Need some battery help :) - RC-Monster Forums

Wildjones · **Need some battery help :) -** 12.10.2010, 01:27 AM

Alright you electric gurus you, I need some battery help. Probably a dumb question too so heads up..

I have a Hirobo XRB SR heli that I really enjoy flying. I packed it up for around a year due to a switch in interests. Stupid me, I forgot to take care of the battery. Finding batteries is hard as heck, and the few that I have found are in the 53-74$ price range, which is RIDICULOUS. The stock battery is a 2S 710mah battery. The problem is the plug.

So I ask you this, the plug combines the charge leads with the regular output leads. Is it possible to take say one of these http://www.amainhobbies.com/product_...tor-74V-730mAh and sodder it up to match this? http://www.amainhobbies.com/product_...ack-74V-720mAh

If yes, how does one go about modifying a plug to do that?

PS. I know this is really a car forum, but you guys have given me excellent electrical advice in the past and trust your guys' knowledge like its the bible

Thanks!

- Mike

rawfuls · 02:01 AM

Holy bajeebus!
That's an expensive battery!

If you still have the old battery, and there's still some charge, I'd say just measure all the voltages across every wire, or hell, even open it up (carefully), and see what's connected to what.
Using that, draw a picture, unsolder the connectors, and hook em up to your new battery..

Or..why not just resolder the PCB (4in1, assuming you have one, or RX or whatever) to match a regular JST plug?

JST's are reasonable for 2S under 2000mAh, so I've found.

EDIT:
After doing some digging around on the web, found this thread:
http://rcudev.rcuniverse.com/forum/m...tm.htm#2471728

Looks it's practically the same as the balance connector, black is negative, red is positive.
So if you connect w/o balance, see if it'll work?

Wildjones · 12.10.2010, 02:02 AM

I can give you some more info if it will help....

The blue wire is negative, the white is the balance wire, and red is positive. I have never seen a single charge wire except on this battery hence why I am confused. The female end of the connector plugs straight into the chassis of the helicopter. I am trying to do the least amount of monkeying around so as to not mess up the balance of the bird...

I dont know if its cool to post links to other forums, but I saw a guy who made a new battery by using the jst plug outputs like they should be, then somehow combined the balance wires to one wire and connected it to the white wire. Heck ill just link to the single post. If I need to remove the link I can always do it later: http://www.rcuniverse.com/forum/fb.asp?m=5257799

It seems like he got away doing it just fine, I just dont know how to go about combining the balance leads. I dont know if its cool to just solder the two together and call it a day or will it short out the pack, must like touching the 2 jst wires would?

rawfuls · 12.10.2010, 02:05 AM

Oh now that's weird..
I'm not guru, so don't take my advice too seriously, just take it into consideration as best-

I suppose the only way to find out would be to either open the pack, or just experiment?
You could also duplicate what the guy did, however, you can't really see what's connected to the balance tap.

Wildjones · 12.10.2010, 02:12 AM

I tried to PM the guy, but got no response. I thought about just trying it, but figured I should ask first. I really dont want to fry the electronics, nor do I want a lipo battery to explode in my face lol.

As an alternative I could make an adapter that would use the original stock plug and just use the positive and negative plug soldered to a female JST plug and bypass the balance wire entirely.Then I would need a proper lipo charger, BUT then I could buy a few packs and swap them, rather than rely on one pack.

Would it be possible that the heli uses the white wire to read voltage and activate the LVC? Common sense would tell me it would read from the positive and negative wires though.

JERRY2KONE · **Advice -** 12.10.2010, 04:35 AM

My advice would simply be to open up your old pack and get aquainted with how your battery is put together. That is what I did with my two sons helis. I was in the same boat looking at the cost of new Lipos for a heli and just could not see spending that much for such a small heli. So what I did first was to gather a few items that I had laying around our shop (battery bars, wire, and some Energizer rechargable AA batteries) and manufactured my own 4 cell battery pack. It is slightly heavier than the Lipo, but not enough to make a serious difference. Live and learn. After doing that I purchased a 4 cell Hydramax battery at TH and made up my own plugs for it. They work just fine and instead of 720mah they now boast a heafty 2500mah, which gives the boys more flight time with their toys. The only way to learn is to experiment and have some fun doing something new. This applies to everything you do in life. Good luck with your adventure.

Wildjones · 12.10.2010, 02:28 PM

Thanks Jerry. This is a relatively small copter so I am held to a weight restriction. Looks like LiPo is the only way to go (or Life if they make small enough cells).

I figured I should ask you electric gurus first. I am pretty handy with my hands, but I am an old school battery guy (NiMHs and NiCDs at best :P). Heck I still use an old school charger thats at least ten or eleven years old lol. Honestly, the last thing I want to do is fry my copter. Results on the web have been... limited to say the least. There was a guy who used to make an adapter to use aftermarket batteries but he is MIA and his email is closed; emails just bounce back.

If anyone else has any ideas that would be excellent. I still dont know if its bad to solder the balance leads straight together...

JERRY2KONE · **Aaa's -** 12.10.2010, 04:23 PM

You can also opt for AAA's to save on weight, and still get more Mah than your tiny Lipo. It really is easy to do, and it works fine trust me. As for your configuration I have no idea what you are dealing with, but using AA's or AAA's is pretty straight forward, and you won't need the balancing taps. Just plug it in. I even used a universal type of charging adapter with adjustable voltage and placed a matching plug adapter on it for this specific issue, which simplified charging even more so. Don't be affraid to try something different. Paying exorbinate prices for Lipo technology is always an option, but it is expensive for sure. Good luck with that.