Xantrex 15

Could you elaborate about the symptom "not getting the power"? I could read your email three or four different ways.

X 15 is a 15 amp charger, right?

Please also describe old batteries and new batteries as far as type (starter, house), chemistry, Ahr, physical size (golf cart batteries ?).

How do you use your boat ?

What do you have available to measure power?

Also, could you tell us
1) How often do you fully charge your batteries?
2) How do you know they are fully charged ?
3) Do you use a generator, dock power, other?
4) Do you have any high current loads?
5) Do you have an inverter ? what is the maximum output?

Thanks Dan. Been boating, so just got your response. Xantex 15 is a 1500 watt inverter with a 75 amp charger. Battery bank is 8 - 6 volt deep cycle @ 232 amp hours each (=928 Ah @ 12V). Fully charged at dock shows +-940 Ah. Away from dock after 36 hours battery bank @ 12.2 V. Ah use is max. 100 Ah per 24 hours. Honda 3000 generator takes 2 1/2 to 3 1/4 hours to charge back to "float cycle". At that time, batteries show full charge, but "specific gravity" @ +- 122 only. Answeres to your questions; I recharge when the bank gets down to +- 12.2 V. I have a battery monitor which shows present voltage, amps being used, and amp hours available. Recharge with Honda 3000 generator, current loads are fridge @ 4 amps (+-8 hours per day, water maker @ 4 amps (yes only 4 amps)(8 hours per day), lighting @ max. 2 amps (all LCD), pumps @ +- 10 amp hours per day. That's it. Xantrex Inverter 1500 watts/charger 75 amp.
Many thanks in advance for your ideas and suggestions.

What is the chemistry (e.g. Lead Acid, Gel cel, AGM, etc) of the old and new batteries? How many Ahr for the old batteries?

When providing battery voltages above, please describe, are they under the same load in each case? E.g. how many Amps being drawn at the time voltage is measured. Are you measuring the voltage at the battery ? What type of meter are you using? If you need to do the measurements over again, think about how you could put a consistant C/20 load, about 50 Amps, for a couple of minutes at the time you do the measurement with no charging systems running. That would help the voltages make more sense to me.

Still not clear to me what the symptoms of the problem are. The math (below) looks good. Could you describe more why you believe there is an issue after 36 hrs? Do you believe it is a bettery issue (maybe not if it charges in 3 hrs) or battery measurement issue?

In your example of the Honda running for 3 hrs, how many Amps are actually getting to the battery vs. your using your boat while the generator is running (fridge, lights, etc.)? Is 15 Amp a fair guess? More ?

THE MATH: Am I missing something, I don't see anything amiss.

Boat in use for 36 hrs = 150 Ahr used, loss factor should be tiny given size of bank, lets call this 160 Ahr consumed.

Charger Capacity is 75 A, assuming 15 A load, leaves 60A for charging, 10% - 15% loss factor x 3 Hour = 153 Amps.

Difference 160 Ahr vs 153 Amp is a tiny difference considering how lose we are with the numbers. Don't see a problem. Perhaps I don't understand yet.

What is the chemistry (e.g. Lead Acid, Gel cel, AGM, etc) of the old and new batteries? How many Ahr for the old batteries?

When providing battery voltages above, please describe, are they under the same load in each case? E.g. how many Amps being drawn at the time voltage is measured. Are you measuring the voltage at the battery ? What type of meter are you using? If you need to do the measurements over again, think about how you could put a consistant C/20 load, about 50 Amps, for a couple of minutes at the time you do the measurement with no charging systems running. That would help the voltages make more sense to me.

Still not clear to me what the symptoms of the problem are. The math (below) looks good. Could you describe more why you believe there is an issue after 36 hrs? Do you believe it is a bettery issue (maybe not if it charges in 3 hrs) or battery measurement issue?

In your example of the Honda running for 3 hrs, how many Amps are actually getting to the battery vs. your using your boat while the generator is running (fridge, lights, etc.)? Is 15 Amp a fair guess? More ?

THE MATH: Am I missing something, I don't see anything amiss.

Boat in use for 36 hrs = 150 Ahr used, loss factor should be tiny given size of bank, lets call this 160 Ahr consumed.

Charger Capacity is 75 A, assuming 15 A load, leaves 60A for charging, 10% - 15% loss factor x 3 Hour = 153 Amps.

Difference 160 Ahr vs 153 Amp is a tiny difference considering how lose we are with the numbers. Don't see a problem. Perhaps I don't understand yet.

Hi Dan

Thanks again for your interest and thoughts.

I am using lead cell batteries: 8 - 6V @ 232 Ah each = 928 Ah @ 12 V, correct? My old batteries were lead cell with 107 Ah each = 428 Ah @ 12 V.

A time of + - 3 hours is normal to charge them using the Honda 3000. This is not my issue however. To answere your question, it charges at + - 13 A.

My issue is, if I have an Ah capacity when fully charged of 928 Ah, and am only using + - 100 Ah per day, should I not be getting a lot more hours life out of the bank, ie; 3+ days?

When measuring the Voltage and Amp hours, I have a battery monitoring panel, which displays the V’s, Amps being used, and Ah available. I have checked the batteries with an Ohm meter to check to make sure the monitor is correct, and it is. When I check the V and Ah once charged to full float, the draw is always between 1.2 and 6 A. I can't remember if I mentioned it before or not, but once the batteries "show" fully charged I have also checked the Specific Gravity (Hydronemeter [sp]). Only once has it gone from red to white (highest 1250), never into green.

I will attempt to run the inverter to a draw of 50 Amps in order to do the test you suggested. I'll let you know the out come.

Again, many thanks.
Rob

What does the "Amps available" show on the battery panel in your example of 36 hours? Does that also show Amps consumed, what is that reading? What model panel are you using? Does that panel work correctly, e.g. show charging ?

You lost me at "A time of + - 3 hours is normal to charge them using the Honda 3000. This is not my issue however. To answere your question, it charges at + - 13 A." Only 13? Do you mean 13 at the time they are fully charged or typical 13 hours of charging? What is the most they are charging, 60 or 75 Amp ?

Do I understand correctly, you believe your at 50% discharge because you read a voltage of 12.2 volts?

I see. Maybe you don't have a problem. Using voltage to determine state of charge can be very misleading. There is an important caveat, I copied here from another site

"Keep in mind that VOLTAGE can only be used in this manner (to determine battery charge) if the battery system has been at 'rest' (no charging or discharging) for some time to allow the batteries to stabilize, and with recent charging, to allow the battery plate 'surface charge' to thoroughly penetrate all the porous, nooks and crannies of the plates... It also allows the battery fluid (electrolyte) to be thoroughly mixed again as it becomes 'more acidic' during the charging process and migrates evenly around the plates - there's lots of 'chemistry' going on inside those 'electron containers' we call batteries!"

There are other caveats. Your battery meter needs to be pretty accurate and connected right at the battery, not at the end of 15 feet of battery cable. So if your drawing 6 amps while your measuring the voltage, you will get a lower number and throw off your measurement.

While you could go repeat the voltage measurements again, I would instead suggest the following:
- Equalize the batteries (function of the charger)
- Run a 14 hour test, start with a fully charged battery, find a C/20 load (47 amps), and every hour write down the time of day, voltage, Amps, Amps Remaining. Stop at either 14 hours (70% discharge) or 11.3 volts. From the point you stop, disconnect the battery from everything, wait an hour, and measure the voltage at the battery.

A good battery at the end of 14 hours will have the voltage on a steady, not accelerated, decline, you should have measured 14 x 45 Amp hours consumed on your battery meter. Look for your battery voltage to rise after an hour of rest to around 12.0 v. If not, then you can use what ever data you collected instead as a base line as you troubleshoot the problem

You could put a C/10 load on your batteries instead, to speed the test, but the effiency losses will make it a less convincing test if everything is actually ok.

While on a C/20 load, please double check your hand held and your battery monitor both read the same voltage. If not the same, note the difference down to two decimal points at 3 or 4 of those hourly measurements in your log. Your handheld is digital right? An analog meter is going to introduce errors into the test.