Minimal output from charger

I have a Xantrex Truecharge 40+ charger feeding 2 AGM 8D house batteries while on shore power. But for some reason, the charger is stepping down to only 2-5A output even though my Xantrex Link 20 monitor says that my batteries are at -320Ah (80% spent). This is further confirmed by the monitor showing close to net-0.0 charge state even with minimal draw on the batteries (in other words, everything is off, but the batteries still aren't charging). I've been doing a lot of troubleshooting with the charger, but now I'm starting to wonder if the problem is actually the monitor. Is it possible my batteries are actually fully charged and it's just my monitor that is out of whack?

Check the batteries with a battery tester. Even a multimeter will give you voltage, if they are really -80% it will show.
I don`t have any Xantrex onboard but plenty of TFers have been uncomplimentary about Xantrex. And you have the double whammy, charger and SOC meter.

That's a good tip. But how would I know if the battery is full? Is there a specific voltage that indicates FULL?

12.6v and above indicates full. It`s a fairly basic test, but if you are really only 20% charged it will be way under that.

Shut everything off and let it sit , NO charge, NO loads, for 24 hours and then measure the voltage. It should be approx. 12.7 or 12.8

A fully charged battery will read from 12.6 to 12.8 volts. 50% charge will be about 12.3 to 12.4 volts. There is some variation in these numbers due to battery type and condition.

If you have standard lead acid batteries, a more accurate test can be done by measuring the specific gravity of the acid. When fully charged it is 1.265 @ 80 degrees F.

In adddition to the above tests which I agree, check the battery terminal voltage with the charger on. It will show 13.5-14.0 volts if the batteries are full and the charger is charging.

My guess is that your monitor needs to be reset to full battery conditions. It should do that automatically when it senses low current output. Maybe that feature isn't working right.

David

I second the hygrometer test from Auscan, it's also the only accurate way to check after an equalizing charge. Let them sit for a couple of hours before testing (I have notion it's 24 hours). They are cheap to buy from car parts places.

So far I'm 50/50 on Xantrex. I think the company itself sucks because unless you have a warranty their products are not supported and they will not provide circuit diagrams for anything they made so unless you are very lucky they are disposable. One good inverter, one bad, one bad charger, one good indicator/controller.

Almost forgot, check the condition of your connections, especially grounds.

I have the exact same charger in a 14 year old boat so I am in the process of upgrading to a three leg 80 amp Charles 5000 series charger. Less charge time and newer technology

Our 2002 NT37 had the 40A Truecharge as well. Nowhere near enough amps to recharge a 500AH AGM house bank in a reasonable time. 8KW genset was loafing, and charging was very slow. And there was a cheap separate inverter, inexplicably wired to only two wall plugs.

Last fall, redesigned the charging system and replaced charger and inverter with a hand-me-down Heart Freedom 2500 inverter/charger (130A charging), and wired the inverter to all wall plugs. Added Victron battery monitor. Replaced diode isolator with ACR's, and original equipment 4D gels for starting and windlasss/thruster with AGM. Batt banks are all AGM now, so can charge at the right voltages for AGM. Much tidier, better function.

Still to do: install 145A alternator and Balmar MC-614 regulator. Haven't gone cruising with the new stuff yet, but it should be way better.

schrater said:

I have a Xantrex Truecharge 40+ charger feeding 2 AGM 8D house batteries while on shore power. But for some reason, the charger is stepping down to only 2-5A output even though my Xantrex Link 20 monitor says that my batteries are at -320Ah (80% spent). This is further confirmed by the monitor showing close to net-0.0 charge state even with minimal draw on the batteries (in other words, everything is off, but the batteries still aren't charging). I've been doing a lot of troubleshooting with the charger, but now I'm starting to wonder if the problem is actually the monitor. Is it possible my batteries are actually fully charged and it's just my monitor that is out of whack?
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If your charger is only delivering +0.3A to the battery bank at XX.XX volts the batteries are essentially fully charged.

Like far too many folks with Ah counting battery monitors yours has become rather grossly out of sync.

• When was the last time you conducted a 20 hour capacity test on the battery bank?

• What is the Peukerts constant for your battery bank?

• What is the reset to 100% tail current set to?

• What is the time period for tail current set to?

• What is the reset to 100% voltage point set to?

• Have you ever conducted a manual reset?

• How many PSOC (partial state of charge) cycles do you do before you plug back into shore power in order to get 10+ hours of solid charging?

Take a read of the linked article below and allow it to absorb. If you do not understand what it is saying try reading it again. Your issue is not at all uncommon and is almost always a matter of simply not comprehending how Ah counters actually work and how they need to be tended to.

Keeping Your Battery Monitor More Accurate



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AusCan said:

A fully charged battery will read from 12.6 to 12.8 volts. 50% charge will be about 12.3 to 12.4 volts. There is some variation in these numbers due to battery type and condition.

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Pgitug said:

I have the exact same charger in a 14 year old boat so I am in the process of upgrading to a three leg 80 amp Charles 5000 series charger. Less charge time and newer technology

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Rumor has it Charles is going out of charger business.

Pgitug said:

I have the exact same charger in a 14 year old boat so I am in the process of upgrading to a three leg 80 amp Charles 5000 series charger. Less charge time and newer technology

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Went to wire the new charger today and found the existing True Xantex 40 Amp charger was Dead. Two hours later I am back up with 80 amps.

sunchaser said:

Rumor has it Charles is going out of charger business.

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That is what I heard also. Probably why I got the three battery, 80 Amp charger for $800.

I'm a little surprised no one suggested by the short answer might be to simply turn on every cabin light and 12 vdc fan, turn off the charger, and walk away for a day or two until the boat batteries are, in fact, dead. (You might want to turn off the refrigerator ... most have low voltage cut off but if not they might not like drinking 10.5 volts).
Next...
Turn the charger back on. Watch (log hourly) the charge rate until the batteries are fully re-charged (as indicated by the charger dropping to little or no amps). The hours x amps (plus 15%) should collectively match your battery AH rating. All the while, log your battery condition meter to see how well it relates.
Pulling the batteries to dead is not a thing you want to do a lot but once wont hurt.

The "Surface Charge" is always an issue when using a volt meter to check battery state because a half charged battery will show maybe 14 volts when the charger is first turned off but the "surface charge" will dissipate like smoke when a few minutes of refrigerator run-time is applied. Vic

A battery tester with a load facility will give you voltage, voltage after load test, and "bounce back" post load test voltage. Cheap (and smoky under load),from ebay. Replacement smoke available separately from all good Lucas outlets.