Maha MH-C9000, 12v, or 16.9v Solar?

[hamlet]

I was wondering if anybody knows if the Maha will tolerate a 16.9/4.4A input from a BP275 solar panel? I'd like a charger that I could operate direct from my 75w P.V. panel. I see from the Maha website that the car charging accessory cord is rated 12-24v, but, that isn't conclusive...

http://www.mahaenergy.com/store/viewItem.asp?idProduct=134&cur=specs#mid

I'm also considering using this model, as it accepts 12v/24v:

http://www.batteryjunction.com/8800.html

Anybody have ideas on other options/chargers that I could use directly from a 16.9v charging source?

Thanks,
Hamlet

 

[Mr Happy]

Are you planning for the apocalypse or something?

The BP275 can output up to 20 V or more, and the C9000 says "Input DC 12 V" on its rating plate. I don't know that I would risk connecting them without a voltage regulator in between.

I imagine a charger that accepts input up to 24 V would be fine though.

 

[hamlet]

Okay, then, does anybody here know of, or can speak for, a good dual voltage (12v-24v) travel-charger that doesn't require mains power?

A caveman would have killed for a good flashlight...

http://www.dieoff.org/page224.htm

Hamlet

 

[Russel]

The voltage from the solar panel will drop some when a load is applied, but I wouldn't connect the MH-C9000 to it directly.

Why, may I ask, do you want to connect directly to the solar panel?

Considering that the panel is 75 watts, a deep cycle group 31 lead acid battery and a charge controller would allow you to connect the charger to the battery as well as store a fair amount of power in the battery for use any time you need. You would be able to make better use of your solar panel.

The other charger (12v to 24v) may be worth considering if you have to connect directly. But I still think you would be better off with a battery and charge controller.

Russ (and my $0.02)

 

[Mr Happy]

Russel speaks the truth. When you want to live "off the grid", you run a 12 V accumulator as a central power source and charge it from solar energy (and/or wind/water power as your situation allows), and then you reduce to the minimum the number of devices that absolutely must be powered by electricity and run them off that 12 V supply.

 

[hamlet]

I don't want to charge any PbSO4 accumulators.
Just a few AA cells once or twice per day. My guess
is the upper limit on 12v chargers is 16v, so perhaps
an LM338 is in order.

Hamlet

 

[gregpack]

What if you tied in a small gell cell/AGM battery in as a buffer/regulator between the two? Those inexpensive booster packs you get at walmart usually have 12-18 amphr batteries in them. Just a thought.....

 

[jhellwig]

Well judging buy this statement:

I don't want to charge any PbSO4 accumulators.

A "car battery" is not what he wants.

 

[Russel]

During the week I've been charging Eneloop AAs as required for daily use. Now that I have a MH-C9000, I decided to run four AA cells through the break in cycle on the MH-C9000 every weekend until I run through my complete inventory. I start a 500ma discharge Friday evening about 6:00pm, then around 10pm, when the discharge is complete, I set the charger for break in mode. The cells are done Sunday afternoon. I've been powering the charger with a UPS so I don't have to worry about a power interuption during the long break in cycle. Then, thinking about this thread, I decided to run the charger off of a solar power system. I've got a 50 watt solar panel connected through a charge controller to a Optima deep cycle battery. The charge controller is older, so it only switches on or off, on at 13.2 volts, off at 14.2 volts. So, I connected the Maha charger to the battery using the cigarette adapter made for the charger, set it to charge some cells, and watched carefully. I confirmed with a Fluke meter that the solar charge controller was in fact switching at 13.2 and 14.2 volts. The charger worked flawlessly. So, I tried a break in cycle with the charger connected to the solar system, monitored the voltage, 13.2 to 14.2 the charger worked flawlessly. Also, just out of curiosity, I got up at 5:30am to check the battery voltage before sunrise, after the charger had been running on the system all night, and measured 12.65 volts at the battery. So, it appears that the charger does in fact work well with a slightly fluxuating 12v power source with out any problem.

Has anyone had problems powering the MH-C9000 from a car battery?

Russ

 

[Closet_Flashaholic]

I decided to run the charger off of a solar power system. I've got a 50 watt solar panel connected through a charge controller to a Optima deep cycle battery. The charge controller is older, so it only switches on or off, on at 13.2 volts, off at 14.2 volts. So, I connected the Maha charger to the battery using the cigarette adapter made for the charger, set it to charge some cells, and watched carefully. Russ

+1
This is the setup that I will eventually use also. Any charger, but in particular Micro-controller-based ones (like the '9000) depend on a reliable input voltage. It can't be "bouncing around" too much, otherwise the CPU's watchdog timer will reset it (just like an initial power-on sequence does). It has to. Solar panel outputs vary 0-max voltage depending on sun intensity, even a brief period of a cloud obscuring the sun, or someone walking in front of the panel would likely drop the voltage and trigger a reset of the charger.

You absolutely need some type of temporary buffer storage to smooth out the brief interruptions. So a small gel-cell might do it. An alternative that I have been looking into is super-capacitors (1-5 Farads @ 12v) Some of the car stereo systems use the same concept to deliver short bursts of high-current when a bass note requires several hundred-amps of current for brief periods of time. You will pay a lot for a capacitor like this (USD 75+), but it should last a lifetime and no acid to worry about.

The advantage of the gel-cel is that you would be able to charge the cells at night (no sun) as well, as long as you size it (in terms of capacity) correctly.