I've parallelled inline shunted 'wattmeters' for significant loads such as engine starting.
The wattmeters are rated for a 200 amps surge.
they come with 8awg pigtails. I attach 45 amp anderson powerpole connectors.
During the engine start test, it was interesting how much more max current one wattmeter recorded than the other one, jutst die to lead length and perhaps condition .
When trying to measure amperage that a charging battery is accepting at high states of charge, I have noticed that while it migh tonly need 2 amps to be held at 14.8v, but when first hooked up, the wattmeter's record/display 18 or more amps before quickly tapering to that 2 amps.
I will ONLY use inline DMMS when i know the surge cannot exceed the 10 amp fuse rating.
A clampon DC ammeter might not read very accurately at loads under 1 amp, but there is no danger of smoking it like one could with a DMM.
I've an older sears craftsman DC clampmeter, and it seems to be capable of measuring relatively accurately down to as low as 0.06 to 0.08 amps @12vdc and within 2.5% of a trusted shunted ammeter, at 120 amps .
My harbor fright free DMM internal glass fuse often is coated with tin foil. too often I had forgotten to move the leads when going back to check voltage after checking amperage, an pop goes the fuse.
Glass fuses are not cheap.
The RC style wattmeters are an awesome tool to have, even if them are imperfect in terms of accuracy.
There are dozens of clones of this basic unit linked below. Some have 100 amp surge ratings and 14awg leads, some have 130 amp surge ratings and 12 awg leads, some have 200 amp surge ratings and 8awg leads.
I pass 45+ amps continuously through the 8 awg ones and started my engine over a paralleled pair of wattmeters through 2 pairs of anderson 45 amp powerpoles. No issues.
https://www.amazon.com/GT-Power-Ana...00C1BZSYO/ref=cm_cr_arp_d_product_top?ie=UTF8
There's also some hall effect dc ammeters available for under 20$ that can handle 100 200 and 400 amps, but most have a 0.2 amp resolution, and nearby magnetic fields screw them up, and they tend to drift over time and need to be rezeroed regularly when it is known no current is passing through the cable which the ring sensor is surrounding.
https://www.amazon.com/bayite-Digit...ca87d&pd_rd_wg=8Y3zR&pd_rd_i=B01DDQM6Z4&psc=1
I've got 4 of the above linked ammeters. 2 battery banks, one reads alternator current from one of two alternators, one reads amps into or out of either battery bank. I trust them to ~ 5 % accuracy, when I rezero them before current passes through the cable/wire the sensor surrounds.
There are shunted ammeters with similar digital displays. Such shunted ammeters, almost exclusively need to be wired inline on the negative cable, whereas the hall effect sensors can go over a positive cable, if that is more convenient which it often is in my uses.
My shunted ammeters, of similar ratings and price point, have not been as accurate as the hall effect sensor from multiple observations with multiple different products.
Do note that the ring sensor of above link, is supposedly match to the display, so if getting more than one do not mix them up.
I've no issues regarding accuracy, when extending teh 3 wire ribbon cable for a much more distant sensor/ display.
