Unusual Battery Charging System

[Bucephalus]

I'm going to be going into rural Nepal for 8 months starting this winter. I would like to be able to take pictures for this time. However, there will be no electricity. I've got a nikon coolpix 4500, which uses a Li-ion rechargeable battery (#EN-EL1) which is 7.4V / 680mA. The proprietary charger (MH-53) takes AC at 100-240V and outputs DC 8.4V / 600mA. The MH-53 supplies only a slightly greater power than the EN-EL1 (5.04W vs. 5.032W)

Anyway, I'd like to design a system whereby I can either simulate a source for the MH-53 and use it to charge batteries, or design a charger which is suitable for the EN-EL1. Frankly, I have no idea which is more practical. I also assume a solar generator will be superior to a mechanical one in this case, though I'm not sure. Ideas?

[laskey]

I say take a 10watt solar panel with you, and build a charge controller that limits your charging voltage to the 8.4 volts your current charger puts out.  

Heck, you could probably buy one of those new folding solar panels that has it own regulator built in.

Cya,

Chris

[Norm]

  It would be a simple solution if you had a camera that uses 4 AA NiCad batteries a couple of those patio solar cell lights...a couple of external battery holders and a set could be charging....at least that's one of my future plans with my camera and a couple of our solar cells lights.

                      ( :>) Norm.

   Have a nice trip!

[Xavy]

I just posted a new topic subject Inexpensive Power Inverter charger which may help.  Perhaps you could obtain a UPS and then ship a deep cycle battery(s) to your new location.  Leave the power cord unused and connect a solar pannel to the battery.  Contact ICP Global with your requirements and they will suggest an appropriate solar pannel to match.  This should allow you 120VAC for several small appliances in bright sun and allow you to meet your needs of charging using the same equipment you use here in the states.

[deerslayer660]

  I would not ues the ups 120vac to power a battery charger as this will more than likely distroy the charger for the camera. lots of previous posts about inverters and chargers disasters.  i would use a radio shack power adapter that goes into car cigerate lighter set at 9vdc to charge battery car schould not need be runing and this small amount of wat drain to charge bat car will start ok  kc8nwn

[Bucephalus]

Is it necessary that if I use this method I somehow have to regulate the current to .6A as is the case w/ the household charger, or is the voltage at 8.4V all that is required (Can a charge controller regulate both?) Though, I guess the current diminishes naturally at a held voltage as the V-drop between the charger and the battery gets smaller. I guess I'm asking, is there an upper or lower limit to the power that the charger can supply (w/o changing it's voltage) that I'd have to adhere to in order to not damage the battery?

Also, I've never built a charge controller, but would probably be able to with directions. I found http://homepower.com/files/pvcontrol.pdf, which seems to be something, but I have no idea about how to customize the plan so that it would put out .6A at 8.4V with a fluctuating solar source. Is this possible?

[wooferhound]

You would regulate the current by obtaining a Solar Panel with a rated output of .6 amps or so, and then using a simple LM317 voltage regulater for the voltage.

[Bucephalus]

Are solar panels generally able to supply a near constant current, or does the charging current not matter too much (so long as it is within a reasonable range)? Is this sort of battery sensitive to the point where I'd have to build a current regulator (like the one detailed at http://www.national.com/ds/LM/LM138.pdf on page 12) to keep at .6A?

[tecker]

   First you need some numbers to work with and of coarse more batts cameras are amp suckers . Condition a set and ( completelly discharge them ) as would the charger would

then charge em up and see how long your charge time is . I think they can take a little

abuse there, so Your charger can be slightly stronger . Take the time line and set up a solar charge cycle based on the a 2 volts over rated battery voltage at 1 amp or so .

Useing a solar charger is the most portable option but the you are going to need to see if the solar cycle will do the trick without tracking (or moving) to top of the batts.

If you want to make up a charger from scratch consider a auto cig plug in with variable voltage most of those  have a  regulator that will cover 9 volts and add a zenor to light up an led  when charging is done .  

[brandy]

Hi

I have the same camera and have been thinking about the same problem.

I think there are several things to consider here:

• do you want to charge the battery while on the move, trekking
  
• do you need a solar panel just for the camera battery or for other uses
  
• can you carry a bigger 12V battery with you
  
• how about a dummy battery insert like Nikon use on the CP3500 series
  
• is there a risk of the gear being stolen
  
  

I'll be interested to see what are your conclusions. Please inform.

[Xavy]

I found a company for flexable, portable PV pannels you may find handy.  Check out this link to the product.  http://debateusa.com/debate/viewtopic.php?t=1464

[Nando]

Bucephalus:

Send to me an email next week to assist you in setting and solving your problem and at the same time to have night lighting.

nando37 -at- comcast -dot- net

Regards

Nando

[Bucephalus]

Just to give an update, I think I've decided to try and imitate the circuit here. However, I still have a while to complete the project and would welcome other ideas. I also assume that a typical perf/breadboard would be best to construct something like this on? In the end, I think I'll have a contained system in a briefcase, with the panel on one side and a circuit (or more) on the other, for charging the battery(s).

Also, with respect to those things to think about:

(1) I will probably not need to charge the battery while moving (which certainly eliminates some of the design problems...)

(2) It is possible that I will want to, say, have the panel be able to charge simple 1.5v AA's, but that should be pretty easy to do.

(3) There is no way that I'll be able to bring a typical, bulky, 12v battery (unless it is in an odd form which can fit in the case--I hope to have everything self-contained)

(4) Frankly, I don't know how this really relates to anything, so I must be missing something.

(5) As with anything, yes, but I don't think it's significant -- I'll usually have any valuables close to my person.

Have you thought about another solution? You can email me [geoffgalgon at earthlink dot net]

[ghurd]

How did this work out?

[PV Power]

Too bad I didn't find out about this forum before today.

I have a few surplus 6" X 10.75" encapsulated 18 cell panels designed to charge an outdoor light battery.

OCV is about 10.5 volts. Rated current is 150mA @ 7.2 VDC but I have seen output of over 200 mA into a 7.2 volt RC car battery.

One of those would have worked perfectly. It would trickle charge an 8.4 volt camera battery without risk of overcharge.

Bob