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RE: Renogy 100ah LifePo4 Lithium - Max Surge Current
For what it's worth...
https://www.ev-power.eu/blog/LiFePO4/LFP-as-starting-battery.html
From that link...
LFP as a starting battery – two concerns
Question: I want to use the LFP battery (4x 3.2V cells) for starting of my car. What SBM (simple battery management board) should I use to protect the battery?
You cannot use a SBM to protect the starting battery. For starting the car, the current will be very high, hundreds or even nearly 1000 Amps, it is not possible to disconnect such high currents.
WARNING: Additionally it is not possible to disconnect the battery from vehicle circuits. The car electronics may burn or become faulty of the battery is suddenly removed from the circuit, as a result of disconnection, during the operation (when the engine is running).
To install LFP battery, the battery must be hard wired to the car, the same way as the lead acid battery is. This brings some risks and problems:
1) No disconnection, no fuse. Note that the car battery is wired without any fuse or disconnection ! ! ! This is a huge risk that exists in all cars. It is crazy, but this is the reality. Yes, this is the most crazy thing about all cars you see in the streets — no high power fusing or disconnection of the 12V battery. This is also one of the main reasons for the many car fires – the fire starts from short circuit on the battery that cannot be disconnected from the car…… so the car will burn completely.
There is less of a issue with the Lead Acid battery, as the Lead Acid battery can give the power for a short time, and it will stat loosing the peak power rating, after longer time of high current discharge.
However for LFP battery, in case of short circuit, the battery will release all power suddenly, constantly and continuously. The LFP battery has much more power that the lead acid battery.
ADVICE: Our definite suggestion is to install a high-power rating fuse for the LFP battery. The rating of the fuse should be 300Amp or even more depending on the starting currents for your application.
2) Deep discharge. If you left your car for long time without care, the on-board electronics (e.g. alarm, security systems, car radio, etc….) will drain the battery to completely empty – the deep discharge. In some cars the battery will be depleted as quickly as in two weeks.
This is a lesser issue for the Lead Acid battery, as most Lead Acid batteries can survive the deep discharge. They can be recharged and they will perform in a reasonable way again. However this is not possible with the LFP battery. If you deep discharge the LFP battery, it is damaged for ever and there is no way to restore it to function.
ADVICE: Our suggestion is that the LFP battery should be fully disconnected from the car in case you park the car and the car will not be used for a longer period of time.
A lead acid battery can withstand a "deep discharge" better than lithium? I think that's arguable.
Every manufacturer of lithium iron phosphate suggests in their documentation that you can run a LiFePO4 to zero and as long as you remove the loads and recharge it immediately, it will recover just fine and you'll do less damage to it, than to a FLA run to zero. The FLA might not even recharge at all, depending on circumstances. Or you'll have to hit it with a lot more amperage than you might have available in most chargers, just to get it over the "Frankenstein activation hump".
The cold cranking amps issue is the real problem, as starters will draw a lot of amps for a short period to turn the engine over. The BMS in most batteries will prevent that occurrence, and cut discharge. However there are some that have been adjusted to allow a much higher surge discharge, as I pointed out previously, with examples.
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MDKMDK
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12/04/19 03:26pm |
Tech Issues
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RE: Renogy 100ah LifePo4 Lithium - Max Surge Current
From the Owners Manual, an Onan QD3200 diesel generator can draw up to 675 CCA under very cold conditions, with a draw of 475A just to get it to turn over at ambients down to 0F. I believe I read somewhere that they can suck up to 300A to start at more comfortable/normal temps.
Once again, any electric (starter) motor or other mechanical device can draw mucho amps when starting/running.
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MDKMDK
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12/02/19 05:43pm |
Tech Issues
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RE: Renogy 100ah LifePo4 Lithium - Max Surge Current
They also have a slightly more expensive (what's a few hundred bucks to get what you need?) model, the RB100 HP with an 800A peak discharge rating and a 1000A discharge cutoff. More in line with the cranking amps ratings of an FLA chassis/starting battery.
DISCHARGE SPECIFICATIONS
Maximum Continuous Discharge Current 100 A
Peak Discharge Current 800 A (2 s)
BMS Discharge Current Cut-Off 1000 A ±100 A (2.2 ±1 ms)
Recommended Low Voltage Disconnect 11 V
BMS Discharge Voltage Cut-Off 9.2 V (2.3 ±0.08 vpc) (4.2 ±0.5 s)
Reconnect Voltage 10 V (2.5 ±0.1 vpc)
Short Circuit Protection 200-600 µs
Just depends on your needs. They've got something for everyone there.
The RB100 has a little bit of a cushion that might keep the BMS from shutting off the discharge circuit at almost 330A, if I read the + or - thing correctly.
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MDKMDK
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12/02/19 03:50pm |
Tech Issues
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RE: Renogy 100ah LifePo4 Lithium - Max Surge Current
Mechanical devices may have short duration high amp draws.
Generator or engine starter motors, are 2 examples that may or may not invoke the excessive discharge/shut down programming of the internal BMS. I have 2 Relion 100Ah low temp 12V batteries in parallel, and they have exhibited intermittent tendencies to shut down during generator starts. Usually, if I depress the gen prep button and hold it for 30 seconds before hitting the start button, it will fire up without issue. Starting the generator with chassis engine running also works/helps. I haven't tried the battery boost switch to start the chassis engine with help from the lithiums yet.
I'm also guessing that SoC of the battery(ies) will affect the decision making process for when the BMS will invoke the high draw shutdown.
It might be the only down side (besides price?) of lithium batteries. I am aware that some of the manufacturers also offer models that are less susceptible to this issue. Relion does, but I wanted the cold weather charging models.
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MDKMDK
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12/02/19 11:47am |
Tech Issues
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RE: Built in vs. Stand-alone GPS?
I use an iPad mini (8” screen) with a Bad Elf GPS dongle and end up with a GPS that I can also check in on RV.net with after I get there.
Try that with your Garmin. LOL.
Funny, I was just thinking how nice it would be to be able to "check in" on RV.net with my dongle. Sounds almost pornographic ....:R
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MDKMDK
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11/26/19 04:17pm |
Tech Issues
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RE: Built in vs. Stand-alone GPS?
We are currently shopping for a new tow vehicle. Trying to decide whether or not we want to shell out $750 for a built in GPS. As much as I like having the built-in system and not having another screen on the dash, I'm thinking I could likely get something much more suitable for towing if I spent less money on a stand-alone unit.
Anyone have any thoughts on using built-in GPS units while towing?
Before you decide, check the cost of updating a map in a built in.
My Wrangler's map updates were quoted as being more expensive than adding a standalone unit WITH lifetime maps and traffic, included.
The other pros mentiioned here for using standalone units are also valid.
That built in update price blew me away. FCA must be getting a huge kick back from Garmin.
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MDKMDK
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11/26/19 02:03pm |
Tech Issues
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RE: V 10 mpg
what mpg is everyone getting with and without an upgrade
What upgrade are you talking about? 6 Speed transmission? One of the after market "tune ups"?
Seriously, I might have averaged 6-7 mpg over the year or so I owned one. Might have seen 10 on the Scan Gauge II on a smooth highway once in a while, on cruise, on the flat, with no head/cross winds. The downside to the V10 is eventually you have to drive off the freeways, in traffic, up hills, into headwinds, and and that's when your real "average" mileage gets crushed.
Asking an owner about the Ford V10's mileage, is like asking a fisherman about "the one that got away".
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MDKMDK
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11/25/19 03:04pm |
Class C Motorhomes
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RE: V 10 mpg
This should be good. :S :R
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MDKMDK
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11/25/19 02:15pm |
Class C Motorhomes
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RE: Non-renewable Lithium...Fact.
This entire thread should be deleted as it is based on the right wing talking point of "EVs bad!". The statement "can't be recycled" is totally false. Many companies have started successful recycling programs and here in Nevada where I live, lithium mining by evaporating salts is big business utilizing the old "poison waterholes" from old Western movies to get some use out of lifeless, desolate wasteland area. Myself, I have been driving electric over 7 years now, the last two getting fueled for free from our rooftop solar. The carbon industry is scared to death of electric vehicles wiping away their livelyhood and so are car dealers as, like I can assure you from my personal use, maintainance and repair of electric vehicles is a tiny fraction of that of petroleum cars. Most electric cars never get their brakes replaced unless parts rust off from age.
https://www.instituteforenergyresearch.org/renewable/the-afterlife-of-electric-vehicles-battery-recycling-and-repurposing/
"right wing talking point" ???
Who, from either side of that argument, has ever said "EVs bad"?
I have said that they wouldn't really be viable for some, in a limited range driving sense, and that the batteries will need to be replaced at some point, which adds a big cost hit to the life cycle, and possibly limits their resale value or viability, and that I wouldn't be likely to own one.
But never have I heard someone say they're bad. They just aren't for everyone.
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MDKMDK
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11/24/19 07:40am |
Tech Issues
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RE: Non-renewable Lithium...Fact.
Sunshine has a time of day limit. It doesn't work after sunset and before sunrise.Darn
X2 :B
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MDKMDK
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11/23/19 09:46pm |
Tech Issues
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RE: Non-renewable Lithium...Fact.
according to Wikipedia this is a list of the top 9-lithium producing countries. several are not exactly friendly to the USA.
https://en.wikipedia.org/wiki/List_of_countries_by_lithium_production
Invade, conquer, own it. The resources, I mean.
Let's face it, you get bad press every day somewhere around the globe for being imperialist invaders. Time to earn that hatred. :B
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MDKMDK
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11/23/19 06:22pm |
Tech Issues
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RE: Non-renewable Lithium...Fact.
Li is one of the most abundant resources, but everything has its limits...except sunshine.
Sunshine has a time of day limit. It don't work after sunset and before sunrise.
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MDKMDK
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11/23/19 06:19pm |
Tech Issues
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RE: Non-renewable Lithium...Fact.
Better get 'em while you can......
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MDKMDK
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11/23/19 04:28pm |
Tech Issues
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RE: Quick question about oil changes
I'd worry more about condensation in the fuel system than in the oil. If you park it for a while fill the fuel tank to the brim.
Driving it once in a while is a good habit also. These things tend to atrophy if you don't use them. Run the generator too if you have one.
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MDKMDK
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11/23/19 02:23pm |
Class C Motorhomes
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RE: traveling during US Thanksgiving
Go for it. Waddya got to lose?
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MDKMDK
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11/21/19 10:56am |
Snowbirds
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RE: Will solid state batteries change the world?
Chuck Berry wrote a song about him so he must be legit.
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MDKMDK
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11/18/19 12:34pm |
Tech Issues
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RE: Battery
Would be nice to know what type of battery, too. Make model age?
Some types of battery self discharge more slowly than others when just disconnected and left in place. If it's a wet cell type, you should try to keep it charged in the very cold temps of winter. AGMs a little less so, and Lithiums even less than that.
If it's not inconvenient, bringing it indoors over winter works, too.
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MDKMDK
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11/17/19 10:36am |
Tech Issues
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RE: Battery Monitors
No fancy graphs.
Awww, why not?:B
Nice thing about lfp no need to fully charge unless you think it's needed.
Yup.
My solar is limited to around 10A on a good sun day (3X100Wpanels), although I've pulled closer to 15A on a perfect sun day last summer. I just happened to be looking at the display and noted the higher charge rate. Pretty much maxed out for my panels. That was before the lithiums were installed though, and was wasted on a couple of barely adequate factory installed FLAs.
My point (from my prior post) is that I believe my system is pretty much "set it, and forget it" now. I still look at the displays, but I worry a lot less about power management, since I added the lithium batteries to the mix.
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MDKMDK
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11/17/19 09:17am |
Tech Issues
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RE: Battery Monitors
Not a clue about Li batt charging profiles. I ASSume they are like other batts where once their Vabs is reached and held there by the charger, that amps will have to taper as SOC rises.
Actually, everything I've read about them says hammer them with around 14.2 to 14.5 volts at whatever charging rate you can manage, until the BMS says they're full. They'll take the full charging current until the BMS burps, and says "I'm full, what's for dessert?". I think the 14.6V display posted earlier is how I would see my bank being full, or very close. They can also be discharged very low, without recharging them right away, or you can recharge them, your choice. They're probably the most flexible type of storage medium you can use these days.
Perhaps one of our members here with Li batts and nothing better to do, can make us an ugly graph like this, only using Li batts. (Or not so ugly if he is a computer whiz)
https://i.imgur.com/htnJ0JNl.jpg
There's a chart in this link about half way down, if you really want one, and some explanatory text around it, as well. Battle Borns are used as the example brand, because that's what they sell. They always seem to get good reviews on the 'net. I've got Relions, also fairly well accepted as not bad.
Happy Lithiums
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MDKMDK
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11/17/19 08:53am |
Tech Issues
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RE: Battery Monitors
"When the amps start tapering down, you are getting closer to fully charged. "
With solar and its typically low charging rate (under 10%) you can be in the 90+ percent SOC zone, but with a better charging rate you will not be close. Even so it takes a long time to get from 90 to 100.
EG, at the 20% charging rate specified for the Bulk stage with AGMs amps will start to taper at about 75% SOC--a long way from being fully charged.
What about LiFePO4 banks? Can't assume everyone is using FLA or AGMs any more.
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MDKMDK
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11/17/19 06:18am |
Tech Issues
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