Topic: What options do I have for charging SLAs at a festival?

[Bdifr78]

Hey everybody,

I am going to All Good Festival in a few weeks and have a slight problem.  There is only one real stage(there is another stage with local acts that I might only want to see 1 or 2 acts), so I plan on setting up in the morning, and staying put till the headliner ends each night.  Which would probably be about 12-15 hours of taping each day. 

I have 2 12V 7.2AH SLAs, with leegeddy's VR box I can run my rig for about 10.5 hours off of each battery.  So that would safely give me only 20 hours of taping.  Not near enough to tape almost the entire festival. 

So I am wondering what my best options are.  I have read that some people schmooze the vendors and ask to plug into there generators, but I don't think I will have the time to do that with how long it takes to recharge these SLAs.  So what should I do.  I could always buy a couple more SLAs, but would like to find another alternative.

Is there a way to charge 12V SLAs off of a car battery?

Any input would be great.  Thanks,
Joe

[Sanjay]

[tms]

Hey everybody,

I am going to All Good Festival in a few weeks and have a slight problem.  There is only one real stage(there is another stage with local acts that I might only want to see 1 or 2 acts), so I plan on setting up in the morning, and staying put till the headliner ends each night.  Which would probably be about 12-15 hours of taping each day. 

I have 2 12V 7.2AH SLAs, with leegeddy's VR box I can run my rig for about 10.5 hours off of each battery.  So that would safely give me only 20 hours of taping.  Not near enough to tape almost the entire festival. 

So I am wondering what my best options are.  I have read that some people schmooze the vendors and ask to plug into there generators, but I don't think I will have the time to do that with how long it takes to recharge these SLAs.  So what should I do.  I could always buy a couple more SLAs, but would like to find another alternative.

Is there a way to charge 12V SLAs off of a car battery?

Any input would be great.  Thanks,
Joe

I need to do the same thing, here's what I'm thinking. Make a jumper to plug into the cig lighter and your battery.  It should charge at the same voltage as your car battery,  14-15 V.  Just don't hook it up backwards. The tip of the cig lighter plug is '+', hook that to the '+' terminal on the battery.

The only thing that might be bad is if the car tries to charge it too fast, check the temp of the battery from time to time to make sure it's not getting too warm.

Also, if you're worried about charging it too fast put in a smaller fuse (10A) for the cig lighter.  You're 7.2Ahr sla would love to be charged at 10A intitially, a bigger fuse wouldn't hurt it either.   

If the initial amperage does turn out to be too high and blows the 10A fuse, I'm thinking of using a car headlamp or maybe a 12V light bulb in series to restrict the amps.  It will dim and lose resistance as the battery charges and the amps drop, self regulating.

I wouldn't use a jumper cable direct to the battery.

[Brian Skalinder]

Which would probably be about 12-15 hours of taping each day.

I have 2 12V 7.2AH SLAs, with leegeddy's VR box I can run my rig for about 10.5 hours off of each battery. So that would safely give me only 20 hours of taping. Not near enough to tape almost the entire festival.

So I am wondering what my best options are. I have read that some people schmooze the vendors and ask to plug into there generators, but I don't think I will have the time to do that with how long it takes to recharge these SLAs.

How long does it take to re-charge the SLAs?  Here's what I've done in the past:

[1] show up with the SLAs fully charged
[2] run SLA-1 til it gets low, ~9-10 hrs
[3] switch to SLA-2 for the rest of the day (~5 hrs max) and...
[4] ...immediately start charging SLA-1 at a vendor and let it charge - in full - overnight
[5] re-start the next morning with SLA-1 while you...
[6] ...recharge SLA-2 - since you only used ~5 hrs capacity, SLA-2 should re-charge before SLA-1 runs out again in ~10 hrs

This may not work if you have a painfully slow charge cycle, but otherwise, oughta do the trick.

[bhtoque]

What Brian said is the way I do it.

Couple other points:

1. check the mA rating of your charger. If it is less than 800 you won't have enough time to fully recharge.

2. A plastic project box for 8AA's is a light, small way to make sure you've got an extra power source.

3. If you have not done so already, make some Y power cables so you can hot swap your power.

JAson

[ethan]

Is there a way to charge 12V SLAs off of a car battery?

I've charged batteries using a power inverter (usually while driving between shows though) powered from my cars cigarette lighter. Although I don't recomend this as running the power inverter for extended periods WILL drain your car battery if the car's not running.

-e

[SonicSound]

Save an outlet for me at All Good

Just got tubes and they love power

[Weirdness]

I have had no success whatsoever with charging 12V batteries off of a power inverter.  6V-No problem, but the 12's don't seem to want to charge off another 12V battery. 

What will likely work though is if you pick up a solar panel designed to keep a car battery charged.  Even on an overcast day, the one that I picked up will give my battery enough juice to start up if the car stereo kills it or whatever.  I'm sure that it would charge an SLA no problemo.  No idea how much time it would take though, but you could always test that out.  All that being said though, you can likely pick up another beefy SLA for a similar cost..

[Fatah Ruark (aka MIKE B)]

Well, the last time I was worried about running out of power, I just bought another 12V / 7Ah battery. They have them here at my local hardware store for about $20.

You can never have too much power.

MIKE B

[dgodwin]

Well, the last time I was worried about running out of power, I just bought another 12V / 7Ah battery. They have them here at my local hardware store for about $20.

You can never have too much power.

MIKE B

honestly.. that's what I was thinking.  Another SLA battery is probably cheaper than any other portable recharging option (solar, inverter, generator, etc)   Even an 8 cell D or AA battery pack would run you close to the price of another SLA battery, and would probably be better for the environment in the long term.

[Bdifr78]

Well, the last time I was worried about running out of power, I just bought another 12V / 7Ah battery. They have them here at my local hardware store for about $20.

You can never have too much power.

MIKE B

This is probably what I will end up doing

honestly.. that's what I was thinking.  Another SLA battery is probably cheaper than any other portable recharging option (solar, inverter, generator, etc)   Even an 8 cell D or AA battery pack would run you close to the price of another SLA battery, and would probably be better for the environment in the long term.

[tms]

I have had no success whatsoever with charging 12V batteries off of a power inverter.  6V-No problem, but the 12's don't seem to want to charge off another 12V battery. 

What will likely work though is if you pick up a solar panel designed to keep a car battery charged.  Even on an overcast day, the one that I picked up will give my battery enough juice to start up if the car stereo kills it or whatever.  I'm sure that it would charge an SLA no problemo.  No idea how much time it would take though, but you could always test that out.  All that being said though, you can likely pick up another beefy SLA for a similar cost..

That would be awesome, but they don't put out enough mA unless you get a really big one.

[tms]

Well, the last time I was worried about running out of power, I just bought another 12V / 7Ah battery. They have them here at my local hardware store for about $20.

You can never have too much power.

MIKE B

honestly.. that's what I was thinking.  Another SLA battery is probably cheaper than any other portable recharging option (solar, inverter, generator, etc)   Even an 8 cell D or AA battery pack would run you close to the price of another SLA battery, and would probably be better for the environment in the long term.

You know the cool thing about D cells is that they have a buttload of amps.  Typical Duracell D cell is rated at 18,000 mA-hr.  It's unbelievable the jump from C cell to D cell.  C's are like 7,000 mA-hr.  That means a pack of 8 D cells can put out a full amp for 18 hours at 12V. Un-frikin-real.

[tms]

Save an outlet for me at All Good

Just got tubes and they love power

I've got a tape of Del McCoury archive.org, that fest sounds like a blast!  Have fun!

[leegeddy]

Typical Duracell D cell is rated at 18,000 mA-hr.  It's unbelievable the jump from C cell to D cell.  C's are like 7,000 mA-hr.  That means a pack of 8 D cells can put out a full amp for 18 hours at 12V. Un-frikin-real.

todd;
i would doubt that eight D cells could maintain that duration, but D cells are beefy indeed.

marc

[Bdifr78]

More SLAs it is! They are cheap enough. I can keep a few in the trunk of the car and never have to worry about not having enough power.

[tms]

Typical Duracell D cell is rated at 18,000 mA-hr.  It's unbelievable the jump from C cell to D cell.  C's are like 7,000 mA-hr.  That means a pack of 8 D cells can put out a full amp for 18 hours at 12V. Un-frikin-real.

todd;
i would doubt that eight D cells could maintain that duration, but D cells are beefy indeed.

marc

Seriously, that's the rating on a normal decent (duracell, energizer)  D cell.  18 A-hr.  You get a lot of bang for the buck on them.  Check it out.

Back on this topic, it looks like the way to go is just pick up another SLA or two, I'm headed back to the battery store myself.