect box (DC175) and DC ground block.

4 Last Sunday, I replaced the interface cable at the suggestion of the Xantrex tech.  The system stayed on until Thursday.  The longest they've stayed on yet.  On reading your notes, I went to check the charge rate settings.  In all the tweaking an toying, I had left one unit at max charge rate.  So, I'll set that to just above minimum and try again. 

Hi Jon C,

I've got the charge rate turned down low as the battery bank is small.  And I haven't yet added any other charging source. 

At the moment I have the system charging the batteries.  Both inverters are float charging and the battery voltage is 27 volts.  I've never seen it go above about 28 volts. 

I don't think it's battery voltage as I can charge with a single inverter without a problem.  I'm convinced it has something to do with stacking the two inverters. 

I'm still scratching my head in puzzlement. 

Looking for anyone who's got some experience with Xantrex's DR series inverters. 

I've got a problem with my power backup system which uses two Xantrex DR1524 inverters. 

The system uses the inverters in a stacked configuration to get 240V.  I bought Xantrex's DRI cable to connect the two.  I've got four 12V 92AH batteries in a series paralell configuration to both inverters.  The batteries are new.  The system will recharge them and I have run it in inverter mode. 

The problem is that the inverters, while charging the batteries, will randomly shut down.  They stop charging and all the lights go off on both units.  Typically, when I power the units on again they'll start charging, but again after anywhere from twenty minutes to several days, both units shut down. 

I can run a single inverter to charge the batteries with the DRI cable disconnected, and the single unit will stay on.  I just can't get the stacking setup to work. 

I've traded emails with Xantrex's tech support.  They had two suggestions:  make sure the systems are grounded and try a different stacking cable.  I've grounded the system seven different ways to Sunday with no success.  I thought I had something when I replaced the communications cable (looks like a phone cable) but after four days it happened again. 

Does anyone have any suggestions?

Yikes! 

60 watts and you crank it for an hour to get... 0.06KWH!

That's a lot of cranking for not a whole lot of energy.

Can anyone calculate the calories you'd burn in the process?

Interesting idea, but I'll stick to lounging in my lawn chair while I capture the sun's much more plentiful energy.