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Old 01-08-2019, 03:42 AM   #31
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4 times 3.8 is 15.2. Packs are 4 cells and maximum voltage per pack was stated as 3.8v
I have the Elite power battery as well though not in service yet. I do plan on following Winstons sound and experienced advise (two years on the road now with his Elite). I have a lot invested in my Elite house battery and I don't wish to see it experience a premature death.

This is similar to a Porsche the factory red lines it at 7800 rpm. That's "max". Other than doing so now and then for fun, who thinks its wise to drive it at 7800 rpm all day long?

Santiago
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Old 01-10-2019, 03:32 AM   #32
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Let's try this again . If your current battery set-up has worked for 8 years , why change now ?
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Old 01-10-2019, 03:34 AM   #33
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If current set-up has worked for 8 years , why change it ?
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Old 01-10-2019, 02:51 PM   #34
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Let's try this again . If your current battery set-up has worked for 8 years , why change now ?
Seems you've answered your own question. As is often said: "If it ain't broke, don't touch it." As we were starting from scratch, our lithium decision was based on technical benefits.

And for those benefits we could see someone with 8 years of success making the 'upgrade'. It's like our TV . . . we finally replaced our old 'tube' 4:3 standard definition set with an HD flat-screen - - the old one had worked for years . . . but we just wanted the benefits of the new technology.
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Old 01-10-2019, 06:13 PM   #35
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Default "Resting Voltage", why Lithium, and results!

Since the question of 'why lithium' seems to keep coming up; I'm adding lithium (in parallel to my existing AGM) to get additional energy capacity with small space that I have available.

The coach AGM battery on my van was mounted under the van near the rear axle, but it was only about 1/2" above the low axle height. Since I take my van off road and through deep snow this was a concern for me. On my last test camping run, I was really happy to have all my batteries inside rather than being dragged through the deep snow ruts.

Winston: I like your charging charts but am not clear on your criteria for a 'resting voltage'. On my Lithium battery, I notice that the voltage drops quite a bit within minutes after charging. How do you define your 'resting voltage'?

I've been testing my 'DIY' Lithium battery for about a week of camping in sub-freezing temps (between 14-23F). So far I'm really happy with the results. I'm charging the battery from the 220A alternator and noticing a peak of about 75A, but an average charge of around 55A. I've got my PowerMon monitor programmed to disconnect the battery after it reaches 14.4V for a continuous 3 seconds. The it will re-connect at 14.0V. Overnight power consumption has been between 25 - 40Ah of energy and the charge cycle (when driving) usually lasts between 25 to 40 minutes before the PowerMon disconnects the battery. The Low Voltage disconnect is set for 12.8V for a duration of 5 seconds; but so far this hasn't occurred. The closest I get is when the microwave oven is running, but it doesn't trip the LVD.


Originally I was concerned about my battery separator keeping my coach and chassis batteries connected, but now I'm less concerned. I listen to a lot of satellite radio on these long cold nights (powered off the chassis battery). The power draw for this hasn't been excessive and I'm now thinking it's a good thing to keep my chassis battery topped up while out in the boonies camping.
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Old 01-11-2019, 05:20 AM   #36
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Winston: I like your charging charts but am not clear on your criteria for a 'resting voltage'. On my Lithium battery, I notice that the voltage drops quite a bit within minutes after charging. How do you define your 'resting voltage'?
All batteries voltage 'sags' after charging. All batteries voltage 'recovers' (increases) when loads are removed.

Our concept of 'resting voltage' is to determine what the voltage is AFTER these temporary sagging/recovery effects have 'run their course'. We find that the pack voltage will 'recover' slowly for several hours after each discharge segment. We consider the recovery to have 'run its course' when the pack voltage no longer increases - - generally we require several hours of 'no (voltage) change' before taking our reading. To be on the safe side, we've been letting our pack 'rest' for 10 hours after each discharge segment.

As we seek to create a chart/table correlating pack voltage as a function of State of Charge . . . and since, for any given SOC, the pack voltage can vary dramatically depending on whether the battery is, or has been, under charge or is, or as been, under discharge . . . we believe that 'resting voltage' provides a meaningful and repeatable standard for battery voltage measurement.
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Old 01-11-2019, 03:48 PM   #37
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Tracking voltage while battery is in service (charging/discharging) throughout the day is pointless. I agree that for voltage reading to be meaningful the battery has to have sufficient time to rest and that means no loads or charging for an adequate period of time, aka resting voltage reading.

While monitoring charging and static voltage is still great data, battery ampere "level" tracking is more meaningful especially in light of lithium's flat voltage curve, unlike what we are accustomed to with lead acid chemistry.

My planned house power design will follow Tom's (TGregg) battery tracking method that he's been using for some time with his lithium bank. That is to measure battery's in and out current similar to a water tank level gauge only more accurate and periodically recalibratable to ensure accuracy as battery capacity changes, monitor errors creep in, etc.

While in service, no need to charge 100%. Setting ampere flow monitor to stop charging when battery ampere capacity level is 90-95% full is safe and will ensure long lithium life. A lower limit setting restarts charging. I like his method.

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Old 01-11-2019, 04:07 PM   #38
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Tracking voltage while battery is in service (charging/discharging) throughout the day is pointless. I agree that for voltage reading to be meaningful the battery has to have sufficient time to rest and that means no loads or charging for an adequate period of time, aka resting voltage reading.
That is an interesting claim. I do not know whether it is strictly true or not. My understanding is that the reason for the "rest" period is simply that it provides a standard condition for measurement. It is not clear to me that some other standard condition (i.e., with a fixed load) would not be just as valid (but with different quantitative standards). If THAT is true, then over a long enough period of time, continuous measurement averaged across the whole range of usage might well be meaningful.

I honestly don't know, but it is an interesting question.
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Old 01-11-2019, 04:21 PM   #39
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That is an interesting claim. I do not know whether it is strictly true or not. My understanding is that the reason for the "rest" period is simply that it provides a standard condition for measurement. It is not clear to me that some other standard condition (i.e., with a fixed load) would not be just as valid (but with different quantitative standards). If THAT is true, then over a long enough period of time, continuous measurement averaged across the whole range of usage might well be meaningful.

I honestly don't know, but it is an interesting question.

What I have read, but have no idea if it is gospel, is that the rest time in lead acid batteries is needed to allow the electron migration through the battery to finish and be uniform. It was referred to as surface charge in reverse, as it gives a similar false actual voltage, but in the opposite direction compared to surface charge. I don't know it it also applies to lithium, and if it does, would it take as long with their high charge and discharge rates?


If discharge rate were stable over time, and you had a conversion chart to what the rested would be for that load, I would think then that the loaded voltage would be a decent reference. Many users do have relatively steady use for fairly long periods, so there are probably lots of users that kind of instinctively know where they are based on loaded voltage and past experience. Personally, I prefer to just look at the battery monitor and know for sure, instantly, what my SOC is.
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Old 01-11-2019, 04:23 PM   #40
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That is an interesting claim. I do not know whether it is strictly true or not. My understanding is that the reason for the "rest" period is simply that it provides a standard condition for measurement. It is not clear to me that some other standard condition (i.e., with a fixed load) would not be just as valid (but with different quantitative standards). If THAT is true, then over a long enough period of time, continuous measurement averaged across the whole range of usage might well be meaningful.

I honestly don't know, but it is an interesting question.
Hi avanti,

Recently you may recall me writing that SOC is determined by me without AND with loads is all I use. 12.13 volts means something different concerning SOC depending on length of resting vs. using a 200 watt appliance. Yes, Mr. booster stated that I had trained myself like a puppy or something like that. Hey, I'm a full grown dog now, just took some time.

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