[OpenTRV-dev] OT: Charge battery

[Kevin Wood]

The AVR has analogue inputs monitoring both voltage across and current
through the battery. It can control the buck converter via a PWM output to
achieve any charging strategy, be that constant voltage, constant current
or a hybrid of the two where it sits in constant current until a certain
voltage then switches to constant voltage.

I'm actually thinking about a project along the same lines at the moment,
hence that AN was fresh in my mind.

I fly gliders and we use 12V 7AH sealed lead-acid batteries to power the
electronics in flight. I'm thinking about a device to discharge these,
counting Ah consumed, to determine if their usable capacity has degraded.

Best Regards


Kevin

> yep
>
> and i want to be able to handle both types
>
>
>
> -----Oprindelig meddelelse-----
> From: Damon Hart-Davis
> Sent: Thursday, May 15, 2014 7:39 AM
> To: Closed list for developer discussions
> Subject: Re: [OpenTRV-dev] OT: Charge battery
>
> In the note it says that NiMH and NiCd charging are primarily current
> regulated, SLA and LiON primarily voltage regulated.
>
> Rgds
>
> Damon
>
>
> On 14 May 2014, at 23:20, Bo Herrmannsen <EMAIL ADDRESS HIDDEN> wrote:
>
>> hmm... buck converter part...
>>
>> i can see a fet is used there, but cant figure if it's used to regulate
>> volt or current... its those spec parts i need... something simple to
>> regulate voltage and something to regulate the current...
>>
>>
>>
>> -----Oprindelig meddelelse----- From: Kevin Wood
>> Sent: Wednesday, May 14, 2014 11:20 PM
>> To: Closed list for developer discussions
>> Subject: Re: [OpenTRV-dev] OT: Charge battery
>>
>>
>> There's an AVR app note that might be interesting:
>>
>> http://www.gaw.ru/pdf/Atmel/app/avr/AVR450.pdf
>>
>> Best Regards
>>
>> Kevin
>>
>> On 14/05/14 21:17, Bo Herrmannsen wrote:
>>> could voltage be done with a n-channel mosfet and the pwm output pins?
>>> if so what abour controlling the current?
>>> *From:* Bo Herrmannsen <mailto:EMAIL ADDRESS HIDDEN>
>>> *Sent:* Wednesday, May 14, 2014 9:55 PM
>>> *To:* Closed list for developer discussions
>>> <mailto:EMAIL ADDRESS HIDDEN>
>>> *Subject:* OT: Charge battery
>>> Hi
>>> i have a few LCD’s and some other bits arround i want to put together
>>> to
>>> make an charger / discharger controlled by and arduino
>>> dis charging is easy enough.... and the math to do it also
>>> but how about charging... i would like to both be able to regulate
>>> voltage and current... depending on what type of battery i have
>>> connected...
>>> i plan to have the supply voltage at 18-20V to cover most needs... if
>>> not i rip that old 18amp car battery charger and use the trafo in that
>>> one...
>>> anyways what is the simple way to control voltage ? and how would i do
>>> current ?
>>> /Bo
>>>
>>>
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