[OpenTRV-dev] OT: Charge battery

[Bo Herrmannsen]

Me thinking the same here...

i want to both charge and then discharge battery's

But i have mixed battery's... SLA for the starter on the lawn mower... same 
in the car... NIMH in the cordless drill...

I have a nice old car charger than can deliver up to 17 amps i think.. plan 
was to rip the trafo from that an use as a PSU... only downside is that is 
that it will not charge the nimh cells in the cordless drill as they are 
14.4V


are the reason for the buck converter that it can adjust the voltage above 
the input voltage from the PSU ?



-----Oprindelig meddelelse----- 
From: Kevin Wood
Sent: Thursday, May 15, 2014 10:25 AM
To: Closed list for developer discussions
Subject: Re: [OpenTRV-dev] OT: Charge battery

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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