One extra Leaf module

[DaveTM]

Long story short....when I purchased my 7 modules of Leaf Batt's, I ended up getting an additional 8th for little $$$

So, now that I have my 7 modules installed.....I'm staring at this one lone module and thinking what to do with it.

So...for you engineers and others who really get this stuff, would it be a good idea to simply "add" this 8th module, via a connection in parallel to one of the batteries in my existing 7 module pack?

Thanks.

Dave

[ag4ever]

I would not. Best option is to keep it on the shelf just in case one module being used starts to show lower volatges than the remaining cells. Or buy 6 more and expand your battery capacity.

You could get a dc/dc step-up converter (6v in to 12v out) and use it as an auxiliary battery for lights, radio, etc... But, you would need another charger. I doubt I would use a BMS for that application, and just roll the dice.

[DaveTM]

[cricketo]

I wonder what would be the caveats of wiring the module to the entire pack in parallel via DC step up to say 58.8v.

[DaveTM]

Originally Posted by cricketo

I wonder what would be the caveats of wiring the module to the entire pack in parallel via DC step up to say 58.8v.

Well, that's what I was asking....unless you mean to parallel one module with the entire other 7 modules? I dunno how that would work.

[cricketo]

Originally Posted by DaveTM

Well, that's what I was asking....unless you mean to parallel one module with the entire other 7 modules? I dunno how that would work.

Yes, that's what I meant. Step up the voltage from the module to the pack's voltage, and then connect that in parallel to the entire pack of 7 modules.

I think the safest way to do this would be to have a relay which would activate this setup only when load is actually disconnected. Think of it like a charger. Then whatever current step-up converter can support, becomes your charging current. It will need to have its own undervoltage protection.

Now the problem of doing it when vehicle is moving I envision would be in the fact the current rating for DC-DC will be inadequate to support the share of the load, and also the fact DC-DC will maintain the constant voltage, while the rest of the pack will experience a voltage drop as the cells approach the depletion.

[ag4ever]

I think that would be tough to do.

Generally the dc-dc converters take a variable input voltage and output a stable voltage.

The main pack voltage will change from the full voltage down to the empty voltage.

This means the main pack will try to feed power through the dc converter to the single cell when the main pack is full, and the single cell will try to charge the main pack when below the stable output voltage.

I don’t think it would be a good idea, and you probably would not see a meaningful change in range.

[DaveTM]

Yeah.....I think I'll just hang on to it and maybe "pick up" 6 more modules at some point in order to extend my range......and just be a BAD A$$..