DC to DC charger - not needed for boats with proper alternators.

[Fuss]

that’s true captain rivet… i’ve only got 1500 hours from my alternators … i’m so incompetent…

[newhaul]

Originally Posted by CaptainRivet

Exactly. The isolation lacquer of the coils starts to deteriorate at 120-140C. Its well known that you reduce the lifespan by half of your alt each 10degrees above 110C coil temp.
Yes they are as always some exceptions with very low rpm high amps that have a higher temp range but these ate mid 5 digits price tag.
But let him ruin his alts and LFP starter....all told him.its a bad idea but well he doesn't listen. Will get a very expensive lessons learned, hope the boat is not burning down...

But will he let us know when they die? The only possibility is he got real lucky and that is the only alternator using the ultra high temp red varnish it doesn't melt untill 170°C
So breakdown starts at 140°C to 150°C

[Fuss]

well , i didn’t buy plastic alternators, as i said real ones have to run at a high temperature or they wouldn’t be able to output 150ah… think about it… if you had a 150ah alternator in your engine room running at full output, how hot would you expect it to get… 100 degrees?? … i think not.

[CaptainRivet]

Originally Posted by Fuss

well , i didn’t buy plastic alternators, as i said real ones have to run at a high temperature or they wouldn’t be able to output 150ah… think about it… if you had a 150ah alternator in your engine room running at full output, how hot would you expect it to get… 100 degrees?? … i think not.

First an alternator puts out current and not AH=capacity....
2nd who tells you that the alternator outputs 150AH...the sticker on it?

Show us fotos of all your magical equipment installed that put us all to shame because we have no idea what we are doing since 20 years+. Till now just blabla and since month you cannot even tell us how many watts you starter has...
But state:
Alternator running for 1500h at 140 degrees celcius, 4xEVE 280 cells without BMS that start since 9 month a starter that needs 1400CCA means 1400amps. EVE 280AH speced 1C cont and 2 C peak but really can do half of that regularly if they should last at least 3000cycles...

[Fuss]

i only deal with reality Capt Rivet , that’s why the threads are drawn out… it’s reality.., it takes time, it’s not internet regurgitation… stick around… you might learn something.

[Fuss]

this would have merit if my alternators had not lasted 1500 hours so far

[s/v Jedi]

Originally Posted by Fuss

this would have merit if my alternators had not lasted 1500 hours so far

You didn’t run them at 140 degrees Celsius so far. Especially with older alternators, the wire insulation is even worse.

Why remove the temp sensors? “To get more powah”

Maybe the designers had a clue when they included alternator temperature measurements?

[CaptainRivet]

Originally Posted by s/v Jedi

You didn’t run them at 140 degrees Celsius so far. Especially with older alternators, the wire insulation is even worse.

Why remove the temp sensors? “To get more powah”

Maybe the designers had a clue when they included alternator temperature measurements?

Just give up, let him fry his alternators and LFP...he just needs to make his own mistakes and expensive lessons leaned.

[Fuss]

i only put the temp sensors on due to comments on this forum… i now removed as i see no difference… the alternators with the old style 600ah 2v 38kg forktruck batteries and the lithium are equally stressed … so 1500 hrs and you want to discuss that it’s not working…

[Fuss]

really CaptRivet… you take so much of this forums time with you so-called expertise.

[Fuss]

Originally Posted by s/v Jedi

You didn’t run them at 140 degrees Celsius so far. Especially with older alternators, the wire insulation is even worse.



Why remove the temp sensors? “To get more powah”



Maybe the designers had a clue when they included alternator temperature measurements?

so I didn’t run them in bulk mode in the last 1500 hours, they never put out their full output for more than an hour in the last 1500 hours , but now that they have been replaced with lithium they will. does this mean that mastervolt made an alternator regulator that ran in bulk mode and burned out your alternator in an hour….

[CaptainRivet]

Originally Posted by Fuss

really CaptRivet… you take so much of this forums time with you so-called expertise.

I learned my lessons and still do.
And all in the last 20 years who claimed to have magic stuff it was figured out that another faulty part of their installation saved their ass and boat.

On alternators the most common reason an unregulated alternator didn't fry when directly charging an LFP (and owner questioned why he needs regulated alternator because its working fine without) was that cabling between alternator and bank was too small, corroded or strands of the cabeling broken so the resistant of that cabling was high enough to limit the alternator output current and by luck this was limiting enough that the alternator stayed below critical temps.

[Fuss]

So why did I remove the alternator temp sensing with the lithium….well on the old 2volt 24v 625ah there was no alternator temp sensing. When these batteries were discharged by 70%, they would accept the full bulk output for more than an hour, maybe 2…this is the same as lithium.

So why is 130-140 degrees C not a problem….well industrial standard alternators are specified for continuous use and this would be at around 110 degrees C for probably 8000 hours…so let’s say the life is reduced by half, 4000 hours sound ok to me… no wonder they have not burnt up at only 1500 hours.

Ok, let’s move on to the alternator burn up internet videos… 180 to 200 degrees C, really those little car alternators and they reach 160 degrees C in under 5 minutes. Who would put something like that in their boat and use it for house batteries, no wonder they burned up, plastic alternators. They need special external regulators, alternator temp sensing, the ability to derate… or here we go… the dreaded dc to dc charger.
You know what… I bet some people have all the external regulator bells and whistles and also the dc to dc charger….I bet they’re out there.

It’s starting to sound more expensive than just getting a high quality industrial standard alternator.

And I’ll tell you what, this industrial standard alternator will not run at 180 to 200 degrees C!! It will run at 130 degrees C. And when you drop the revs, it drops its output, just like I would expect….. I guess the burn up one’s had someone fiddle with the pulley sizes…

I bet there is people vacuuming up V belt dust regularly… do you know how much additional heat this puts into your alternator!

And the last thought, it’s an enclosed boat engine room, unsuitable alternators will always need all the derating parameters and I’m sure a lot of them still aren’t lasting.

My alternators with lithium are performing just the same as with lead, I notice no difference at all.

So there we have it, Lifepo4, no different to a large AGM bank from the previous decades or a big 2v traction bank like I had as far as alternators are concerned.

[Fuss]

And if you are worried about your BMS cutting your alternator off, then put one of those relays that cut off a 30a relay at a specified voltage…you can by them in eBay for 10 bucks… just make it do this when your lithium enters the knee but less than the hvc of your BMS.

[GreenWave]

Originally Posted by s/v Jedi

So let me repeat a tip for those who charge LFP from the alternator, who have a temperature sensor on the alternator and a spike/surge suppressor that hopefully protects the alternator diodes:

If you have access to the battery cells or if you use 12V batteries in series to create 24V or 48V then you can easily create a controlled shutdown of the alternator without touching a BMS.

For this you need a Victron Smart BMV-712 battery monitor. The shunt that comes with it has two inputs: battery positive and AUX. Battery positive measures battery voltage as well as powers the monitor and you connect AUX to the terminal that has half your battery voltage, i.e. the positive terminal of the 2nd cell in a 12V battery, or the battery terminal that shows 12V in a 24V system etc.
Now you configure the BMV for battery midpoint monitoring and to raise an alarm when balance is suspect. Also, to trigger it’s internal relay on that midpoint monitoring alarm. You can probably add a high voltage alarm to that as well.

On the back of the BMV display module you have the contacts of this relay. With those you can enable/disable the regulator. If your regulator doesn’t have a feature for this you can simply switch it off. You can even interrupt the blue field wire that runs to the alternator. Note that you probably need a bigger relay in between when you don’t have a remote enable/disable.

You don’t need a $1000 BMS to do this and many already have that battery monitor installed and just don’t use it’s features

As I am in midst of upgrading to LFP, I am catching up on this thread, and you sir, just solved my biggest question/problem. I had been trying to figur eout if I could do what you suggest here (using the Victron Smart BMS) but this could work for sure.