Kraton New to RC, My first purchase

[f1andy83]

All,

I am very excited to start this new hobby, my first purchase is below, and I was wondering if people could give me a few points. (Off-road Bashing)

- 2018 Kraton 6S BLX
- 2 x 2S SMC 7400 - XT90
- Hitec X2 AC Plus 2 Port AC/DC Charger + XT90 cables.
- Batsafe Charging Box

I figured, I would go with a 4S setup, and not 6S in order to easy my way into this.

I am hoping to receive everything by July 10th.

But I need help with a few things.

- Does the Kraton has a low battery voltage safe built in?
- Does anyone know the settings for Storage/Charge for the 2S - SMC 7400 batteries that I should put on the Hitech X2 charger?
- I think the Hitech X2 charger comes with 2 balancing boards, hopefully I can use them without purchasing new balancing boards?
- Is there a pre-check I should do or post-check on car before and after playing?

Any other tips or hints for people new to this?


Andre

 

[Jerry-rigged]

Congrats!

4s is a great way to start. Run it once or twice, then swap to the included 14t 'speed pinion'. This is how my Kraton is set up. I did run it on 6s a few times, but I like 4s better.

- Does the Kraton has a low battery voltage safe built in?
Yes. I think the cut-off is 3.2vps (volts per cell), which puts the batteries at about 3.5vps resting. At the end of the day, you will want to 'storage charge' the packs to 3.85vps (or so)

- Does anyone know the settings for Storage/Charge for the 2S - SMC 7400 batteries that I should put on the Hitech X2 charger?
I think that is a 5a or 6a max charger? So run it at max amps. Typically, you want to charge lipos at "1C" - one times the capacity, so 7.4 amps for your batteries. IMHO, Hitec makes great products, but that charger will be under-powered for 1/8 truggy usage. Also, of you start buying 4s or 6s bricks, it will only charge them at about 3.2a / 2.1a due to the overall wattaging being low. For someone buying into 1/8 RC, I recommend getting a 200w minimum charger, as a 6s of that same 7400mah would need about 175w to make 1C / 7.4a. If you have budget, I would really recommend returning the Hitec and putting that $100 towards a stronger charger.

- I think the Hitech X2 charger comes with 2 balancing boards, hopefully I can use them without purchasing new balancing boards?
Yup.

- Is there a pre-check I should do or post-check on car before and after playing?
Give the truck a quick look over to check for loose screws, wheels, pillowballs, etc. Wiggle all 4 tires to check for access slow / pillow balls loose, blown bearings, etc. Give it a drop test - just drop it about a foot, landing flat, and listen for any extra squeaks / rattles. Put 'eyes on' the shocks spring perches, inner wheel bearings, pinion / spur mesh, all screws on the bottom of the chassis (to see if they are starting to back out) I do all this pre and post run, once you do it a few times, it takes like 15 seconds. Also post run, I check motor /ESC/Battery temp. (I use the $12 'non contact thermometer" from Harbor freight - car-key-fob size, so it is in my pocket when I run) Also, use a pocket lipo meter to check the battery pre and post run. pre-run to make sure you grabbed a charged pack, and that both packs are charged, and post run to make sure one cell is not out of wack.

Any other tips or hints for people new to this?

Don't forget to have fun!

 

[f1andy83]

Thanks for all the answers. The charging and upkeep on the batteries has been my greatest learning curve. Are you saying this charger might be a bit slow in charging? or it wont be able to handle it? I think if it can handle, my budget is already over what I set to spend, so I will be okay with slow charging if it charges and wont cause damage.


EDIT - WRONG INFO BELOW
Charges NiMH, NiCd, LiPo, LiHV, LiFe, Li-Ion and Lead Acid Batteries

• NiCd/NiMH Cell Count: 1-15 cells

• LiPo/LiHV/Li-Ion/LiFe Cell Count: 1-6 cells

• Pb voltage: 2-20 volts

• Charge Current Range: 0.1-10.0 amps

• Maximum Charge Output: AC 200W / DC 300W (200W + 100W)

• 20 Programmable Profile Settings

• Independent Cell Balancing Circuitry

 

[Jerry-rigged]

Slow will be the biggest issue. There is also the potential of an early death of the charger due to it being run at max power all the time, but with Hitec, that is a lower risk than other brands (quality brand).

1C charging will (nominally) charge a battery in about an hour. 1/2C would take 2 hours, 2C would take about half an hour. If you charge your 7400mah pack at 5 amps, from LVC / full dead, it will probably take about 1.5 hours.

Edit - I did a spec check on the Hitec X2 - it looks like it is more than just a 2 channel version of my x1. On AC (wall plug) it can do 100w SHAIRED of power (so 50w per channel), and up to 10a per channel. Now, the 10a is nice, but he 50w will limit you to about 6a. However, this chager allows you to power it via DC power, and then it will give you a full 100w to each channel. This will be enough to run the charger at 7.4a / 1C.

For a DC power supply, if you have an old unused PC, you may be able to harvest the power supply and convert it to 12vdc - this is not hard, just requires a few wire splices to the spaghetti harness. Also, there are lots of converted PC and server PSU's for sale on ebay for reasonable prices.

 

[f1andy83]

Thanks, I am trying to understand how this works. so pardon my ignorance. Hitech X2 says Maximum Charge Output: AC 200W / DC 300W (200W + 100W). so that 200W isn't 100 w per port? and I wont be able to charge at 7.4 /1C

EDIT.. You are correct. I was looking at the wrong specs. sorry. nooob here.

Edit 2: lol, so it sounds like ill have to setup the charge mode to 5.0/1C for both ports when charging bot batteries? it will be a slower charge, but it wont damage the battery or charger?

 

[Jerry-rigged]

Should not damage anything at 5a.

But for clarification, 5a is not 1C. 1C is "One times the capacity in amp hours" - so for your 7400mah battery, that is 7.4ah, so 1c=7.4. If you battery was 5000mah, then 1c would be 5a. Make sense?

 

[f1andy83]

Should not damage anything at 5a.

But for clarification, 5a is not 1C. 1C is "One times the capacity in amp hours" - so for your 7400mah battery, that is 7.4ah, so 1c=7.4. If you battery was 5000mah, then 1c would be 5a. Make sense?

I get it, so I can charge the battery as fast as 1C in this case, 7.4, but charging at 5 will not damage. I think I finally got it. Thank you. What I definitely don't want to do is charge at over 1C or 7.4 for a 7400 battery. If the battery was 5000 then 5.0a, etc...

 

[Jerry-rigged]

Well, it depends... LOL

You have to know your lipo specs. Many lipos will list the max C charge rate, and it is often 2c or even 5c. I have some Graphine packs that are rated at 10c (which would be 60 amps!).

For SMC, charge rating is a bit hard to find, so I emailed them, and Danny replied -

Hi Jerry,
You can go as high as 6C if need be but one thing to note the higher you charger at the less mAh is being put into the pack due to the way Lipos get charged. Due to this I find 2 to 3C to give the best combination of time to charge and mAh put into the pack.

Regards,
Danny Sullivan

So if you had a beastly charger, you could hit those SMC 7400mah packs with 44 amps, safely, and charge them in about 10 minutes.

 

[f1andy83]

Thanks for all the help. So much to take. I haven’t even started diving into the mods and parts.

 

[GuyFromCanada]

So if you had a beastly charger, you could hit those SMC 7400mah packs with 44 amps, safely, and charge them in about 10 minutes.

1.21 jiggawatts!

 

[f1andy83]

ROAR Approved
True Spec Premium 7.4V-7400mAh-149 Amps/90C pack

Is the one I got.

 

[f1andy83]

So to wrap it up, The configuration on the charger to charge these batteries will be set to 7.4A, 7.4V (2S).

 

[Jerry-rigged]

That would be ideal.

But even if you set the charger to 7.4, due to the 50w per channel limit, it may only charge at around 7.1a, (tapering to closer to 6a as the pack charges), if you are using both channels. If you only use channel one, then yes, 7.4a (because the charger will power share to channel 1 if the wattage is not needed in channel 2)

As a side note, I don't have this charger. I did have a guy on FB that owns one of these that he charged 2 x 4s packs @ 5a each, on AC - which should not possible per the specs unless you are using a DC power supply. So maybe Hitec under-specs what the charger can do.

So I'd say try 7.4a on both channels and see how the charger handles it.

 

[f1andy83]

I’ll let you know sometime next week.

 

[f1andy83]

Batteries here. Car and charger tomorrow.

 

[f1andy83]

So after some fun on the wet grass. A ridiculously lucky flip I called it a day. But now oh man this thing is dirty. What kind of cleaning should be worried about doing ?

 

[RCROD]

So after some fun on the wet grass. A ridiculously lucky flip I called it a day. But now oh man this thing is dirty. What kind of cleaning should be worried about doing ?

Lots of ways, depending on how dirty it is and what is on it. If just grass, try some just picking most it of, use rags, brushes, and even try some compressed air (careful if compressor has lots of air pressure and where you point the air gun, especially not directly at the bearings). Another option if extremely dirty and muddy, is using a water hose. Just dry and lube afterwards to prevent any rust (I use a dry lube to not attract dirt). I always point water hose away from electronics, just to be safe, even though Arrma ESC, etc is waterproof. Furthermore, I usually remove and clean the body, then use the water hose on just the front rear and rear end areas. You can even plug your wheels with some tape when using hose, unless you have already vented your tires (then any water will just spin out of wheels).

What you need is some rear mudguards (not only protect rear from rock, dirt, debris, etc, but also less cleaning...)

 

[Jerry-rigged]

RCRod gives good advice. Only thing I would add - use the dry lube only on suspension pivots. For bearings, use a proper light weight, non evaporating wet lube. Also, don't use WD40 as a lube - it is a cleaning agent, not a proper lube.

 

[Plumo]

I also run 4s and I’m wanting to change to the 14t pinion. Will this make much of a difference to the temps that I need to keep an eye on ? Do I also need to use some blue or red loctite ?

 

[Jerry-rigged]

the 14t on 4s is a good fit for the Kraton on 4s. Give good speed. The motor will get hot, but it stayed in acceptable range for me. Best is to get a temp gun so you can track temps yourself. Home Depot has one (with the electrical tools) for $20 or Harbor Freight for $12. Keep the motor temp under 170f.