Sam's POB + Eneloop = :)

[FredM]

After thinking about it and looking at the Eneloop performance at high amps I decided to try them out in my POB.

So I made a quick pack using some cheap connectors and put 20 eneloops in a pack of 2P/10S thinking 1.2x10=12V.

Well my first runtime test was dissapointing being only ~37minutes. I was hoping for much longer. Then I saw that the N30 uses 11 cells in series and thought that the voltage dropped to low so the Eneloops could not use all their capacity. I am going to make a new pack with 2P/11S and hope for close to 1 hour.

Even if it is only 45 minutes or so that is fine because I will probably never use the light that much and it it VERY VERY light now. I dropped probably 5 pounds from the light and it has LSD batts!

updated runtimes coming soon!

 

[lasercrazy]

A 12 cell pack will work as well.

 

[FredM]

A 12 cell pack will work as well.

At what point could I possibly fry the ballast? 12 cells would be much higher voltage than the SLA battery.

 

[Mugrunty]

I have gone up to a 14 cell pack and had no problems. The voltage was about 16.7v under load (18v when charged). The only bad thing is you can never find out when the batteries are dead. What chemistry are those batteries your using? For NiMH and NiCd, you shouldn't go below 1v per cell...otherwise you risk cell reversal. I'd like to build a small circuit with a power transistor and an op-amp to turn off the battery pack when it falls to 14 volts. But, I don't really feel like it. You're right about the weight though...It's amazing how much lighter it gets without the SLA battery!

 

[FredM]

LSD Eneloops.

 

[BVH]

The two packs running parallel only gives you about 4 Amp Hours as compared to the SLA at 7 AH, IIRC. You're bound to get significantly less run time.

 

[FredM]

The two packs running parallel only gives you about 4 Amp Hours as compared to the SLA at 7 AH, IIRC. You're bound to get significantly less run time.

No the SLA at that high current is only 4AH. Eneloops give 1.8ah at over 2 amps so if I really cared that much about runtime I could run 3 or even 4 parallel and have a much longer runtime.

If the SLA really had 7AH it would last almost 2 hours because the amp draw is about 3.6 amps.


The real advantage to me is using AA's, LSD, and the weight (huge!)

It makes this thing a totally different light.

 

[Mugrunty]

Hey, I have an idea! Since the relay in the POB shuts off the charging process at about 14.25 Volts...You might be able to use a 10 cell NiMH back. Charge voltage needs to be at least 1.41V per cell for a full charge, so thats 1.425v if you use the built in charger! This way you could charge the pack without removing it! Yay...maybe.

 

[FredM]

Hey, I have an idea! Since the relay in the POB shuts off the charging process at about 14.25 Volts...You might be able to use a 10 cell NiMH back. Charge voltage needs to be at least 1.41V per cell for a full charge, so thats 1.425v if you use the built in charger! This way you could charge the pack without removing it! Yay...maybe.

I thought about that but don't want to risk my Eneloops since I know little about charging and the specifics. I also did not know there was a relay I thought it just hit it with 750ma not matter what. Thats cool though probably would work. Kinda slow at 750ma though.


Plus I am fine with the ~45 min runtime I should get with the Eneloops. If you really wanted to go all out you could just get the D cell's that have 11.5Ah and it would have over 3 hours runtime. 10D cells easily fit. I tried when I was messing around.

 

[Mugrunty]

Cool, yeah i was wondering if D cells would fit. I don't really know too much about eneloops. I looked them up when you talked about them. It looks like they are just Low self-discharge NiMH batteries. The only odd thing is that the sanyo site said they have a higher cell voltage. A little weird if you ask me.

 

[FredM]

Can anyone recommend some decent block style AA battery holders?

The ones I had melted on a runtime test

 

[Neubauej]

Assuming the ballast is of an automotive type, you should be able to operate it anywhere between 12.0v and 14.4v. Hope that helps some.

 

[FredM]

Yeah someone said 12 cells is OK, which would be way over 14 volts.

I have kinda given up without decent battery holders and I don't want to use the AA's to make a dedicated battery pack.

 

[TheGreyEminence]

AA Holders?...Like THIS one?:http://www.onlineelektronik.de/shop/images/X-WE12451.jpg
This would be for six, but i suppose you´re able to connect two of them somehow

Regards...

 

[lasercrazy]

Forget any of those crappy holders for a light like this, the current will melt them all pretty quickly. Why not just get 2 7.2v rc packs and link them in series.