Also don’t forget that if you don’t change the battery cut off on the VESC you can over discharge the batteries
1 Like
That’s why I tried the alarm thing 
This is the type I’ve always used… adjustable alarm voltage…
1 Like
Assuming that the capacity of the booster is identical or lower per P group of the main pack you should be good, if it’s higher than the main pack you can still have energy left on the booster and over discharge the main pack
1 Like
OK, so basically it should work as long I watch both packs for over discharge? My battery is a 10s3p vtc6 pack with 9.3Ah, the lipo is a 2s 8Ah zippy.
Exactly, but with this mixed setup you will need to pay even closer attention
The lowest you should go with the Lipo is 3.5~3.6 V, but the 18650 you can go between 2.8~3 V
Yesterdays prototype:
It was working but is way too bulky (I used an old external harddrive case) so since it rained today I build a better one out of spare kydex:
First you have to build some shape out of wood or similar:
Then you heat up the kydex in an oven (150°C) for some minutes until it becomes soft. This soft mat has to be placed quickly on top of your shape and then you use some foam and wood to press it as good as possible onto the shape. If its not perfect its not that bad, you can always use a heatgun to make it soft again and improve it punctually (foam plus wood and press)
After some time it looks like this (actually I already cut the outer shape with a saw on the picture)
I then placed the lipo in it (using neoprene for insulation and less vibrations), put a cut out plain piece of kydex on top and hotglued it together
The Lipo discharge warner fits perfectly:
Complete build, now you see why I put in the higher spots
btw, the warner got loose yesterday, I’m almost sure that todays test will be more successful 
4 Likes
Update: It works perfectly, I’m not sure if I want 10s all the time so the booster is a nice way of having the extra power when I want it
3 Likes
The tool batteries have their own internal BMS with low-voltage cutoff, correct? This would eliminate the need for a low-voltage alarm and manual disconnect, right?
@amazingdave I think you should change the title on this thread so the word “loopkey” is not in it. This is dangerous and they way it’s being done isn’t what the initial title suggested. I think you’re using the charge port, right?
6 Likes
This 
We should all attempt to be clear on topic titles. In this case I’d hate for a 14 year old to plug a lipo into the loop key because he failed to read.
4 Likes
You know damn well there plenty of adults on here that dont read too.
1 Like
Yeah, I know a few… @Skunk, I mean I’ve even talked privately with a few @Skunk. I wonder if I should name names @Skunk. 
5 Likes
My problem is i read to much so nothing sticks lol Oversaturation
5 Likes
2 Likes
I went ahead and changed it, looks like the op hasn’t been on in a few days.
2 Likes
This thread all ways did my head in, I was like how can this work?? Then it got cleared up and made sense. Over the weekend I was thinking, we should really change the title of this thread. !! I can sleep soundly now.
4 Likes
Yeah me too. I’ve been worried for days that someone was gonna plug a lipo in their loop key port just to see if it worked
when you take care of
- polarity (has to be in series with your main battery of course)
- that both batteries never get drained below cutoff
- use xt90s as connector to prevent the spark
it works fine.
1 Like
OK. But that is more of a voltage booster than range extender. So slightly different topic. Also I’m on 12s, so I can’t just add more series voltage with current vesc hardware. Its a cool idea though, you could have a 6s / 12s build for slow and fast versions. Id want to be able to change vesc settings by bluetooth for this though.