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Old 08-09-2010, 06:24 AM   #1
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Default Stacking LiPo balance taps

Hi guys,

I'm new to this forum so be nice

Here's the scenario:

I have a savage flux with 2x2S LiPo. I want to use an onboard LiPo monitor capable of monitoring up to 6S, but as you know the truck comes with 2 separate batteries.

What I need to do is stack 2x 2S taps into 1x 4S tap using an adapter wire.
The batteries are using JST/HX taps for balancing

From what i can see using my DMM, the red and black wires on a 2S pack are at the same point as the main high current line. The third blue wire is connected between the 2 cells.

Since I don't have a 4S pack to test with, I can only assume that it also has red/black and also 3 other colours, where the red and black are parallel to the high current line and the 3 colours are connected to C1+/C2-, C2+/C3- and C3+/C2-.

I've made a crappy hand drawn diagram of how my adapter would be wired.. As far as i can see measuring any 2 adjacent pins would net you a cell. I need someone to shoot down my theory before I go start a fire..

Diagram: hxxp://i34.tinypic.com/ojnvb7.gif
(I'm too new to post links so replace hxxp with http)

Thanks,
Dan.
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Old 08-09-2010, 07:32 AM   #2
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scriptasylum.com/rc_speed/_lipo.html lets you select many different configurations and it gives you a diagram of how the cells are wired to the balance connector. You'll have to copy/paste the URL since I haven't got enough posts up to let me link to external URL's.

Other than this I have no helpful advice other than not to go messing with lithium polymer batteries, search youtube for lipo fires
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Old 08-09-2010, 07:51 AM   #3
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nofearofspeed thankyou very much, that's exactly what I was looking for!

Turns out I DID have it wired right.. now I just have to choose the safety of having one wire snipped in case the taps get reversed, or being able to monitor the voltages with the ESC off.... HMM
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Old 08-09-2010, 08:40 AM   #4
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Why monitor them at all? I've been using my savage flux for a while now with no issues at all. I try not to run my car down so far that it hits the cut off. Mine slows down when the power gets low and if you keep running then it does the hard cut off and stops the car completely so I stop running either just before it slows it down or immediately after it slows down. I also balance charge on every charge, not sure if that's good or bad after hearing so much conflicting info on what is and isn't good for them I just decided to do what I feel is best.

You could use a timer like the heli pilots do but I usually stop playing with mine after my friend hits his low voltage cut off which seems to usually always leave me with 3.7v per cell so I use my mate's LVC as my drive timer

Unless you're unaware of the auto cut off the castle esc has (assuming you're using the HPI blur/mamba monster esc they come with)?

Your car should make a few chimes when you turn it on, then beep the number of cells it detects and then another chime to say that it's armed. If it only does the musical chime and doesn't beep then you probably either have the cut off set manually or completely disabled which isn't something I'd advise leaving it set to if you're running lipo batteries. Grab yourself a castle link and check your settings ASAP.

Quote:
being able to monitor the voltages with the ESC off.... HMM
Oh and that little switch behind the ESC doesn't turn it off, it only cuts the power the ESC supplies to the reciever. The ESC draws power all the while it's plugged in, if that's what you meant by that. Otherwise unplugging the batteries from the ESC doesn't hinder a voltage monitors ability to read the voltages off the balance lead.
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Last edited by nofearofspeed; 08-09-2010 at 08:45 AM. Reason: missed some info
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Old 08-09-2010, 08:50 AM   #5
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Quote:
Originally Posted by nofearofspeed View Post
Why monitor them at all? I've been using my savage flux for a while now with no issues at all. I try not to run my car down so far that it hits the cut off. Mine slows down when the power gets low and if you keep running then it does the hard cut off and stops the car completely so I stop running either just before it slows it down or immediately after it slows down. I also balance charge on every charge, not sure if that's good or bad after hearing so much conflicting info on what is and isn't good for them I just decided to do what I feel is best.

You could use a timer like the heli pilots do but I usually stop playing with mine after my friend hits his low voltage cut off which seems to usually always leave me with 3.7v per cell so I use my mate's LVC as my drive timer

Unless you're unaware of the auto cut off the castle esc has (assuming you're using the HPI blur/mamba monster esc they come with)?

Your car should make a few chimes when you turn it on, then beep the number of cells it detects and then another chime to say that it's armed. If it only does the musical chime and doesn't beep then you probably either have the cut off set manually or completely disabled which isn't something I'd advise leaving it set to if you're running lipo batteries. Grab yourself a castle link and check your settings ASAP.

Oh and that little switch behind the ESC doesn't turn it off, it only cuts the power the ESC supplies to the reciever. The ESC draws power all the while it's plugged in, if that's what you meant by that. Otherwise unplugging the batteries from the ESC doesn't hinder a voltage monitors ability to read the voltages off the balance lead.
I agree. What is the purpose of you monitoring the cells? Maybe you just want a back up to the speed controls lvc?

If you want an easy back up to the speed control cutoff, you can check out the low voltage alarms. Put one on each pack and that would give you back up voltage detection. They just plug into the 2S balance taps. They are around $15 each.
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Old 08-09-2010, 09:35 PM   #6
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I don't need to monitor the voltages.. But I certainly can do it because it can be done..

I found one of those cheap remote data kits and I want to see how it goes when hooked up! I most likely won't end up using it for everyday use.

Also it will be a huge reminder for me to unplug the batteries from the ESC after I'm finished.. way not careful enough.
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