Battery charging in high temps

[Guest avid]

I have read that if you charge a deep cycle battery at temperatures above 120 degrees it can damage the battery.  In my garage during the summer, the air temperature often exceeds 100 degrees.  

I have a trojan marine 100AH deep cycle marine agm battery for my TM, but have not yet gotten a charger.  I want an automatic "set it and forget it" charger.  Any suggestions?

[Way2slow]

Make sure you get one that says it's a Smart or Intelli charger. You should get one thats rated for approx 10 amps and it's better to get one that drops into a float mode. It should also have settings so it could be set for AGM batteries. To get the max life from your battery, the charging cutoff voltage for an AGM is approx 14.4 volts and the recommended float voltage is approx 13.6 volts. THese are very different than your standard flooded cell lead acid deep cycle batteries and your standard battery charger will charge it to a voltage much too high before cutting off and most float voltages will be too low for AGM. A good charger will cost between $60 - $100, depending on where you get it and what kind of discount you get. Good and cheap are not two words that go together when it comes to chargers.

Yes, you are right about the temprature, as the temp increases, you should decrease the charge rate and should not charge one if the temps are 130 degrees where the battery is at. With my onboard charger in my boat, I have an optional temperature probe stuck to one of my TM batteries so the charger automatically compensate for temp changes.

I should also mention, the little extra you pay for a good charger will pay you back in the increased life of the battery.  Properly charged and maintained  with a good charger, that battery could last your a whole bunch of years.  It's common to get 6 - 8 years out of one that's treated right.  Fiugre less than half that from one with the wrong charger.  That holds true even for your cheap Wally World batteries.  

A good, high frequency, Smart charger will give you about twice the battery life as your standard automatic chargers.  Equalize one once or twice a year, keep in on the charger/maintainer, try to never run it down below 20%, don't let it sit disharged.

[Guest avid]

Wow, thanks for that detailed and informative reply.

If I was overly concerned about $$ I wouldn't have gotten a Trojan AGM, but after alot of research I determined that this best suited my needs.    

I don't want to spend money foolishly but I will pay the necessary dollars for a quality charger that will do the job safely and efficiently.

I would appreciate specific recommendations.  The more detail the better, for example, brand, model name or number, dealer outlets. etc.

Much thanks.

avid

[George Welcome]

http://www.sears.com/sr/javasr/product.do?cat=Automotive+Accessories&pid=02871222000&vertical=AUTO&subcat=Power+Accessories&BV_UseBVCookie=Yes

[Way2slow]

George,

Sorry but that is the last thing you want to get. That is your standard automatic charger, plug it and leave it and you will probably fry the battery.

As a minmum I would go with one of these http://www.batterychargers.com/details.cfm?prodid=SSC%2D1000A&catid=2

This is another http://www.homedepot.com/prel80/HDUS/EN_US/jsearch/product.jsp?pn=100375932

I would think you could do a search on line and find them a little cheaper.

Keep in mind, I've not used either of these chargers so can't say for sure just what their charging and float voltages are.  A good DVM will let you check that and if they are not right, take them back.   The chargers I used are commercial and cost hundreds of dollars, so don't think you want to go that route.  

I do swear by my little BatteryMINDer's though for maintaining a battery I don't use reqularly.  Those are high frequency and I can take the cover off and adjust the float voltage to the exact voltage the battery manufactor recommends.

[Al Wolbach]

Way2slow, I am trying to identify a battery. If it has a nonimal float voltage of 13.5-13.8v, does this alone identify an AGM battery? Thanks.................Al

[Way2slow]

No, the battery does not determine the float voltage, that is stickly controlled by the charger/maintainer, which is too high for a standard flooded cell deep cycle battery, should be approx 13.2. Normally, AGM's and gels will have somewhere on the label they are gas valve regulated. If you can shake it and hear water sloshing, it's just a sealed flooded cell battery. I just got through calling GNB to identify four batteries of theirs. The label said they were gas valve regulated but had nothing about which they were, but knew they had to be one or the other because they were installed laying on their side and those are the only two kind you can lay on their sides.

[Al Wolbach]

Way2slow, thanks a bunch. The battery I'm trying to identify is a GBN product also. Would you share a phone number for GBN? This battery does not indicate a gas valve regulation nor does it slosh. However, the label is in tact..........Thank you.........Al

Sorry for stealing the post...

[Way2slow]

1 800 537 8244 I think this was their main office but I think I called this number for their nearest dealer 1 770 530-1290.

I've got a ton of notes written and a lot of numbers on the same page but think these are the right ones.  The 770 number should get you what you need to know.

[Al Wolbach]

Many thanks............Al

[Way2slow]

Wouldn't be a 6V about the same size as a group 27 rated at 195 AH on a 5 hour rate.  I've got four good AGMs if anybody needs them.  These electric motor fishermen should love them.  Will give you 24Vs rated at over 200 ah based on a 25 amp draw.

[Guest avid]

The CB27-AGM you purchased is a 100 amp-hour battery and I recommend that you charge this battery at 8 to 10 amps. Unfortunately, we do not carry this large a charger but you can purchase an automotive battery charger at Sears or Walmart that will work fine. However, I would never charge this battery at more than 12 amps. Please let me know if I can be of further assistance and thank you for your order.

Best regards,

Bob

The above comes from a rep at ebatteries, the online store where I got mine.

Below is quote from the Trojan Battery website.

Most deep cycle applications have some sort of charging system already installed for battery charging (e.g. solar panels, inverter, golf car charger, alternator, etc.). However, there are still systems with deep cycle batteries where an individual charger must be selected. The following will help in making a proper selection.

There are many types of chargers available today. They are usually rated by their start rate, the rate in amperes that the charger will supply at the beginning of the charge cycle. When selecting a charger, the charge rate should be between 10% and 13% of the battery's 20-hour AH capacity. For example, a battery with a 20-hour capacity rating of 225 AH will use a charger rated between approximately 23 and 30 amps (for multiple battery charging use the AH rating of the entire bank). Chargers with lower ratings can be used but the charging time will be increased.

Trojan recommends using a 3-stage charger. Also called "automatic", "smart" or "IEI" chargers, these chargers prolong battery life with their well programmed charging profile. These chargers usually have three distinct charging stages: bulk, acceptance, and float.

It therefroe seems to me that the best charger for a 100AH AGM battery would be a bulk charge of 10amps an acceptance charge of 6, and a float of 2, just like way2slow said, problem is I looked allllllllllllllll  day yesterday and could not find one.

I bought a Shumacker 10/2 automatic from autozone beacause I needed something right away. I hope it works well.

My plan is to let it charge up to about 80% on 10amp then flip the button to 2 amp and forget about it . Same a float charge charge no?

I had no idea this stuff was so freakin complicated

I miss my oars :'(

[Way2slow]

Avid,

Both the links I gave in my other post were three stage chargers and both have the AGM mode that can be selected.   I would not use that 10/2 Autozone charger if you want to get good life out of that battery.  I would see if they wouldn't take if back and check out Home Depot's Husky brand or see about finding the Schumacker SSC-1000A.  Like the Trojan folks said, you really should stick to a three step Smart charger.   AGM batteries charge at a lower voltage and require a higher float voltage than flooded cell batteries and those little hot boxes burn up enough fooded cell batteries, they will destroy your high dollar AGM so you will be lucky to get a couple of good years out of it.   However, as I always say, it's your equipment and no one to tell another person how to take care of his equipment, just how I would take care of my own.

[Guest avid]

Well said.

thanks.

I'll keep the 10/2 for back up and use it till I find the recommended design.

[Way2slow]

Avid,

I read your post again and even if you use that 10/2 charger until you get the right one, DON'T leave it on the battery. Disconnect it after 10 - 12 hours or put a light timer on it that will turn it off completely after about 12 hours. You can not use the 2 amp setting as a float charge, that's way too hot to leave on the battery for and extended period. Even if its an automatic cutoff model, the trickle voltage they have is too much. What happens if left on the battery over an extended period, the trickle voltage will overheat/overcharge the battery to the point that it will make the charger come back on, greatly overcharging and overheating it even more until if totally fries it.

If it's not an automatic, charge it for four or five hours on 10 then cut it back to two for three or four hours, then disconnect it, but it's still a guessing game if you get it fully charged without a voltmeter to check it.

Think AGM aren't a pain to properly charge, check this charge pattern out on a set of industrial GNB AGM's. This is why the commercial AGM chargers are hundreds of dollars and fully progammable.

Charge at 20 amp/100 ah until it reaches 2.37 V per cell

Charge at 2.37 Vpc until current is less than 2 amps/100 ah

Charge at 2 amps per 100 ah to a max voltage of 2.55 Vpc

Terminate charge 3 - 4 hours after the beginning of step 2.

These particular batteries were a set of four group 27 six volts seriesed for 24V, cost $330.00 each and the charger was $480 but are intended to last approx 1000 cycles. That discharging them to 20% and recharging them 1000 time. If only discharge to 50% they could last over 1500 cycles. That would be 1,500 fishing trips for you.

Basically what your doing in relation to your 12V, 100 aH battery is charging it hard until it gets to 14.22 volts, then holding it at that voltage until the current is down to 2 amps (3 - 4) hours and charging it at 2 amps or less until it reaches 15.2 volts. Then you would drop into a 13.6 V float charge where you would leave it until you got ready to use it again.  One note though, the charging at 15.2 V is to equalize the cells and Trojan does not recommend to equalize their AGM's

[Guest avid]

Like I said before, I put alot of research into this battery and paid a pretty penny for it.  My style is to pay top $$ for top Quality then get all that I paid for and more.  I have just ordered the 10/6//2 from an online source.  I'll use the 10/2 carefully untill the real deal arrives.  Then the 10/2 can go to my favorite charity.  My son.  ;D

Thanks w2s for your knowledgable and timely replies.

avid

[Way2slow]

Avid,

Got Trojan to send me a charging profile on their AGM batteries. On your battery is shows you can start off with as much a 20 amps and charge it until it reaches 14.4 volts. Even starting off with 10 amps, you still want to charge until it reaches 14.4V, just takes longer. Then hold it at the 14.4 volts until the current drops to 2 amps or lower. Hold it at 2 amps or less and 14.4 volts until it reaches 104% charge. Basically hold it at two amps for a two or three hours. Then it would be maintained with the 13.6 volt float voltage. They do not recommend ever going above the 14.4 volts, which is what you would do to equalize a battery.

This is why I recommended you get a computer/logic controlled "Smart" charger with the AGM mode. There's just not one of those little hot boxes like that Autozone, Sears, or any other brand in the county that can properly charge them.

I tried posting the profile but I ain't smart enough for that. It's in a PDF program type file and I can't even get pictures posted with my IP.

[Guest avid]

I got the Schumacher SCC 1000A.  It is alot smaller and lighter than I thought it would be.  

Question.   the charger has three battery type settings.

Regular

Deep cycle

AGM/Gel cell

My instincts tell me to use the AGM rather than the deep cycle setting.  But they have been known to fail me now and then  

whatcha tink?

thanks,

avid

[Way2slow]

Well now, as I mention before, I've never used one of those but use the AGM.  It does kinda surpise me they have the AGM and Gel in the same mode.  They both charge pretty much the same but the recommend float voltage on the AGM is 13.6 volts and on the Gel it's 13.2 volts.  

They are light because they are a solid state, high frequency units and don't run those big old heavy transformers the old fashion chargers run.  They will still charge three times faster than those old transformer things.

If yoiu happen to own a digital voltmeter or know someone that would loan you ones for a couple of days, I would be interested in what the voltages are after it hits the 80% and after it has been in float for a few hours.  Ideally it would be 14.2 - 14.4 VDC and 13.6 VDC, that would be the perfect setting for your battery.

[Guest avid]

Well I'll see what I  cand do.  The unit has a digital % charge meter and an voltage meter, so I should be able to supply the info you requested.  Of course they are on the same switch so I have to flip from % to voltage, but that's no big deal.  (I guess)

I understand the 13.6 VDC as the ideal full charge for my AGM but I"m not quite sure I understand the following sentence

Ideally it would be 14.2 - 14.4 VDC and 13.6 VDC, that would be the perfect setting for your battery.

does this mean that the battery will charge as high as 14.4 VDC but then will settle down to 13.6 after a few hours at float charge?

[Way2slow]

Yes, the battery is not fully charged until it reaches 14.4 (ideal) and is held there for about three hours or so.  Then the charger should stop charging the battery and drop into the float mode of 13.6 volts.   In the float mode, the 13.6 volts is the ideal maintenance voltage that keeps the battery charged while not in use, provided you keep the charger on and connected 24/7.

Here's what happens

After using the battery and connecting it to the charger, the charger will start off charging at max amperage until it gets enough charge in the battery for the voltage to reach 14.4 volts.  It will then hold the 14.4 volts and the current will start dropping as the battery gains more charge until the current has droped to minimum, approx 2 amps or less  Once the current reaches minimum, it should continue to charge at the 14.4 volts and minumum current for another hour or so.  Basically until it overcharges the battery 2% - 6% ideally.  Now the battery is fully charged and it drops into the 13.6 float voltage that maintains full charge on the battery until you are ready to use it again.

Now, all these times are strickly guestimations and are totally dependent on the level of discharge and the charging capacity of the charger.

[Guest avid]

I hope by the time I need my next TM they will all run on flashlight batteries.  ;D

Thanks for the info W2S.  Your input was extremely helpful

avid

[Al Wolbach]

Way2slow, I would like to thank you as well. I have been following this post since your info applies to me also. Very informative and probably has saved me a lot of grief. So much info is available on the web but often contradictory.

I did contact GNB about my batteries, using the phone number you provided, and they were very helpful also...............Thanks again...........Al

[Guest avid]

A little plug here for Auto zone.  I took back the original battery charger I bought from them over 2 weeks ago and their was no problem.  They did examine the box and ask for the receipt but the box was in good shape and the receipt was from that exact store so no problems.