Highest Energy Density?

[Web Monkey]

I rebuilt a Dive-Rite MLS1 Canister light I bought used on eBay, and I'm extremely happy with it, except for the run-time.

I love the 50W halogen bulb, and don't really want to move down to 35W. A 12V 8AH Gel Cell runs for about 50 minutes.

Does anybody know of any other rechargable battery types that have a greater energy density (watt hours/battery volume)?

I'd like to replace the Gel Cell with something that would give me about 2 hours run time if possible. Anybody have any ideas?

Thanks!

Terry

 

[Charlie99]

NiMH has higher energy density; chargers are readily available, and doesn't require any electronics to drive the light. I don't have volumetric energy density figures handy, but IIRC, the NiMH isn't quite double that of lead acid gel cell / SLA batteries. (In wh/kg its right a bit more than double --- 30wh/kg vs 70wh/kg, but lead acid batteries are quite a bit more dense than NiMH)

Lithium ion has even higher energy density both by volume and weight. The two drawbacks are 1) expensive, and 2) battery voltage varies signficantly during the discharge cycle so you would have to add a DC/DC voltage regulator.

Unless you want to make a big engineering project of it, I'd just go find the NiMH cells that best fit and see if the life is adequate for you.

 

[Tiny Bubbles]

Is this a new 'gel cell' or did it come with the light (used off eBay)? I would expect more than 50 minutes out of it. I get 60 minutes driving a 50 watt bulb with my 5 amp-hour sealed lead acids. Still, you'll want something closer to 10 amp-hours to go for 2 hours, or else you're stuck using a 35W bulb. A bunch of NiMH cells shrinkwraped together seems to be the battery of choice these days.

An alternative would be going to an HID lighthead to get your 2 hours+ out of the battery you have.

-Tiny-B.

 

[Web Monkey]

Sounds great!

I'll order up a NiMH battery pack as soon as I measure how much space I have inside the cannister.

Thanks!

Terry

NiMH has higher energy density; chargers are readily available, and doesn't require any electronics to drive the light. I don't have volumetric energy density figures handy, but IIRC, the NiMH isn't quite double that of lead acid gel cell / SLA batteries. (In wh/kg its right a bit more than double --- 30wh/kg vs 70wh/kg, but lead acid batteries are quite a bit more dense than NiMH)

Lithium ion has even higher energy density both by volume and weight. The two drawbacks are 1) expensive, and 2) battery voltage varies signficantly during the discharge cycle so you would have to add a DC/DC voltage regulator.

Unless you want to make a big engineering project of it, I'd just go find the NiMH cells that best fit and see if the life is adequate for you.

 

[Web Monkey]

I replaced the battery, but I can't find anything bigger than 7AH that will fit in the case. It's good for somewhere just under an hour before it starts to lose brightness. I never let it go down significantly because the last time I did, it ate a battery (battery never took a charge after that).

I can switch to 35, but I really like the 50, so I think i'll try a battery pack.

Terry

Is this a new 'gel cell' or did it come with the light (used off eBay)? I would expect more than 50 minutes out of it. I get 60 minutes driving a 50 watt bulb with my 5 amp-hour sealed lead acids. Still, you'll want something closer to 10 amp-hours to go for 2 hours, or else you're stuck using a 35W bulb. A bunch of NiMH cells shrinkwraped together seems to be the battery of choice these days.

An alternative would be going to an HID lighthead to get your 2 hours+ out of the battery you have.

-Tiny-B.

 

[pescador775]

Rechargeable lithium ion batteries come in several flavors. The cell with highest energy density is made with cobalt cathodes. Designing a battery is not for amateurs. Incorrect charging or discharge circuits may cause a fire or explosion. I wish I could advise you how to do it as the Li-ion is truly a powerful cell. You will need support from the manufacturer if you decide to do this project.

 

[Web Monkey]

What kind of support would I need?

I've narrowed it down to using 2 10 D-cell packs in parallel for runing the light, and 2 12V LiOn chargers to regarge them seperately.

Thsi should get be 12@20AH, which is about 3x what I have now.

Am I missing something important?

Is there an advantage/disadvantage to having a 10 cell pack with welded tabs, or 10 D cells in battery holders?

Terry

Rechargeable lithium ion batteries come in several flavors. The cell with highest energy density is made with cobalt cathodes. Designing a battery is not for amateurs. Incorrect charging or discharge circuits may cause a fire or explosion. I wish I could advise you how to do it as the Li-ion is truly a powerful cell. You will need support from the manufacturer if you decide to do this project.