Arising from the small difference in voltage over the charge cycle, I wonder how a solar panel controller is able to manage its output? Also, if floating is undesirable, how does it decide when to stop?
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That's why it pays to buy a good solar controller. The Victron ones have battery management built in and alter the charging voltage accordingly. This is an extract from one of their manuals about the 75/15 model I have:Arising from the small difference in voltage over the charge cycle, I wonder how a solar panel controller is able to manage its output? Also, if floating is undesirable, how does it decide when to stop?
To add to that both the Victron & the Votronic Solar regulators are user programmable you can set your own prarameters, bulk charge voltage, absorption time etc.That's why it pays to buy a good solar controller. The Victron ones have battery management built in and alter the charging voltage accordingly. This is an extract from one of their manuals about the 75/15 model I have:
1.7.1. Bulk During this stage the controller delivers as much charge current as possible to rapidly recharge the batteries.
1.7.2. Absorption When the battery voltage reaches the absorption voltage setting, the controller switches to constant voltage mode. When only shallow discharges occur the absorption time is kept short in order to prevent overcharging of the battery. After a deep discharge the absorption time is automatically increased to make sure that the battery is completely recharged. Additionally, the absorption period is also ended when the charge current decreases to less than 1A.
1.7.3. Float During this stage, float voltage is applied to the battery to maintain a fully charged state. When the battery voltage drops below float voltage during at least 1 minute a new charge cycle will be triggered.
I’m not sure what the EZA electronics do in terms of stabilising the voltage presented to the rest of the vehicle. I think that the natural voltage of (four cells of) LiFePO4 is 12.8V which is close to a fully charged Lead Acid battery. What can harm some 12V devices, though, is the voltage applied during charging. If EZA shields the habitation circuit from high (or very low) voltages, it may be that the use of such a system could prolong the lives of the equipment using it.
That's why it pays to buy a good solar controller. The Victron ones have battery management built in and alter the charging voltage accordingly. This is an extract from one of their manuals about the 75/15 model I have:
1.7.1. Bulk During this stage the controller delivers as much charge current as possible to rapidly recharge the batteries.
1.7.2. Absorption When the battery voltage reaches the absorption voltage setting, the controller switches to constant voltage mode. When only shallow discharges occur the absorption time is kept short in order to prevent overcharging of the battery. After a deep discharge the absorption time is automatically increased to make sure that the battery is completely recharged. Additionally, the absorption period is also ended when the charge current decreases to less than 1A.
1.7.3. Float During this stage, float voltage is applied to the battery to maintain a fully charged state. When the battery voltage drops below float voltage during at least 1 minute a new charge cycle will be triggered.
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Arising from the small difference in voltage over the charge cycle, I wonder how a solar panel controller is able to manage its output? Also, if floating is undesirable, how does it decide when to stop?
The theory is fine and well documented. I'm wondering how a charging regime is achieved when the cell voltage is not going to change much, and could be confusing when another source is trying to take over (such as EHU or alternator).
As I said above I would program both the float and CV voltage to be around the 95% mark. The solar controller would then no be able to push current into the batteries beyond that charge point/What I am trying to understand is how a solar panel controller would operate. It will wake up when the sun is right, but then what? I had imagined that it would decide what to do based on the voltage it sees across its output but, if that voltage is not going to vary (much), I’m not sure how it can make the right decision about the type of charging to perform, if any.
PS: Just had a thought. If you are leaving your van for say 2 months or more. You could change the programming profile so that float/cv voltage is at the 60% mark. Change back to 95% mark a week before you need the van or put it on EHU charger.A LiFePO4 battery requires no floating charge to maintain its voltage. Not only that, I understand that they are best stored between 50% and 75% charged, so I’m also curious how that will be achieved using solar panels.
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Very succinctly put.Thanks for the info, I'll wait for the technology to mature and come down in price. Plus if Samsung can get lithium technology so wrong.........
No disrespect intended, but I am certainly aware of the differences, as I believe are most reading this threadLithium Ion and LifePO4 are completely different.
The reason Lithium Ion can be so volatile, is it reacts badly if exposed to air.
LifePO4 (Lithium Phosphate) doesn't react badly with air.
The Samsung, Boeing, Tesla, etc fires all use Lithium Ion. The better leisure batteries are all Lithium Phosphate.
They are completely different technologies. I wouldn't touch Lithium Ion either.
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I think the ones used by Boeing and Samsung are Lithium Manganese, probably because they can pack more energy into a smaller battery. I don't think it is the lithium that is the problem anyway, it is the other chemicals used as an electrolyte that misbehave. When it comes to dangerous chemicals I am not a great fan of the Sulphuric Acid used in Lead batteries.Lithium Ion and LifePO4 are completely different.
No disrespect intended, but I am certainly aware of the differences, as I believe are most reading this thread
Perhaps it is telling you something when organisations such as Boeing still use lithium ion storage cells in their multi million $ passenger carrying aircraft?
There have been a number of major developments announced in cell composition and technology over the past year. This article is one of many: https://www.forbes.com/sites/jamesc...echnologies-keep-getting-better/#4f78e9fb4e62
Until the emerging technologies sort themselves out and prices become sensible, I will keep my hands in my pockets.
Thanks for the info, I'll wait for the technology to mature and come down in price. Plus if Samsung can get lithium technology so wrong.........
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Excellent and informative posts, Gromett, as I have come to expect of you. Many thanksThere are three main chemistries floating around at the moment. They are All Lithium Ions.
Samsungs and Boeings problems were with Lithium Cobalt Batteries I believe.
Lithium Iron Phosphate batteries however are a different beast. They are a bit less energy dense, do NOT explode or flame out when abused..
The other thing worth noting is we are not trying to pack them into a very small area like Samsung did where they suffer from flexing and impacts. And we won't be abusing them with cheap chinese chargers. Boeings issue was a manufacturing defect. The same defect with LiFePO4 would not have the same issue...
You will note in all my posts I use the full chemistry of LiFePO4 to distinguish them from other cells. Please do not mistake them for LiCoO2 or Li2MnO3 cells.
A lot of posts around the net use the Term Lithium polymer (Lipo) which is not really a good description as it doesn't give the chemistry. Lipo is simply the way the electrolyte is constructed.
Saying all Lithium batteries are unsafe is not accurate, as the chemistry, construction and safety vary massively.
That all said. You could get 4 winston cells. wire them in series and treat them as a lead acid battery. You would get a longer lifespan out of them than a Pb battery and it would reduce your weight.
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I notice that the same supplier does a ready made 12v 90ah comprising 4 Winston cells but it does not include cell balancing. However, they built each one from matched cells and those of us that had time to sit through the whole video lecture might recall that the lecturer said this was a good alternative if, as he suspected, cell balancing might often be omitted for cost reasons.
If anyone is interested this link will show you how Relion build their LiFePO4 batteries.
https://www.solacity.com/docs/RELiON/RELiON_Cell_Features_and_Design.pdf
You will perhaps be reassured to read that if a bullet should penetrate a cell, the battery will continue to function but at a lower capacity. If someone shoots at me concern about the workings of my leisure battery might take second place to concentrating on bowel control.
I followed that at the time. It was an interesting project and part of what started me looking at it. However back then the cost was extortionate for my needs. Thanks though@Gromett There is some interesting info here
http://www.technomadia.com/2015/02/living-the-lithium-lifestyle-3-5-year-lithium-rv-battery-update/
These guys fitted Lithium to their RV 4 years ago and posted a review of the performance. It has some good advice on building a battery pack and setting the charging parameters and to maintain performance. Seems they had issues with temperature causing ageing of their pack.
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