SIMPLE BATTERY CHARGER

[electricvehicles]

I take it your batteries are rated at the 20hr rate ? at a 5hr rate their capacity it approximately 86amp hour.
For a 8 hour recharge time you would realistically need a 15Amp output.
12amps for an 11 hour recharge and 10amps for a 12 hour recharge.
Hope this helps

Regards
Dave

[ianmoore]

Hi yes they would be at the 20 amp rate.

I guess I would only half discharge them also....
so really Im only looking to charge at 6amps for 10 hours or so.
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(I am going to eventually Solar charge them using 5 Solar Panels
the panels are 55 watts each.
out of interest do you know if it is safe to add all the solar panels together in series to charge the 60v battery bank.
I guess i could run a wire to each battery and have 1 pannel for each battery... but its just not very pretty wiring...better if its ok to put all the panels all together... what do you think?)
------------------

anyway back to the charger...
im gonna try the variac onto the transformer tommorow...
I'll let you know how it performs.

[aminorjourney]

I think you will need some form of regulation for the solar charger of course

[ianmoore]

actually....
I was going to say... yes of course ...I'll ned regulation for the solar panels,
Ive already got a regulator.....

BUT THEN ...I REALISE.... its a 12volt regulator!

I'll need 5 of em!

mmmmm.... I can make a circuit (comparator using 741 or similar) to determine when the battery is charged 67 volts or so... this can switch the solar panels off using a relay.

[EVguru]

In my experience most batteries are murdered, rather than dying of old age. A charger with a reasonable degree of control and accuracy is needed to get the best out of batteries. The tall industrial cells need a lot of gassing to de-stratify the acid, but gassing flat plate semi traction or even worse leaisure batteries to this extent will likely cause shedding of active material.

If you're intent on building your own charger, then take a look at;

http://www.powerdesigners.com/InfoWeb/r ... 4s5p1.html

[ChrisB]

Nice link there Paul

ChrisB

[ianmoore]

Hi Paul,

well... I've been doing electronics for 25 years...
and stuff like that is.... simply...... confusing!
no component values etc. SCR.... WHAT SCR? resistor WAHAT RESISTOR.
too much theory and no enough hands on circuit building.

It is supprising though that a SIMPLE battery charging system hasnt been designed and the circuit designs readily available for folks on a low budget.
I would have thought that if someone had got an EV up and running this would be the first thing that would be needed.

I understand that..... 'you can't treat batteries like that'
I understand that..... 'its going to take some serious control circuitry'
I understand that..... 'the only real way round it is to buy a high frequency inverter with Computer control'

I also understand that I've heart stuff like this about all kinds of 'electronics and projects' and actually there is usually some simple low cost solutions that will get you up and runnin' for now.

Anyway.... I'll thrash one out here and post it...eventually

[electricvehicles]

Hi Ian

Please dont despair, I might have a few RD40 controllers in the pit. Normally there only upto 48V but with a simple resistor change they will work on more or less any voltage. Next one is the transformer. Sticky one 60Volts is not a common voltage as far as traction goes especiallly with the very low outputs you require. Most of our stuff is 25amps upto 180amps. Do you have to run at 60V ? 48V would make things so much easier.
Working nights for the next couple of day but will let you know what we have available.
Remember -- where there's a will there's always a way !!!!!!!

[ianmoore]

hey... thats great!

yes please do let me know thanks

I also have a friend with an ev who has the same proble...charging 72 volts
whereas mine is 60volts.

so Im trying to get the answers for us both.

but that would be great if you do have one.

we are taking our little EV to the Big green gathering in a few days...
hope I can charge it....
I might have to charge each battery individually with a 12 volt charger!

see our ev on our website www.arcvillage.org




cheers http://www.arcvillage.org

[ChrisB]

It is supprising though that a SIMPLE battery charging system hasnt been designed and the circuit designs readily available for folks on a low budget.
I would have thought that if someone had got an EV up and running this would be the first thing that would be needed.

Ian dont panic my man there is and your pretty much spot on for bog standard Flooded Lead acid batts.

Components

1 x Transformer
1 x Bridge Rectifier ( couple of diodes if you want to be really cheap)
Some cable

Thats it nothing more nothing less, the only tricky bit is matching it all up and buying the correct rated transformer/rectifier for the job.

On my fiesta I used a standard 110v yellow building site transformer which I bunged a 10A bridge rectifier in mounted on a heat sink.
Yeah it wasnt great and wouldnt win any speed records for battery charging but it was simple and it worked and cost all of about 50 quid from memory my system was 120volts nominal so of course 110v tranny is no good for you, I'm thinking you need to be looking at a 55volt tranny for yours OR you might find a 24-0-24 volt tranny and link the windings in series would work for you ?? cheap simple and it would work.

Might not be the fastest charger in the west and you might have to see where it tops out at as it might not produce enough volts at the end of the charge to fully recharge the batts but its a start and its cheap and simple


ChrisB