Paralleling batteries of different Ah?

[Crash Machine]

I'm sorry that's on the Fusin battery. It's got a different b.m.s.I think. I still haven't went to get a new voltmeter. Been cleaning up flood damage. I'll check before I charge it. I may have to charge that cell individually?

 

[wildnrg]

why do you think its a capacitor? do you have picture or can you describe it and read the stuff printed on it?

Picture attached to my previous post.

I know when I see an electrolytic capacitor 3300uF 35V marked on it with markings to indicate which side is negative.

 

[dnmun]

ok, never saw that attachment. i was thinking of the same thing myself on my pack, but that is a huge cap3300uF, no spikes on that cable. but you never put it back when you replaced the connector? i thought the fusin battery was a prismatic cell battery but those looked like cylindricals. can you post up pictures full sized front and back of the BMS? you have two different types?

 

[wildnrg]

ok, never saw that attachment. i was thinking of the same thing myself on my pack, but that is a huge cap3300uF, no spikes on that cable. but you never put it back when you replaced the connector? i thought the fusin battery was a prismatic cell battery but those looked like cylindricals. can you post up pictures full sized front and back of the BMS? you have two different types?

No I haven't disconnected the capacitor off the extension cable, and I don't intend on putting it onto my new cable unless its actually necessary.

I am guessing that the capacitor is possibly for reducing possible surge on connecting the batt to the controller??

 

[dnmun]

no, the cap there won't prevent the spark, but it smoothes out the current fluctuation leaving the battery. no you don't need it, but it helps with the current spikes to the controller a little.

 

[nightowlgk]

IS there anyone in the States who can build me a diode harness with heat sink / 10 ga. with 45 amp Andersons for my 15ah ping and Bosch 6ah packs?

 

[dnmun]

you can buy a pair of either the 25A or the 40A schottky diodes from allelectronics. mount them back to back with a heat sink type piece of metal between them. keep the heat sink electrically isolated because it will be the same potential as the diode output.

the outside legs would come from each battery, you can tie the two legs of each of the back to back diodes together, and the output legs in the center can be tied to the positive wire to your controller.

http://www.allelectronics.com/make-a-store/category/205400/Diodes/Schottky/1.html

 

[scoot]

Have you looked at the "ideal diodes" that tiberius makes. I know that he had some anderson connectors installed on his first version. I am not sure if they will install neatly on the final version, but I suspect so... maybe with a pp spacer included. If he notices this post, maybe he can reply and let us know; and, if he would be willing to pre-install them for us. I would like to know myself.

Here is the thread describing them:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=11016

 

[Tiberius]

Hi Scoot,

On the latest version of the IDs, I moved the terminals apart slightly so they would take yellow automotive crimp terminals. (I don't know if you use the same scheme in the US, but here the colour (sic) relates to the size wire they take - yellow is the biggest.) But then I added some extra solder pads at the right spacing to take pairs of Anderson Powerpole connectors.

So they are designed for direct connection of the 30 A Andersons, though I've not actually built any that way yet. I don't know about the 45 A ones.

I'm also working on a kit for putting a pair of IDs in a potting box with busbars and heatsinks. It will be the same price as a pair of IDs. The end user will get to pot them as a pair, so I won't have to pot them individually and that difference will pay for the extra bits.

That may be just what you need nightowlgk, but it will be towards the end of next week. Right now I'm on holiday in France logging in with a dodgy internet connection.

Nick

 

[scoot]

Heck, speaking for myself, I'm in no hurry. I have all winter to complete the 2 projects of mine. :lol:

I thought it best to take this back to your thread though...

 

[dnmun]

Have you looked at the "ideal diodes" that tiberius makes. I know that he had some anderson connectors installed on his first version. I am not sure if they will install neatly on the final version, but I suspect so... maybe with a pp spacer included. If he notices this post, maybe he can reply and let us know; and, if he would be willing to pre-install them for us. I would like to know myself.

Here is the thread describing them:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=11016

yes, love nick's idea and design.

i had just been searching the allelectronics site and saw they had the new listing for the 40A diode, and i figure back to back they could take a ton of power, but who knows if they work well either and don't get too hot. just figured that was the place to put that link.

 

[scoot]

Have you looked at the "ideal diodes" that tiberius makes. I know that he had some anderson connectors installed on his first version. I am not sure if they will install neatly on the final version, but I suspect so... maybe with a pp spacer included. If he notices this post, maybe he can reply and let us know; and, if he would be willing to pre-install them for us. I would like to know myself.

Here is the thread describing them:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=11016

yes, love nick's idea and design.

i had just been searching the allelectronics site and saw they had the new listing for the 40A diode, and i figure back to back they could take a ton of power, but who knows if they work well either and don't get too hot. just figured that was the place to put that link.

I'm sorry dnumn, I did not make it clear who I was trying to reply to (nightowlgk) . I was keying in on the "anderson connector" aspect of nightowlgk's question and I recalled Nick's Ideal Diode so I just threw it in the conversation. After going back and re-reading the last few pages, I realized how hard it is (for me anyway) to keep clear who is conversing with who, and I just made it worse :lol: Thanx for that link too, BTW.

I have a question though... when paralleling two "real diodes" (not IDs), couldn't that present a problem with one diode taking on more power than another if they are not perfectly matched? I was under the impression that most diodes will not work well if paralleled. I was thinking that if you could make sure each had exactly equal resistance it could work, thought the current will usually bypass one of the diodes. Isn't it better to buy one with the proper amp rating than parallel two smaller ones? On the other hand, since the "Ideal Diodes" really aren't diodes in the traditional sense so the limitations with diodes don't come into play. Aren't they a FET based control circuit providing the same function as a diode but without the common limitations? I was thinking they would work well in parallel and that is one of their greatest benefits besides the minimal voltage drop.

 

[dnmun]

yes, nick's ideal diode uses the FET and so you don't have the .4V voltage drop you have with the diodes. at 40A the power is .4x40=16W. that's why using the ideal diodes is so much better.

but you can put the diodes in parallel if they are matched, and that spreads the power loss out over two devices.

 

[wildnrg]

Well here is a new twist.

My second battery that I ordered from the same company arrived this afternoon, even though the voltage and capacity are the same, and the cells are the same, it comes with a physically bigger BMS, and on this one there are 3 wires. A pair of wires for discharging and a pair of wires for charging and from what I can see a they go to different points on the BMS and battery pack and there is some 3 wire connection in the middle.



Also on the discharge cable is an extension cable with a3300uF 35V capacitor, which I don't have a clue what its there for, anyone have an idea what the capacity is there for??
View attachment 2
View attachment 1

I've found that connecting a full charged battery to my bike there is a small arc on the terminals. But when I used the capacitor, no arcing.

 

[swbluto]

The capacitor could have the benefit of reducing the voltage spikes caused by the extension wire's stray inductance and it could also have the benefit of reducing the pulsing on the battery which can be hard on a battery, although considering it's only on the extension cable, it's likely to do with combating the inherent stray inductance.

 

[Crash Machine]

I started this thread a while ago because I thought I would have the Ping 48v 15 Ah battery sooner. But Chinese holiday was at that time, then a gear broke and I had to wait for replacement parts, then Fed-Ex lost said replacement parts for a week. So I finally got the battery here and got some "break in" cycles on it.
It also came with the diodes Ping recomended. I'm going to go ahead and use them. I figure if he sent them with the battery he must of had a reason. Besides I need the experience building things like this. I'm committed to electric transportation now(selling my cars) so I need to learn as much as possible. I'm only running 500 watts so any one of these batteries alone will handle my needs. I'm looking for a modular set-up 15 Ah battery for 30 miles, 10 Ah battery for only 20 miles, and both parellel for 50 miles, so I can just carry the battery I need. Plus I want to experiment/learn. But I may step up to a BMC V2-T in the future so this(parelleling)may be a necessity.
So here's my two questions:
One: Can I parellel batteries at a distance? I had to put the 10 Ah on the front of the bike and run some wire to meet the other battery. Will this work?
Two: Which way does this thing go? You can see what an absolute noob I am by this question. I think I know, but keep second guessing myself. Here are pics. of what he sent me. Thank you in advance...View attachment l_dca62ad0d4c445399820e43e85239165.jpgView attachment l_d2953f0af111452d9e5f0b27c700e3c6.jpg

 

[scoot]

OK... I'll take a stab at this even though I'm a newb also, and the experts can confirm or otherwise :? .

I believe that the arrow direction designates the direction that the current flow can pass. To verify, I would connect the left side of your diode to a battery and use a volt meter to see if there is near full voltage when measured on the right side of your diode. Turning the diode around and hooking it up (the other direction) should yield little or no voltage reading when repeating that procedure.

 

[Crash Machine]

That's exactly what I was thinking. I gotta take a minute and try it with a voltmeter good idea. Tested for resistance last night but I'm not sure what setting to be set on. Serious learning curve involved here. I operated cranes but if one broke down we just called a technician. I guess I shoulda' hung out and watched instead of going to lunch. Story of my life...

 

[Tiberius]

The Ping diode looks like a pair of dual Schottky diodes, TO-247 package. The most likely thing is that each package contains two Schottky diodes, with the common cathode going to the centre pin.

So it will be 4 Schottky diodes in parallel, with some metal work to spread the heat. Current flow would be left to right in the photos. With a multimeter it will measure high resistance one way; the other way low (probably; it depends on how the multimeter interprets the half a volt drop). Beware of trying to determine direction with a multimeter alone; they don't all work to the same convention when measuring resistance.

Nick

 

[Crash Machine]

Cool, that's the way I thought it would be. He sent two so I'm gonna make a Y connector running these diodes in line. But like your bike (one in the avatar)Tiberius I have one of my batteries in front. Balance is Important. Will paralleling from a distance cause problems?
Thanks a whole lot. I'll post pictures when I'm done.

 

[gilnet]

crash zone lunch is good.