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groingo
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# Posted: 22 Sep 2015 10:29pm
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Looking for info telling Lithium battery input charge voltage.
Am looking for something that will accept more voltage as my flooded batteries are limiting input charge voltage.
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MtnDon
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# Posted: 22 Sep 2015 11:28pm - Edited by: MtnDon
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There are different types of lithium based batteries. I assume you mean the LFP type such as the GBS and Winston prismatic 3.2 volt cells?
I don't understand what you mean by "accepting more voltage". LFP and other lithium varieties actually have less tolerance for voltages above their design parameters than FLA (flooded lead acid).
Also am not sure about the reference to "flooded batteries are limiting input charge voltage". FLA's do self limit charge current as they become more fully charged, but they will accept pretty much whatever voltage you care to deliver to them. Not w/o some undesirable side effects mind you.
Maybe I don't understand the question or the problem you see with the FLA's you have?
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creeky
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# Posted: 23 Sep 2015 09:27am
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As your batteries charge the peak voltage limit is hit and then the amperage begins to taper.
See my diagram.
A is the voltage my batteries are at right now. I just took the screen shot.
Under that is the voltage my batteries will get to. It should read 14.5 but the batteries are cold.
B is the amperage going into my batteries. This is the most important number.
Remember: Its Voltage (A) times Amperage (B) equals watts (C).
So lithium in the (lfp) configuration charges more efficiently than flooded lead acid (fla) because it doesn't have the resistance that lead has. So my fla pack will hit 14.5 today probably around 80 amps charging. Once that happens (around 10 a.m.) the amperage begins to drop so that the voltage doesn't rise any further. My batteries are accepting the maximum amount of power they can handle. After 3 hours the voltage will drop from 14.5 to 13.5 or float. And amperage will drop to 0 until the float limit is hit and then will slowly climb. Mostly due to loads like lights, the fridge etc. The batteries are fully charged.
Lithium on the other hand, the amperage will stay at 80 as the voltage will not rise as quickly, no resistance. Once the voltage does rise to 14.2 (a good voltage peak for lithium) the amperage will quickly taper to 0. That's because the batteries are now full. the float voltage of 13.2
This is one of the advantages of lithium. The ease with which they accept a charge. You get maximum amps out of your solar panels for a longer period of time. And your "absorb" period is much shorter. If you were running on a genny charging this would save a lot of gas. A lot.
This is tricky. Just remember volts and amps are linked. And it's the amps going in that counts the most.
The charge voltage tells you the state of your batteries (how full they are). In fla you have to look at amps as well. In lithium it's clearer where your batteries are at just based on voltage.
An example of this is my batteries. When they are fully charged the voltage will still be 14.5 but the amperage will fall to 10 (mostly because of loads). When they are at 20% depleted. The amperage required to get to 14.5 can be 80 amps or more.
groingo. I sometimes think you just make these questions up so that MtnDon and I have something to write about. 
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groingo
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# Posted: 23 Sep 2015 10:36am - Edited by: groingo
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Creeky and Don:
The question should be simple but after trying to get an answer from Tesla and a few others all I got was more questions because they couldn't answer the first question, what rate of charge voltage can they accept?
Bottom line, I am looking for something that will charge faster than flooded.
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MtnDon
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# Posted: 23 Sep 2015 10:50am
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I am the charge voltage? The charge voltage is a simple matter of what is the battery pack voltage. It is the current that does the actual charge...the voltage should just be higher enough to push the current into the battery. Not excessive. Reason being you have only so many watts available to charge with. If the voltage is needlessly high then you have fewer amps. It's the old amps x volts = watts thing.
The maximum charge rate in amps should be listed in the specs. If not avoid that maker. It is not unusual to see the charge rate = to the AH capacity of the cells.
Lithium will charge faster than lead acid. Creeky mentioned that. They charge faster as they have less internal resistance.
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CabinBuilder
Admin
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# Posted: 23 Sep 2015 11:42am
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Quoting: groingo the first question, what rate of charge voltage can they accept?
I think you meant to ask what rate of charge current can a specific battery accept.
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creeky
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# Posted: 23 Sep 2015 12:45pm
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right. you should be asking about charge current. or the voltage times the amperage.
and lithium can charge at a huge rate. the balqons will charge at 350 to 500 amps. That's triple or better over a similar lead acid pack. (My pack peaks at 110 amps).
So. A lithium battery pack can charge at up to 3C (in practice, .5 C is recommended). While a lead acid pack you're looking at .1 of C.
Plus, with lithium almost everything you create goes into the battery. Where with lead acid resistance creates heat, etc.
Just a note: the tesla battery chargers for the car. their max charge rate is stated as 800vx24amps: or 20k watts. They go high voltage over high amps. Most use a 400v charger tho. and if they plan to recharge your car in 10 minutes? You can read that there's a 120k charger in the works.
Note: With lead acid, as we all know, resistance is futile.
(sorry)
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MtnDon
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# Posted: 23 Sep 2015 02:41pm - Edited by: MtnDon
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Quoting: creeky the balqons will charge at 350 to 500 amps.
LFP charge at high rates, yes... but the actual number of amps depends on the size and number of cells. Let's not get too carried away. The pack I would consider today, if I needed to or wanted to go in that direction has 8 cells of 160 AH per cell and a recommended maximum charge rate of 120 amps when at 80% depth of discharge. As the battery gets more full I believe the charge rate does slow some. That is less than 1C, but a lot more than what a lead acid would be happy with.
I know someone with a 5.1 kWh GBS LFMP battery (8 cells of 200 AH each). Since the switch from FLA the same PV panels with the same CC recharges the same typical use in about 26% less time. That is significant.
GBS lists a maximum charge rate oif up to 3C, but at the same time lists a recommended standard charge rate of up to 0.8C. In general my experience has been that doing anything at a maximum rate shortens life of whatever it is.
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creeky
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# Posted: 23 Sep 2015 04:15pm
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Quoting: creeky So. A lithium battery pack can charge at up to 3C (in practice, .5 C is recommended). While a lead acid pack you're looking at .1 of C.
exactly MtnDon. most of the folks I know with lfp packs or who i've read about their experiences with lfp (and even Balqon) recommend the .5C max charge rate. Still way above lead acid.
I mean. I'm going on my solar system. I rarely get to .1C. No worries there. Well. Unless I go to a 3 kw system. Then I might hit .15. 
and 26% is huge. Especially short day / heavy cloud season. thx MtnDon for a real world verification.
Another advantage to lithium is , unlike lead acid, it doesn't reduce the lifespan of the battery pack to be below 100% state of charge (SOC); this means you're much more flexible in when you use your power.
By example. I don't run my dishwasher at night. It uses 2kw of power. That would overdischarge my batteries for maximum life. So I wait for a sunny day. But with lithium I could easily run the dishwasher at midnight and then even wait for days at 50-80% charge until the sun comes out. To me. This is the great advantage of lithium or lfp.
Sure the advantages are part lower maintenance, part wildly extended lifespan; but in particular, more flexible energy use.
So that's why I keep saying. Buy a lithium battery pack.
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MtnDon
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# Posted: 23 Sep 2015 06:26pm - Edited by: MtnDon
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Quoting: creeky and 26% is huge. Especially short day / heavy cloud season. thx MtnDon for a real world verification.
The FLA were L-16's and about 5 - 6 years old, seemingly good condition but probably a little degraded. So maybe a real world comparison of new FLA to new LFP would be a little less.... 20 - 22% better??? 
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groingo
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# Posted: 24 Sep 2015 12:04pm - Edited by: groingo
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What I have been looking for is the same information common to flooded batteries but elusive when it comes to most Lithium based batteries (especially the Powerwall), this information I want to determine what size or kind of charge controller I would need and if the battery needs to charge much faster than flooded to offset the shorter winter days which is the ultimate goal.
What I am doing is trying to see if the batteries can be added to my existing solar system or I if will need to build an entirely new system around them?
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creeky
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# Posted: 24 Sep 2015 02:12pm
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hey groingo. heating up pizza, so ...
while real charge info on batteries is always hard to find. lithium in particular. it's new. there are many different flavours. sort of like saying "what's the best way to brew beer?" i mean what kind of beer. pilsner? stout? lager? american? german? english?
that said.
a basic mppt solar system will do for most kinds of batteries. lead acid or lithium.
for the tesla powerwall, who can say. buying a tesla powerwall is like buying a tesla car. it's a premium brand aimed at the upper end of the market. if that's your budget all power to you. but expect that they will have "premium branded" accessories.
if you're in the mid range market. an mppt controller. solar panels. and a battery pack. doesn't matter what kind of battery pack. you're all good.
the advantage of a lithium battery pack is it will outlive me. it has charging and discharging performance benefits.
keep your system. buy a balqon battery pack. you're good to go. (and the only reason I mention balqon is it is still. grumble grumble. the only lithium pack available for us little guys. if you find another. please let me know).
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groingo
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# Posted: 24 Sep 2015 02:31pm
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Creeky:
You mention Balqon but as before, when I call all I get is their mail box is full, never has anyone picked up the phone plus their price for a 5 kwh battery is the same as Tesla's 7kwh battery, this is why I keep asking these questions.
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MtnDon
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# Posted: 24 Sep 2015 02:37pm - Edited by: MtnDon
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Elite Power, uses GBS cells
Their packs are missing the HD DC relay IIRC. But those are available. They will also reconfigure their BMS controller if at some point one would want to add more cells to increase capacity and buy more cells from them.
If the charge controller you have has fully adjustable set points (absorb and float) and if you can disable any automatic EQ setting, you should be able to use it with LFP. The guy I know uses the same FM 80 Outback CC he used with FLA.
Personally I would forget about Tesla for a small system. They will most likely only be dealing with people who want to install brand new complete installations. At least in the beginning. Just my opinion. Also it seems their system uses very high voltage so there is a good chance you'd have to buy new hardware. At least with the 3.2 volt LFP cell approach the batteries can be built to match the existing PV equipment.
Quoting: groingo ....if the battery needs to charge much faster than flooded to offset the shorter winter days which is the ultimate goal.
With the same number of watts of PV panels and everything else equal, the LFP cells will charge quicker than any FLA. As mentioned a couple of posts above, you can probably safely figure a 20% reduction in time to recharge the same number of watt-hours. The LFP battery has no physical need to charge faster, but it can absorb the charge current at a higher rate.
Whether or not your short winter sunshine hours are able to recharge fully daily is another question. Have you any metering system on the existing setup, such as a Trimetric? That would be able to track the amount of watt-hours, or amp-hours, your system puts into the FLA. If it is close to being able to recharge the FLA (within 20%) then a switch to LFP should be a good fit. If your panels can not come close to covering your average winter daily uses then you need more PV panels. Maybe a new or second CC too.
What I'm getting at is if you know how good or how deficient your panels are in winter, then you can calculate how good the LFP will be recharged. LFP recharge quicker than FLA, but they are not magic, unless you count 20% better as magic.
Hope that helps.
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groingo
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# Posted: 24 Sep 2015 06:22pm
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Don:
Glad you mentioned the metering, I forgot to check....mine shows 6995 ah since Jan 16 which is when I discovered that the cc had been reverting to its default setting of 13.6, since Jan 16 it has held at 15 which made a huge difference....but I want MORE!
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MtnDon
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# Posted: 24 Sep 2015 08:02pm - Edited by: MtnDon
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Groingo, pardon me, but I have trouble interpreting numbers when they are not accompanied by descriptive units.
default setting 13.6, what? float voltage?
held at 15, what?? 15 sounds like an EQ voltage?
MORE? ...more AH might be easier to get by increasing the size of the PV panel array, not changing the battery type....
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creeky
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# Posted: 24 Sep 2015 08:09pm
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hey groingo. ya. the difference between the tesla powerwall and the balqon is that you can buy the balqon today and have it arrive at your doorstep soon thereafter. the tesla at whatever the cost claimed is still vapour ware. i think they are starting sales in australia now. the gbs look okay. balqon is a better package in my mind. but. eh.
anyway. after seeing that you've made 7k ah over 9 months. and if i remember right you're running a 12v system ya? with inverter. that's 10 kws of power (give or take rounded up etc).
so divide by 9 for months; divide by 30 for days and you're using roughly 40 watts of power per day.
now don't you have 400 watts of solar panels and 2 crown 295 batteries (6 volt in series for 12v at 295 amps @ 20% dod = 750 watts of usable power per day).
So from my reconin' you should have 500-800 watts of overnight power. plus your 400 solar watts should be making, well double that. so you should be using, well, 750 watts per day. and a peak of 2000 wouldn't surprise me one bit.
i'm not sure your problem is your batteries. we should probably look at your wiring of the panels to the controller, controller to batteries. batteries to inverter.
and you can probably just start turning on more stuff. use more power. see what happens.
remember. going by battery voltage is like a wonky gas gauge. it's a hint at how much power is available. but really. you probably have tonnes to use. gobble it up.
i think mtndon mentioned getting a trimetric. that's one thing i wish i'd gotten earlier too. you might want to get one. there's other kinds. maybe somebody has another brand to mention.
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groingo
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# Posted: 25 Sep 2015 12:28am - Edited by: groingo
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Creeky:
Have you ever gotten hold of anyone at Balqon, I have tried many times by phone and email to their California locarion and nothing.
I also agree that the Tesla Powerwall is vaporware, when nobody can answer any questions about anything and now production has slipped from this past summer to next summer.
As far as the Lithiums, just exploring the possibilites.
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creeky
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# Posted: 25 Sep 2015 08:16am
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I was able to get ahold of the owner, and he basically told me to buy a pack before asking any questions.
I did get some charge and temperature info from him tho. It came down to keep your batteries above freezing when charging. And your charge controller must accept a custom charge profile, ie. Be programmable. The times and voltage limits are different from fla. You turn off equalization and temperature compensation.
Pretty straightforward.
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MtnDon
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# Posted: 25 Sep 2015 09:30am - Edited by: MtnDon
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Quoting: creeky I was able to get ahold of the owner, and he basically told me to buy a pack before asking any questions.
Ditto. And the guy I know who bought LFP had a similar experience which was one reason he bought the GBS from elitepower. One thing he and I also both like about the GBS cells is the protective "cap" they supply with each one that covers the terminals. Small detail.
Quoting: creeky Pretty straightforward.
Agreed.
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groingo
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# Posted: 25 Sep 2015 11:04am - Edited by: groingo
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I have tried the only only phone number listed...3103263056 and their sales email as well and get "the mailbox is full" by phone and no reply on email.
I can't believe for a second that anyone would plop down thousands of dollars without any background or technical information on anything unless those mushrooms were not what you thought.
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creeky
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# Posted: 25 Sep 2015 11:24am
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oh ya. those mushrooms. i miss the west coast.
re: balqon. i know. he'd sell a lot more batteries if he'd invest in some customer support. weird to see all that r&d just sitting there unappreciated.
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groingo
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# Posted: 25 Sep 2015 11:29am - Edited by: groingo
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Has anyone looked at this site, lots of useful information and you can talk to them...just google smart battery.
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MtnDon
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# Posted: 25 Sep 2015 03:18pm
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Quoting: groingo smart battery
let's see:
@ Balqon a 12 volt 2 kWh battery is priced $1500
@ ElitePower a 12 volt 2.6 kWh battery is $1700
some differences in what you get, more or less equal cost....
@ smart battery a 12 volt 1.2 kWh battery is $1300. Or about $2600 to be comparable.
The 'smart battery' is an LFP made of cylindrical cells; dozens, hundreds in a large battery bank. The Winston (used by Balqon) and GBS cells are prismatic. Prismatic are the large case type where for a 12 volt battery there are only 4 large cells connected in series... at least that is the way Balqon and Elite package things. You could also series parallel smaller LFP prismatic cells but that complicates the BMS. Cylindrical cells are what are found in tools and laptops. Prismatics are what are used by every serious RV and Marine lithium battery bank that I have seen. Personally I would avoid the batteries made up of numbers of cylindricals packed in a battery case, even if the pricing was better.
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creeky
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# Posted: 25 Sep 2015 05:16pm
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i'm with mtndon on this. the bigger the cell amperage the better. what i like about the balqons is that they go up to 1000 amps per cell. while gbs goes to 200.
i also know more about the winston chemistry. and the technology has improved nicely in the past six months. i don't know about gbs cells. guess i gotz some reading to do.
i do like the price on the gbs. they seem to be about 20% cheaper than the balqon. again. all things with caveats. they also don't have the well put together bms, contactor, fuse etc. but they can come with a charger preinstalled. if yer going the genny charge route that would save some money / headaches.
they too have no info (just like balqon) on how to integrate with a solar system. which is pretty much what everyone (well, me) is looking for.
which I just find so odd. you'd think that off grid / cabin / cottage solar is a good market right now. and growing into the home market over the next few years. i mean brands are built (not to get technical marketing guy here) in first to market and best to market. and proven "off grid" would be a killer marketing boomph come the home integration phase.
Musk and his giga factories are the visible part of the iceberg (and trying to define the first to market brand position. which. all power to him {oops. pun not intended}). things they are a changin'.
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Just
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# Posted: 25 Sep 2015 07:31pm
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Quoting: groingo I also agree that the Tesla Powerwall is vaporware
Could be the Edison ploy .
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MtnDon
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# Posted: 26 Sep 2015 11:17am - Edited by: MtnDon
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Link to a couple who have been using the GBS LFP's in a converted bus (bus = RV) for several years. Now with solar PV. With updates over time. It is nice to have pioneers as it has not all been roses.
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NorthRick
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# Posted: 26 Sep 2015 12:32pm
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Quoting: creeky they too have no info (just like balqon) on how to integrate with a solar system. which is pretty much what everyone (well, me) is looking for. which I just find so odd. you'd think that off grid / cabin / cottage solar is a good market right now. and growing into the home market over the next few years. i mean brands are built (not to get technical marketing guy here) in first to market and best to market. and proven "off grid" would be a killer marketing boomph come the home integration phase.
I suspect that's because they are after utility size installations. That's where the money will be at. Not us little homeowners.
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MtnDon
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# Posted: 26 Sep 2015 03:25pm
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Do any utilities actually use batteries? Not that I know of.
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Bret
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# Posted: 26 Sep 2015 03:40pm
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Hey Don, thanks for the link. Lots of good info to share.
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