Amp battery size and fitment question.

Hello. So I have a 100% stock Amp and I'm looking at getting a new battery for it however I read in another thread (https://ecxforum.com/threads/recommended-ecx-amp-upgrades.291/) that certain size batteries wont fit without the use of a battery strap.

So what I'm wondering is: If a 3800mAh battery is said to fit under the stock battery holder and a 5000mAh doesn't. Will a 4500mAh battery fit the stock battery holder or will a strap be required?

I'm just trying to find out whats the largest (in terms of mAh) battery I can get without having to use a strap to secure it.

I've found that most hard-case LiPo batteries will fit in the AMP tray. I've noticed slight variations of a mm or two in battery length and height between brands. Kinexis, Reaction, Dynamite, Venom 2s batteries all fit no problem, regardless of the capacity.

Typicaly though, it will be the number of cells (2s, 3s, etc) that will most affect the overall dimension of a battery pack, not the capacity.

That's what I was thinking, mAh shouldn't impact the physical dimensions of the battery. It might be that the person's post that I read that said his 5000mAh didn't fit was one of those "hump" designs and just didn't mention that detail?... I suppose I could just order one and return it if it doesn't fit as long as I don't plug it in. I just figured I'd ask as see if anyone knew for 100% sure.

Yeah, NiMh batteries will definitely be weird sizes/shapes at larger capacities and voltages. Within the same number of cells (2s, 3s, etc) the case size (especially the height or thickness) seems to say fairly consistent. Of course "shorty" packs being one exception, but those are more for racing.

I ended up getting the 3300 7 cell 8.4 volt which is noticeably longer than the stock 1800 6 cell 7.4 volt that the ECX Amp originally comes with. The new 7 cell *barely* fits. Now I see what that guy was talking about in the thread that I linked above. The differences in 6 and 7 cell as well as the 7 cell configuration (flat and hump back).

Plan on replacing your stock ESC, as soon as I went with a bigger battery I started burning up ESC's, on my 3rd one before I decided to give up and order something better.

JMC2135 said:

Plan on replacing your stock ESC, as soon as I went with a bigger battery I started burning up ESC's, on my 3rd one before I decided to give up and order something better.

Click to expand...

Good to know, saving me from wasting money on buying multiple stock ESCs to figure that out.

ddxxe said:

I ended up getting the 3300 7 cell 8.4 volt which is noticeably longer than the stock 1800 6 cell 7.4 volt that the ECX Amp originally comes with. The new 7 cell *barely* fits. Now I see what that guy was talking about in the thread that I linked above. The differences in 6 and 7 cell as well as the 7 cell configuration (flat and hump back).

Click to expand...

I'm surprised that 7 cell fit. I originally bought a 7 cell 4500 and it didn't fit and kept coming loose in crashes. I got a 4 pack of velcro straps which helped, but eventually cut the 7th cell off the end and remounted it on top to make a humpback pack. It was a tricky solder job. You need a high powered solder iron and can't leave it on the battery more than 3 seconds without damage to the cell. They are usually spot welded and I don't recommend trying solder. The cell can explode if not done properly. Guess I got lucky because it works fine. Don't think I'd do it a second time though.

Jeb said:

I'm surprised that 7 cell fit. I originally bought a 7 cell 4500 and it didn't fit and kept coming loose in crashes. I got a 4 pack of velcro straps which helped, but eventually cut the 7th cell off the end and remounted it on top to make a humpback pack. It was a tricky solder job. You need a high powered solder iron and can't leave it on the battery more than 3 seconds without damage to the cell. They are usually spot welded and I don't recommend trying solder. The cell can explode if not done properly. Guess I got lucky because it works fine. Don't think I'd do it a second time though.

Click to expand...

Holy crap, that's scary haha. Yeah I can solder basic stereo wires for a car but I don't think I'd ever try converting a 7 cell from a flat formation to a hump back. Kudos to your success with it. And for the record the 7 cell flat BARELY fits lol. It doesn't sit in the tray all the way it's lower "lip" wedges in there and I have to strap it down.

@ddxxe, this what i did with my AMP to accommodate a thicker battery. I run Castle Brushless motors (4600Kv to 5700Kv) in all my trucks and had to raise my battery compartment with aluminum stand-off's. I did this with all my trucks and also use battery straps. The battery i use i the GEN Ace 7000 mAh 60C/120C. Use your ingenuity and creativity that's what this hobby is all about. Happy RCing! See the thumbnails

@weave where did you get the standoff's at? Would like to get some as well - type size brand? Or link to where you bought them would be great - thanks.

Trupix, we have a used electronics warehouse here in Santa Clara, Calif. called Halted, here's the web address; http://www.halted.com/commerce/index.jsp. Once you get there, click on All Products and on the right, click on Hardware and Stand Off's. I believe you can order online from them. However, you should be able to find these parts in your local hardware store, Home Depot, Lowe's, ect. Any type of aluminum, brass, nylon, plastic or ABS tubing should work has long as it can accommodate a 3 mm or 4-40 to 6-32 screw. Depending on the length of the stand off you use, you will have to increase the length of the screw. I hope this helps you out.

trupix, you can also find these stand offs at Amazon or on Ebay. You can get a whole set for around $ 10.00.