Lossy Connectors

xyster · Feb 20, 2007

After connecting in series new subpacks last month using crimped quick connects and a quick connect adapter, I noticed my batteries' apparent voltage sag more than doubled -- from 4 volts to 10 volts at 35 amps. Suspicious, I just replaced the quick connects

and adapter

with a good 'ol screw-on wire nut.

Voltage sag at 35 amps is now 6 volts instead of 10! Wow, that's almost like getting a whole extra 4 volt lithium subpack for free!

I've still got other quick connects and crimped wire butts (sounds like me after a long ride

)

I'd like to replace, but they're stuck inside very tightly packed battery boxes. There isn't room for wire nuts, powerpoles, or bolted ring terminals, and I don't want to solder those wires together.

Any other ideas?
Any similar experiences out there?

safe · Feb 20, 2007

After switching from a "cheapo" six prong connector that was made by "who knows" and had very small wires coming out of it to the Dean Connectors with thick wires (and switching the controller at the same time) my bike has tons of extra power now. While the controller was the likely problem the new wires also are sure to help a lot.

Xyster has said he doesn't like the Deans Connectors because they don't "snap", but on mine they are held in tightly enough with the little spring loading so that they seem to be fine. Dean Connectors are (as far as I know) about the BEST choice for low power losses through the connector. They are just about "ideal" from a low resistance standpoint. (they can also withstand current loads into the 100 Amp level and beyond)

So I'd say:

1. Be sure to have thick wires EVERYWHERE. (no exceptions)

2. Use a good connector because if not you might waste those good wires.

fechter · Feb 20, 2007

My experience with those quick connects is very poor with currents over 10 amps. That's tough if you want disconnectable yet low profile.
One approach is to use multiple quick connnects in parallel, to spread the load out over more contacts. Otherwise perhaps longer wires so you can put the connection somewhere that has space for a larger connector.

xyster · Feb 20, 2007

My experience with those quick connects is very poor with currents over 10 amps.

What's your experience with crimped butts? I mean as far as efficiently passing amps... :oops:

:lol:

Matt Gruber · Feb 20, 2007

another example of how handy my 53a halogen tester is.
mail me a few with 6" of wire in each end and i'll test them for u.

i never use crimped butts, i use wire nuts or solder the wires directly

fechter · Feb 20, 2007

xyster said:
What's your experience with crimped butts? I mean as far as efficiently passing amps... :lol:

I work in San Francisco. I've never seen a crimped butt around here :wink:

If you use a good crimping tool and make a proper crimp, they rarely fail.
They are prone to corrosion over time if exposed to moisture.

xyster · Feb 20, 2007

If you use a good crimping tool and make a proper crimp, they rarely fail.

But how lossy are butt connectors? They're about the same diameter as the wire, except hollow. I could ship one to Matt to test, and I might, but I'd rather save the postage.

I work in San Francisco. I've never seen a crimped butt around here

And in a hospital to boot. If you ever need free components, I bet their ER keeps an impressive collection of light bulbs, tubes, motors and batteries, previously crammed into bodily cavities

Bet my bottom dollar you could build an entire scooter!

safe · Feb 20, 2007

xyster said:
I bet their ER keeps an impressive collection of light bulbs, tubes, motors and batteries, previously crammed into bodily cavities Bet my bottom dollar you could build an entire scooter!

Just don't tell me the phrase you might invent to name such a scooter...

Lowell · Feb 20, 2007

http://www.andersonpower.com/files.php?file=DS-PP45.pdf

Notice the big difference in temperature rise between 10 and 12ga wire. Not sure how this relates to voltage drop, but it's a good case for using 10ga or thicker wires.

xyster · Feb 20, 2007

Just don't tell me the phrase you might invent to name such a scooter...

I'm not going to do that. Whatever such a phrase might be, it'd certainly be in poor taste. :lol:
Besides, my wholesome mind doesn't easily conjure such things. Just to prove it, these were the only phrases to pop into my brain:

The Colo-Roller
The Pooper Scooter
The enTrail Rider
The Cowl Movement
The Impacted Tractor

safe · Feb 20, 2007

Lowell said:
Notice the big difference in temperature rise between 10 and 12ga wire. Not sure how this relates to voltage drop, but it's a good case for using 10ga or thicker wires.

That was the upgrade. It's all 10 gauge wire now and joined with Deans Connectors so the overall system is working very well.

I managed 47 mph for 5 seconds today...

Matt Gruber · Feb 26, 2007

xyster said:
My experience with those quick connects is very poor with currents over 10 amps.

Click to expand...

What's your experience with crimped butts? I mean as far as efficiently passing amps... :lol:

in the interest of science LOL i tested a butt today at 30a and it had 29mv drop. at first it read 20mv, in a few seconds it was 29mv.
your butt may vary

xyster · Feb 26, 2007

in the interest of science LOL i tested a butt today at 30a and it had 29mv drop. at first it read 20mv, in a few seconds it was 29mv.
your butt may vary

Thanks Matt! I can live with a 29mv drop. The shunt for the ammeter of course drops 50mv. I may have a full volt's worth of sag from crimped butts and stuff, but replacing them all wouldn't be worth it. I'll know next time to plan the wiring better.

Ypedal · Feb 26, 2007

What i " Would " replace in your setup is those charger ports... a big block of Andersons would probably cut back multiple minutes in your charging routine ! lol.... :wink:

xyster · Feb 26, 2007

What i " Would " replace in your setup is those charger ports... a big block of Andersons would probably cut back multiple minutes in your charging routine ! lol....

It's a good suggestion, so I'll take it seriously. You're right Anderson's would be much better than the xlr ports, in part because I've had problems with a couple ports maintaining connection to a charger plug. Problem with using Anderson's is the ports are scattered from front to back on the bike, installed closest as possible to their respective subpack of batteries. I could switch the xlr's for Anderson's but then I'd have Anderson's dangling out of the xlr port's holes, and connecting them one at a time from their disparate positions wouldn't save any time. If I bunched them all up in a big block, I'd still have 40 wires streaming out of the sides of my bike, making it look like a rolling bomb. To use the anderson's I'd have to pull all the battery boxes I worked so hard on (even though it doesn't look it, I did!) redesign them to pass the charging wires through hidden conduits to a central charging block. If I was to do that, I'd rather just put all 20 chargers on board the bike too, then run a power cord between them all, exiting the bike in back to be plugged into a wall outlet.

Yikes! Looks bad, but it only takes me about three minutes to connect or disconnect all 20 plugs AND check the voltages of each associated 15-cell subpack to double check that all 300 cells are balanced. Less time than it takes to pump a tank-full of gas!

Matt Gruber · Feb 26, 2007

just dont trip and fall LOL

YES next time build the chargers INTO the bike. ONE PLUG!

xyster · Feb 26, 2007

Absolutely. Good news is there's always a "next bike". Bad news is it costs money to get that next bike just right!

Perfectionism makes for low ROI (return on investment).

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