ehsjr said:
Chris said:
kell said:
yeswedeliver wrote:
I'm disabled, don't drive a car - but I have a 48 volt electric scooter
that I use to get around town - it's just great. It runs on 4 12 volt
lead acid batteries. I have a nice charger for when I"m home - but need
to build a durable, simple, small one to take with me, on the scooter,
for long trips...
Does anyone have any schematics or plans that come to mind that that
you can share or that you could point me toward? A quick steady charge
for a [near] full charge on a return trip...
Thanks alot - happy building...
Jerry
http://www.fieldlines.com/story/2006/5/8/6559/50626
This guy uses a dimmer.
If you have experience doing this sort of thing, you might try it.
If you don't have experience, you are just going to ruin your
batteries, injure yourself.
This link is hilarious. Thanks for the humor.
I particularly like how he's got it set up on a board on the grass,
with strategically placed cinder blocks and prefab shed in the
background.
Best quote: "My big problem is seeing through my cheap helmet. I am
going to get those solar powered helmets that auto darken."
The only things missing from the page are a tailless one-eyed hound dog
and a Pontiac Trans-Am on the cinder blocks.
Needless to say, the charging method shown in the post is, if not
suicidal, definitely insane.
Hmmm.... What part(s) do you find a problem with:
1) Pulse charging
2) Charging a 36 volt bank to 40 volts?
3) Charging at 1.02 amps
4) The "hay-wire" setup?
5) Or ?
Ed
Hi, Ed. The whole thing:
DO NOT DO THIS!
UNSAFE CIRCUIT! Bridge
Rectifier
.---------------. .-----.
| | | |
o---o Lamp Dimmer o----o~ +o--------o-------.
| | | | | +|
120VAC '---------------' | | | ---
| | | -
o------------------------o~ -o---. | | Wheelchair
| | | | | Lead--Acid
'-----' | | +| Battery
| / \ --- Bank
| ( V ) - to be
| \_/ | "Charged"
(sadly)
| | |
| | +|
| | ---
| | -
| | |
| '-------o
| / \
| ( I )
| \_/
| |
| |
'------------'
(created by AACircuit v1.28.5 beta 02/06/05
www.tech-chat.de)
I'm not sure how many ways this is bad practice, especially for an
application where safety and the reliability of the batteries are the
primary concerns.
The cheapie DVM is reading average voltage, not peak. The other
cheapie DVM can't see peak current, either. The pulses are just blips
that are averaged out over the whole line cycle. If there's a voltage
surge or sag, even BillyBob the former NASCAR driver would take a
second to adjust the lamp dimmer. A voltage spike -- forget it. Of
course, then you just chuck the battery on the pile out back, and go
get another one after the boneyard closes. No problem if you're using
batteries for arc-welding out back of the shed. They die on him all
the time.
Controlled pulse charging is good. Obviously you have to raise the
battery voltage above nominal to charge it. Controlled current can
(and should) be more than 1 amp if you want a successful overnight
charge. But there's no control here except the guy out back on the
collapsible lawn chair with the dimmer dial in one hand and a Pabst in
the other. There is no pulse-to-pulse control here.
There's way too much that can go wrong. Although it's possible you
might get a somewhat successful charge, it's every bit as likely you'll
also end up with a somewhat damaged battery with reduced life after
even the first charging cycle, even if you are trying your best.
You'll probably end up with both. Battery life should be progressively
lessened on subsequent charges.
And you're really depending way too much on the series resistance of
the light dimmer, the house wiring, and the fusebox here (as well as
the 200' extension cord chain going from out back of the house to the
shed).
A wheelchair is actually a living space. I can see a battery explosion
here. Welcome to your nightmare, especially if you're away from home
and dependent on service people (most of whom are actually nice guys
who are OK with taking care of the disabled -- it's their sponsoring
companies who are unprintables).
Of course, BillyBob could always throw the wheelchair on the pile out
back, and wait for the boneyard to close to get another one.
Cheers
Chris
