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Steve_S
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# Posted: 2 Nov 2024 08:55am
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A point of interest, going by my local hospital groups policies they replace the batteries every 24 months on all portable medical equipment as part of the maintenance cycle. I had a chat with a tech there while I was in Oncology wasting time. They are also not using the Valence Batteries anymore as the support contract changed. I'm not sure what that means, if it was an issue with Valence or Economic or ?
A point, please do yourselves a favour, Do NOT Buy a battery pack based on cost, it really is not worth a cheaping out on a No Name "fingers crossed it's ok" buys. Stick to known good, reviewed, torn down & tested commercial packs. Remember "Penny Wise & Dollar Foolish".
As for Paralleling Battery Packs, I am a firm believer in proper Busbar systems with appropriate fusing etc.
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paulz
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# Posted: 2 Nov 2024 01:35pm - Edited by: paulz
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24 months on a lifepo4 sounds like nothing.. I read a while back that Valence sold the company, don’t know reason. They still pop up for sale on the used market.
Good advice on battery brands. If you enter on Amazon ‘lifepo4 100AH’ you will see brands with the most unknown strange names in the low price range.
My wife was in the hospital this week coincidentally (we were worried about a lump on her neck, all testing negative, just a giant zit or something). I drag life questions around with me too, but I forgot to ask about batteries, darn it. All I came up with was those paper throw away long legged pants they had her in. Sure would be handy around the cabin. Burned great n the wood stove too.
Cabin bank still seems to be charging, holding voltage better after tightening that one bolt.
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Steve_S
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# Posted: 2 Nov 2024 05:26pm
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Think of it this way... Consider how a DC Welder is using an arc, simple stuff really. But in effect, a loose connection does the same thing, anything from bleeding away power, up to and including generating enough heat to cause a fire. I've had lugs burn off an LFP battery terminal, as well as serious scorching which was "just caught" before ignition. (only took a few seconds) There is no BMS that can catch that either, only if there is a short (between +&-)
Those lugs BTW were not as advertised (a tinned alloy of some sort) and from a formerly reputable domestic supplier. Point is, never underestimate what those batteries can put out ~ Respect The Power ~ LOL
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Atlincabin
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# Posted: 2 Nov 2024 06:39pm
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Steve,
I'm putting together a new lithium bank for the cabin and looking at a 2s3p setup using 6 12v 100Ah batteries to end up at 24V. I would include a balancer in the system. Alternative is 3 24V 100Ah batteries. The 12s are considerably less expensive, but I'm concerned about the series causing problems. I read (DIYsolar among others) that one would be better off with the 3-battery setup. Thoughts on whether/why the 3-battery is better than the 6-battery + balancer? (I realize there are more connections in the 6-battery, but assuming those connections are tight)
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ICC
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# Posted: 2 Nov 2024 08:12pm
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Quoting: Steve_S Consider how a DC Welder is using an arc, simple stuff really.
I have welded broken steel parts, off-roading damage, using two 12 volt batteries hooked in series with jumper cables. I carried welding rods, welding glass in a foldable cardboard shield.
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ICC
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# Posted: 2 Nov 2024 08:14pm - Edited by: ICC
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Quoting: Atlincabin Alternative is 3 24V 100Ah batteries.
My personal preference is to avoid series connections whenever possible. And to always use buss bars when dealing with multiple batteries. But that may be just me.
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ICC
Member
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# Posted: 2 Nov 2024 09:44pm
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Quoting: paulz As Steve has mentioned they were top of the line grade A stuff back then.
I think you were lucky when you bought your first Valence battery. Lucky in that it was a quality make. T could have been some less good. Ebay, etc is such a crapshoot when we buy on price, on the looks of the item, etc.
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paulz
Member
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# Posted: 3 Nov 2024 12:09am
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Yes, very lucky. But I don’t remember there being tons of Li battery brands back then like there is today.
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Steve_S
Member
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# Posted: 3 Nov 2024 12:57am
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Quoting: Atlincabin I'm putting together a new lithium bank for the cabin and looking at a 2s3p setup using 6 12v 100Ah batteries to end up at 24V.
In all honesty, don't do that, you will come to regret it. If your target voltage is 24V then use proper 24V LFP Packs. 24V.100AH on up are readily available and if you want to build then it's not hard, if you have the proper electronics equipment (crimpers & whatnot).
Having battery packs in Parallel can balance between themselves and simply act in a Fallback/Failover backup system. When things are in series & parallel the potential for Murphy's Laws kicking through your door goes up.
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paulz
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# Posted: 3 Nov 2024 01:59pm - Edited by: paulz
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Had to run the genny charger last night for one hour, 60 amps in. Wife had TV on all day plus micro a couple times, usual full time fridge and modem. Volts went from 13.0 (flickered 12.9 a couple times which scared me) to 13.7, dropped to 13.3 when genny shut off. 13.2 this morning, good enough for today plus whatever solar comes in.
It does seem to charge faster and stay longer with that bolt tightened.
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Steve_S
Member
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# Posted: 3 Nov 2024 03:43pm
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@Atlincabin
I also need to add, that I run a 24V System and it suits my application. I learned several lessons. Partly because of my timing (as in when I started my Solar Adventure) and building out this stuff. 24V is now pretty much an oddball and thus has limited products to support it. This also makes growing a system more difficult & thus more costly.
Today, in November of 2024, I would say, go 48V systems. 48V/100AH LFP Battery ($1150 USD) from respectable commercial companies in USA. Inverter/Chargers, Solar Controllers and even the All In Ones now available are more oriented to 48V, plus the choices make them cheaper.
My Samlex 24V/4000W Inverter still costs $2000 today ! That would buy me a choice of Victron's (with 240V Split Phase) OR EG4 6000XP Off-Grid Inverter | 8000W PV Input | 6000W Output | 480V VOC Input | 48V 120/240V Split Phase | All-In-One Solar Inverter ($1400 USD btw)
Also consider that each of my Midnite Classic SCC's cost 1 grand each, the Above AIO could take my current array and use it all just fine. The cost of my SCC's alone would have more that paid for that AIO or even going the Victron route with separate Solar Controllers (still better deal).
I'm sorry if this is sorta rambling, not intended. But sometimes a rethink before you're Eyeball Deep into a commitment (investment) it may be prudent to stomp the brakes & rethink. "The Money Pit" is a universal gotcha lurking everywhere.
Check out Signature Solar USA.
https://signaturesolar.com/
They don't sell the equipment I use.
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paulz
Member
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# Posted: 3 Nov 2024 05:37pm - Edited by: paulz
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Wow 48volt, will that shock you? One thing I like about my ‘arcane’ 12v system is hard, if not impossible to get jolted in messing around. Combine that with the many auto/rv related items, tv, fridge, modem, water pump.., it’s handy. Larger gauge wite sure, maybe more current drop downsides.. More?
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Atlincabin
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# Posted: 3 Nov 2024 07:26pm
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Steve, thanks for the thoughts - not a problem with "rambling" at all. I'm pretty much locked in to 24V as I built my system 11 years ago when that was more common. Magnum inverter and Midnite SCC have worked perfectly since then, so I'm not willing to toss them just to go to 48V. I guess the Midnite could be reconfigured to 48V, but not the Magnum. I'm mostly looking to expand my storage to accommodate a power-hungry Starlink and a few other things I've added over the years.
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ICC
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# Posted: 3 Nov 2024 07:26pm - Edited by: ICC
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Quoting: paulz Wow 48volt, will that shock you?
Not likely; 48 volts is generally considered safe. But it's a good idea to use caution when handling any voltage equipment as shorts can cause thermal burns from arcs.
My home system is 48 volt based. I have never received so much as a tingle when connecting cables. But I also do not intentionally grasp a positive and negative at the same time.
I do have a special set of tools for handling cabling. For example, the combination end wrenches are completely insulated except for where the wrench will actually engage the bolt or nut hex. And only one end on each wrench is non-insulated; I have one 9/16” with the box end uncovered and a second with the open end uncovered.
I also have a set of Wiha screwdrivers & pliers that are highly insulated, designed for electrical work. One can insulate screwdriver shanks with shrink wrap to insulate them and make work safer.
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Notes
Member
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# Posted: 3 Nov 2024 07:50pm
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@Atlincabin, what is your power usage for Starlink. I have been considering getting it for monitoring my Midnite classic and some cameras.
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ICC
Member
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# Posted: 3 Nov 2024 08:00pm - Edited by: ICC
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Quoting: Atlincabin Midnite SCC
I don't know if it is even worth mentioning, but I ran into a situation that my Midnite SCC had trouble with when I changed to a lithium battery at my cabin.
Once when I was away for a few days, on my return I found the battery BMS had put the system to sleep. Nothing had been left connected and working. It was "lightning season" and past excitement had taught me disconnection was best when away. To wake the BMS a charge current was needed. Midnite controllers and a few others need to sense a voltage before they can charge. I had to jump start the lithium battery as I had no other charger at hand. Some chargers do not need to sense the voltage. I changed to a Victron SCC and sold my Midnite to a relative. The Victron record the voltage of the battery last connected to in memory and will use that to start a charge. There are also some inverters that have a similar problem. You may or may not have a problem. It may depend on how the BMS works. I have no idea. Maybe Steve has something to say.
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Atlincabin
Member
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# Posted: 3 Nov 2024 08:13pm
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Notes, the Starlink uses about 90W for a couple minutes on powerup, then runs about 40-45W while running. I believe it draws relatively more power when it is actually doing something as opposed to being idle, but I'm not sure. Before I got my system, I put a kill-a-watt meter on a friend's system that was used for "average" usage, i.e., no gaming or extreme data handling, and it averaged 41.5W/hour over a 4-day period. That was running continuously including overnight. That was also a gen2 version. I have the gen3 but have not yet put a meter on it (I won't be back at the cabin until next summer), but looking at the power usage on the Starlink app (not very quantitative) suggests about the same for the new version. We are at 60N latitude and most of the satellites are 6-700km away on the horizon, so that may or may not play a role in the power usage.
ICC, thanks for the warning. I talked to the Midnite people last summer when I was starting to plan for this transition, and they said that I should update my software for the lithium. Whether that will address the problem you mention, I don't know. I will try to remember to post back to this thread next summer.
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Steve_S
Member
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# Posted: 3 Nov 2024 09:29pm
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@Atlincabin
I hear ya with the Magnum (great stuff) and so on. Just felt I had to say it. There are good 24V/100AH + Packs out there. Stick to native Voltage.
Midnite Classics need to sense the battery voltage when powering up (what a PITA) because with Lithium if they are off, the Midnite can come up as 12V as a default. Not sure about Kidd & others.
Inverters don't need to sense Voltage, they are designed for specific voltages.
BMS' vary a lot. Typically, a decent SmartBMS will shutoff a battery at the cutoff point but can still be accessed by the phone APP. Sometimes, needs a button push on battery to kick the BMS. These often have an "emergency" ON mode to power up the battery for a short while only.
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ICC
Member
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# Posted: 3 Nov 2024 09:49pm
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Quoting: Steve_S Not sure about Kidd
... The Kid just would not connect or do anything until the BMS was awakened and it sensed the voltage. The Outback FlexMax were exactly the same. Dead until BMS was awake and a battery voltage present. Those got sold and replaced as well. (old home system) I never minded that with lead-acid batteries. I thought it was good as the CC would always sense the correct battery voltage and set itself to the correct working voltage; everything was fine.
Here's the reference I was thinking of ...
"Which chargers CAN’T recover a sleeping battery?
AIMS power 12/24v and 36/48v converter chargers
AIMS Power inverter/chargers
Magnum Inverter/charger units
Midnite Solar charge controllers
Outback FlexMax solar charge controllers
Voltronic All-In-One inverter/charger units"
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Atlincabin
Member
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# Posted: 3 Nov 2024 09:57pm
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Well, that sucks if I have to climb into the loft every day to start the controller. Hoping that upgrading Midnite software will fix this. If not, perhaps somehow leaving a small battery in the system that doesn't have a smart BMS to keep the CC sensing the proper voltage? Leave on a small constant load? Surely there is some way around this problem, but if not, I may be in for a completely new setup....
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ICC
Member
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# Posted: 3 Nov 2024 10:38pm - Edited by: ICC
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A full time residence with something operating at all times should keep the BMS "alive" and a voltage present. Some BMS (SOK) allow setting the time the system will wait with no loads, no charge, before entering sleep. I would think that a load like an small LED light should keep the system awake. (LED light like a nightlight, but on very low always? Night light with black tape over the light sensor?)
In the case of my cabin I am absent much of the time and do not like to leave things running unnecessarily. I have one 24 volt 100 Ah battery and manage fine if I watch what's on. I turn the inverter off over night and save a fair number of watt-hours. I do have a few DC direct lights.
In the case of my house I used an Outback inverter system that had a great sleep system which saved a lot of battery power when active. I did not have electric fridge or similar appliances back then with the lead=acid batteries. The inverter sleep caused issues with the CC wakeup most mornings when I investigated lithium batteries.
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Atlincabin
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# Posted: 3 Nov 2024 11:54pm
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ICC, thanks, that is more encouraging. Easy enough to leave a small load on overnight, as I have plenty of solar in summer at 60N to cover the load. It becomes more of an issue into September when the days are shorter and we use more lighting etc. I may leave the Starlink on 24/7 depending on the situation. I've been considering getting a small weather station and/or webcam, so it would be nice to have the internet connection as a constant and that would mitigate the sleep problem.
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ICC
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# Posted: 4 Nov 2024 01:26am
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60N!
A long ways north of me
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Fanman
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# Posted: 4 Nov 2024 02:33am
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I'm trying to get a handle on determining the state of charge of LiFePO4 batteries. I've seen the voltage vs. SOC charts, but it's not clear whether the voltages are under load or resting. I know that for AGM batteries, you have to measure voltage after resting a half hour or so for it to be an accurate representation of SOC. Are lithium batteries the same?
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ICC
Member
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# Posted: 4 Nov 2024 03:58am
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Yes. Resting voltage is best. It's a narrow range.
A coulomb counter is another, possibly more accurate method. Here's a link to explanation Not a specific product endorsement, but an idea. I had one by that I used in a small power pack I made. I don't see it listed anymore but it is similar to this one.
These most often use a shunt resistor for large loads (100 amp.....) This is lower amp so can skip that but at 50 amps is more than what I think your fuel pump would need.
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ICC
Member
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# Posted: 4 Nov 2024 04:58am - Edited by: ICC
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20 amp range ???
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Fanman
Member
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# Posted: 4 Nov 2024 11:09am - Edited by: Fanman
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Quoting: ICC 20 amp range ???
I put something like that in our camper, only it uses a Hall effect sensor instead of a shunt.
Pity you can't get something like that built into the battery. It already has a built in BMS, adding the display and associated electronics would be a simple matter.
In the R/C world they used to sell "expanded scale voltmeters" to display the discharge range of nicad batteries, they had an analog meter that wouldn't look as much out of place in my plane as a digital display.
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paulz
Member
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# Posted: 9 Nov 2024 03:00pm - Edited by: paulz
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A test problem yesterday I haven’t figured out. First, I fired up my big Onan two cylinder lp generator I haven’t been using. Plugged in the two 40 amp Meanwell chargers, 80 amps into the four Valence LFPs as usual. Lately I’ve been using the old gas generator I built the cabin with, will only put in 60 amps. I have a voltage/amp gauge, the negative battery cable from the bank passes through a ring sensor (I forget what you call those) that gives the amp gauge its reading. All the above is working as normal.
Then I thought why not jumper and plug in the one spare Meanwell, in theory it should give me 120 amps into the bank. No such luck, still 80 amps. I recabled, switched them around, tested each one individually..
Thinking maybe the generator was maxed out, I fired up both generators and plugged one charger into it. No help, still only 80. Hmm. Maybe the bank will only take in 80? Looked it up, they should take more easily. Cables? I’m using car battery cables, thick. Gauge? It has at least two digits, should go up to 99 at least. Terminals? Nothing got hot..
I don’t need the 3 chargers hooked up, probably better having the one spare. Just confused why it didn’t work, the faster charging would be nice.
Pic of the gauge with no charging going on the 6 amps is going out powering cabin stuff.
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Steve_S
Member
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# Posted: 9 Nov 2024 03:28pm
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Only thing I can think of is the Battery Resistance. As they charge the resistance increases & amps taken drops. Just my guess, anyways.
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paulz
Member
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# Posted: 9 Nov 2024 03:55pm
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Good guess Steve. I have noticed that normally, as the bank charges the amps do drop from 80 to 70ish as the voltage goes up slowly. Maybe above 80 it’s more pronounced. Going back to the grid today, the spare charger is still out so when I get back will give it another try.
Taking your prior post about new tariffs coming in, I inquired about one of these 460ah batteries that popped up on CL locally, new in box, $750. Missed it though. Should have been quicker, just lazy because my bank seems to be hanging in there for now.
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