Novakane 

I'm building up (still, yes... I know... it's been *years*) my halogen geek light and it's almost ready to go. It's mainly for suburban riding with street lighting and I'm just looking to fill in the darker spots between street lights or back pathways.

I'm running 2x 7.2v 2000mAh in parallel which gives me about an hour and a half of decent light for this purpose. I've been looking into getting a second pair of these battery packs (they're ni-cd cells for R/C cars) with the intent of running two packs of two in parallel (for 14.4v and super bright light) - but I've been finding they're not as cheap at the moment as the clearance deal I got them at before.

Yada, yada... I've been looking at alternatives and came across something like this for the same price as 1 of my R/C packs: https://batterysolutionsinc.com/index...oducts_id=7528

It's a 12v 5000mAh battery. It weights 4.25 lbs which is pretty hefty, but I ride with big packages of cat litter sometimes from the store so a few extra pounds doesn't intimidate me too much. I would need to find a charger as well.

So my two questions are - has anyone tried one of these, and how do the sealed lead-acid batteries perform compared to ni-cd?

jbabic

I've used much larger SLA batteries for my lighting. The AH rating you need will depend on your wattage and burn-time requirements. Chargers are as plentiful and cheap as a car or motorcycle charger from Sears though technically one could do better.

SLA are a proven and established technology. Most folks go for a lighter weight to power ratio these days. If that's of less concern to you, the SLA route will work fine.

Novakane 

Thanks, I'm looking at sla since the volts/amps is more bang for the buck. I've got the whole light rig assembled and did a test ride with my ni-cads, but the charge time is ridiculous (5 hours per pack, I have two and probably need 4) compared to run time (1.5hours on low light, 45 minutes on high)... Searching for options, but I need to find a compatible charger.
How dependent on the voltage is a charge for sla? Most of the ones I find seem to be 12v, which is why I was looking at a 12v battery... Can one charge a 14v (for example) sla battery with a 12v charger?

Pepper Grinder

SLA? Ni-Cd? They still make that?

It's 2010, my friend, and you're still building an SLA/Halogen system? Get with the times - lithium-ion/LED all night long.

Novakane 

I understand what you're saying but I've already got a working halogen system that just needs a power source upgrade. I'm in no rush to go start buying cree's, optics, voltage regulators and heatsinks and spend further time rebuilding what already works. Thanks for the suggestion, but it's not practical at the moment.

jbabic

Hee hee; holy wars are amusing. Don't road bars offer more hand positions than flat bars?

Each chemistry has it's merits. NiCds offer twice as many charge cycles as NiMH, and at less cost and less risk of fire than Lithium. SLA is a good bang for the buck. It's the electrical storage chemistry of choice for many, many applications. Cars still use 'em...

I hear what you're sayin' but, halogen puts out. I have a question for you - have you done a side-by-side comparison of a good halogen with your best LED? Readily available halogen beats specialty LED dollar for dollar (I'm talkin' your nearest Wal Mart or local car parts store - simple 55w MR16 driving lights <$15/pair).

I switched from halogen to LED last year to cut back on some weight. That halogen setup was bright but heavy. There's a post on it in here somewhere - look it up for a good laugh.

Get a good electric multimeter and measure the charger and the battery both while charging and not charging. You'll be surprised at what you see.

There are charger circuits designed specifically for each chemistry. I advise against charging SLA with a NiCd charger. Remember, SLA chargers are cheap and readily available.

Somewhere I read fast charging of most any storage chemistry can impact a battery's life - particularly NiCd & NiMh, though these chemistries work well when they are fully discharged, as can happen while out riding. Lithium can start a particularly nasty fire if charged too hot. It's such a hazard that special methods were developed to guard against these fires. It is my understanding SLA is more tolerant of high charge & discharge rates but don't do well under deep discharge cycles. In that sense, be sure to choose your SLA capacity to not deplete itself for your expected use, plus some. That's what amp-hour ratings are for. Keep in mind temperature affects all this too.

It's my understanding a 12V SLA battery is topped off at 13.8V. At this point a good charger will apply a trickle charge appropriate to the size of the battery so it stays topped without cooking it.

I hope this helps your search. Sorry I didn't get back to you sooner.