Cg2 charger/battery spec

[dannyboy123]

I've just got my second hand gc2 and don't think the charger is genuine. What is the spec of the original charger output voltage and amps? I'm also trying to determine what mah the batteries are aswell if anyone knows. I know the batteries are 1.2v 7/5a cells bit don't know the mah

[Ronsc1985]

I bought mine used from someone who purchased it from new Foresight. The power supply is from a company called Scepter Power and has a 15v output at 2400 ma.
As to the mah rating of the battery components it's kind of irrelevant since you are constrained by the physical size you can use if you plan on fitting into the GC2 case. The battery can be rebuilt by replacing the 6 NiMH cells in the battery pack. My battery pack, which is as delivered from the factory, lasts about 4 hours when disconnected from the power supply to completely discharge it. There are instructions that you should completely discharge the battery once a month to extend battery life

[dannyboy123]

I bought mine used from someone who purchased it from new Foresight. The power supply is from a company called Scepter Power and has a 15v output at 2400 ma.
As to the mah rating of the battery components it's kind of irrelevant since you are constrained by the physical size you can use if you plan on fitting into the GC2 case. The battery can be rebuilt by replacing the 6 NiMH cells in the battery pack. My battery pack, which is as delivered from the factory, lasts about 4 hours when disconnected from the power supply to completely discharge it. There are instructions that you should completely discharge the battery once a month to extend battery life

Cheers for the info.
The batteries I have found are 7/5a 1.2vdc 3700 mah, I'm just not sure if 3.7a is too much for a gc2. I don't want go damage it.

[andygg1986]

The mAh refers to the battery capacity, or how long it can run once it is unplugged from the charger. The units are milliAmp * hours, meaning that it can provide 3700 milliAmps of current for one hour. The same battery could provide 100 milliAmps for 37 hours. A higher number means that you can use it longer without re-charging it. There is no harm in going to a bigger number. The higher the mAh, the larger and more expensive the battery is going to be. But usually in a given size and type of battery (NiMH in this case) you aren't going to see much variation in mAh.

[dannyboy123]

The mAh refers to the battery capacity, or how long it can run once it is unplugged from the charger. The units are milliAmp * hours, meaning that it can provide 3700 milliAmps of current for one hour. The same battery could provide 100 milliAmps for 37 hours. A higher number means that you can use it longer without re-charging it. There is no harm in going to a bigger number. The higher the mAh, the larger and more expensive the battery is going to be. But usually in a given size and type of battery (NiMH in this case) you aren't going to see much variation in mAh.

Thanks for that,
I understand the concept but obviously the higher the mah the longer the charge and the more heat etc is produced. Just don't want to overwork the charger/gc2.
Thanks

[andygg1986]

The charger will be rated for a voltage and number of amps. The voltage rating needs to be the same, and the number of amps needs to be the same or larger than the Foresight one. A larger number of amps means it could provide more power if needed. Inside the GC2 there will be battery charging circuitry that regulates how fast the battery charges though, so that will be the limiting factor on the charging speed, not the charger. If you have a battery with a larger capacity it will take longer to charge, but it won't overwork the charger. A larger capacity battery should not get any hotter than a smaller one either. Batteries get hot based on how fast the current comes out of them, not how big they are. The GC2 should draw the same amount of current with a small battery pack or big one.

[dannyboy123]

Just what I wanted to here cheers.
Would be interested in what power and amp the foresight charger is. I know the power pack is 15v 2.4amp but no idea kn internal charge circuit.

[andygg1986]

Yeah, I don't know about that. I doubt they would want to publish that sort of information. Usually, a battery charging circuit will charge quickly at first and then slow down so it doesn't overshoot. You might notice when you charge your cell phone that it takes less time to go from 0-50% than from 50-100%. Your power brick that plugs into the wall needs to provide enough power for that initial high speed charging. Six NiMH battery cells are 7.2V, so 15V at 2.4 amps could provide 5 amps at 7.2V.

Are you planning on building your own battery pack or replacing the charger that you got when you bought it? I know Foresight has replacement batteries but I don't know how much they cost. If you have a Batteries Plus store near you, they will build pretty much any type of battery pack you need.

[dannyboy123]

I'm going to build my own. Have built plenty of rc lipo packs so should be no issue. The power supply I have is the same spec as the oem one so should be OK. Think I will just go with the 4amp cells and see how it goes. Works out as less than half price

[andygg1986]

I don't think you can use Lipo batteries. Each one of them is 3.7V instead of 1.2V that the NiMH cells are. Normally there are 6 NiMH cells for a total of 7.2V. Two Lipo ones would be 7.4V, and Lipo batteries take different charging circuitry than NiMH.

[andygg1986]

Also, if you run a Lipo battery all the way down it kills it. They need special protection that keeps the voltage from going too low. And discharging them can make them explode (remember all the stories before christmas about hoverboards catching on fire?)

[dannyboy123]

Wasn't going to use lipo, was just saying I have a little experience building battery packs

[Ronsc1985]

I'm going to build my own. Have built plenty of rc lipo packs so should be no issue. The power supply I have is the same spec as the oem one so should be OK. Think I will just go with the 4amp cells and see how it goes. Works out as less than half price

Here is a link which may give you some insight as to what is inside the GC2 with respect to battery charging. http://www.powerstream.com/NiMH.htm

Replacement cells for the GC2 battery are something under 7 bucks US so for $42 max you can have an exact replacement that fits inside the GC2 without any reliability concerns. Given that the replacement cost for a GC2 is thousands of dollars, 42 bucks seems a cheap replacement strategy. The internal battery charging circuitry in the GC2 charges the battery stack at something like 8.5 or so volts. You can observe this when the batteries are completely discharged and you plug in the charger and start the system.

[andygg1986]

That is an interesting website on battery charging. I agree that $42 is not too much to build your own battery pack. Just to be clear, they have to be NiMH cells, NOT Lipo cells though. It would be a shame to ruin a GC2 by trying to use Lipo rc packs instead of buying the right type of cells. I'm sure Foresight would sell a replacement battery pack too, but it will probably be at least $100. Then again, when you have spent several thousand on a device, spending an extra $60 isn't that bad if you aren't exactly sure what you are doing.

[dannyboy123]

Like I said above I do have a little experience, I wasn't going to use lipo cells instead of nimh I just wanted to know what mah the oem packs are and spec of the gc2 charger.
Thanks for the info guys

[andygg1986]

Sorry I misread your earlier post as saying you have lots of lipo packs, not that you had built lots of lipo packs. Just didn't want you trying to use the wrong thing! I agree it should be straightforward and an easy way to save some cash.

[dannyboy123]

So I rebuilt my battery pack today. I used 6x gp 7/5a 3700 mah Nimh cells. Took me 0.5 hours and cost £31. Result. Will check it out tomorrow to see how long the batteries last!! Thanks for the help guys.