Battery monitor may have ruined my batteries

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Tim- sounds like you are looking at determining SOC by at rest voltage. I don't think that is a good strategy. Better to look at charging volts and charging amps. When at bulk charge volts, which should be around 14.5, depending on your specific batts and their temp. When amps taper off and volts still 14.5, that is 100% charged. You can determine that without waiting a day.
 
I consider mine 100% charged when the charger has been in float charge over night and the battery acceptance rate in around 1A.

Your bulk and absorption voltages might be around 14.5V, but your float will be much lower at around 13.6V. Check your charger manual for the voltages in the AGM profile. But if you stop charging at 14.5V with ample current still flowing into your battery bank, you're cutting it off before the 100% mark. The charger needs to switch to float to top off the battery.

Fortunately, AGM batteries have a much higher acceptance rate to a higher SOC than lead acid batteries. It might be that cutting it off early on an AGM bank would have less negative effect than doing the same on a lead-acid bank like mine.
 
Some chargers, like my cheap POS, switch to float voltage based on a timer. Others switch to float when acceptance amps drop. This is better, but can be complicated if bank is being drawn from by fridge or other loads. The charger can't tell if the amps being provided are going to loads or to charging. In that sense, the timer might be the best option as long as the interval is carefully selected.

But you've got to get them up to 14.5 long enough to see the amps taper off.
 
If you have a bad battery in parallel in a bank, it is just a big fat heavy resistor. It eats charging current and emits heat. Even worse once the chargers or alternators go away, it just eats the other batteries' energy.
Good to unhook the bank and look at each battery after charging if things are not behaving - as in one of the posts- this is a sure culprit finder.

Also note if you have a diode based isolator in use for house bank, it will drop .6v or so across it under current. So to get to 13.6 on the downhill side, need 14.2 on the uphill. I prefer auto combiners instead for little voltage drop from the alternators and even voltage to all banks.
 
This is how I understand my 100 amp Charles charger works

The charger starts out in a bulk charge mode with voltage at 14.2 volts.

When the batteries near a "full charge" (full charge is not specified) the output current will decrease and the charger will enter a 4 hr timed absorption mode.

After 4 hours the output will drop to a float rate of 13.6 volts temperature compensated to slightly less if above 25 C or slightly more if below 25 C.

In practice while on the hook the charger never reaches the float rate due to the 4 hr timed absorption mode. This time of year with the OAT more comfortable we only run the genny to charge the batts.

What I have notice since removing the dead battery is the amp gauge on the charger and the amps being absorbed by the battery bank as indicated on the monitor drop quickly after about an hour of charge indicating the charger has gone to the absorption stage. Confirmed by the voltage dropping from 14.4 to 13.6.
That's when I turn the genny off.

So while on the hook, the batts will never get fully charged unless I leave the genny on for 5 hours or more which is not practical.

I don't know if this damages the AGM batteries as while on the hook they never are fully charged. Generally we get to a marina about once a week where they go through the full cycle and complete the absorption mode and enter the float mode.

Ski's comment about the refig running while charging is applicable. The fridge cycles and when on draws 7 amps. I don't know if this confuses the charger and it thus cycles to the absorption mode too early.

Any suggestions??

Perhaps running the genny all night once during that week on the hook is a good idea.
 
I don't know if this confuses the charger and it thus cycles to the absorption mode too early.

Probably,

The answer could be a number methods.

Find an old RV converter and install it. If you want I have a $20.one.

These were made to not discharge the bats as demands like water pumps , fridges , lights ,etc operated.

The voltage was usually 13.2 ,so little watering was required , as there was almost no charging being done.

The tiny inland fish killers (300hp on a 18ft boat) use chargers that charge each battery alone.
So if 24 V (2 12v batts for trolling motor) is on one string and 12v on the other , no problem each gets 12v , would charge a 36 or 48v system, each batt sees only its 12V charger .

Not powerful so only for slip use , and some make RFI , so radio reception may suffer.

The newest smartest chargers shut down when the float is finished , saving water, and only turn back on when a set point is reached. Weather it could be set to not come on with the fridge ? Maybe
 
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I guess I missed it, what size, type, year and brand of inverter do you have? And the inverter is not with a built in charger - you have the Charles only?
 
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Tim- If you get amps to decay at 14.2, that last bit of charge from the timed 4hrs is probably not a huge part of your SOC. If you let it go through the full cycle once a week, that should be enough. I too would not bother running the gen for 4hrs to just finish the timed cycle.
 
The SOC only calculated the % of charge from the amps out vs. amps in. It's a straight count after synchronizing at a full charge and inputting the AH capacity of the bank...much like a digital fuel flow/fuel quantity counter. It doesn't use battery voltage to compute SOC.
Click to expand...

That's interesting, I thought the Victron was more sophisticated than just an amp hour meter. My Magnum took a number of factors, to calculate the batteries' charge efficiency and ultimately SOC. "At rest voltage" as Ski notes, (and Trojan and Magnum agree) is probably the most difficult to get a good reading (you have to decommission the bank for a fairly long period of time) and anything other than a true at rest reading is almost meaningless, since loads draw down voltage.

I had some of this same confusion myself when I was a newbie to a fairly complex system. Mr. Calder and Magnum set me straight.
 
timjet said:
This is how I understand my 100 amp Charles charger works

The charger starts out in a bulk charge mode with voltage at 14.2 volts.

When the batteries near a "full charge" (full charge is not specified) the output current will decrease and the charger will enter a 4 hr timed absorption mode.

After 4 hours the output will drop to a float rate of 13.6 volts temperature compensated to slightly less if above 25 C or slightly more if below 25 C.

In practice while on the hook the charger never reaches the float rate due to the 4 hr timed absorption mode.
Click to expand...

I read in a recent thread (cruisersforum) that :
- bulk charge = constant amps, with voltage rising (end when absorption voltage is reached)
- absorption charge = constant voltage at absorption rate, with amps gradually falling

(Hadn't seen it expressed so succinctly, before.)

In our installation, with a 40-amp charger, presumably that would mean a cycle starts with a bulk charge at 40-amps (the charger's max) until reaching 14.7v. That agrees with the charger manual, which says a "Fast charge" [is] maximum current output until batteries reach 14.7v." (That would have been a max voltage of 14.1v, if I had selected the gel option, instead of the FLA/AGM setting on our charger.)

That would presumably be followed by a 4-hour absorption charge at 14.7v while amps gradually decrease from 40 down to.... er... something. (That too agrees with the charger manual; in this case, 4-hours is my own user-selected time period.)

Our charger then goes to float at 13.5v, whether set to FLA/AGM or gel(and that would have happened at the end of the timed cycle, whether that was set at 1, 2, 3, or 4 hours.)

Perhaps our charger's reaching 14.7v (in our case, at our FLA/AGM setting) is the same as your manual's reaching a "full charge"?

-Chris
 
timjet said:
...So while on the hook, the batts will never get fully charged unless I leave the genny on for 5 hours or more which is not practical.

I don't know if this damages the AGM batteries as while on the hook they never are fully charged. Generally we get to a marina about once a week where they go through the full cycle and complete the absorption mode and enter the float mode...
Click to expand...

This should be fine with no damage to the batteries. When we're out, we typically move about once a week and get the batteries fully charged. During the time at anchor, we only charge the batteries to about 80-85%%. I agree with you, it's not practical and isn't necessary to get them to 100% everyday. We monitor the voltage at the same time we monitor the amps in/out. After 7 years, we're able to determine the battery state just by the voltage even though the batteries haven't fully "rested". The morning is the best time for us, when only the refrigeration system has been on.
 
This quote is directly from the Victron Precision Battery Monitoring Datasheet.

Precision monitoring

The essential function of a battery monitor is to calculate ampere-hours consumed and the state of charge of a battery. Ampere-hours consumed is calculated by integrating the current flowing in or out of the battery. In case of a constant current, this integration is equivalent to current multiplied by time. A discharge current of 10A during 2 hours, for example, amounts to 20Ah consumed. All our battery monitors are based on a powerful microprocessor, programmed with the algorithms needed for precision monitoring.

More info is available on the Victron datasheet linked above.
 
Although I am not a battery expert, I know (from years of doing and replacing) that replacing 3 out of 4 batteries in a battery bank is only going to cause problems down the road. Constavolts, (by whatever brand name they are) charge to the lowest denominator) In your case, to the battery that can 'take' the least charge.
When replacing batteries, replace them ALL. That way they all work in at the same rate of use and capacity.

If you want to see how batteries work, find a 'battery recycler' business and ask for a tour of their facility. It is sort of amazing how batteries are recycled and reused. (successfully!)
 
As bad as lead acid batteries are these days..it's really hard unless you do pretty extensive testing on the battery you just bought whether its going to fit with the others OK.

Granted...don't mix 3 new batts with a 3 year old or older battery...but a year or two old battery may be just as healthy as a brand new one according to people who have checked into these things.

The only real test of batteries and battery banks is how they work day in and day out with your loads.
 
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In a non ideal world I'm of the belief that mixing older and newer batteries, brand A chargers, brand B inverters and brand brand C BMKs is asking for problems. To hopefully get to a seamless setup, two years ago I installed an all Magnum setup of inverter, charger and BMKs.

Since Balmar doesn't have a market share of inverters or chargers all they can offer is a monitoring kit, for no less material dollars than Victron or Magnum. Reading through a Magnum manual is indeed seamless to understand how all three should work and be setup. Magnums PNW office will take all and any inquiries on their units, a huge plus for those of us who do not profess to be marine electricians.

I shed my perfectly operating Xantrex inverter charger Link 2000 unit knowing it was entering middle age and no factory support was available according to many including this forum. My marine electrician experts concurred stating an all Magnum setup was far easier to install and trouble shoot; problem solving which I've not had to do with the new Magnum install.

It would be interesting to know if beyond bad batteries, TJ's issues relate to 3 different brands of electrical gear not able to communicate. In this day and age these types of issues should not occur unless faulty design, maintenance, install or equipment is the case.
 
ranger42c said:
I read in a recent thread (cruisersforum) that :
- bulk charge = constant amps, with voltage rising (end when absorption voltage is reached)
- absorption charge = constant voltage at absorption rate, with amps gradually falling

(Hadn't seen it expressed so succinctly, before.)

In our installation, with a 40-amp charger, presumably that would mean a cycle starts with a bulk charge at 40-amps (the charger's max) until reaching 14.7v. That agrees with the charger manual, which says a "Fast charge" [is] maximum current output until batteries reach 14.7v." (That would have been a max voltage of 14.1v, if I had selected the gel option, instead of the FLA/AGM setting on our charger.)

That would presumably be followed by a 4-hour absorption charge at 14.7v while amps gradually decrease from 40 down to.... er... something. (That too agrees with the charger manual; in this case, 4-hours is my own user-selected time period.)

Our charger then goes to float at 13.5v, whether set to FLA/AGM or gel(and that would have happened at the end of the timed cycle, whether that was set at 1, 2, 3, or 4 hours.)

Perhaps our charger's reaching 14.7v (in our case, at our FLA/AGM setting) is the same as your manual's reaching a "full charge"?

-Chris
Click to expand...


Your definitions above are exactly correct for bulk, absorption, and float. To them add equalizing charge, which is a short time over voltage charge say at 16v to intentionally out gas the cells to remove sulfation. Most people don't use this very often or at all. It makes a lot of H2 gas and requires high ventilation and observation. We would do this maintenance on submarine lead acid batteries to extend their life. Each one was a giant 2v cell.

With all the new cheap Edison and quark gadgets intel is making I would expect some cool new charging systems that might even talk to the loads and batteries. I might have to create one!!!
 
The charger starts out in a bulk charge mode with voltage at 14.2 volts.

I thought AGM had a lower charge voltage to avoid gassing out the liquid?
 
FF said:
The charger starts out in a bulk charge mode with voltage at 14.2 volts.

I thought AGM had a lower charge voltage to avoid gassing out the liquid?
Click to expand...



Our charger offers settings for FLA/AGM (combined) at 14.7V and for Gel 14.1V.

Newer chargers by the same maker offer several more profiles, some specific for AGMs (separately from FLAs) and with two different high rates, 14.4V and 14.6V... both of which are slightly lower than the same unit's two profiles for FLAs (14.8V and 14.7V) and higher (sorta) than the Gel profiles (14.0V and 14.4V).

Ref is here: http://promariner.com/wp-content/uploads/2013/09/CEC-_PRONAUTICP-MANUAL-PRINT.pdf

I haven't read that manual in great depth, but given there are generally two preset profiles for each chemistry, I gather that one chooses the settings that most closely match the battery manufacturer's charging recommendations.

Do AGMs have "liquid" that could gas out? (Perhaps electrolyte that can become liquid?)

-Chris
 
FF said:
The charger starts out in a bulk charge mode with voltage at 14.2 volts.

I thought AGM had a lower charge voltage to avoid gassing out the liquid?
Click to expand...

I called Decca, maker of East Penn batteries maker of my AGM's.

Charge Absorption Equalization 13.8 - 14.6 volts

Float - Stby 13.4 - 13.6 volts
 
Larry M said:
This should be fine with no damage to the batteries. When we're out, we typically move about once a week and get the batteries fully charged. During the time at anchor, we only charge the batteries to about 80-85%%. I agree with you, it's not practical and isn't necessary to get them to 100% everyday. We monitor the voltage at the same time we monitor the amps in/out. After 7 years, we're able to determine the battery state just by the voltage even though the batteries haven't fully "rested". The morning is the best time for us, when only the refrigeration system has been on.
Click to expand...

Tim,

I had the same problem, which on my crossing, really got worse, in that the Victron was showing a small discharge (-1.0 A) while underway.I pretty much do as Larry does above.

So I spoke to a Victron Product Manager at eh Ams boat show and he pointed out that in addition to syncing, I must reset when I know that 0 current is running. Clearly, that was my problem, I must have reset it back in Rhode Island with a positive current from the solar panels.

Also, while theoretically you should wait 24 hours hours to get a true value on a rested battery, the actual value will be very close, within tenths of an amp, if you have no load for a little while.

Also, when I record the SOC numbers, I always record, the voltage, the current and the CE. That way, it gives me a sense based on the current draw how accurate the voltage is and therefore the CE and SOC.

Richard in NYC
 
denloe1; said:
With all the new cheap Edison and quark gadgets intel is making I would expect some cool new charging systems that might even talk to the loads and batteries. I might have to create one!!!
Click to expand...

Look no further than what is available for solar array systems with battery back up. Reuben Trane can and has waxed eloquent on this subject.
 
Al, this is a good read about various methods used to measure the house battery system SOC and the variable pitfalls. It also tries to describe the latest BelMar SOC and how it works. It's backed up with some intensive logical testing.
Bill
 
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