Charging lithium from the Alternator

[Technispark]

Sorry, but why would I pay 4 times the price of the 110AH LA I bought, when I clearly didn't and don't need it? I did very nearly get sucked into Lithium, and at much less than the £300 you quote.

We are100% wild campers (as far as that goes in van). This not only covers where we stay, but also how we stay; we're very minimalist within the constraints of a motorhome.

It depends how vigilant you are looking after the LA. Battery . I only got a couple of summers from the cheaper LA bats. so Lithium will be cheaper for me. It was worth paying more for the Ecobat to get electronics in the battery compatible with the alternator and mains charger in my 18 year old van without any other complications!

 

[Robmac]

Sorry, but why would I pay 4 times the price of the 110AH LA I bought, when I clearly didn't and don't need it? I did very nearly get sucked into Lithium, and at much less than the £300 you quote.

We are100% wild campers (as far as that goes in van). This not only covers where we stay, but also how we stay; we're very minimalist within the constraints of a motorhome.

Yeah but consider as well though that you wouldn't have to pay for paraffin for the lamps anymore Kev.

 

[Pudsey Bear]

It depends how vigilant you are looking after the LA. Battery . I only got a couple of summers from the cheaper LA bats. so Lithium will be cheaper for me. It was worth paying more for the Ecobat to get electronics in the battery compatible with the alternator and mains charger in my 18 year old van without any other complications!

I suppose so if you don't have a decent solar controller, not the right place to cut costs though.

 

[Pudsey Bear]

Yeah but consider as well though that you wouldn't have to pay for paraffin for the lamps anymore Kev.

As a couple, we just don't use much when parked up, and we don't park up early, so most stuff is done while driving. Liz uses more than I as she's a fecking teenager and NEVER off her phone at night.

 

[Boris7]

As a couple, we just don't use much when parked up, and we don't park up early, so most stuff is done while driving. Liz uses more than I as she's a fecking teenager and NEVER off her phone at night.

Maybe if you got off here and talked to her more

 

[trevskoda]

Sorry, but why would I pay 4 times the price of the 110AH LA I bought, when I clearly didn't and don't need it? I did very nearly get sucked into Lithium, and at much less than the £300 you quote.

We are100% wild campers (as far as that goes in van). This not only covers where we stay, but also how we stay; we're very minimalist within the constraints of a motorhome.

Lith batteries are now the same price as la, but its the extras that mount up, b2b and a lith battery charger is required.

 

[Pudsey Bear]

Maybe if you got off here and talked to her more

I do when I'm away, one of the reasons I go away is to get off the forums, I like to catch up when I get back though. I look in when we stop when away sometimes.

 

[MERL]

I'm guessing there must be a 9mR resistance somewhere in that circuit. Won't be easy to find!

Just measure the voltage between any 2 points and the current along that particular cable . with a clamp meter. Voltage over current gives you the resistance.

 

[marchie]

Just measure the voltage between any 2 points and the current along that particular cable . with a clamp meter. Voltage over current gives you the resistance.

Not significant; in act, Robin Sarstedt used to sing about it, in a song composed by Hoagy Carmichael - 'My Resistance is Low' ...

Steve

 

[Geek]

Just measure the voltage between any 2 points and the current along that particular cable . with a clamp meter. Voltage over current gives you the resistance.

That's easier to write than it is to do.
The relevant bits are in a chasm at the back of, and underneath, a cupboard underneath the table. Behind 'only just removable' panels.
Electrically easy, but physically awkward to access.

 

[MERL]

Sorry, I consider chatgpt to be even less dependable a source than the Daily Hate Mail. AI merges opinions without evaluating them.

You don't need to trust it implicitly, let AI do the donkey work and then fact check the results, you can actually let AI help you with the fact checking process by asking where it's actually sourced it's info from.
For example WRT the post about the performance of modern power MOSFETs and their Rds on. I fact checked it's original information simply by asking which readily available low voltage Power MOSFET has the lowest figure for Rds ON and in less than 30 seconds it came back with this.

Nexperia PSMNR55-40SSH (40 V) — RDS(on) max 0.55 mΩ @ VGS=10 V, in LFPAK88. It’s widely stocked (e.g., Digi-Key) and Nexperia promotes it as a class-leading 40 V device.
Along with a link to the Digi-Key reference for purchasing.
The alternative would be trawling through catalogues and web sites searching for the best devices.
I find it extremely helpful for this kind of stuff and can trawl the net far far better than I can. I've been periodically searching for maybe a couple of years on and off for science based research on the ACTUAL effects on lifepo4 cells and long term elevated float voltage but have never been able to find any, a couple of minutes on chatgpt and bingo, it found a study along with links to the research papers.

 

[Pudsey Bear]

I have used it a lot lately, right now it is cataloguing 2.5k+ of MP3 files to put the first release dates in.

"

• You’ve got ~2,500 MP3s.
• The job is to split Artist + Title and look up the first release year for every track.
• I’d then build you a neat CSV:

Artist - Title,Artist,Title (Year),Year


That file drops straight into MP3Tag and updates all your tags in one hit. "

I have been doing it manually for over a year, a few at a time and it is very tedious, hence let the chatbot do it.

 

[Nabsim]

My 4 Relion 100amp lithiums batteries are over 6 years old now and only get charge from my alternator or my solar no b to b so I guess I must be doing something right .I do have a mains charger but have never used it.

Now, now Geoff, full disclosure, that's not quite what you are doing

You have a lithium relay between alternator and Lifepo4 like a lot of the Yanks use

 

[MERL]

Now, now Geoff, full disclosure, that's not quite what you are doing

You have a lithium relay between alternator and Lifepo4 like a lot of the Yanks use

To be fair Neil, although Jeff may well have a lithium relay it's actually achieving very little.
The relay's main job is to disconnect the alternator from the battery when full charge is reached, the reasoning behind this is that long term floating at voltages above 13.6v is harmful and without the lithium relay the battery would be held at 14.4v constantly while driving.
The research article I mentioned in post 131 is the only science based study into the actual damage caused by high voltage floating I've been able to find and it's findings are interesting. They took prismatic lifepo4 cells ( the same cells as we regularly see in most MH batteries) and float charged them at a 15v ( they used this rather high voltage to accelerate the damage) and measured the capacity fade over time, the cells showed a 30% capacity loss after 2 years. This may appear to be quite a lot at first and would certainly be significant if you were a delivery driver or taxi but when you crunch the numbers for typical MH use it actually works out at next to nothing.
Two years as used in the research at 24/7 equals 17,520 hours on constant float charge at 15v
If you did 4000 miles a year at an average of 40 mph that's just 100 hours of driving so 175 times less than the research, this equals just 0.175% damage every year. When you consider that the research showed that degradation was slow at first but increased at a faster rate after around 5000 hours. Also as mentioned they used 15v to float the cells to deliberately accelerate the damage, at an alternator voltage of 14.4 volts degradation wouldn't be as severe, also not all of that 100 hours driving would be floating the battery because some of the time the battery would actually be sub 14.4 volts and actually charging.
Taking everything into consideration, the research article shows that for a typical motorhomer a lithium relay achieves almost nothing and is essentially pointless.

 

[Nabsim]

Does the Victron bit of kit Geoff has not prevent surge when starting engine if battery is very low as well then Merl? I just assumed it was a similar thing to what the Yanks use

In Geoffs case with the amount of tillable solar fitted I doubt very much he actually has much charge coming from the engine anyway lol

 

[MERL]

Does the Victron bit of kit Geoff has not prevent surge when starting engine if battery is very low as well then Merl?

Not sure on that one Neil, there's more than one commercial 'protection' device available for lithium charging via the alternator so I guess it'll depend on which one Jeff's using. As I mentioned the main claim for them relates to preventing over charging/floating.
Obviously there's always more than one way to skin a cat but don't a lot of the yanks simply use a large relay energised via the D+ and/or a switch anyway?

 

[exwindsurfer]

I hope you two realize I haven't a clue what you talking about lololol

 

[barryd]

I do when I'm away, one of the reasons I go away is to get off the forums, I like to catch up when I get back though. I look in when we stop when away sometimes.

Why do we have to feel guilty for being on the forums Kev? You, like me are an internet sensation! You can't let your audience down by not posting when on a trip!

 

[Pudsey Bear]

No guilt here matey.

 

[barryd]

No guilt here matey.

Nah. You're just too tight to pay for Data when in France.