Not a TriMetric, but for $20 might be worth trying out...
Bayite DC 6.5V-100V Digital ammeter voltmeter Amazon suggested this for me and I'm thinking for $20 I might just give it a try. Has very good reviews too.
Forum Discussion
The main problem I see with this unit (and many but not all of the digital DC ammeters available on Amazon etc.) is that it can only measure current in one direction. You can monitor battery charge current or battery discharge current, but not both with the same device, at least without an external switch to reverse the shunt sense lines.
