labeeman
Solar Enthusiast
A coulomb meter cannot measure the self-discharge of the battery so after some time needs to be reset when the battery is full or discharged.
Like I said. I am using the juntek to measure how many amps I have used and have left.Don't confuse Amps and Amp-hours. Take this in the kindest way, but a lot of the way you are using some your terms - amps, coulomb meter, amp meter, etc. suggest a learning opportunity.
BMS AH readings are not very accurate.
What meter are you using? Use a quality shunt meter, like a Victron Smartshunt if you want an accurate measurement.
FIFYI am using the juntek to measure how many amp-hours I have used and have left.
I have a JunTek and yes it needs to be synced every now and then. But as far as counting coulombs I feel it's very accurate and there are YouTube videos that will confirm the accuracy. In fact I recently received another one for my other battery but I haven't installed it yet. The JunTek needs to be set up properly to begin with. I have attached the quick start guide. JunTek has more detailed instructions on YouTube.I'm not up to speed on that Coulomb counter, but labeeman may be correct. Most of them will get out of sync somewhat over time and the pack must be charged to 100% occasionally to get it back in sync.
Even the Victron recommends doing a full charge once in a while to re-sync.
You are confusing Amps and Amp-hours. The sentence above should be:Like I said. I am using the juntek to measure how many amps I have used and have left.
Like I said. I am using the juntek to measure how many amp hours I have used and have left.
If you search out research papers on the topic you will find a memory effect can exist where the cells are short cycled. Taking the cell through a full charge cycle removes the effect, but required more energy than a normal charge cycle. This is one of many reports on the effect,Lithium cells do not have a memory.
This actually works fairly well if you have plenty of battery and don't need to squeeze every bit out of it.Might go back to using the voltage as a fuel gauge instead again LOL.
Ok it is off. Fair enough. But by 70 or 80 amps?You are confusing Amps and Amp-hours. The sentence above should be:
I think you have confused some of the responders who are miss-understanding your question.
Coulomb counters are not perfect. They need to be synced to 100% periodically. They won't account for self discharge, power consumed by the BMS, and many don't account for charge efficiency. In short, it is not surprising that the meter reads 100% before the battery is fully charged.
Ah heck. Really? I had hoped we were done with that craziness.If you search out research papers on the topic you will find a memory effect can exist where the cells are short cycled. Taking the cell through a full charge cycle removes the effect, but required more energy than a normal charge cycle. This is one of many reports on the effect,
Memory effect now also found in lithium-ion batteries
Lithium-ion batteries are high performance energy storage devices used in many commercial electronic appliances. Certainly, they can store a large amount of energy in a relatively small volume. They have also previously been widely believed to exhibit no memory effect. That's how experts call a...phys.org
Mike
Wow, ok that is crazy stuff. And extremely significant to me as I use my batteries for my mobility scooter.If you search out research papers on the topic you will find a memory effect can exist where the cells are short cycled. Taking the cell through a full charge cycle removes the effect, but required more energy than a normal charge cycle. This is one of many reports on the effect,
Memory effect now also found in lithium-ion batteries
Lithium-ion batteries are high performance energy storage devices used in many commercial electronic appliances. Certainly, they can store a large amount of energy in a relatively small volume. They have also previously been widely believed to exhibit no memory effect. That's how experts call a...phys.org
Mike
If you search out research papers on the topic you will find a memory effect can exist where the cells are short cycled. Taking the cell through a full charge cycle removes the effect, but required more energy than a normal charge cycle. This is one of many reports on the effect,
Memory effect now also found in lithium-ion batteries
Lithium-ion batteries are high performance energy storage devices used in many commercial electronic appliances. Certainly, they can store a large amount of energy in a relatively small volume. They have also previously been widely believed to exhibit no memory effect. That's how experts call a...phys.org
Mike
Ok thanks for the insight to that paper for one.OK -- we should all agree to burn this paper -- i had to study this for one of my courses and honestly -- its best just to never read it .... most of us are using LiFePO4 and the paper is on Lithium ION and certain types and uses ...
also -- for the OP -- I'm not sure why you don't want to charge your batteries to 100% more than every 6 months ... nothing wrong with blasting it and shaking the cobwebs off it often ... LiFePO4 loves being pushed -- or at least thats what I tell myself ... but top balancing allows me to synch my meters often ... so I noprmally run my batteries between 87-90% and every 2 weeks max it out ...
If you search out research papers on the topic you will find a memory effect can exist where the cells are short cycled. Taking the cell through a full charge cycle removes the effect, but required more energy than a normal charge cycle. This is one of many reports on the effect,
Memory effect now also found in lithium-ion batteries
Lithium-ion batteries are high performance energy storage devices used in many commercial electronic appliances. Certainly, they can store a large amount of energy in a relatively small volume. They have also previously been widely believed to exhibit no memory effect. That's how experts call a...phys.org
Mike
very interesting, thank you!Consequences of the memory effect for electric and hybrid vehicles
The memory effect and its associated abnormal working voltage deviation have now been confirmed for one of the most common materials used as the positive electrode in lithium-ion batteries, lithium-iron phosphate (LiFePO4). With lithium-iron phosphate, the voltage remains practically unchanged over a large range of the state of charge. This means that even a small anomaly in the operating voltage could be misinterpreted as a major change in the state of charge. Or, to put it another way: when the state of charge is determined from the voltage a large error can be caused by a small deviation in the voltage. The existence of a memory effect is particularly relevant in the context of the anticipated steps towards using lithium-ion batteries in the electric mobility sector. In hybrid cars in particular, the effect can arise during the many cycles of charging/discharging that occur during their normal operation. In such vehicles, the battery is partially recharged during each braking operation by the engine running in a generator mode. It is in turn discharged, and usually only partially, to assist the engine during acceleration phases. The numerous successive cycles of partial charging and discharging lead to individual small memory effects adding up to a large memory effect, as this new study demonstrates. This leads to an error in the estimate of the current state of charge of the battery, in cases where the state of charge is calculated by software on the basis of the current value of the voltage.
so cycling at 1C at -5 deg C is bad for life.Figure 2. Discharge profiles for cells: No. 17 (30 °C, -5 °C). (a) This panel shows the long-term cycling (with a C-rate of 1 C and a temperature of -5 °C). (b) This panel shows the reference cycling (with a C-rate of 0.3 C and a temperature of 25 °C). This figure has been modified from Ruiz et al.39.
If I had your money then I would. But I don't so I don't.Too many amps all at once or over time? All at once would be determined by cell capacity and specifications. Over time the voltage will top out and the BMS will cut you off. I am with GW66... no reason to baby these things. They work for me, I don't work for them.
Of course you and GW are right... It seems people forget if a cell with specs of 2000 cycles is cycled every day at the full C rate it will last apx. 5.5 years and still have 80% capacity left. How many do this? Many including myself keep the SOC between the knees which will increase cell life. Of course temps need to be taken into consideration. Most likely the cells will degrade due to aging before anything else.Too many amps all at once or over time? All at once would be determined by cell capacity and specifications. Over time the voltage will top out and the BMS will cut you off. I am with GW66... no reason to baby these things. They work for me, I don't work for them.