Inverter current draw for running a 240V inverter. Potential over draw for Lithium batteries internal protection !

Jaahn · Guru

Inverter current draw for running a 240V inverter. Potential over draw for Lithium batteries internal protection !

Peter_n_Margaret · Guru

These are not lithium battery problems, they are limitations of the inadequate battery management systems that they choose to use because they are cheaper than ones with larger capacity.
I use a 125Ah AGM as a crank battery in the OKA. That will easily exceed the current draw that makes these lithium MBSs fail.
Cheers,
Peter

Whenarewethere · Guru

The starter motor on my car uses 238amp. My four 26ah gel batteries have a combined 5 min output of 360amps or 5 second load of 1080amps. So I can jump start & have wired in Anderson plugs ready to go if needed. But the setup is really for my fridge.

I agree with above post. If you have have heavy loads don't under design your system, you will pay for it later.

Monica W · Veteran Member

Jaahn wrote:
Lithium batteries have been a revolution to living off the power grid. There are still problems to be sorted though.

No problems need to be sorted out with Lithium batteries. Have to buy correct equipment for needs
Power consumption list is iffy, better to use 10W on 240V is 1A draw on 12V

Scubadoo · Veteran Member

Peter hit the nail on the head. Internal BMS circuitry maximum current handling is the limiting factor. Our 4 cell 300Ah Sinopoly LiFePO4 battery has no internal BMS. It is all handled externally. For the last 6 years of full-time travel it has both started the 3.9l TD engine and supplied the power to the house. Maximum peak current measured is 742A. It has survived perhaps thousands of engine starts and still performs to specs. Built in BMS "drop ins" are not an option for us.

Peter_n_Margaret · Guru

Scubadoo wrote:
Built in BMS "drop ins" are not an option for us.

Or us.

Having such serious current draw limitations totally negates one of Li batteries best features and only leaves weight as any reason to spend the significant money.

So far, AGM has done everything we need to do electrically, and at a price that is still too low for lithium to compete with. I recently replaced our 400Ah of AGM for $1,000. The last ones lasted 9 years. so it is unlikely that we will ever need to replace them.

I am starting a new long term 4WD motorhome build though that needs to be under 4.5T GVM, so I will need Li for that, but I will probably use either Winston or Calib cells (or something similar) built up to 400Ah.

Cheers,

peter

Monica W · Veteran Member

Peter_n_Margaret wrote:
Scubadoo wrote:
Built in BMS "drop ins" are not an option for us.
Or us.
Having such serious current draw limitations totally negates one of Li batteries best features and only leaves weight as any reason to spend the significant money.
So far, AGM has done everything we need to do electrically, and at a price that is still too low for lithium to compete with. I recently replaced our 400Ah of AGM for $1,000. The last ones lasted 9 years. so it is unlikely that we will ever need to replace them.
I am starting a new long term 4WD motorhome build though that needs to be under 4.5T GVM, so I will need Li for that, but I will probably use either Winston or Calib cells (or something similar) built up to 400Ah.
Cheers,
peter

Sadly you get know it all posters that are clueless to the wants and needs of users, or options of how equipment may be used.
Built in BMS batteries does not negate at all the best features of Lithium batteries for RV users.
Not all RV users requirements are to use high powered devices. Lithium sealed batteries offer many other advantages to RV.
Reason loathe replying to forums when you get the know it all's that know everything, have to reply to every post, fail to look at the advantages equipment can offer users that may not suit their needs.

Peter_n_Margaret · Guru

Monica W wrote:
Lithium sealed batteries offer many other advantages to RV.

Maybe you could list them for us?

Cheers,

Peter

Whenarewethere · Guru

I was quite happy to buy lithium, just couldn't find a size that would fit in the car. My fridge uses 12 - 15ah per 24 hours so if needed I am quite happy to run them down every now & then.

Bicyclecamper · Guru

Peter_n_Margaret wrote:
Scubadoo wrote:
Built in BMS "drop ins" are not an option for us.
Or us.
Having such serious current draw limitations totally negates one of Li batteries best features and only leaves weight as any reason to spend the significant money.
So far, AGM has done everything we need to do electrically, and at a price that is still too low for lithium to compete with. I recently replaced our 400Ah of AGM for $1,000. The last ones lasted 9 years. so it is unlikely that we will ever need to replace them.
I am starting a new long term 4WD motorhome build though that needs to be under 4.5T GVM, so I will need Li for that, but I will probably use either Winston or Calib cells (or something similar) built up to 400Ah.
Cheers,
peter

Peter what are you going to with your current camper, are you going to sell It?

Bicyclecamper · Guru

Monica W wrote:
Peter_n_Margaret wrote:
Scubadoo wrote:
Built in BMS "drop ins" are not an option for us.
Or us.
Having such serious current draw limitations totally negates one of Li batteries best features and only leaves weight as any reason to spend the significant money.
So far, AGM has done everything we need to do electrically, and at a price that is still too low for lithium to compete with. I recently replaced our 400Ah of AGM for $1,000. The last ones lasted 9 years. so it is unlikely that we will ever need to replace them.
I am starting a new long term 4WD motorhome build though that needs to be under 4.5T GVM, so I will need Li for that, but I will probably use either Winston or Calib cells (or something similar) built up to 400Ah.
Cheers,
peter
Sadly you get know it all posters that are clueless to the wants and needs of users, or options of how equipment may be used.
Built in BMS batteries does not negate at all the best features of Lithium batteries for RV users.
Not all RV users requirements are to use high powered devices. Lithium sealed batteries offer many other advantages to RV.
Reason loathe replying to forums when you get the know it all's that know everything, have to reply to every post, fail to look at the advantages equipment can offer users that may not suit their needs.

Monica, People like Peter n Margaret, know a lot, and we whom have been here longer than 5 minutes like you, value their advice. Until you can put the same expertise ang knowledge forward, with proof that you know what your talking about, I suggest you be more civil with your comments!

yobarr · Guru

Bicyclecamper wrote:
Monica W wrote:
Peter_n_Margaret wrote:
Scubadoo wrote:
Built in BMS "drop ins" are not an option for us.
Or us.
Having such serious current draw limitations totally negates one of Li batteries best features and only leaves weight as any reason to spend the significant money.
So far, AGM has done everything we need to do electrically, and at a price that is still too low for lithium to compete with. I recently replaced our 400Ah of AGM for $1,000. The last ones lasted 9 years. so it is unlikely that we will ever need to replace them.
I am starting a new long term 4WD motorhome build though that needs to be under 4.5T GVM, so I will need Li for that, but I will probably use either Winston or Calib cells (or something similar) built up to 400Ah.
Cheers,
peter
Sadly you get know it all posters that are clueless to the wants and needs of users, or options of how equipment may be used.
Built in BMS batteries does not negate at all the best features of Lithium batteries for RV users.
Not all RV users requirements are to use high powered devices. Lithium sealed batteries offer many other advantages to RV.
Reason loathe replying to forums when you get the know it all's that know everything, have to reply to every post, fail to look at the advantages equipment can offer users that may not suit their needs.
Monica, People like Peter n Margaret, know a lot, and we whom have been here longer than 5 minutes like you, value their advice. Until you can put the same expertise ang knowledge forward, with proof that you know what your talking about, I suggest you be more civil with your comments!

Ric,I absolutely concur with your assertions,and I can only hope that Monica's comment about "know it alls that know everything......" was not directed at Peter 'n Margaret,as there are few,if any,members of this forum who have a more diversified range of areas of expertise than do Peter 'n Margaret.There are not too many topics to which they cannot make a valuable contribution,and I have learned much from their valuable posts.Cheers

Peter_n_Margaret · Guru

Bicyclecamper wrote:

Peter what are you going to with your current camper, are you going to sell It?

Well, I have been telling people for a long time that it is near impossible to build a serious 4WD expedition vehicle and keep it under 4.5T GVM.

Now I am going to try, so I hope I have to eat my words. We will see. :)

It is a long term project that I will build as we can afford it over a period of maybe 5 or 6 years and I will be wanting to investigate some quite diverse ideas like fibreglass parabolic sprigs that are used in some trucks.

Alloy wheels, lithium batteries, light weight solar, no steel sub frame under the camper section, plastic bumper bar, aluminium cab body panels, FRP sandwich panel, polycarbonate glazing biggrin , light weight FRP seat shells, plastic fuel tanks, .......

When it is complete, then Yes, OKA196 will be for sale (to pay for the new one).

Cheers,

Peter

Tony Bev · Guru

Jaahn wrote:
Hi
I received a Technical bulletin from Lithium Labs as a previous customer, about continuous use above 100A from their battery powerpacks.
As these have an internal fuse that limits current to 125A continuous and ~250 for 10 seconds, if you use more that those currents the fuse will blow. They offer a solution if this is a problem. I guess other brands may need the same comments.
I thought people here may be interested in the perceived problem caused by possible over-use of the power available using big inverters. So I have edited a short version where they point out some typical 12V currents drawn by running a 240V inverter for these typical items and some comments.
Jaahn

Below is a list of items often used in a caravan or mobile homes and the typical 12V current that would be drawn by an inverter from a 12 volt battery.
Phone charger                1-2A               Small 800W microwave                                                       120A
TV 24 LED              3.5A             Toaster, 2 slice.                                                             120A
Washing machine            25A               Single element induction cooktop. 2000Wmax.    170A
Milk frother 500W            45A               Hair dryer 2100W                                                          185A
Airconditioner 0-80A          Kettle 2200W                                                     200A
Coffee machine 1500W     120A         Fan heater 2200W                                           200A

As can be seen from this list, in order to keep under the rated 100A continuous discharge, these devices can be used, but for limited time and not together.
Lithium batteries have been a revolution to living off the power grid. There are still problems to be sorted though. The answer to solve these issues is to go for a higher voltage system, 24V or even 48V as we have done in the past. Something to consider for your next caravan perhaps

-- Edited by Jaahn on Sunday 5th of July 2020 07:41:40 PM

Very interesting number, Jaahn, so thanks for that

Below is a snip from a West Australian, reseller of drop in Lithium 120 AH battery

I have (and I suppose plenty of others, like me), no way of knowing, if the specification sheet is correct, until people have tried these batteries, in the field

I do notice that the continuous discharge rate is 150 Amps

I also seem to remember, that this battery was on special for less than $700, and it is now just less than $1,000

I had read, (a few months ago), that some people were claiming that this battery was only good for less than 100 Amp continuous discharge

I have no way of knowing, if this drop in Lithium battery, is some sort of breakthrough, or pie in the sky

Lithium 120 AH.png

Lithium 120 AH Benefits.png

Peter_n_Margaret · Guru

When I see statements like "105Ah usable capacity" alongside "Equivalent to 200Ah lead acid battery", I relegate everything else that is said to the rubbish bin.

And what does "380Ah maximum discharge" mean, exactly? Well, I know, it should say '380A maximum discharge'. If you can't get stuff like that correct, everything is suspect.
And "Charges from solar (12V regulator must be used)" and "Series connection for 24V-30V"?
"Life cycles 80%: 2000" - 80% of what??
Lots of conflicting statements?
Cheers,
Peter

Whenarewethere · Guru

As a comparison the Victron 100Ah battery

15kg

197 x 321 x 152mm (9.612 litres volume)

Maximum continuous discharge 200A

Recommended continuous discharge <100A

End of discharge voltage 11.2V

The Victron 150Ah battery is closer in size but still a bit smaller volume than the 12kg battery.

20kg

237 x 321 x 152mm (11.564 litres)

The 12kg battery has a volume of 12.845 litres. I would be interested what is or isn't inside!

Hylife · Guru

Once again the old dinosaurs who cant or wont get with modern technology run off their mouths with bullsh!t knocking Lithium's.

If you are using your batteries as a crank battery, then you should just buy the appropriate Lithium designed for cranking, not the lithium designed for RVs.

Just like a standard 100AH AGM deep cycle is useless for cranking with a recommended maximum current draw of 80-100 amps, because that is not what they are designed for.
Deep cycle lead acid batteries are rated for a discharge rate of 0.05C over 20 hours.

Crank batteries on the other hand are designed for high discharge rates of 2C over very short periods, and are next to useless for RV use as deep cycling severely shortens their lifespan.

Lithium's are imminently far more suitable for "modern" RV use than ancient style Lead Acid batteries, so long as you recognise that the modern traveller and modern RV has no need of 240V appliances and would never have a need to draw down more than 10amps at once.

So comparing inefficient inverter driven 240v use is like comparing apples and oranges. If you can't let go of your 240V appliances you really should be staying at van parks where yo have 240V supplied.

For modern RV use, Lithium's cost is cheaper than lead acid because they last 4 to 10 times more cycles with nearly double the depth of discharge, and they are a third the weight.

Why is it that on one hand, you dinos spout constantly a safe depth of discharge level for lead acid at 50%, yet you cant seem grasp the math for LiFePO4 being able to safely go to 95% DOD for around 2,000 cycles?

Yes, that's right, 2,000 cycles is 6 years, or at 50% DOD it's 5,000 cycles. That's 14 years!

100AH LiFePO4 are now down to around $500 each, so spending $1,000 on 2x100ah LiFePO4 is like having 400AH of Lead Acid, and you cant buy 400AH of lead Acid for $1,000.

Also, at around 38kg for a 100ah lead acid battery, you are looking at 152kg, versus 30kg (2x15) for 200ah of Lithium's.

Whenarewethere · Guru

My fridge won't run any longer with 104ah of lithium instead of 104ah of gel & 16kg extra in lead is only half a spare wheel.

& Just having 52ah doesn't give my the option to get a few extra days with inclement weather.

Typically I would use my batteries 90 days a year at 25% discharge so they will last longer than their designed life.

-- Edited by Whenarewethere on Tuesday 7th of July 2020 07:19:25 PM

Bicyclecamper · Guru

Peter n Margaret, I have come across Renogy thin flexible solar panels that I am going to use on my Teardrop, and they have very good reviews and you can buy them here. And back when I was first looking at solar panels for my house roof, you could get Copper Iridium panels, ultralight very efficient, and worked very well in cloudy weather. Maybe by the time you are ready to put solar panels on their will be many more light and efficient panels out there.

Peter_n_Margaret · Guru

Bicyclecamper wrote:
Peter n Margaret, I have come across Renogy thin flexible solar panels that I am going to use on my Teardrop, and they have very good reviews and you can buy them here. And back when I was first looking at solar panels for my house roof, you could get Copper Iridium panels, ultralight very efficient, and worked very well in cloudy weather. Maybe by the time you are ready to put solar panels on their will be many more light and efficient panels out there.

Ta, I hope so as they will be a 100% requirement.

Cheers,

Peter

Muskat55 · Veteran Member

What a pity T1 Terry was made extinct by the dinosaurs, he would cut through the BS.

StormCamper · Member

The BMS "fuse" is just switches, has to be or else they could never fit the protection in these sealed batterys. Most large amp BMS which are slim compact units with multi FETs are rated for very high breif current for a few secs, but their cont ratings are chinese amps, not real amps. So my general rule is halve the sticker BMS rating for continuoius, your setup, your call... But if you parallel blocks you spread the load. Now here is the real kicker, most of these batteries can't discharge more than ~0.5C without loosing alot of capacity anyway, oh they forgot to mention the voltage drop didn't they? add in the system's wireing resistance & you can easily loose 15-20% of the capacity. Why would anyone do that for such high price??? Just ask DIY EV guys about this.

Leaving dropins behind, Now the better way to go about the BMS is use a quality relay that gets turned on/off by the BMS, if BMS turns off from a high cell for example is cuts the power to the relay. Simple & reliable. How are going to use 300-400A cont? Never gonna happen. Add in a victron battery protect & of course the proper fusing & that is all the BMS you will ever need for a respectable 4S 12V setup, add in the BMV712 & your laughing! for balancing well you could use the dinky BMS itself, or just manually re-balance every so often with your own plug in active balancer. Anyone who knows lithium knows a basic 4S setup with quality cells & used properley don't go out of balance much at all. Well this is how I do it & this is how many serious setups are done and it works. For parallel setups you just duplicate the BMS & relay & with sizing the bank so the max C rates are no more than say 0.3C you will have a good reliable system. Lithium is pretty simple (in some ways more than LA).

So for a bare sell build there is no limitation of the BMS, most quality cells can safely put out about 1C cont. Most large banks like 400AH plus will never see above .5C really. The way cells are going these days getting smaller you can fit 400AH in the back of a 4wd if you know what you are doing.

For those who still don't know a good LA DC can be taken down to 80% DoD each & every cycle, proved beyond a shadow of a doubt. I touture tested some cheapo AGMs this way & they were fine after 40 hard cycles to 90%...The secret here is re-charge to full after each & every cycle if possible. Well that is why you go lithium, because they are fine with PSOC cycling.

StormCamper · Member

Hylife wrote:
For modern RV use, Lithium's cost is cheaper than lead acid because they last 4 to 10 times more cycles with nearly double the depth of discharge, and they are a third the weight.

Why is it that on one hand, you dinos spout constantly a safe depth of discharge level for lead acid at 50%, yet you cant seem grasp the math for LiFePO4 being able to safely go to 95% DOD for around 2,000 cycles?

Yes, that's right, 2,000 cycles is 6 years, or at 50% DOD it's 5,000 cycles. That's 14 years!

100AH LiFePO4 are now down to around $500 each, so spending $1,000 on 2x100ah LiFePO4 is like having 400AH of Lead Acid, and you cant buy 400AH of lead Acid for $1,000.

Also, at around 38kg for a 100ah lead acid battery, you are looking at 152kg, versus 30kg (2x15) for 200ah of Lithium's.

This post is completley incorrect & full of unsound reasoning it's scary! Just for any poor sucker, the information is out there so do your reaserch & beware of the internet fanboys who have 0 experince with this stuff. A 100AH $500 lifepo4 will be using cheap garbage cells that are not matched & are of grade B or C. The cycle life is a complete fabrication just like so many other things in the world. You cant compare Li to LA with DoD, because the cycle life is not 1:1, but calender life well good AGM can last up to 8-9years, some lifepo4 cells showed their age after 8years.... NMC made in Korea & Japan is getting very high cycle life, you got alot to learn son.
For the cost of a Lifeline 125AH AGM I could get similar sized high quality chinses prismatic barecells. That is why you do lithium.

Jaahn · Guru

StormCamper wrote:
The BMS "fuse" is just switches, has to be or else they could never fit the protection in these sealed batterys. Most large amp BMS which are slim compact units with multi FETs are rated for very high breif current for a few secs, but their cont ratings are chinese amps, not real amps. So my general rule is halve the sticker BMS rating for continuoius, your setup, your call... But if you parallel blocks you spread the load. Now here is the real kicker, most of these batteries can't discharge more than ~0.5C without loosing alot of capacity anyway, oh they forgot to mention the voltage drop didn't they? add in the system's wireing resistance & you can easily loose 15-20% of the capacity. Why would anyone do that for such high price??? Just ask DIY EV guys about this.
--------

Hi StormCamper smile

Actually as the original poster, I was quoting from the manufacturers Technical Bulletin which says they have fuses that will blow at the currents specified. They also have a BMS. You might know more than them but I doubt it.

I will not comment on the rest of your posts other than to say people should be careful to research what they are buying and how to install it well. It is easy to get less than you thought you would. furious

Jaahn

-- Edited by Jaahn on Sunday 19th of July 2020 09:49:58 AM