Someone sent me a question about the chargers I use on my EVT 4000. My answer is extensive enough that I want to document it for the public rather than just for this guy. Also some others may want to weigh in with their method.
I've done a similar thing on both my EVT 4000 and my Lectra motorcycle. It's a pseudo-bank charging setup. Typically EV's are sold with a pack charger which matches the pack voltage. The EVT 4000 being 48v comes with a 48v charger, etc.
My EVT 4000 charger died when a screw came loose inside the charger and was rattling around. One day I was showing someone the charger and heard this pffft sound with a nasty plasticy smell and knew the loose screw had rattled itself to where it let out the magic smoke of some component. Back then (2003) there werent' as many EV components shops as now but I managed to find a pair of 24volt soneil chargers. Don't recall the specific model but seem to recall these are their 24 volt 8 amp charger.
On a pack charger setup the charger voltage is the same as the pack voltage. 48v charger for 48v pack, in other words.
On a bank charger setup there is one charger per battery. A bank charger setup on the EVT 4000 is 4 12v chargers. Others of y'all have 60v scooters so a bank charger setup has 5 12v chargers. Of course those of you lucky enough to have lithium ion batteries have a different sort of charger choice. I'm talking about lead acid batteries.
With 24v chargers it's not a proper bank charging setup, and it's not a proper pack charging setup. Hence pseudo bank charging.
Each charger is connected to a 24v sub-string of the pack. e.g charger #1 connects across battery #'s 1-2, charger #2 connects across battery #'s 3-4.
If you take a voltmeter and hunt around inside a battery pack you'll see how this works. Voltages of substrings of a pack add up to the sum of the batteries in the substring. Hence battery #'s 1-2 have a 24 volts out of the total 48volt pack.
My Lectra motorcycle has a 60 volt pack. The original charger setup was 1x 12 volt charger and 2x 24 volt chargers, which adds up to 60 volts.
Bank charging (and pseudo bank charging) do a better job of ensuring balanced voltage within a pack. That is assuming the individual chargers are calibrated properly to the same voltages. And assuming all the chargers continue to function. Earlier this year one of the chargers on my Lectra motorcycle died and I didn't recognize it right away. That meant one substring of the Lectra pack didn't get recharged over a couple rides, saw a bad deep discharge, and now those cells are weaker than the rest of the pack. In other words not all is rosy and wonderful with bank charging.
It's good to regularly check the voltages of your batteries to see if the pack is remaining balanced.
The EVT 4000 has a screwball wiring for the pack. At least mine does and I assume they've continued this idea as it's a rather interesting idea.
Each individual batteries has a wire pair that ends in a high amp anderson connector. The normal way to wire a pack is to directly wire from one battery to the next. Instead EVT (EVT Taiwan), as I said, does it differently. On the frame of the battery box is a matching set of anderson connectors with connections between them which form the battery-to-battery connections that make the pack. If you have an EVT 4000 open the battery compartment, pull out the batteries, and you'll see what I mean. Pulling out a battery means disconnecting its anderson connector from the bike and pulling out that battery.
For my EVT 4000 bank charging I traced this set of connections inside the battery box to trace out the two 24v substrings of the pack. I connected a wire to the negative- and positive-most of each substring, and brought those wires out to a separate connector. I wired a matching connector to the charger. That lets me easily connect and disconnect the chargers.
A proper bank charging setup (12v per charger) for EVT 4000 would of course be simpler. For each battery in the pack bring out one pair of wires for the charger connector.
My stock charger, a blue Chroma 67145 has broken. My question is "Shall I get it fixed, replace with a better one from dealer for $325, get a some Soneil?" If you had these options, would you still have gotten 2 chargers at 24 volts each? The 4 batteries are AGM lead B.B. Batteries EB50-12 with replacement value approaching $1,000.
Actually the simplest is to get a single charger and it's not necessary to spend that much on one.
For example: http://electricscooterparts.com/48vchargers.html
It looks like they even have a matching plug for the EVT connector.
But the reason I went with multiple chargers still remains. A single charger doesn't do anything to balance the pack. An imbalanced pack can lead to early pack death. One way to a balanced pack is by individually charging the batteries with a bank charger setup as described above.
An important consideration is whether the charger setup you select fits in the EVT underseat storage area. On the 4000 the underseat storage isn't that big and the 2x 24 volt chargers I picked filled it (along with the power cables). The 1x 48v charger also fit in the same compartment. However 4x 12v chargers would not fit unless they're small chargers.
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki