Deep Cycle's Toast Maybe?

[knottybuoyz]

I'm having a problem with my two deep cycle house batteries. Yup, the ones I thought were doing well after getting a good charger. When I hook up the XPower 1000 Watt inverter I get sparking at the battery terminals. That's the first symptom. Second is the inverter fault light comes on with the audible alarm. The Xantrex user manual is no help, it only indicates the alarm is for low voltage. The fault light is any one of a half dozen potential problems mostly to do with poor connections, which I've checked.

Resting voltage (after 48 hrs) is 12.65 V on each battery. I hook the inverter to my starter battery and it works fine. Is/could the fault & alarm indicate a bad cell in the batteries?

[hellosailor]

"Resting voltage (after 48 hrs) is 12.65 V on each battery."
That indicates a perfectly good battery, literally perfect. Anything higher is just a surface charge that goes away overnight anyway.

Using the same voltmeter, what does the starting battery read?

If those deep cycles were allowed to go dead or to sulphate up, it could be that you've regained voltage but not capacity--so they are failing under load when the invertor tries to suck power out of them. You could test that by measuring the voltage under load (i.e. when the invertor is connected and on) to see if it drops. Or, by using a real battery load tester like this cheap one for $20:
Harbor Freight Tools - Quality Tools at the Lowest Prices

Battery makers usually require the use of a load tester like that to actually certify if the battery will be replaced under warranty, they don't care what the voltage is except as measured under load. It is essentially a cheap voltmeter and a heavy duty resistor in a metal box, nothing really fancy.

[knottybuoyz]

Reminds me of a line from the old TV comedy, Cheers. Norm walks in the bar and Woodie automatically hands him a beer and Norm says: "Hello Sailor!"

12.65 was the voltage w/o the charger on. I'll try hooking the inverter up w/charger on see what it does. The voltage on the starter battery is 12.7 after a full days rest w/o charger.

I hauled the batteries out of the basement last week and had my buddy mechanic test them with one of those. They checked out fine and stayed in the green under load.

I've checked voltage at the inverter terminals and it's 12.63 so there's a little loss in the 6ga cables (temp test leads). Cables on the boat are 1/0 to the inverter. I'll check s/g of all the cells tonight and see what's up.

[hellosailor]

Rick, do you remember the old text-based computer games? Zork? "Hello Sailor" is a recognized phrase there too. Then of course, there's the rumour that same phrase has been used as a greeting for faceless sailors in the night in rough ports all around the world. But, you know how rumours can get out of hand.<G>

If they load test OK, but the intertor says "fault!" then all you can do is believe it--and try to find the fault in the invertor, no?

Had you posted recently about a false fault indicator and a ground loop from the ac/dc systems or something like that? Or am I just confusing threads about fault lights?

Stick a piece of black tape over it and ignore it?<VBG>

[knottybuoyz]

Originally Posted by hellosailor

Rick, do you remember the old text-based computer games? Zork? "Hello Sailor" is a recognized phrase there too. Then of course, there's the rumour that same phrase has been used as a greeting for faceless sailors in the night in rough ports all around the world. But, you know how rumours can get out of hand.<G>

Don't remember those games *lol* must be before my time! *wink* I've heard that phrase a few times in ports I've visited. In fact, if you walk down Barrington St. in Halifax, down near the train station you'll hear it over and over and over! Very friendly ladies lemme tell ya!

Originally Posted by hellosailor

If they load test OK, but the intertor says "fault!" then all you can do is believe it--and try to find the fault in the invertor, no?

What's weird is it works perfectly fine on the starter battery. The only uncommon denominator is the deep cycles. Wish the Xantrex manual was better so I could see if it was some other fault the inverter is seeing other than just low voltage. Wires aren't reversed, that'd blow the fuse in the inverter immediately.

Originally Posted by hellosailor

Had you posted recently about a false fault indicator and a ground loop from the ac/dc systems or something like that? Or am I just confusing threads about fault lights?

Nope, don't think that was me. But then again, don't ask me what I did yesterday I couldn't tell ya!

Originally Posted by hellosailor

Stick a piece of black tape over it and ignore it?<VBG>

Honey! Is the boat insurance paid?

[knottybuoyz]

Specific gravity on all cells are 1.275 or better! *scratching head* That's supposed to be good if I remember correctly and these are 4 yr old batteries! Any Xantrex experts out there?

[PBzeer]

Are you using the same cables to attach to the start bank as for the house bank? Have you tried the house batteries one at a time on the inverter? Are the start and house batteries the same type of batteries (flooded, gel, agm)? If dissimilar types, the default setting of the inverter may be set for the start battery type and not the house bank.

[Rick]

It is normal to have sparking when tentatively connecting the second lead of the inverter to a battery. The input capacitor(s) are being charged and a tentative connection is usually a make-break-make-resistive-make connection in a short period of time. What happens during the fast "break" or "resistive" time is that the inductive components are causing the arcing to the battery terminals from the charge so far received by the caps.

IF you make a definite first-time connection then the caps will accept an instantaneous current as high as the parasitic resistance allows from your battery and sometimes the terminal voltage drops sufficiently long so as to have the inverter electronics "set" a low voltage condition.

Start-only start batteries fully up will normally deliver more short circuit current than your deep-discharge house bank will and, therefore, the inverter does not detect a "low battery" condition.

I suspect that either your house batteries are demonstrating a high internal resistance (still showing full charge with a hydrometer reading) which could be improved and/or your connections are poor between the inverter cables and the internal chemistry of the battery (somewhere along that total path).

If you charge up the internal caps of the inverter by using your starter battery and then quickly move to attach the inverter wires to your house battery does it come on O.K. then?

[knottybuoyz]

Originally Posted by Rick

I suspect that either your house batteries are demonstrating a high internal resistance (still showing full charge with a hydrometer reading) which could be improved and/or your connections are poor between the inverter cables and the internal chemistry of the battery

BINGO! We have a winner folks! And the prize goes to the hansome fella in the Coast Guard Hat!

I had cleaned the bottom portion of the wing nut post where I usually make the connections and I decided to have a closer look. The bottom of the posts are almost completely corroded away! I cleaned that up and it works perfectly!
I feel like such an ijjit for not having seen that earlier!