Haynes Manual Build a Robot

[McMullet]

As an alternative, I use one of these: https://hobbyking.com/en_us/pd606-charger-uk-plug.html

I don't think it's as well-featured a piece of kit as the Accucell ones but it does have advantage that the AC/DC conversion is done inside - i.e., it comes with a UK plug so you can just run it right out of the box, rather than having to get an external 12VDC supply (it can run from an external DC input as well, if you're "in the field" and running from a car battery say).

[AdamST180]

As an alternative, I use one of these: https://hobbyking.com/en_us/pd606-charger-uk-plug.html

I don't think it's as well-featured a piece of kit as the Accucell ones but it does have advantage that the AC/DC conversion is done inside - i.e., it comes with a UK plug so you can just run it right out of the box, rather than having to get an external 12VDC supply (it can run from an external DC input as well, if you're "in the field" and running from a car battery say).

I might go with that as simpler the better for me

I might aswell get a LiPo at the same time then, people have suggested https://hobbyking.com/en_us/turnigy-...html?wrh_pdp=1 but its out of stock, can I get a different mah or S rating?

To drive 2 x argos drill motors and potentially a linear actuator?

Cheers

[Ocracoke]

I would recommend sticking, for your first machine, with as similar spec as you can. Stick with 4S (which is the cell count in series, meaning 14.8v) if that is what the various components in your robot can take, namely your motors and speed controllers. I would say perhaps this - https://hobbyking.com/en_us/turnigy-...ack-xt-90.html. Only slight hiccup is that the battery appears to only be in the EU, not in the UK so the delivery charges are going to be more.

If you are not going to have a linear actuator, I know that at least 2100mAh is OK, The Honey Badger used 2x 2S LiFe batteries in series originally and even Azriel, with its axe, still uses 2100mAh LiFe batteries in 5S LiFe (2S and 3S in series). If you are going to use a linear actuator, I would recommend at least 3000mAh.

[AdamST180]

I would recommend sticking, for your first machine, with as similar spec as you can. Stick with 4S (which is the cell count in series, meaning 14.8v) if that is what the various components in your robot can take, namely your motors and speed controllers. I would say perhaps this - https://hobbyking.com/en_us/turnigy-...ack-xt-90.html. Only slight hiccup is that the battery appears to only be in the EU, not in the UK so the delivery charges are going to be more.

If you are not going to have a linear actuator, I know that at least 2100mAh is OK, The Honey Badger used 2x 2S LiFe batteries in series originally and even Azriel, with its axe, still uses 2100mAh LiFe batteries in 5S LiFe (2S and 3S in series). If you are going to use a linear actuator, I would recommend at least 3000mAh.

Shipping is actually the same strangely! I will need XT-60 to XT-90 adaptors it seems, would I be right in saying the battery is the female connector?

[Ocracoke]

Ah, I had missed it was a XT-90. You would need one of these - https://hobbyking.com/en_us/xt90-mal...-2pcs-bag.html - to make the connection.

[AdamST180]

Ah, I had missed it was a XT-90. You would need one of these - https://hobbyking.com/en_us/xt90-mal...-2pcs-bag.html - to make the connection.

Sorted, cheers

This robot building is expensive!

[Ocracoke]

Hahhaa, that it is. I once totaled up how much my second version of The Honey Badger cost me. Close to about £400 but then again, I was things like a pricey transmitter at the time and such.

[AdamST180]

Hahhaa, that it is. I once totaled up how much my second version of The Honey Badger cost me. Close to about £400 but then again, I was things like a pricey transmitter at the time and such.

Yeah lol, I managed to get a second hand DX6i for not too much, but between the ESC and everything else plus tools its cost a fair bit and this is just the prototype, got to get the HDPE next

[Ocracoke]

The thing is, as a one off, it is expensive, yes but you do end up reusing tools and components from one machine to the next as you go along. My Middleweight needs a new body but the parts from the current version can easily be transplanted so that will only cost me about £300 or 400 to get the parts and for me to machine them to make it work.

[James Williams]

Expenses wise, the worst part is always starting up. Once you're up & running it's not so bad & as Lucy said the vast majority of it can be reused & more expensive things like transmitters usually don't get damaged in combat. I've had a pretty rough run over the last couple of events (1 lipo fire, 1 other lipo die & multiple big hits from spinners) but once I've added it up it was less than half what I spent on the hotels for the events.

[AdamST180]

Yeah most of it is reusable thankfully! Just gotta price up the HDPE once got the design finalised.

LiPo and chargers ordered and dispatched from hobby king, so think I have everything I need now

[AdamST180]

Im sure i remembering reading it on here before but looked in many threads and cant find it.

How do I work out what fuse size I need for this; https://hobbyking.com/en_us/turnigy-...ack-xt-90.html

[McMullet]

The max current from your battery is the capacity in Ah multiplied by the C rate (in this case you have a burst and continuous C rate, so use the lower of the two, i.e., the continuous rating). That's 4.0 Ah x 60 C = 240 A. The fuse must be less that that.

However, with two drill motors and a linac you'll never get close to 240 A. So to protect your motors and ESCs you are probably better off with something around the 100 A mark, or even less. We have an 80 A fuse for a similar setup to yours.

[Ocracoke]

You work out the burst amperage of the battery and get a fuse below that amperage as per the rules:

7.8.3 Fusing
A fuse rated below the maximum burst discharge of the battery MUST be fitted. The maximum burst discharge current is calculated by multiplying the C rating by the capacity. E.g. 25C 2200mAh = 55 Amp

So in that particular batteries case, it is 4 amps * 120C = 480amps (240amps constant). That, to me, sounds crazy and you'll likely never draw that much. I'd figure on it being a quarter of that, so 120amps but from experience, a 60 or 80amp fuse will be sufficient. I've yet to blow a 80A fuse in either my Featherweights or my Middleweights.

[McMullet]

Looks like we're largely in agreement here Lucy!