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Old 12-04-2011, 04:48 PM   #21
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RE: Equalizing and desulphitating batteries, comments and experiences

Will do... Thanks guys.
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Old 12-06-2011, 06:36 PM   #22
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RE: Equalizing and desulphitating batteries, comments and experiences

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sunchaser wrote:
Gonzo* -- I load test*and monitor*my Link. I will turn on several space heaters and draw down* to 1/2 the rated amp hours*following the volts* along the way. In my case I draw out 440 amps (12 volt system) which gets me down to about 11.7 to 12.0 volts. If you cannot draw out at least 1/2 of your amps while staying above 11.6 volts or so, your batteries may be problematic.
I'm not clear whether you are referring to voltage under load or resting voltage here but either interpretation is wrong.* Voltage under load will vary depending on the load so it is meaningless for SOC calculations.* Generally accepted numbers for resting voltage at 50% SOC are much higher than you are suggesting.* For lead acid batteries look for at least 12.2 resting volts @ 50% SOC and for gels a little higher.

One of the best summaries of battery information that I know of is here:

http://www.phrannie.org/battery.html

If you are discharging to 11.6 resting volts your batteries are effectively dead at that point.*
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Old 12-06-2011, 08:36 PM   #23
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RE: Equalizing and desulphitating batteries, comments and experiences

Bob

Good article, I've seen it several times before but didn't recall the detail of SG vs resting volts. Do you know if he*has updated it to*detail the inverter advancements during the past 15 years?

My comments were meant for under load, drawing 110V through the inverter and reading the Link*as close to 2500 watts are being drawn. My Link and Xantrex manuals are not in front of me but I seem to recall as much as a 0.5 voltage lower differential between max inverter*draw and resting voltage.

I'll watch the resting vs discharging volts*more closely next time I do a 50% draw down at anchor.
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Old 12-07-2011, 08:13 AM   #24
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RE: Equalizing and desulphitating batteries, comments and experiences

Quote:
sunchaser wrote:
..........

Do you know if he*has updated it to*detail the inverter advancements during the past 15 years?

........but I seem to recall as much as a 0.5 voltage lower differential between max inverter*draw and resting voltage.

I'll watch the resting vs discharging volts*more closely next time I do a 50% draw down at anchor.
I use that page as a battery resource - I doubt that the inverter information has changed but the inverter efficiency doesn't really change what is happening to the batteries.* I think you'll be surprised how much difference there is between the voltage with a ~1000-1500 watt load and the real resting voltage.* We routinely see over a volt difference with 3x8Ds under a 12-1500 watt load.*

Somewhere I've got life cycle expectancy charts which show the effect of lifetime discharge cycles.* In summary they show that if you can use the top 25-40% of the batteries you will dramatically extend their useful life c/w using the top 60 or 70% of the battery bank.* I have my Trimetric set to show 50% discharge when we've really got more like 60% of the bank left and we have a hard and fast rule that we never let it get to 50% - more typically we'll start the gennie at 60% indicated which is likely closer to 70% SOC.* Currently we're well into our 8th year on Lifeline AGMs with no measurable deterioration in their condition.
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