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Charge rate and capacity for FIAMM FLX 300 AGM batteries

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CoachMcG

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I just installed my SAMLEX EVO 2224 at my cabin. I have 4*12v batteries. I believed they were 75Ah but the sheet attached says 82.5. They are setup in a series/parallel configuration so i guess my system would be 165Ah.

At one point i was told that i should charge at no more than 20Amps. I think my inverter/generator is set by default at 40Amps. I don't have solar panels yet so the generator will be my charging unit for the time being. I don't see anywhere on the spec sheet mentions of charge rate... but honestly, i'm still new to this and a lot of this technical jargon goes right over my head.

Can someone have a look at the spec sheet and explain in plain language how long i could run this system prior to recharge? Do i recharge once it reads a specific Voltage? I've read that AGM shouldn't go beyond 50% discharge. How do i know that i reached 50%? I believe i can set an alarm on my EVO2224.

If this helps, i had all my lights running and was reading 55W... i have one more circuit to run but that would only mean an extra couple of lights.

Any input appreciated?
 

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The easy answer is, lead acid batteries should be kept at 100% at all times unless absolutely necessary to use them. When you HAVE to use them, discharge them as little as possible.

Yes, for DEEP CYCLE batteries 50% is good; however, you don't have deep cycle batteries at all.

"Ideal for:
- High rate discharge UPS application
- Emergency power supply systems
- IT network operations and data centers
- Emergency lighting Up to 10 year design life at 77°F on fl oat"

These are a poor choice for a cycled power system as you describe. They are designed to sit for very long periods of time until they are needed as backup power, then they can delivery a lot of current for a short period of time. Cycle them much, and they don't last too long.

The high float at 13.62V is almost indicative of poor cycle performance as deep cycle batteries usually have float voltages in the 13.2V range.

IMHO, you should recharge them when they hit 80%.

General rule for lead acid batteries of any type is 0.1C or 16.5A in your case. Many can charge at higher rates, but it's manufacturer/type dependent.

Google Fu yielded:


Lists "boost" voltage at 2.4V/cell or 28.8V for bulk/absorption

AND


Clearly identifies the FLX line as for BACKUP power systems... stuff that just sits there and only gets used in an emergency.
 
snoobler said:
The easy answer is, lead acid batteries should be kept at 100% at all times unless absolutely necessary to use them. When you HAVE to use them, discharge them as little as possible.

Yes, for DEEP CYCLE batteries 50% is good; however, you don't have deep cycle batteries at all.

"Ideal for:
- High rate discharge UPS application
- Emergency power supply systems
- IT network operations and data centers
- Emergency lighting Up to 10 year design life at 77°F on fl oat"

These are a poor choice for a cycled power system as you describe. They are designed to sit for very long periods of time until they are needed as backup power, then they can delivery a lot of current for a short period of time. Cycle them much, and they don't last too long.

The high float at 13.62V is almost indicative of poor cycle performance as deep cycle batteries usually have float voltages in the 13.2V range.

IMHO, you should recharge them when they hit 80%.

General rule for lead acid batteries of any type is 0.1C or 16.5A in your case. Many can charge at higher rates, but it's manufacturer/type dependent.

Google Fu yielded:


Lists "boost" voltage at 2.4V/cell or 28.8V for bulk/absorption

AND


Clearly identifies the FLX line as for BACKUP power systems... stuff that just sits there and only gets used in an emergency.
Click to expand...

Thanks for your Honest feedback Snoobler. I reaaly appreciate it! I have no doubt that there's probably a better battery out there that would meet my needs. There are probably as many opinions as there are batteries too? that being said, i had a great deal on the batteries and i'm still quite happy with my purchase. I'm hoping that with proper care, like you mentionned, they will last a 3-5 years. I spent a fair amount of $$ on my initial setup so if all works out, i can spend more on the batteries next time around?
 
If you're paying less than the going rate, and you have a short term outlook, then nothing wrong with getting a good deal even if it's not the best choice for long term value. I make those choices all the time.

Battery designs are different for different applications, e.g., deep cycle batteries have thick plates for better deep cycle performance with less surface area to both deteriorate and to supply current. As a result they last longer.

Starter batteries have thinner plates to deliver higher currents during start. As a result, they have more surface area for degradation with cycling, so they lose their capacity faster.

What you have is somewhere between those two, closer to starter batteries for the high current. Limiting the depth of discharge to 80% remaining will probably keep them happier longer.

Back to your original issue, a battery monitor that can be programmed for capacity can count current and give you a good estimation of % charged. I have my 300Ah battery bank attached to a cheap battery monitor using a shunt to count current in and out. When I know the battery is full, I reset it to 100%, and it keeps decent track for awhile. It will occasionally drift and needs to be reset. I set the 300Ah battery as a 150Ah battery, so regardless of voltage, I know that if the meter says 50%, I've only used 25% of my bank.

And 40A charging a battery of that size is a concern. If you can dial that back to 20A, I would. Additionally, if you can set the absorption termination current to 5A, you can be confident your battery is fully charged. If you can't program it, but you can see the current going into the battery, you know you can shut the genny off when the voltage is 28.8 and the current has tapered to 5A.
 
snoobler said:
If you're paying less than the going rate, and you have a short term outlook, then nothing wrong with getting a good deal even if it's not the best choice for long term value. I make those choices all the time.

Battery designs are different for different applications, e.g., deep cycle batteries have thick plates for better deep cycle performance with less surface area to both deteriorate and to supply current. As a result they last longer.

Starter batteries have thinner plates to deliver higher currents during start. As a result, they have more surface area for degradation with cycling, so they lose their capacity faster.

What you have is somewhere between those two, closer to starter batteries for the high current. Limiting the depth of discharge to 80% remaining will probably keep them happier longer.

Back to your original issue, a battery monitor that can be programmed for capacity can count current and give you a good estimation of % charged. I have my 300Ah battery bank attached to a cheap battery monitor using a shunt to count current in and out. When I know the battery is full, I reset it to 100%, and it keeps decent track for awhile. It will occasionally drift and needs to be reset. I set the 300Ah battery as a 150Ah battery, so regardless of voltage, I know that if the meter says 50%, I've only used 25% of my bank.

And 40A charging a battery of that size is a concern. If you can dial that back to 20A, I would. Additionally, if you can set the absorption termination current to 5A, you can be confident your battery is fully charged. If you can't program it, but you can see the current going into the battery, you know you can shut the genny off when the voltage is 28.8 and the current has tapered to 5A.
Click to expand...
Well you speak a language that i don't understand 100% BUT i will definately be looking for those key points you mention in my manual! Much appreciated!
 
20% capacity in amps is okay, but for series connected you might want to be a bit more conservative.

Excessive gassing needs to be avoided on AGM's. Little gas is created below 13.5v per battery so watch current level above this voltage on each battery.

If pressed for time, below 13.5v you can go to 30%C but make sure you drop down current above that voltage. Don't get distracted and forget to check.
 
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