Just bought 72v 20a adjustable charger

So I just purchased this charger:
https://www.amazon.com/gp/product/B07FLBWJRM/

Going to test it out next week and see how it handles higher currents. The charger I own right now is 72v 3a so this should provide a nice increase. Considering my batteries are rated at 1a standard charge and 2a fast charge, I should have no problem with my 20s9p @ 1a (9a on charger control).

Does anybody have experience with this type of charger?

As long as you're using lead, it's probably ok. But it's not designed for lithium, and may not safely charge lithium packs.

As noted in the ad:

Suitable for lead acid batteries (GEL & AGM)

Click to expand...

It is also rather large and heavy, and is likely not a switching power supply (SMPS), probably uses a large transformer with several taps, and a switch that selects between them, to output to a rectifier / capacitor bank (it may not even have capacitors, and may use the battery to filter the rippled DC to flat DC).

Most likely it will only do 20A on a 12V battery, and the higher voltages will be proportionally less (but probably not electronically limited), to keep the transformer/rectifier wattage within the same limit (about 250W).

Based on the question and answer section it looks like it only does in the range of 6 amps at 72 volts. What does it actually terminate at? If higher than 84 volts, you will damage your battery and that's on a perfectly balanced pack. 82 volts is better.

Better inexpensive charger will be a SMPS + boost converter. 48v SMPS + 1 or 2 1200w amazon cc/cv boost converters with fans will let your battery be charged at its potential.