Anyone got a charger for top balancing cells higher than 5amps.

Nature of the beast I'm afraid. If you have 16 300Ah cells and they came 50% charged, even with a 10A charger that would actually charge all the way up to 3.65V with the 10A (it won't - not even close) with 30W (10A times 3.2V) will take 7500Wh / 30W = 250 hours. In practice a lot more than that, as the amperage goes down towards zero when the cells get more and more charged, so up to 3-4 weeks. Double that if you have two cells in parallel in your pack!

My solution: forget about top balancing. It's a fool's game. Every week you spend top balancing the cells, you lose time and you lose money. Bang the cells into a battery, make it work for you and make it start paying its way and let the BMS top balance the cells over time

If you parallel 4 cells and then connect each of your 4 paralleled cells in series to make a 12v battery you could get the majority of your charging completed with a car battery charger @ 12v to do the majority of the charging and then split them again to balance them.

This! And if your BMS has active balancing, you don't need to unmount and top balance. It is overrated.

My theory is that this is a self-perpetuating old wives tale. Based on the past where BMS did not have active balancing and cells were very expensive, so it was important to get every last Ah of capacity out of every cell. A bit like people saying you need to way oversize your array of solar panels for your inverter as your inverter is very inefficient at lower loads. Another old wives tale that has been around for many years, totally false now.

Seplos doesn't have active balancing. So in your case I would do as @on_the_roots suggested, hook up the inverter and try get the battery (in series) charged as much as you can with it (the Seplos will protect cells from overvoltage) and when it won't charge no more, dis-assemble battery, connect cells in parallel and wait however long it takes before all cells are 3.65V. Could still take weeks.

Alternatively, leave the battery connected in series and attach an active balancer. There's a cheap one for sale on adverts from one of the forum regulars (it used to be mine). It will do the job for you and once top balanced, just remove it and either keep it or sell it on...