BATTERIES

This is a good place to ask..........the last charger that i bought was a 6 volt 12 volt, 2 amp, 10 amp, and 55 amp starter..........if i run my golf cart 6 volts  down a ways...can i hit them with the 55 amp, then the 10 amp, and then 2 amp to finish off the charge........

will the 55 amp setting be to much for charging purposes???..........i always keep a close eye on the batteries while charging....

thanks a lot Ray for the lesson........

digiacomo...

The charger you mentioned is basically a light duty, 10 amp, 12 volt charger...that 55 amp 'starting' setting is usually meant to be used for a limited time to give a dead battery a 'boost' so you can get a vehicle started - not for bench charging over a long period of time - check the charger's owner's manual...

This kind of light duty charger won't actually charge for long at the 10 amp rate - check the ammeter on the charger when you hook it up to a battery, and you'll usually see that it will move fairly rapidly down the amp scale to a lower rate - and usually down to 2 amps or below as the battery approaches about 80% charged - the 'finishing' charge can take a long time at this low rating...

We use a 6 amp charger for most of our recharger needs in our shop - difference is it puts out a constant 6 amps, without tapering off!  We can hook up to nine 12 volt batteries in series and it will pump a constant 6 amps into each one of them - does a great job when left on overnight - fully charged batteris ready to go in the morning!

Ray

Thanks Ray..........your explanation of correct charging is the way that i have always done it..........[with a ten amp or under charger].........

I  have built a battery back up system for my stick house. This link will give you all the info you need to make a determination of which battery you want. http://www.windsun.com/Batteries/Battery_FAQ.htm  I am thinking of a couple of these for my house batteries.

The OPs question was the better of two conditions,, my answere would be a combo of 4 6V batteries to extend his range.>>>Dan

will the 55 amp setting be to much for charging purposes???..........i  always keep a close eye on the batteries while charging....

Click to expand...

Amplifying a bit on what Ray said, your charger won't actually produce 55 Amps for more than a very brief period. In techno-speak, it is a pulse-width modulated signal which means it is 55 amps for a few moment followed by several moments of 0 amps, then repeats.  The average output over an hour will still be 10 amps.  That's to prevent it burning up the electronics and/or melting the small charge wires to the battery. Those dinky wires and small clamps won't handle a 55 amp load for more than a few seconds at a time.

Just checking to see if I got "it"... the short form I can remember, I hope.

If you have 4 GC2 house batteries, you have a an advertised capacity of about 420+ amp-hr.  If "fully charged"... 13.3 to 13.4 VDC and the charger "floating"; you have about 200 amp-hr available at a 10-12 amp rate which is a few lights, 2-3 hours of TV and a furnace blower if it is not too cold for 12-13 hours.  The voltage after this better not be below about 11.2 to 11.4 VDC.  The next morning, unless you have a big solar array, it's genny time until the charger gets to "float" mode for at least 30 minutes or so.  When you turn off the genny, the voltage ought to be back to the 13.3 to 13.4 level.  Do this 6-10 times and expect to add some distilled water.  Somewhere in this sequence, the charger will do a conditioning cycle and take longer than usual to charge.

Is that reasonable?

http://www.usbattery.com/usb_solar_renewable_energy_p2.html Try a couple of these.

L-16's are a great alternative - same footprint as golf cart batteries, but significantly higher capacity. Some coach manufacturers are installing L-16s on their new models. One caveat - they're heavy, and they're also taller.

Here's a VOLTAGE CHART that I carry around with me to refer to when asked questions about using VOLTAGE as a guide to determine the state of charge of one's battery system...

Keep in mind that VOLTAGE can only be used in this manner if the battery system has been at 'rest' (no charging or discharging) for some time to allow the batteries to stabilize, and with recent charging, to allow the battery plate 'surface charge' to thoroughly penetrate all the porous, nooks and crannies of the plates... It also allows the battery fluid (electrolyte) to be thoroughly mixed again as it becomes 'more acidic' during the charging process and migrates evenly around the plates - there's lots of 'chemistry' going on inside those 'electron containers' we call batteries!

I like to let the batteries 'rest' a few hours, or over night at best...

The voltages shown below would be at the battery terminals for the most accurate readings - this being impractical for most of us, you could also read at the battery cables where they attach to your fuse panel to get a usable reading...if you measure at a 12 volt receptacle, the readings you get may be slightly 'less' due to increased resistance in the size and length of the wires from the batteries all the way to your measuring point...

VOLTAGE CHART

16.00 - Equalizing
14.36 - Gassing
13.46 - Float
12.78 - 100%
12.48 - 75%
12.16 - 50%
11.96 - 25%

As you can see, there is very little difference in voltage between 100% and 50%, so an accurate digital voltmeter is required to use this method of determining state of charge of your system...

I've installed a 'Volt Minder' that I got from BestConverter.com, about $25 as I remember...The digital meter on the 'Minder' has large numerals (xx.xx) and is east to read...I installed it with the leads attached to the battery cables at the fuse panel, and mounted the meter nearby...the Volt Minder has a low voltage 'alarm' that you can set yourself to remind you that your battery system needs charging - neat gadget!  The VM does 'draw' a very small amount of current while hooked up, so you may wish to add a switch, or unplug it when your RV is in storage...

Ray
 

Ray, are those no load voltages? If so, since our batteries are always under some load, is voltage even useful for measuring SOC?

taoshum said:

Just checking to see if I got "it"... the short form I can remember, I hope.

If you have 4 GC2 house batteries, you have a an advertised capacity of about 420+ amp-hr.  If "fully charged"... 13.3 to 13.4 VDC and the charger "floating"; you have about 200 amp-hr available at a 10-12 amp rate which is a few lights, 2-3 hours of TV and a furnace blower if it is not too cold for 12-13 hours.  The voltage after this better not be below about 11.2 to 11.4 VDC.  The next morning, unless you have a big solar array, it's genny time until the charger gets to "float" mode for at least 30 minutes or so.  When you turn off the genny, the voltage ought to be back to the 13.3 to 13.4 level.  Do this 6-10 times and expect to add some distilled water.  Somewhere in this sequence, the charger will do a conditioning cycle and take longer than usual to charge.

Is that reasonable?

Click to expand...

I guess NOT. The voltage in the morning better be 11.8 to 11.9 VDC? or I'm below 25%?  Actually if I press the battery voltage display button, it better be 12.1 or higher if I want to stay above 50%!!!  BTW, if I'm using the batteries every night, I cannot let them "stabalize" overnight to get a reading, so now I don't have a clue.

Ned, the VOLTAGE CHART would reflect battery voltage with no load - and yes there might be some 'load' on all battery systems, but with lights off, no water pump running, etc., this method could be considered a 'guide' to the SOC of the battery system...

Sure it isn't full proof, by any means, but since most RV mfg's install some kind of a volt meter near the distribution center, it may be helpful to have a guide to correlate the meter's reading into a sort of State of Charge, so to speak...

Regarding questions about accurate readings and the state of 'rest' of the battery system - I know it isn't practicable to let the batteries just 'sit' overnight - you have to use em'...Just be aware that if the charger's been running, the voltage on your meter will read 'higher' than the 'at rest' voltage, and you'll have to 'swag' the reading...Same for the system that's been under heavy use (load) - the voltage will read 'lower', and you'll notice the voltage rise as the system rests...

Ray

Ray, thanks for the explanation.  With everything turned off, except my inverter, there is still about a 10A load on my batteries.  We shut the inverter off overnight when boondocking as a result.  We have Link 1000 so are always aware of exactly how many AH we've used, so the voltage is only of mild interest for us, but for others it should help.  Any serious boondocker should have something like the Link monitor to track AH usage and not rely on voltage for SOC of their batteries.

do you have a link to the Link Monitor?  Does it use an amp or so too?  Amp meters are usually in series with the circuit or use a CVR and amp.

Here's a link to the Xantrex Link 1000 page.  It uses very little power, just enough to light the LED display and even that can be turned off.  I leave it on all the time.  It uses a large shunt for the ammeter and AH measurements.

Here's a link to a good after market solution.

[quote author=Ned]With everything turned off, except my inverter, there is still about a 10A load on my batteries.[/quote]

That comment had me curious, so I just went to the boat and checked things out. With "everything off except the inverter", the battery draw is zero, or at least below the 0.1A resolution of the Link 2000. This is with a Heart Freedom 3000 inverter. Of course, as I turn on (110V) lights, refrigerators, freezers, and other appliances, the load goes up accordingly.

I just checked the Xantrex specs for their current (no pun) equivalent/replacement for the Heart Freedom 3000, now called the Freedom Marine 30. They show "No load current draw (idle mode)  0.12 A". My sanity was restored, but I'm wondering where the additional 9.8A is going from your batteries.

FWIW I've never turned the inverter off while boondocking, either in the coach or on our boat, nor do I turn off any appliances. I have more & larger loads on the boat, but I also have more battery capacity (1100AH on the boat and 440AH on the coach). Usually, we have 2 TVs running well into the wee hours, and I usually have a latop running most or all night. I can only recall a couple of nights in the coach where the battery voltage fell "too low".

Methinks I'll do a little research next time we're boondocking with friends, either on land or on the water. I'm curious whether anyone else is seeing a 10A quiescent current draw.

Been using the Link 2000 for 10 years, and the Link 1000 for 5 years prior to that. I reached the point where I was able to eyeball the voltage, and that's usually a good enough indication for state of charge. It's certainly good enough to tell me when I need to turn the generator on or can turn it off. I often forget or don't bother to reset the AH in the Link after recharging. Another calibration for me ... Chris likes a cup of tea in bed early in the morning; So, when I turn on the electric kettle, I peek at the battery voltage.

That 10A includes some things that could be turned off, but not conveniently.  This includes the DirecTV DVR, microwave, home theater in standby, video switch, etc.  If I turn off the inverter, the load drops to <1A as expected.

Ah, so "everything turned off except the inverter" doesn't mean what it says. Makes more sense now.

BTW I didn't turn the inverter off to read the low quiescent current; I merely turned 110V breakers off individually on the panel, leaving the inverter turned on with no load. The quiescent current is so low (on the Link display) that it doesn't change when I turn the inverter off.