[OpenTRV-dev] OT: Charge battery

[Kevin Wood]

You are only really controlling one thing - the pass element that drives
current into the battery, so you don't control voltage and current
individually. The voltage across the battery influences the current
through it and vice versa. All that changes is the strategy your software
uses - i.e. it can control the pass element to keep either the current or
voltage constant.

Kevin

> oki
>
> but how do we control voltage vs current is say  we use an n-channel
> mostfet
> on a PWM pin?
>
> i got it on how to messure the 2 things
>
>
> -----Oprindelig meddelelse-----
> From: Kevin Wood
> Sent: Thursday, May 15, 2014 11:49 AM
> To: Closed list for developer discussions
> Subject: Re: [OpenTRV-dev] OT: Charge battery
>
>> are the reason for the buck converter that it can adjust the voltage
>> above
>> the input voltage from the PSU ?
>
> No, although you could use a boost converter instead to achieve that. I
> suspect the prime reason for using a switching converter is efficiency and
> to reduce size and heat dissipation. I think the ap note was aimed at
> small battery powered appliances using AVRs.
>
> If you're not so worried about efficiency, you could make the pass element
> a simpler linear device, but still control it using a voltage derived from
> one of the AVR PWM channels. You could do something similar to make an
> active load for testing the batteries.
>
> Best Regards
>
> Kevin
>
>
>
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