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Paul Carmichael avatar image
Paul Carmichael asked

Auxiliary charging

Hello all.

I'm going to have to bite the bullet and buy lithium, as my Hoppecke FLAs have died after just 8 years.

I say died, but they still function. They just lose voltage very rapidly.

I was thinking of leaving the FLAs where they are and keeping them trickle charged "just in case".

It's a 48v system.

Has anybody here done this?


PS: It's a Quattro 48/8000

battery charging
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matt1309 avatar image matt1309 commented ·
Hi @Paul Carmichael


When you say leave in place do you mean still connected to the system?

The charge profiles for Lithium (im guessing you're going for LiFePO4) are quite different to FLA. I don't think it's possible (or at the very least not recommend that you connect both at the same time ie in parallel, without further devices/configuration to protect both batteries).


I've not got any experience with this just sharing what I've seen on other posts.

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Paul Carmichael avatar image Paul Carmichael matt1309 commented ·
I meant just trickle charging, to keep them "ready for action". I could then swap them over manually and change the charge profile temporarily, should the need arise.
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Paul Carmichael avatar image Paul Carmichael Paul Carmichael commented ·
I've just read the manual, and it seems that the 48v Quattro does not have an aux output.
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matt1309 avatar image matt1309 Paul Carmichael commented ·
Ohh I see.


So you'd have a separate charger that would be trickle charging the FLA's and then if anything went through with LiFePO4's or if you needed batteries for any other reason you would adjust the system back to working with FLA and disconnect LiFePO4's and run off FLAs again? Have i followed?


If you just want to trickle charge the FLA's with excess power once LiFePO4's are full then you could use a smart switch (or maybe a relay on GX device) to turn the separate battery charge once the LiFePO4 batteries are full. You could control the relay/smart switch via node red or probably the VeConfigure assistants. (I do a similar thing but for turning on a water heater to use up excess power rather than trickle charging FLA's)

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Paul Carmichael avatar image Paul Carmichael matt1309 commented ·
Yes, you have understood perfectly. But I'm afraid the inverse is another matter. I shall have to read your messaage several times and consult all the manuals to figure out what to do. This is mostly about not throwing stuff away.
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matt1309 avatar image matt1309 Paul Carmichael commented ·
When you say inverse do you mean utilising the power in the FLAs when LiFePO4 are lower in power? To solve that problem i would say the cheapest solution would be to use a DC to DC charger to discharge the FLAs into the LiFePO4 (I think you'll also need a smart shunt between the DC to DC and the LiFePO4 to mointor the power "generated"/passed back to LiFePO4's)
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Paul Carmichael avatar image Paul Carmichael matt1309 commented ·
Heh. I was referring to the fact that you had understood me perfectly, but what you said went mostly over my head :-)

I don't even know if what you just said will work with my FLAs, because as soon as they start to discharge, the voltage drops to 45.

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