[Healeys] Electrical problem NON HEALEY

[Roland Wilhelmy]

Each battery has to deliver 22.5 amps.  The nine batteries are in series.
The voltage adds but the current is constant .  Then you correctly add the
currents for the two parallel circuits.  20 minutes at 23 amps will quickly
discharge your batteries.  At high discharge rates you don't get the
advertised amp hours.
-Roland

On Sat, Sep 30, 2023, 9:06 AM Michael Salter <michaelsalter at gmail.com>
wrote:

> This group has been a huge help in the past and I am wondering if
> there are any electrical guys out there who can help me with a DC
> electrical problem.
>
> I'm trying to help my BIL with the propulsion system for a 30 ton
> wooden boat on our lake.
> This 100 year old boat was originally steam powered but in keeping
> with modern times it has been converted to electric propulsion.
> It is fitted with a 106 volt DC motor
> At normal cruise the motor draws 45 amps.
> It has eighteen 220 amp hour AGM batteries.
> The batteries are arranged in 2 banks of 9 in parallel so each bank
> produces 108 VDC
> By my calculations ...
> For a total of 45 amps each bank would deliver 22.5 amps.
> Consisting of 2.5 amps from each of the 9 batteries.
> Each battery is 220 amp hours.
> Presuming that you want to avoid discharging below 50% the usable
> capacity of each is 110 amp hours.
> So my calculation for the running time is 110/2.5 = 44 hours !!!!
> It only runs for about 20 minutes before the amperage starts dropping
> off rapidly.
>
> Are my calculations correct?
> If not, where are they wrong?
>
> Thanks
>
> M
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