Series/Parallel switching to charge in parallel, Part 2 - Simplified

Here's the discussion with e-doggies:

I really like the "parallel charging" scenario. So much so that I am incorporating it into the new wiring on my rebuilt Currie Scooter. Each batt terminal will have a single 10awg wire to a "cluster" of Power Poles. All four "-" to one 2X2 "receptacle" (I am running 4 12V 12Ah B&B's), and all four "+" to another 2X2 in close proximity. Probably try to mount them in a box or panel. Each battery charger cable would then need to branch into 4 10awg conductors that are crimped and locked into a 2X2 "plug".

Do you have any good (or otherwise) suggestions on how to fasten 4 10awg wires to the end of one battery charger cable?

When I unplug the charger cables from the scooter, I can replace them with a "jumper harness" to get the pack in series for discharging. I could even easily reconfigure from a 48V 12Ah pack, to a 24V 24Ah pack, just by changing the positions of the jumpers.

I got it all worked out in my head except the part about splitting the battery cable into 4 conductors. I just can't "see" a neat way to do that. Appreciate any ideas.

Thanks again for all you do.

Harlow

P.S. Do you have a good source for PowerPoles? Looks like they are widely used in the Radio industry. A fair selection at westmountainradio.com

Harlow,
That's a really good idea. I don't know why I didn't think of that. If you care to post what you are going to do in the original thread, than I can add a link to the topic post to your reply. Here's the thread.

I'm trying to figure out how to combine the wires too. I think I'll probably use a terminal standoff with a large 6 AWG or other lug, and stick all the smaller wires in the lug, then crimp and solder it. I have some terminal standoffs that are similar to these here. But they are a little different, I can send a pic of them when, but I don't have them with me right now.

Than the stock charger clamps can be used, or the charger wires can be crimped to lugs and bolted to the terminal standoffs if the charger will remain on board. This also makes the terminals accessible in case you need to charge with jumper cables from a car, or to power an inverter or something.

Another maybe better option I just thought of is to combine the wires into an anderson connector. It would have to be a larger connector to have a large enough wire size lug, like maybe the 75 amp size which can handle 6 AWG. Than, a mating connector can be put on the charger, and a connector can also be made with just open wires so that jumper cables can attach. This also cuts down the bulk some, as you could remove the charging connector without having to unbolt it from a terminal standoff. This sounds like a better solution for your application.

A third option is if you can find a 6 AWG or larger splice crimp connector maybe at a hardware store. Than connect 6 wires into one side, and than you can use a 10 AWG wire out the other, and solder it after crimping, than cover with heat-shrink. The wire out can be put to a smaller Anderson connector to reduce size and cost.

Anyway, I have a suggestion. It's a good idea to have fuses on each battery terminal in your case. Every circuit should have a fuse to prevent fires from shorts (think of house burning down!). I would use some blade automotive fuses in the little in-line holders they have. The closer to the battery terminals, the better. In order to cover every possible circuit for a short, every battery terminal needs a fuse, or 8 fuses for your application. I know the automotive fuses are only rated at 32v, so I don't know what the dangers could be to using them in a higher voltage circuit. I tested some 15 amp ATO fuses at 72v, and the fuses broke the circuit without exploding, so I'm going to use these on my motorcycle. I should of got a video. On one test, I blew away almost half of the fuse terminal in a fireball.

I ordered some Anderson connectors from http://www.powerwerx.com . They also have some blade fuses and holders.
...

Harlow,
I just realized that a 6 AWG lug or anderson connector will probably not be large enough for 4 10AWG wires. Here's a wire size chart http://www.powerstream.com/Wire_Size.htm You may need to use 14 AWG out from the Andersons in the charging connector, as that'd make it easier to combine them.

I had planned to have one 40A blade fuse inline at the positive terminal of the 48V pack. The controller is 35A so I thought a 40 fuse would be right.

I did notice that you had a fuse on every terminal in your drawing on the thread about parallel charging. I assumed you had them there in case you forgot to unplug one of the interconnects. Since I will be completely removing the "series jumper harness" before charging is possible, there should be no chance of a short, right?

I have no problem adding fuses and connectors, just trying to understand why it's necessary (or desireable). Is it a bigger concern because of the higher voltage? 48V?

Have you ever tried the round glass inline fuses? Neater looking installation. I found some last night (forgot what site) that were had gold-plated compression ends. Now that's Elegant!

I guess my question might be this. What's the risk if I decide to have only one inline fuse in the whole 48V pack? What would be some logical reasons for it to blow? Shorted motor/controller/wiring? I'm uber sensitive to fires, since I had an arsonist pay me a visit in Virginia. Should be only one of those allowed per paying customer. Very Stressful Time. So, I don't want my batteries to send me back there. What situation might cause a fire if there were insufficient fuses?

Harlow,
I'm just trying to play out any shorting scenarios. This setup is kind of unique, in that there is risk of shorting a single battery, or a section of the pack. And since the wires to each battery are drawn out (instead of a direct connection to adjacent battereis like in normal series string) it's a real good idea to fuse each battery now. A fuse is a way to try and protect from a short because you can't always be sure the wire insulation will hold up, especially on an EV with a lot of vibration and harsh environments.

Think of it this way. When building a larger car or truck conversion, one might have two main battery packs. One in the front and one in the rear. But, it's recommended to have a fuse for each battery pack. This is because if the interconnecting wire contacts the other main power out of one of the packs, than kaboom! The pack that's not fused sends thousands of amps through the wire, and it'll start a fire pretty fast.

Even these small batteries can provide a hell of a lot of shorting current. I shorted two 12v 12ahr batteries with a small wrench, and it blew away part of the wrench, and instantly the wrench was hot enough to burn me. Luckily I haven't shorted my motorcycle batteries yet, but I have a lot of work coming up on it, so we'll see how that goes. Like I said, I shorted 72v of batteries in series (and some of these were just small 2.3ahr 12v batteries) to a 15 amp fuse to see what would happen. There was a fireball about an inch in diameter, and the terminal was half way gone, even before the fuse filament melted.

Anyway, enough said, it's your own risk, but I highly recommend a fuse on each positive or negative battery terminal as close to the battery as possible. You can cut the fuses down to half as many as I have in the diagram I realized, because you won't have any direct interconnecting wire, so shorting current has to travel through a positive and a negative 10 AWG wire to complete the circuit (which depends on the short), so fusing one will do. But if there were separate interconnecting wires, than this wouldn't be true like I have in my diagram.

So that's 4 fuses, one for either + or - of each battery.

I hope the PP180s can handle it. I'm planning to send upwards of 600 amps through them. We'll see.

Okay, this is brilliant. Totally brilliant.

Or not. Maybe Todd's idea of using diodes will work, I'll see tomorrow.

David,
I realized I could setup one PP180 Powerpole and test it today.

I tested it at 600 amps for 10 seconds. To do this, I had to wire two batteries in series. The load tester jaws were smoking, and the load-tester 4 AWG wire got warm to hot.

I felt the contact surface of the PP180 right after the test. It was barley warm. The 2 AWG wire I had in the circuit was warm to the touch.

I guess it's important to note that these are rated for power transmission. And, the specs Anderson gives for pulse current are very conservative. The pulse current graph says I can pulse 600 amps for 3-4 sec through the PP180. I can probably pulse 600 amps for over 30 seconds with marginal heating.

2 AWG wire is only rated for 94 amps power transmission, and 4 AWG is 60 amps.

I finished the more complicated setup of doing this on my bike. Here's the setup:
"Bank Charging" by charging in parallel, w/one charger

Comments here: Re: Re-amped the beast

In general, I would not do this for a high powered system. Anything requiring larger than PP45s (and 10 AWG wire) I would shy away from due to the time required for setup, hassle dealing with the connectors, and expense of the components. This makes it a fair option for small scooters, ebikes, and pocket bikes. Also, it can be done with multi-pole and multi-throw switches which might be an easier to manage system when done.

For example, a 24v system appears to only need one DPDT (double pole double throw) switch. It looks like it would take N-2 poles as the number of battery terminals, and half of those double throw.

Harlow, funny that you mention it, I'm doing the same thing to charge using terminal standoffs:

I usually just leave mine in parallel until I'm ready to ride. I don't think it matters much though, as charging them in parallel should have charged all of the batteries to 100% SOC, and that is the goal of doing this. It shouldn't hurt to leave them in parallel until you are ready to ride.

The main risk is if one battery has a shorted cell, then it will pull the other batteries down in voltage. It is probably best to not leave them paralleled if the scooter will sit for an extended period of time.