Also keep in mind that Lithium batteries, are not usually subject to Peukert's law. (Capacity loss due to high discharge rates is balanced by voltage gain due to self heating.)

Jay

On 3/13/19 4:38 PM, Dan Baker wrote:
Good points Jay.  I'm concerned with Peukert's law but if I could perform under similar loads it would mean more to me and less to stated ah.  Both would be ideal I guess- one for me and one for the evdl list. But maybe I'm the last guy here running lead so results given back wouldn't be of much value here lol.

Thanks
Dan

On Wed, Mar 13, 2019 at 4:46 PM Jay Summet via EV <ev@lists.evdl.org <mailto:ev@lists.evdl.org>> wrote:

    I think it would be better to measure at a higher amp rating if
    possible. (Make your test go faster, and more accurately model the true
    draw on the battery under load).

    How many amps will the batteries see under your particular usage
    scenario? If you can replicate that same amp draw (either with lots of
    lights, a big resistor in a bucket of water or whatever....) it would
    probably be the best test for your situation.  (Plus, if the amp
    draw is
    higher, the precision of the amp meter would matter less....)

    Jay

    On 3/13/19 3:38 PM, Dan Baker via EV wrote:
     > Thanks guys- never thought of this, I have a similar unit in my boat
     > already.  I typically use it just for monitoring amp output and
    volts.  I
     > have two throttles on my boat, a spring loaded Curtis-PB6 which I
    use for
     > docking/ maneuvering and a 5k knob style pot that I switch over for
     > cruise control, set the pot for desired amps/speed off of the
    gauge.  I'm
     > not sure if it will accurately pick up a small 1 amp load as it
    is rated
     > for up to 400 amps.  Anyone share what they used for a test load- a
     > resister or a bulb?  I assuming around 1 amp (12 watts) will be
    closest to
     > measuring true a/h readings.  Given that these lithiums only
    charge to 12.6
     > volts means my cut-off voltage will likely be closer to the
    stated BMS
     > cut-off, somewhere between 9-10 volts or when the voltage starts
    sharply
     > falling off?
     >
     > On Wed, Mar 13, 2019 at 3:23 PM John Lussmyer via EV
    <ev@lists.evdl.org <mailto:ev@lists.evdl.org>>
     > wrote:
     >
     >> On Wed Mar 13 11:06:36 PDT 2019 ev@lists.evdl.org
    <mailto:ev@lists.evdl.org> said:
     >>> Yep Totally agree. I use several of these to monitor voltages and
     >>> currents in my DIY EV. Nice thing about them is that they work
    both ways
     >>> and will take into account regen and charging as well as
    discharge. I
     >>> found them to be as accurate as shunt based meters at a similar
    price
     >>> range BTW.
     >>
     >> I use this one:
     >>
     >>
    
https://www.amazon.com/Programmable-Digital-meter-battery-monitoring/dp/B0043BDFYA/ref=sr_1_1
     >>
     >> has 2 relay outputs, counts AH in both directions, uses a shunt for
     >> currents over 5A.
     >> I've found it to be pretty accurate.
     >>
     >>
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