My battery boiler and it's true numbers.

[jmacstack]

I'm getting ready to take the coach out on her final journey too Fort Flagler State Park over and up in Washington near Port Townsend. I'm doing some maintenance on her, ie, checking battery water and filling my reserve tank with oil, etc. Once again it got me thinking about my electrical system and the 6 new monster batteries I just installed this summer. In wanting to take good care of them I decided to check out the specs on the current battery charger. Here is what I have and I would like to have a better understanding of what the numbers on it really mean.

Magnatek TU-775-2
120 V 6HZ 14.5 amps
Average Charge Rate: 7.5 amps
12.0 VDC 75 Amps Total
Red Lead, Positive
White Lead, Negative

What exactly do all these numbers mean?

I am leaning towards a Progressive Dynamics..the 80-Amp Converter/Charger.

Is it hard to change the Magnatek to the Progressive Dynamics. Am I going to have to add any wires or connecters? It looks fairly straight forward. There is this funky household looking junction box in front of the battery charger.

I look forward to your input, Jennifer

[jdaniel]

I just bought the Progressive Dynamics 9200 but before I hooked it up, Gordon gave me some info that fixed my charging problem. My Heart inverter/ charger is now working correctly and no longer cooking the batteries. Let me know if you would be interested. jddani@aol.com

[fulltiming]

If that funky looking junction box is about 6" x 8", that is the transfer switch between shore power and generator power.

As to the numbers:
The top line indicates that it uses standard 120 volt 60Hz (likely a typo 6Hz) AC current with a maximum line draw of 14.5 amps. This is 1740 watts maximum draw on your generator or shore power.
The next line, although strangely worded, appears to indicate that it will settle to 7.5 amps charge rate over time as the battery recharges. This is high for a constant charge level or float these days and is the reason that it would eventually boil your batteries.
The last line indicates that at 12.0 volts DC, the maximum amperage flowing to the batteries is 75 amps or 900 watts. Today, most chargers would be rated at 13.4-13.6 volts DC with a maximum charging voltage in excess of 14 volts but this is listed at the old 'nominal voltage' rather than the actual operating voltage which would have to be at least 12.8 volts to actual raise the potential high enough to charge the battery.

At maximum output, this charger uses approximately half of its input power (wattage) to drive the output and the remainder is given off in heat.

Installation is difficult primarily due to limited space, at least in my coach. The red wire is the positive lead, the white wire is the negative lead and the AC cord plugs into the electrical outlet in the bay. Make sure that it is unplugged and the batteries disconnected before removing the red and white (or black on most newer converters) leads since they will be otherwise still capable of delivering the full potential of the battery bank.

[chockwald]

From a true electrical neophyte, it was actually not that difficult. It was more intuitive than I thought it would be. The only thing that gave me pause was the need for 2 grounds. The boiler I took out only had one ground. You will have to buy the stranded heavy gauge wire, because I don't believe the IntelliPower provides the wiring, except for cord that plugs into the electrical outlet. I believe the installation instructions will provide you with the recommended wire gauge to use. I'll take a picture of how mine is set up and post it tomorrow. I have to run by the storage facility tomorrow, anyway.

[chockwald]

Jennifer, here are some pictures of my setup. You will see in the first picture the black and red wire coming out of the front. The red is the "hot" wire, and the black is the first ground wire. The red wire goes up to a junction box seen in picture 2. Picture 3 shows the second ground wire, and picture 4 shows the entire setup, which includes the power cord plugged into the outlet.

[jmacstack]

Thanks for the help! This forum is an amazing resource. I will order a new charger when I get back from Washington and install it myself! Looks fairly straight forward. Thanks for all your help and thanks Clarke for the pics! I think removing the old charger will be more complicated than installing the new one! Thanks again, Jennifer

[chockwald]

Jennifer, the old charger weighs over 25 lbs! It is very, very heavy, and a little difficult to handle as you are trying to pull it out of the bay area. The new one can be held in one hand.

Enjoy the trip to Washington!

[prairieschooner]

wanting to put my 2 cents worth in;
Keep in mind that if you will be doing any Dry Camping that you may want a large output Battery Charger. Our HEART Power Inverter has a 100 Amp DC, 3 Stage Battery Charger. This means that if I watch the Battery Voltage and keep them within the 50%-85% Charge Range I can Charge the House Batteries rapidly (less than an hour) using the AC Generator to power the HEART Inverter.
Here is a link that may help with Battery Charging; http://www.westmarine.com/webapp/wcs/stores/servlet/westadvisor/10001/-1/10001/Battery-Charging.htm

We also have Solar Panels that Charge the House Batteries. I did up-grade the Regulator to a BLUE SKY Solar Boost 2000E: http://www.blueskyenergyinc.com/products/details/solar_boost_2000e/

[Bill N.Y.]

wanting to put my 2 cents worth in;
...This means that if I watch the Battery Voltage and keep them within the 50%-85% Charge Range2 more cents to add to this... a 50% state of charge is NOT 6 volts. Too many times people mistake this and I wanted to clarify it.

When dry camping, fire up your generator when your batteries are between 85% and 50%. Checking the state of charge actually involves using a hydrometer... but in the real word, using the voltage will get you close enough.

Also, technically you should use the voltage rule only after the batteries have been left uncharged or draining with a load for a minimum of an hour or more as a battery will tend to recover some of its lost voltage. I've found that when the voltage reads 50% or 12.2v, by letting it sit, it will recover to around 60-65% or about 12.3v without doing anything.

Yes... that's right... 1/10 of a volt separates 13% more of a state of charge.http://www.newellclassic.com/forum/images/icons/icon4.gif

Percentage of Charge Chart

http://www.luxurycoachlifestyle.com/attachments/photobucket/img_6455_1_e186d2fd6bd75cfb15cea8986fea6ee7.png

[prairieschooner]

thanks Bill, good clarification. Proper Charging and Discharging of the Batteries will result in longer Battery Life.