[chbot] High voltage batteries and electrolytic capacitors

[Richard Jones]

In relation to the explosion part of the question...
It is also important to check that the ripple current rating of capacitors
is not exceeded.

Richard

On Thu, Oct 1, 2020 at 11:19 AM Stephen Irons <stephen at irons.nz> wrote:

> At a previous company, when I did hardware develoment, the policy was 200%
> maximum design voltage. For example
>
>    - Nominal 12 V, with 5% regulator -> maximum design voltage is 12 V x
>    1.05 = 12.6 V. Minimum capacitor voltage rating: 25.2 V, so you would have
>    to use a 35 V capacitor, not the 25 V one.
>
> There was some flexibility. If space or cost were tight, we could probably
> negotiate the smaller one in this example, because it is all under our
> control. But for external inputs, where things are less controlled, we
> would go the other way.
>
> No idea where you would find 800 V capacitors?
>
> EV City (Waltham Street) have a Nissan Leaf cut in half (diagonally, so it
> is still has 4 wheels and is drivable) showing the internal components. I
> think they also have an open drive unit and control unit. You might be able
> to see what they use.
>
> Stephen Irons
>
> On Thu, Oct 1, 2020 at 09:16, Peter Harris <petes.username at gmail.com>
> wrote:
>
> General question: What is the rule of thumb for selecting the voltage of
> electrolytic capacitors?
>
> Specific question: I am working with a Nissan Leaf battery, the absolute
> maximum pack voltage is 405V. Are 450V electrolytics likely to explode used
> at 405V?
>
>   P
>
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