12v alternator disconnected from lifepo4 while paralleled with mini AGM 1.5ah

[Fuss]

Will the alternator be damaged?
Lucas 16acr car alternator producing around 35-40a.
The lifepo4 is 280ah and the mini lead acid is 1.5ah and costs new 11€.


I will disconnect the alternator from the Lifepo4 while it is producing its maximum output. This alternator is not of great quality and has a very small diode pack. It was mainly used as a car alternator in the 80s. It also was sometimes installed in another form on some marine engines.


This diode pack is very easily damaged. It has 9 diodes and 3 connected in the pack, I seem to remember that when you blow the pack, you can simply take the blown diode wire and then solder it to one of the other diodes and the alternator works again. It normally blows one diode at a time.
What do you think, will the alternator be damaged?

[SailingHarmonie]

If you disconnect it while it is at full power output, that is the best possible way to destroy it. The lower the output at the time of disconnect, the more likely it is to survive, but never a guarantee.

What kind of battery you are connected to does not matter at all.

[Fuss]

I will try to explain a bit clearer...
I am just doing an experiment to see if a 11€ 1.5ah mini lead battery can protect the alternator...sort of like an alternator protection device that everyone likes on here.

Just to be more clear... The lifepo4 280ah is in parallel with a 1.5ah mini lead acid. I will perform the equivalent of a BMS disconnect on the lifepo4, leaving just the mini lead acid connected to the alternator.
So what do you all think....will the alternator be damaged?

[Paradox111]

1Maybe a Balmar APM-12 Alternator Protection Module would help?
https://balmar.net/product/apm-12/

and
https://youtu.be/tAuPfgZgXec?si=hPrsAUIivS2jEhwJ

[barnakiel]

The diode bridge will burn.


You can only disconnect before the alt kicks in. But you can always soft switch. There are special switches that go for A to B to A&B - they do not have 'disconnect' in any position.


b.

[Fuss]

I am just doing an experiment to see if a 11€ 1.5ah mini lead battery can protect the alternator...
It’s an experiment… so the question is…
Will the alternator be damaged?

Or to put it another way….
Is it’s not damaged then we no longer have to keep discussing damaging the alternator when the BMS disconnects right.

[NorthCoastJoe]

I had one of those alternators on a MG. I jump started one car and it blew the diodes.
What if you blow up the battery too?

[Fuss]

Its an experiment so its not going to blow up anything, especially not the 1.5ah mini lead battery.
But anyway, here is the huge advantage over an alternator protection device....
So..when you have one of these mini lead batteries in parallel with your huge lifepo4 bank. You can test all your stuff like alternator and multiplus configurations ...all on the mini lead acid battery. you immediately see charging cutoff points from the alternator regulators and multiplus configurations. This enables you to immediately check without the long wait that can occur when you have such a big capacity battery. All configuration changes can be made in 5 minutes as the times between empty and full on a 1.5ah battery are very short.

Your configuration says it cuts off at 27.2/13.6v or whatever you set to, so now you can verify it, instead of just believing it...you do verify it right??

So think about that....is this not a far superior solution than the APD.

Now, I hear what you are thinking..."you can't run a 150ah alternator into only a 1.5ah battery"

well... I've been using this charging configuration test method for a while now.

So what do you all think....will the alternator be damaged when I disconnect the huge Lifepo4 from the alternator, leaving only the 1.5ah mini lead battery connected?

So far, no one has commented clearly on this ...I guess there is no real hurry as I won't be doing the experiment for a while yet...