Battery Chargers:
These chargers are designed to work with sealed lead acid (sla) absorbed
glass matt type (agm) batteries. They will charge the batteries up to about
13volts which is normal for this type of battery.
Sla batteries agm type are used in jump starter units and are quite easy to find
(being sold in BigW, Supercheap autos etc (in australia)).
A standard car type wet cell battery charger will not charge an sla battery
up to 13volts, they can be used but the sla batteries wont be fully charged. I
think they go up to about 12.8volts.
The chargers are very sensitive devices they do not like being bumped so you
never find them mounted on ebikes in china (there would be millions of them in
use in china these days, I think last year there were about 7 million ebikes in
use in china). Its best to leave charger at home or work.
Below is the charger dimensions and its case.
A few pics of the insides of the chargers. They use a transformer to step down
the 220-240volt power supply. They are quite complex and have quite a few
components in them, but unfortunately I have no idea what the components are
for. I will try to get some more information on the chargers as I'm not sure if
they are constant current type or other type. (note charger I opened up has
slightly different case, there are two different brands I can get).
There are two led lights which can be seen out the outside of the case. They are
both red when the unit is charging batteries, when the batteries are fully
charged one of the lights turns to green.
The chargers have a fan inside them to keep the transformer cool. So its
necessary to make sure that they can get a good airflow around them.
Its important
to get the correct charger depending on what size your batteries are (measured
in amp hours (Ah)).
The general rule of thumb is as follows:
12ahr size or smaller batteries: charger will deliver less than 2 amps of
current, between 1.5 to 1.8amps.
17ahr to 20ahr size batteries: charger delivers over 2 amps of current (usually
around 2.5amps).
The chargers come in three different voltage types: 24volt, 36volt and 48volt.
Charging times are usually from 4 to 6 hours. The slower you charge a battery
apparently the better it is for the life of the battery.
You can use a >2amp charger on 12ahr or smaller size batteries, it will
charge them in a faster time, but at some sacrifice to the lifespan of the
battery. You cannot use a <2amp charger on 17ahr or 20ahr batteries as the
charger will get hot and possibly burn out as it will try to deliver more
current (due to the lower resistance of the larger batteries) than it is
designed to deliver.
How to Damage a charger: dos and donts!! (based on my own experience with
them) they are very sensitive devices and must be used correctly.
1. battery polarity must not get back to front when connecting charger it
will be damaged : wire colours for polarity for different chargers may vary.
2. you must connect the batteries to the charger before connecting to the ac
power supply (wall socket)
when charging is finished you must first disconnect the power supply from ac
socket, then disconnect from batteries. (manufacturers also state this)
3. the battery circuit must be very secure, if for some reason there is a break
in the connections between batteries during charging the charger will be
damaged (from experience!)
4. put batteries on charger immediately after a ride, leaving in an undercharged
state will effect their lifespan.
The plugs : computer type plug is for battery connection. Plug with two pins
is for mains power (note: pins are two vertical pins you might need to swap plug
to be compatable with your power outlet or get an adapter from local electrical
store, I'm trying to find adapters to put in with the chargers but haven't found
a source in china yet)
Closeup of plugs: + sign on output plug (computer type) is very small but there
is a + symbol on the plug, same with the - symbol, do not use the central
connector hole on the computer plug it may damage charger if you use it.
Note: its preferred if you check with me first by email before you connect up a
charger so I can tell you what is polarity of your charger.
Led indicators: two leds, one stays red and indicates power is on at wall
socket, other led turns to green when battery is charged, it will be red when
batteries are not fully charged (some chargers have an orange colour appears
when battery is 90% full and then turns to green when fully charged, not all the
chargers have the orange colour system)
How to connect to your batteries.
1. 48volt chargers only (for 36v chargers see note right at bottom of this
page)
I usually remove the computer plug, but you
can leave in place if you like and use a female computer type plug with it (you
could easily find on an old computer or buy from a shop the female computer plug
part).
Below: cutting off the computer plug you will see a brown wire (goes to positive
battery terminal), a green wire (don't use, if you use charger will be damaged
most likely), and a blue wire (goes to negative battery terminal).
Below: put whichever type of plug you choose on the brown and blue wires making
sure you know which terminal of the new plug is postive and negative.
Below: make sure the joints are soldered and covered in heatshrink or electrical
tape so that a short does not occur ( a short would most likely cause damage to
the charger)
Below: how to connect batteries in series for charging. left picture: shows
set up on my small trike, picture on right shows the setup as a diagram.
24volt or 36volt battery banks would be set up in the same manner.
Below: left: how the charger connects to battery bank. right: closeup of
connector which battery charger plugs into (its labelled in left side photo as
'battery charger connection' but is too small to see clearly).
Below: the wire which connects to the controller from negative end of battery
bank, at the circuit breaker or fuse I usually disconnect when charging as the
controller always uses a small amount of current if left connected to the
batteries (only about 50mA). A high amp switch in the circuit either on the
positive wire to controller or negative wire to controller would also do the
same job, on this trike I just unhook the wire from the circuit breaker as shown
( circuit breaker is from a jump starter battery pack, they also have a nice
high amps on/off switch in them).
2. 36volt chargers:
I've recently discovered that 36volt chargers have the colour coding for battery
connections reversed!!
So the blue wire goes to the positive battery terminal and the brown wire to the
negative battery terminal.
beware of spray ebike company:
more info
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