charging trouble deux

[labrador]

Have a xantrex smart charger with AGM batteries. While at the boat the other day, wanted to check everything out for this coming weekend. Generator wouldn't start, not enough voltage to get it to turn over. Started looking at things and found the battery charger charging less than 5 amps. upon further investigation saw the charger set to wet cell batteries and not AGMs so corrected that and the charger started charging 20 to 30 amps right away. Let it go for a while and got out my load tester and all batteries 3, were fine. about 45 min later, tried the gen and started right up. Went back to the boat last night and the charger was set to AGMs but charging less than 5 amps again. Tried the gen and same thing as before, not enough juice. Started the mains and no problems there, charging on the alts were 13.7. 10 min later started the gen with no problems. I'm lost on this! anyone have any suggestions?

 

[REBrueckner]

I would have thought the wet cell charger setting sufficient to charge AGM's enough for starting....not optimum maybe, but surely enough to turn over a generator...don't get that.

I'd jiggle the AGM/Wet cell switch and see if that bumps up the charge rate again.

This Xantrex charges port, stbd main engines (which started ok) and a separate genny battery...which did not?? Is that correct??

If so, I'd check the voltage during charge at the gen battery...see if it's close to the port and stb voltages at those battery terminals. Could be a loose connection to the gen batt from charger, or from the gen battery to the gen?? Maybe a starter problem...common on some ONAN's. If you have a battery combiner, with gen batt on the secondary, could be a dirty combiner contact....

{I just went thru several weeks of inconsistent starter turnover on my riding lawnmower... am running it daily to cart mulch around....I had the starter off, disassembled, looked good about a monthor more ago....then the starter relay, seemed ok, too ,....I thought the battery was failing and I'm still not positive, but since I tightened battery terminal bolts..and they did NOT seem loose...starter turns over just fine. . }
It's usually something minor!!!

(PS: rsmith: see, I do actually fix some things myself despite your disbelief!!)

 

[labrador]

Thanks Rob, I checked the terminals at the battery an no sign of any corrosion at all. Terminals are tight, will check the connections on the gen itself. It's a Phasor 8.5kw and haven't had any problems except the start issue. While sailing on a friends boat we charge from the main yanmar and it developed a spot on the starter where it was dead until you phyically hammered the starter, then would turn over. I don't want to have to do that!!!! You can see on the amp meter that it's pulled way down below 10 volts when I try to start the damn thing. just not getting enough juice and can't figure why?????

 

[Canuck Dennis]

Grounds, grounds, grounds...re check them all, specially on the gen set...

 

[jim rosenthal]

Yes, and Xantrex chargers aren't the most reliable ones, although mine has behaved itself....it sounds like something is wrong in the charger itself. Not with the connections to it, but inside it.

 

[Boatsb]

Sounds to me like the genny battery is not getting a charge because the charger sense circuit is not monitoring that battery properly but what do I know.

Anyone need some 64 Ohm resistors?


Oh sorry they are for isolator installs.

 

[REBrueckner]

"...the charger sense circuit is not monitoring that battery properly.."

Possibly....Different chargers sense differently...On my Xantrex STATPOWER 40's, the sense circuit is on the left most terminal when facing the front of the charger. So that's the terminal that should typically be connected to house batteries which are the ones likely to get the most discharge.

I had multiple chargers and to avoid that sensing issue I connected different terminal "1's" to different battery banks....that way I knew one charger would ALWAYS sense a low battery bank.

 

[Boatsb]

"...the charger sense circuit is not monitoring that battery properly.."

Possibly....Different chargers sense differently...On my Xantrex STATPOWER 40's, the sense circuit is on the left most terminal when facing the front of the charger. So that's the terminal that should typically be connected to house batteries which are the ones likely to get the most discharge.

I had multiple chargers and to avoid that sensing issue I connected different terminal "1's" to different battery banks....that way I knew one charger would ALWAYS sense a low battery bank.

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Each bank should have it's own voltage monitoring. If you charge all the banks based on the needs of the house bank you can fry the others. Thats why you have multiple banks on the chargers. Multiple charges on the same battery makes no sense either.

 

[Trojan]

Grounds, grounds, grounds...re check them all, specially on the gen set...

If this is a new problem. Like said check the grounds. Your looking for a high resistance in the connections going and coming to the batteries. The charger is most likely seeing a low draw ( high input resistance )and thinks the battery is full. Clean the terminals and grounds before doing anything else.

BILL

 

[REBrueckner]

"Each bank should have it's own voltage monitoring. If you charge all the banks based on the needs of the house bank you can fry the others. Thats why you have multiple banks on the chargers. Multiple charges on the same battery makes no sense either."

zero out of three!!

Xantrex and several other brands, which I don't recall discussed here in the past, only have one bank monitored.

Hooking up the sense lead is what the manufacturer recommends.

Multiple chargers makes as much sense as twin screw engines....when you need extra power, you've got it, and redundancy....

 

[labrador]

Found the problem and fixed it Fri. morning. Battery cable to the Gen was a little loose. Tightened up on the hot leg and she started right up. Only took about 1 1/2 turns on the nut to tighten however guess that's enough to ruin the contact. Thanks for the help as we stayed out at Cape Lookout for three days with PERFECT weather! GJH was out there also along with a throng of boats. Had the beach to ourselves yesterday morning however as most left 1st thing on Mon. morning.

 

[REBrueckner]

Usually a good idea to separate a loose connection, clean the contact surfaces shiny to remove any arc pitting, then reassemble tightly.

I got into the habit of then spraying with the purple battery terminal protector...I used to use grease...both messy.....Don't know if it REALLY does any good or not....that purple stuff stays wet so when you lean or brush against it, you still get dirty...on the other hand it's really easy to wipe off when modifying or cleaning terminal connectors later.

 

[Trojan]

Good for you. Glad it was that simple. As I said most problems with auto charging batteries is bad connections. Everyone wants to throw out there chargers and buy new. Good auto charging has been around every since IC's were invented. Not many changes in theory, only construction. I still coat all my batteries terms and connections with good old Vaseline. It's been working for me for over 66 years. El cheap'o

BILL