Ho Alt - Not Performing ?

[FiQ150db]

I have HO Alt (exact same 250a one that Usampfreak runs) whih I think may be underperforming.

It regulates itself so voltage can be anywhere between 13.7v and 14.7+.

Is there any way I can test how many amperes its putting out without a clamp meter ?

Also how reputable are HO Alts as I bought via the RE distro in the Uk.

Thanks