lifepo4

[danny_galaga]

Sorry, I should have said stator, not field. My point is that regulating the output instead of the input is no big deal when it's only say 20 amps at most. You forgot to mention that the regulator is doing those steps many times a second. When described in steps people may not realise it. It's a fairly smooth operation from our point of view.

 

I admit I know nothing of how it affects anything other than a lead acid battery. Those are pretty forgiving. Just pointing out that for general purposes they work just as well as regulating a rotor (which as you point out is actually the field winding,  permanent magnets being the alternative to an electrically created field)

[RFguy]

hundreds of times per second. each time there is a stator pole  pulse . Usually an electronic component called an SCR is used which gets turned on by the regulator, and turns off by itself at the end of the pole pulse.

[facthunter]

THAT would have to create electrical noise, surely,. Permanent magnets can lose some of their magnetism also but they are self exciting and others relying on residual magnetism may not start if the Battery is discharged. The switch is often start Off Run.  Nev

[RFguy]

usually with the simple ones, the SCR turns on at start of half cycle, and turns off at the end of the half cycle. no noise. If it turned off or on  during the cycle, IE when there was voltage there, that would create noise because of the instantaneous step current.

[Freizeitpilot]

Silent Hektik regulators get a mention on a European ULM forum. I know less than zero on this subject, but just thought I’d mention it in case it is remotely useful to someone here.

 

I note they have a presence in Australia.
 

https://hektikgroup.com.au/

[pluessy]

2 hours ago, Freizeitpilot said:

Silent Hektik regulators get a mention on a European ULM forum. I know less than zero on this subject, but just thought I’d mention it in case it is remotely useful to someone here.

 

I note they have a presence in Australia.
 

https://hektikgroup.com.au/

I think you got the wrong company, no regulators in their offering?

[BrendAn]

6 minutes ago, pluessy said:

I think you got the wrong company, no regulators in their offering?

You might want to look at skippys post on the prev page

[skippydiesel]

On 12/06/2024 at 7:31 PM, BrendAn said:

You might want to look at skippys post on the prev page

https://www.silent-hektik.de/UL_R_912.htm

 

[Freizeitpilot]

I note that Rotax is now re-branding and selling EarthX LiPo4 batteries.

[RFguy]

the problem with those batteries is some of them can disconnect themselves ... that is bad for electronics both lack of power supply, and consequent high voltages and nasties that will occur with the perm mag alternator driving  no battery

Rotax have  shown poor engineering judgement  (lack of capability, understand, experience and knowhow) 

 

[Freizeitpilot]

The marketing spiel that comes with them is……

 

”come with a battery management system that includes over-discharge protection, redundant charge and discharge circuits, local LED battery fault indicator and remote battery monitoring connection via EFIS or panel mounted LED light “

 

[Freizeitpilot]

2 hours ago, Freizeitpilot said:

The marketing spiel that comes with them is……

 

”come with a battery management system that includes over-discharge protection, redundant charge and discharge circuits, local LED battery fault indicator and remote battery monitoring connection via EFIS or panel mounted LED light “

 

RFG - how do you interpret this marketing gumpf ?  Is this ‘battery management system’ there just to protect the battery, with no downstream consideration to the aircraft electrics / avionics if the battery decides to suddenly ‘protect’ itself ?

 

Interested to hear your thoughts on this. LiPO4 battery technologies clearly have some pros, but good to know the cons as well.

[RFguy]

the BMS MAY do a number of things

1) first and foremost- ensures cells stay balanced. usually this is done by shunting current around a cell if it is higher than a max voltage. IE it stops a high  cell rising further. 

most have passive balancing- think of a 3.6V zener diode (or approx that) across each cell.  during charging, if the cell tries to rise above the zener voltage of 3.6V, the zener tries to short the current, preventing current flowing through the cell (preventing more charge). 

there is some active balancing systems where there will be some controller that attempts to equalize the batteries  by pushing charge around.  I'd expect most vehicle batteries (EV) to do this. 

2) low voltage disconnect - I wouldnt want this in an aircraft.... often they wont reconnect without some specific charge type.

3) over voltage disconnect - not so common-  disconnecting the battery from the terminals if the voltage  is getting too high (charge source unsuitable) .

 

LIFEPPO4 batteries are in general not compatible with common charge systems.. this is because their internal resistance is very low, and the batteries being charged looks like a short circuit- chargers need to be current limited. Voltage wise, they're quite compatible with lead acid ... as long as  a lead acid charger (usually used for remote power systems) doesnt have an equalise mode enabled where it intentionally gases all the cells (high voltage) to get them all the same.

Edited September 9 by RFguy

[kgwilson]

Modern EVs have quite sophisticated Battery Management Systems and is one on the main reasons for their long expected life. My EV will balance the batteries every time it is charged to more than 60% of its capacity when charged from an AC outlet which is a slow charger. My home EV charger has a maximum output of 32 Amps single phase. Fast DC charging will not balance the batteries & if the vehicle is charged for a long period time using fast DC chargers, the car will tell you to use an AC slow charger to balance the batteries. MG provide a 10 year 250,000km warranty on all its EV batteries & in China & Thailand they provide a lifetime warranty capped at 20,000 km a year.

 

This demonstrates how good modern Li-ion (NMC & LFP) batteries are with BMS systems.

[ClintonB]

On 6/9/2024 at 6:50 AM, Moneybox said:

I just wrote this on my iPad and it disappeared when I posted it so I'll try again using the laptop.

 

I just wanted to post my opinion of LiFePO4 batteries.

 

I replaced our 4x120ah eight year old Rittar AGM batteries with 2x100ah Solar King lithium batteries.

 

The AGM batteries took eight years of severe abuse with poor recharging and too many discharges beyond their recommended limit. The AGM batteries were utterly reliable and gave me the security of being a backup for emergency starting if the start batteries failed. They performed admirably with their only drawback being the 100kg weight penalty. 

 

The lithium batteries are extremely light weight and hold their voltage well until they reach that critical point of discharge when the battery management system will disconnect them without warning. They will not come back to life until all current drawing devices are disconnected or turned off. I have used them ONCE for an emergency start. They gave me perhaps one second of start power before disconnecting but that was enough to crank the 4.8L Isuzu to start. It took me the next half hour to get the lithium batteries back on line. Any small hiccup in the electrical circuit will cause the lithium batteries to spit the dummy and then there's always a delay getting them back. These lithium batteries are the most unreliable power source I've ever experienced and I wouldn't want to have my life depending on them. 

Working in the caravan industry I see this all the time. People are caught up in the hype. If you are an occasional weekend user I cannot see the sense in spending $8k on a complete lithium change for bugger all gain over lead acid batteries that work well if looked after. Some I look after have had batts for over 10 years and still working fine.

if a caravan is that close to its weight limit that a 40kg Saving on 2 batteries is the least of its problems.

some have even got the idea that lithium and solar replaces their generator to run the AC on and inverter. This is not good for the batteries lifecycle.

[spacesailor]

Lead-acid batteries can only be safely drained to 

9 volts , then it degrades its life hugely. 

Better have those expensive Lithium Iron batteries. 

For longer life .

spacesailor

[ClintonB]

On a technically, you should not be draining your system that far. 10.6 v is pretty much 25% left. Most items in a modern caravan will not run below 11.5v like Hot water systems, tvs, fridge control boards etc. 2 panels of 200w and 2 by 120Ah batteries will keep most going satisfactory. It is when they add a few extra batteries on the same charging system, and try to run inverters that it becomes an issue.

i have to spend half of my days fixing up these kind of muff ups.

 

[spacesailor]

My poor Delica had two 750 ah 12 v batteries ( 3 years old ), I Killed them ( overdischarged ) twice they were doomed .

Replaced by some " calcium " something batteries .

They lasted less than 12 months. 

So back to " flooded wet cell " batteries,  & two years later still going strong .

spacesailor

 

[Red]

Wow 2 x 750ah ?!!!...I didnt know you could even get that high a capacity 12v battery outside of some sort of industrial use...what electrical things were you running in your camper SS?

(Im imagining a mahoosive killowatt sound system with killer bass bins😁)

[spacesailor]

Just standard camping gear , 4 amphour fridge/freezer .

CB radio & a small number other bits. 

 But left on overnight . So probably 48 hours  total hours from my 1500 ah truck batteries .

I should have had a 4 ah solar input , but it got shaded .

As the diesel motor needed the "" preheater " before starting it only just failed  ( turned over slowly ). 

My ' emergency jump-start ' just melted a terminal off .

spacesailor

 

[kgwilson]

1500 Ah is a bit of an overkill. They would run your fridge without charging for over 2 weeks on a full charge.

[onetrack]

750 A/H batteries?? Surely you mean 750 CCA, not A/H? Even the biggest truck batteries are only 200 A/H.

[spacesailor]

Your all correct ! .

It is CCA. .

As it's now three years since putting those  batteries  in 

I hope you can give Me forgiveness for  my forgetfulness. 

spacesailor