Charging a 12 Volt Battery

Post by **Elderberry** » Sat Aug 22, 2009 10:03 pm

I have several 12 Volt (deep cycle I think you call them) batteries I was thinking about bringing to the playa. I am also bringing a generator that has a 12 volt receptical for charging batteries.

I was thinking I could use the generator to charge the batteries during the day and then use the batteries to power lights in the evening to cut down on noise.

So, my question is...how long do I need to leave a battery connected to charge it? Can you leave a battery connected too long and blow it up?

Thanks,

JK

oneeyeddick · Post by **oneeyeddick** » Sat Aug 22, 2009 10:07 pm

If you are running it anyhow, you are better off with regular charger that has an auto-off on it.
Plus, the guege will tell you how much more it needs or not.

Most of those gennies put out 8 amps, which can damage your batteies if left on too long.

akmojo · Post by **akmojo** » Sat Aug 22, 2009 10:21 pm

you want to get an inverter to convert your 12v dc to ac.. depending on how many watts you plan to use will determine how large ie, 1000w.. 2,500w.. etc
real nice ones are sine wave which work better with electronics...
I believe you can hook your generator to an inverter and leads to your batteries .. then use the ac plugs on the inverter and it should also charge your batteries...

oneeyeddick · Post by **oneeyeddick** » Sat Aug 22, 2009 10:36 pm

that makes no sense what-so-ever

Ugly Dougly · Post by **Ugly Dougly** » Sat Aug 22, 2009 10:39 pm

I used to understand magic, now I have a collidge degree.

ygmir · Post by **ygmir** » Sat Aug 22, 2009 10:51 pm

yup, I agree, use an automatic charger on the A/C side.....they are cheap, and, won't overcharge the battery.

you can't know how long it'll take unless you know how much power you used on that "cycle"........but, it'd probably be hours, not minutes, if you are running things off them all night.....

Mr.? · Post by **Mr.?** » Sat Aug 22, 2009 10:53 pm

I've been using deep cycle batteries for the last four years on the playa. I can probably answer your questions, but first off I need to know more about your charger.
Charge cycles vary depending on what type of charge you want to do. Most chargers have different measurements for charging, which are rated by amps. A real heavy fast charge is 30 or more amps, while a slower more filling charge is 2 amp charge. Once again most battery chargers have settings where you can set it at a fast charge, and when it reaches a high level of charge it automatically slows down to a trickle charge. If your generator doesn't have these settings read the manual and let me know what it says.
How many AH does your deep cycle have? How many watt inverter are you using? What is this generator you speak of?
You can always go to Sears and purchase a new charger for $50 that will charge your battery much smoother and make it last much longer. I just purchased a new one from Sears last week. They had a sale on them and my old one took a beating last year when someone put it too close to the exhaust of the generator.

motskyroonmatick · Post by **motskyroonmatick** » Sat Aug 22, 2009 10:57 pm

Definitely run a 120v charger off the generator to charge the 12 volt batteries. I have heard that charging off of the 12 volt port on a generator is really slow.

gyre · Post by **gyre** » Sun Aug 23, 2009 12:08 am

akmojo wrote:you want to get an inverter to convert your 12v dc to ac.. depending on how many watts you plan to use will determine how large ie, 1000w.. 2,500w.. etc
real nice ones are sine wave which work better with electronics...
I believe you can hook your generator to an inverter and leads to your batteries .. then use the ac plugs on the inverter and it should also charge your batteries...

I think you're thinking of an inverter/charger.
Standard on many rvs.
Not all inverters are made this way.

rodiponer · Post by **rodiponer** » Sun Aug 23, 2009 12:37 am

Have you guys ever charged a small 12 volt battery by connecting it directly to a larger one?

I have a small 12 volt AGM battery that's about the size of a can of beer. It's 10 amp/hours, and will be used to power bicycle lighting...

My pop-top camper van has a much larger AGM battery that will be charged with solar panels.

I hate to run my inverter to charge the small battery, since it's so inefficient and would need to run for hours. What do you think of charging it by directly connecting it to the larger battery?

CaptainNemoOfTheNautilusX · Post by **CaptainNemoOfTheNautilusX** » Sun Aug 23, 2009 12:49 am

We use a standard battery charger we got at radio shack and it works fine and hasn't over charge the deep cycle its connected to. One word of warning most A/C battery chargers have small fans that suck in all sorts of dust on the playa. I recommend having some compressed air on hand to clean it out every now and then or it will probably clog that fan and will toast the charger.

akmojo · Post by **akmojo** » Sun Aug 23, 2009 1:13 am

gyre.. you're right and I meant to say hook your inverter into your ac out on the generator and then plug your lights and batteries into the inverter/charger..
length of charge and overcharging are difficult to say but should have more info inc with them or online..?? this would seem to be the type of inverter/charger that would be good for the job..
using a standard auto battery charger, I don't know if it's possible to hook in parallel or if you'd have to charge one at a time.. nowadays most have fast/slow amp rates..
when you said run lights I figured you'd need an inverter/charger type device...

gyre · Post by **gyre** » Sun Aug 23, 2009 1:28 am

rodiponer wrote:Have you guys ever charged a small 12 volt battery by connecting it directly to a larger one?

I have a small 12 volt AGM battery that's about the size of a can of beer. It's 10 amp/hours, and will be used to power bicycle lighting...

My pop-top camper van has a much larger AGM battery that will be charged with solar panels.

I hate to run my inverter to charge the small battery, since it's so inefficient and would need to run for hours. What do you think of charging it by directly connecting it to the larger battery?

I wouldn't do it.
It might work, but it will be hard on the battery at best.

Get a better inverter or a dc-dc charger.

Token · Post by **Token** » Sun Aug 23, 2009 8:48 am

The DC output on a Honda is not the best way to go. It will take five times as long to charge compared to a good 40A battery charger on the AC line.

You cannot charge batteries from one to another of same type and nominal voltage. Batteries have an internal resistance that is balanced. This is what allows batteries to be connected in parallel without discharging through each other.

To do this type of charging you must decouple the batteries with a DC-DC converter. A laptop adapter for the car is an example of this application.

You can also go with a DC to AC inverter then use a regular car charger.

Post by **Elderberry** » Sun Aug 23, 2009 9:27 am

Interesting...and more complicated than I was expecting not knowing much about batteries or generators. Let me give you some additional information and maybe it will make it easier to advise.

If any of you are familiar with the company American Power Supply (APC), they make emergency back up and power conditioning divices for computers. So if your power goes off, you can either continue running your computers or shut them down gracefully and not risk any damage to the hard drive or other electrical parts.

Well, I have one of these on steroids. Actually the entire unit ways way too much to even lift in its entirety without a fork lift. I used to keep my company servers in the office and needed the backup power to keep an entire rack of servers online in case of a power outage for eight hours.

There is a main device that actually charges the battery banks. That device has one battery and would work by itself for a short period of time and only weighs about 90 lbs or so. Each additional battery bank holds six 12 volt batteries and attaches to the main device.

I actually wanted to take the main device and one bank of batteries and run it off the generator during the day, but the plug on the main device doesn't fit with the generator, or any other normal plug, as it's one of those three plug, twist-in plugs. (I'm sure it has some sort of special name to electricians.)

So, what I was thinking is maybe just taking some of the batteries and then charging them with the generator or maybe now thinking about buying a special charger, and only using it to power 12 volt devices (lights for the yurt mainly), so that I wouldn't have to worry about inverters and such.

Hence, my first question was about charging these on the generator when I found out the generator had a 12 volt charging option, which from above posts, am finding out this probably wouldn't be the best way to go.

The instructions in the manual for the generator are almost useless, as there are no specifications on anything other than "12 Volt DC Recepticle" and a warning to not try to jump-start a car directly from the generator and 8.3 A (which I assume means Amps).

I really appreciate all the input so far.

JK

Token · Post by **Token** » Sun Aug 23, 2009 10:14 am

Sounds like an APC Matrix system.

These are very nice. They put out pure sine wave output.

I would not mess with them by trying to load at the battery terminals. Too many unknowns.

Just get a conversion cable for the locking NEMA plug to a standard household connector that is compatible with your generator.

Then use CFL 120V lights in your shelter. They are ~ 13w each and a couple few should run a long time.

The plug on the APC will have a number on there somewhere like

L5-15
L5-20

Here is a reference chart:

http://www.stayonline.com/reference-nema-locking.aspx

The generator end will be an:

N5-15
N5-20

or somesuch.

You can usually find the correct cable in Home Depot. If not they do have the plugs and sockets for making one.

Sail Man · Post by **Sail Man** » Sun Aug 23, 2009 10:43 am

Or you could go to west marine, buy a guest portable charger and plug it into your gennie. They cost bout 50-60$. It starts out with a higher charge, then automatically drops to a trickle or maintenance charge. They have status lights on them to tell you the state of the charge. I've used in on my last boat with a gel cell, and my current one with a pair of deep cycles and its worked great. No fan to suck shit in. I will be taking mine.

Or, one could go solar as well. I have a 15w ICP panel that I will be using to replenish my camper battery from running lights and the kids/wifes idiot box.

gyre · Post by **gyre** » Sun Aug 23, 2009 10:45 am

Or 12 V cfls.

Ideally parallel batteries should run through big honking diodes on a heat sink.
That prevents cross charging.
Banks should be from the same box and lot number, and company.
Resistance varies.

In the case of an optima, it is extremely low.
They charge fast.

Post by **Elderberry** » Sun Aug 23, 2009 12:14 pm

I didn't even think about someone making a converter plug. If I can find the plug that can bridge the APC existing plug to my generator plug, I think that would be my ideal solution.

Yes, it is sine wave--totally scrubbed and clean and voltage regulated power.

I just outgrew my space and had to move all my equipment to a data center and all of that was provided. It just seems a waste to see it all not being used, so hopefully I'll find the conversion plug.

Thanks to everybody that posted on this thread. I really appreciate the help and suggestions.

JK

Post by **Elderberry** » Sun Aug 23, 2009 2:43 pm

Well I just got back from checking the plug on the end of the UPC and it's 30 Amps. The generator will only handle 20 Amps; so I think I'll check out regular chargers and the combo inverter chargers.

JK

Post by **Elderberry** » Sun Aug 23, 2009 3:21 pm

I just opened one of the battery banks and here is all the info on one of the batteries:

12V 75Ah
CSB Battery
GPL 12750
Standby Use 13.5 - 13.8 V
Cycle Use 14.4 - 15V
Initial Current 22.5 Amps Max

JK

gyre · Post by **gyre** » Mon Aug 24, 2009 12:37 am

jkisha wrote:Well I just got back from checking the plug on the end of the UPC and it's 30 Amps. The generator will only handle 20 Amps; so I think I'll check out regular chargers and the combo inverter chargers.

JK

I think that's just the plug rating.
The generator should have a power rating for charging.

Token · Post by **Token** » Mon Aug 24, 2009 10:30 am

JK, the plug on my RV is also rated 30A but I plug into my Honda EU2000 that only produces 13A and it runs just fine.

The plug number is just a rating for maximum capacity.

If you brought all battery banks and the fork lift, then maybe it needs to draw 20 or 30 A.

With just one bank, your Honda will likely be fine for topping off the batteries.

So the plug is likely a L5-30.

Verify fr sure and just get the right parts.

Use the "Easy" button on this.

Kinetik V · Post by **Kinetik V** » Mon Aug 24, 2009 10:50 am

Not to drift the topic too much but I've got a question...actually 2. I've got both a small motorcycle battery (AGM type, 3 AH capacity, 4L-BS) and a larger car battery that have been deep discharged. I suspect the internal plates are sulfated. I've heard there's a way to slightly overcharge the battery to "reverse" the sulfation and give a battery one last shot at being useful before it gets sent to the recycler. Does anyone have experience with bringing batteries back from the dead?

I'm starting on projects for next year....and while I will buy brand new batteries before heading to the playa, I'm just trying to get a bit more use out of what I have during the build process.

Also a side question...one of the old timers in farm country in Nebraska told me that he revived a couple of non-sealed batteries by popping the caps and putting 1 teaspoon of Epson Salt into each cell then topping it off with distilled water as a way of getting a bit more life out of an older battery. (This is presuming they can't just run to the local parts house and buy more electrolyte). Has anyone heard of this approach?

gyre · Post by **gyre** » Mon Aug 24, 2009 11:11 am

I just add distilled water.

There are techniques.
Danger varies.
High frequency higher voltage is used sometimes.
Caution is advised.

Be careful about banging discharged batteries.
Flaking in discharge is often what shorts them out.
No fix for that.

AGM often helps with that physically.

theCryptofishist · Post by **theCryptofishist** » Mon Aug 24, 2009 11:38 am

JK, why not just use a hand-crank?

Token · Post by **Token** » Tue Aug 25, 2009 8:20 am

K5

Lots of the fancy computer controlled new chargers have a recondition mode for reviving sulfated batteries. It runs a 24 hours charge/discharge on them and works well.

Don't know about the Epsom salt. Doesn't sound right.

Sail Man · Post by **Sail Man** » Tue Aug 25, 2009 4:35 pm

jkisha wrote:I didn't even think about someone making a converter plug. If I can find the plug that can bridge the APC existing plug to my generator plug, I think that would be my ideal solution.

Yes, it is sine wave--totally scrubbed and clean and voltage regulated power.

I just outgrew my space and had to move all my equipment to a data center and all of that was provided. It just seems a waste to see it all not being used, so hopefully I'll find the conversion plug.

Thanks to everybody that posted on this thread. I really appreciate the help and suggestions.

JK

RV and Boating stores both sell adapter plugs for 30 amp cords. i just bought yesterday both an adapter for my rv shore power to the gennie 240? outlet, (the 4 rounded plug type) and another for the standard household style. The former is 30 amps and the latter is 15 amps.

gyre · Post by **gyre** » Tue Aug 25, 2009 6:33 pm

The rv center at walmart may have them.

munney · Post by **munney** » Thu Aug 27, 2009 12:07 am

Try Charging the Battery, and after a few hours, take off the charger and measure it with a Volt Meter, If you have the 6 or 12+ volts needed then move to the next battery.

In terms of Blowing Up, NO, Overcharging will boil the water, Or worst cast scenario cause a small China Syndrome

Munney

Camp Million Dollar View, 7:30 & Outer Ring w/ 9 Deep Cycles

Charging a 12 Volt Battery

Charging a 12 Volt Battery

Deep Sickle