Victorious1 wrote:I need a little more range from my GIO 500W+ which is currently equipped with 4 lead/acid batteries 48 volts with 20 ah output per battery.
Your best bet is to replace that very heavy SLA with lighter batteries, like a Ping 48V 20Ah, which will weigh less *and* actually give you a lot closer to 20Ah than the SLA do. The SLA are probably only giving you at best 10Ah for the nearly 50lbs of battery you're carrying around. Even a 48V 15Ah Ping will give you more range for a lot less weight.
Adding more SLA may actually decrease your range especially if the bike and rider/cargo is already heavy, and you have to deal with hills or lots of stops and starts.
I just want to be able to reliably get back and forth to my destination and back home again on one charge.
Another issue is that if you are not recharging your SLA at your destination, then they are sitting in that discharged state for however long you are there, and that is degrading them simply by sitting in that state. They'll be decreasing in lifetime and in capacity because of that--exactly how much depends on how long they sit, how they are made inside, temperatures, how far discharged they are, etc.
So any other SLA you add may increase range for a short time, but then as they are damaged by not recharging immediately, more each cycle, your range will continue to drop until it becomes less than you need.
I would have pedaled the bike home but the darn pedals kept falling off
If the pedals are falling off you *REALLY* need to go over the entire bike and do basic maintenance to it, before something else does, too, and ends up causing you to crash. If they are falling off not because of bolts/nuts being tight, etc, but rather because of design or manufacturing problems, you might want to fix those problems before continuing to ride, and check the whole bike over for other such problems. I build my stuff from recycled parts and often have problems because of it, and I can tell you it is no fun at all when they happen in traffic or whatever, or far from home.
Anyway, Im thinking that I could increase my range by adding 1 or 2 extra, identical, batteries in parallel to the pack, but, what I don't know is what will happen to the system with all this extra current available.
Since SLA come in 12V blocks, then you must add 4 of them in the same configuration your originals are, to have 48V, if you want to add them in parallel.
If you add less than that, you msut add them in series instead, which will raise the voltage of your whole pack, and may damage or destroy your bike's electronics if they are not rated for that. You would need to check if they can take that (my guess is probably not), and upgrade the electronics if they can't.
So you would have 4 original SLA in series for 48V, plus another 4 SLA also in separate series for 48V, with teh two wired in parallel at their end terminals.
a) Can the motor and controller take the extra current available,
There is no extra current (A) just by adding batteries. Your system will draw whatever it needs from the batteries; they simply have more capacity (Ah).
There *will* be more power drawn for longer periods when you go up hills or slopes, and also when you startup from a stop or otherwise accelerate, because of the huge amount of extra weight of the SLA, but this power should not be a higher level than what it is all limited to anyway internal to the controller. It will probably take longer to get to speed than before, because of the extra weight.
On hills or slopes it may not go as fast as it did before, and that might cause the motor itself to get hotter.
b) How will charging be affected? I have the stock GIO charger, the one that is well vented and has a built in cooling fan. Does this stock charger have the ability to charge the extra battery if hooked in parallel?
It will probably take twice as long to charge. If the charger is programmed with a shut-off timer (not likely) then it may not complete a charge until you unplug it and plug it in again.
If for any reason it will not charge them while paralleled, you can always charge first one bank and then the other.
EDIT: looks like while I was typing up my reply, others already stepped in and answered most everything.
Guess i need to type faster.