charging 24 volt packs with 12 volt charger

[weirdeh]

OK not sure how to ask the question. I have 4 12 volt SLA 24AH batteries. wired in two banks of 24 volt. they connect to the trike with a set of anderson connectors. I have been charging then by simply plugging the 24 volt charger into the anderson connector. something happened to the charger. I was thinking that I could take the 12 volt 2 amp car battery charger and "gang" it to the 4 separate batteries and charge it that way. by "gang" I mean alligator clamp and a "spider" from each battery to the charger WITHOUT disconnecting the cabling that connects them now. I would of course disconnect from the trike. will this work?

 

[Rassy]

No. The pairs that you have hooked in series to get 24 volts need to be separated also. If not, you will be in effect shorting the positive and negatives of those batteries together. Once the batteries are separated your car charger should work fine. If it has a 10 amp setting you could use that for a quicker charge, since that would only be 2.5 amps per battery.

 

[weirdeh]

crap was kind of hoping it would be easy. oh well must start looking for "new" 24 volt charger

 

[dumbass]

OK not sure how to ask the question. I have 4 12 volt SLA 24AH batteries wired in two banks of 24 volt. they connect to the trike with a set of anderson connectors. I have been charging then by simply plugging the 24 volt charger into the anderson connector. something happened to the charger. I was thinking that I could take the 12 volt 2 amp car battery charger and "gang" it to the 4 separate batteries and charge it that way. by "gang" I mean alligator clamp and a "spider" from each battery to the charger WITHOUT disconnecting the cabling that connects them now. I would of course disconnect from the trike. will this work?

OK, you want to do exactly what I have been doing for 2 years now. I also use Anderson connectors to setup my twin 24v 18ah packs. I think the difference with the way I connected them is the "packs" are actually not wired into 24v within the actual pack. They are wired into 24v on the bike. therefore, when I am charging them I use a standard 12v charger. This accomplished by installing a set of wire leads to each 12v battery. In my situation I have 2 batteries in a battery bag. So I have 2 sets of leads (12v each) with Anderson connectors exiting each bag. I arrange the Anderson connectors to form a cube alternating red, black, red and black again. On my bike I have a matching set of Anderson connectors. The only difference is that I connect a jumper wire between one black (negitive) and one red (positive) . The remaining set of anderson connectors go directly to my controler. If I have exsplained this all clearly enough you should now realize when you plug the pack "cube into the bike's cube you convert the 2 12v batteries into 1 24v pack. By the way I use a fuse connector as my jumper wire so I servers double duty as well. Because the "packs) are only 12v batteries when not pluged int othe bike they can be charged by a standard 12v SLA charger. I also use Anderson connectors (6 sets) on my charger so I can charge up to 6 batteries at a time. And yes I do this all the time and it work great. I even use the same charge to charge my ilpo4 packs. Which by the way are wired exactly the same way. One last thing I have 2 of these Anderson plug arrangements on each of my bikes therefore, allowing for the twin packs.

I currently do not have a wiring schematic but if you are interested in trying this and need it I guess I could make one for you.

 

[Rassy]

Well, there is another "simple" option using your 2 amp 12V car charger. Without unhooking your current harness you could run parallel lines from your charger to one of the batteries in each 24V sub pack. Then, when those two batteries are charged, you would switch to the other two batteries and charge them. The problem with this method is being careful not to hook anything up wrong, and you must complete the total charging process before using the bike so that the "series" batteries are balanced.

Edit: This is not correct. Only one battery can be charged at a time if the connections between the batteries are not removed. Sorry.

 

[dumbass]

Well, there is another "simple" option using your 2 amp 12V car charger. Without unhooking your current harness you could run parallel lines from your charger to one of the batteries in each 24V sub pack. Then, when those two batteries are charged, you would switch to the other two batteries and charge them. The problem with this method is being careful not to hook anything up wrong, and you must complete the total charging process before using the bike so that the "series" batteries are balanced.

If I understand you correctly you are saying to leave the packs setup as 24v while charging. If I'm not wrong this is a big no..no that causes big sparks. But I could be wrong but I remember a few people on this forum saying it will cause a direct short.

 

[Rassy]

Re-Edit: I deleted this post because I think I am wrong. Sorry. You should only charge one of your batteries at a time if the strings are connected in parallel. To do more than one battery at a time you need to disconnect the batteries completely.

 

[dumbass]

dumbass wrote:

If I understand you correctly you are saying to leave the packs setup as 24v while charging. If I'm not wrong this is a big no..no that causes big sparks. But I could be wrong but I remember a few people on this forum saying it will cause a direct short.

Yes, but not exactly. I am saying to only hook up one of the batteries in the series to the 12 volt charger, which then acts like a "single cell" charger on that (two battery) string. Then I said to also hook up the charger to one of the batteries on the other string at the same time. This keeps the two strings balanced as the voltage comes up on the connected batteries. Then the process is repeated for the other two batteries. Of course it would be better to disconnect the batteries, both at the parallel and series connections, so that there is no chance of hooking them up wrong. But weirdeh did not want to unhook his batteries.

OK, now I understand better what your saying. I guess I missed the point of not unpluging the packs but this I will never understand considering an Anderson plug is pretty easy to unplug. But we all have our own reasons for what we do and/or want to do. As for me I normally car rack my bikes and remove the packs. So when I get home the packs are already off the bikes.

 

[vanilla ice]

I wish there were a commercially available rotating timer module that goes from one battery to the next. Then you could get a 24 to 72+ volt balance charge from one inexpensive readily available 12v auto trickle charger..

 

[dogman dan]

Changing your wiring on the vehicle may help. If you have two batteries paralelled, at 12v, then series connected to make the 24v , you could then charge two at a time. You would be disconnecting the series connection to charge, but at least two would stay connected, and charge together as a single 12v 48 ah battery. A seperate set of leads for charging would help keep you from reversing polarity, but same leads as the main connections could be used.

 

[amberwolf]

If using the larger andersons like I have on my bike (out of a UPS and off a wheelchair), no need for a separate charging lead, either. I unplug the power lead to my controller and plug the charger directly into that power lead, battery side.

Since my charger is only 24V but my pack is 36V, I also unplug one battery, then plug another anderson wired as a shunt into the packside connector of that (gotta be careful with this part, don't ever wanna do that on the battery side!), so the charger only sees two in series for 24V.

I have a Sorenson currentlimited bench supply I use to charge the third one, set to 1.5A (it's max rated output) and 14.4V, which charges it up for cyclic use per the batteries' own label, and works fine so far. My lighting is connected to this battery (only), so it is the one I charge separately solely because it is usually a bit lower than the other two.

 

[weirdeh]

I think the easiest way is to rewire to the twin 12 volt packs (2 24 AH batteries per pack) thus I can disconnect from the trike, which I always do anyway. and could build a dual charge cable so that I could charge both 12 volt packs at the same time. the charger has a 6 amp setting as well.

in fact that is how I have the folding bike set up not sure why I didn't just think of doing that with this one.

thanks for the help guys. somethimes you just need to "hear" it from someone else for it to make sense.

 

[Rassy]

dogman wrote:

Changing your wiring on the vehicle may help. If you have two batteries paralelled, at 12v, then series connected to make the 24v , you could then charge two at a time. You would be disconnecting the series connection to charge, but at least two would stay connected, and charge together as a single 12v 48 ah battery.

Good morning weirdeh. Still feel bad for being so far off yesterday. Woke up this morning with the correct answer, but dogman had already posted it. If anyone here remembers Xyster, he was the first one to instruct me to first hook batteries in parallel to make the required subpacks, then hook the subpacks in series to make the final battery pack. I didn't really appreciate the difference until I saw how a ping pack is set up with a BMS for protection and balancing the cells.

weirdeh wrote:

I think the easiest way is to rewire to the twin 12 volt packs (2 24 AH batteries per pack) thus I can disconnect from the trike, which I always do anyway. and could build a dual charge cable so that I could charge both 12 volt packs at the same time. the charger has a 6 amp setting as well.

If you do charge both sub packs at the same time, you still need to disconnect the single wire that connects the two subpacks together.

 

[weirdeh]

dogman wrote:
If you do charge both sub packs at the same time, you still need to disconnect the single wire that connects the two subpacks together.

right.

I will do that by making that connection on the bike. I use 4 connectors and run the single wire between the set on the bike. I make sure that no matter which pack is on which side the polarity is the same.

the drawing is not much the blue boxes are the connectors. the black lines are negative and the red is positive.
http://farm4.static.flickr.com/3500/3904441026_ed342a4d0f_o.jpg

 

[Rassy]

The diagram looks good weirdeh.

Now if you make a short two wire "charging" harness that allows you to plug the two + wires together and the two - wires together you end up with a nice big 12V battery pack, and only have to connect your car charger at one point to charge everything up evenly.