Proof that you do not know what you are doing:
a) There are roughly four (4) lead-acid battery charger circuits. There are any number of variations, but on basic themes.
i. This does not count the computerized Arduino-based systems. Just what is available OTC at your local auto-parts store.
ii. This does not count charger-starters, or those items with a built-in jump-starter.
b) Two of which are smart. Two of which are pretty basic, but effective.
i. Differences between each are a matter of scale, not so much circuitry.
ii. And, heavier chargers will need heavier circuits. Obviously. And why Harbor-Freight is not a good place to start, pretty much with anything.
c) Five minutes, or less, of internet manipulation would have made you aware of all of these things. And even have given you a head-start on diagnosis.
d) Suggesting that you are not very savvy in the first place. Subsequent events have borne that out.

So, we have established that you are looking for a magic bullet: Do *THIS ONE THING* and all will be well.
We have established that you have no concern as to quality-of-parts or for the source of those parts: You purchased relays in bulk and for cheap from eBay.
We have established that you are in that habit as well: dubious quality purchased as cheaply as possible.
We have established that your time is worth nothing to you. And by extension, nor is anyone else's time.
We have even tried to help - by suggesting that you not continue down a futile path attempting to resurrect a piece of junk, but to replace it with one more suitable to *your* purposes.
We even suggested that there is some risk attached to your process.

At this point, just go for it!

Peter Wieck
Melrose Park, PA