Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Batteries & Chargers => Topic started by: Seaspray on January 20, 2007, 02:37:47 pm
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Hi All
Having a good year and half away from the pond i didn't always remember to top up charge my Gell Cells.
Now the 6 volt is showing 5.95 v which I think is o.k
One of my 12v is showing 10.29v and the other is 6.95v. They have been on and off the charger for a good week or so.and this is the best voltage I can get.
They haven't been used for that time and was wondering if i was to use them to almost flat then recharge and then again,would the voltage come up to the 12v.
Or are they on the way out ?
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by the sounds of it, they are kippered, O took my 6v down to 2v and it would not recover. your 6v may be savable
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Hi Seaspray,
If you can't get any higher voltage than stated out of the 2 batteries that you are struggling with then I'm afraid that they are "stuffed" and should be disposed of accordingly.
Gell cells should be "topped up" on a regular basis ( I do mine once a year if not used) or as soon as possible after use as these type of batteries are difficult to recover if left discharged for any length of time.
Terry.
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At least I've the other batteries charged.Forgot about these two 12v ones till the shed roof felt was torn off and had to clean up the wet inside the shed. :(
Cheers lads
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sea spray dead batteries may still be useful, they make good tension weights for placing on top of things that need to be held down during glueing
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Well they'll be heavy enough @ 5-6lbs each. :) certainly will be a good idea.
Looking through some posts and seen that some members recharged batteries with a car battery charger. Speaking to another forum member today about this and will be giving it a go.
I'll let you know if I've blown up the workshed.
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One way of getting a new shed ;D ;D
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blowing up the shed, that will really get the nannystate comming down on us, !
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Hi, sounds like the other chaps have given you sound advice and the death knell has sounded for your cells. Off load, batteries will read in excess of their stated voltage when fully charged so as yours have been given a good pounding with the charger and still fail to make the stated voltage, they do sound as though they are U/S. The only true way to test a battery is to charge it and put it under load, a good battery will hold its voltage under these conditions. One which won't even display this offload is usually destined for the fishing weight foundry! :'(
Chris
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Looking through some posts and seen that some members recharged batteries with a car battery charger
Never use a car battery charger without some form of regulator between it and the battery. They do tend to be a bit vicious for our size of battery. Lead acid types will require voltage limiting and probably current limiting, NiMH and NiCad both need current limiting and all need to have a careful eye kept on them. Commerical "proper" chargers should do this for you. Lithiums I wouldn't even think about using a home-made device.
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Gell cell batteries should only be charged at about 1/2 amp per hour, they are not vented and will possibly explode if charged at to high a rate
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Looking through some posts and seen that some members recharged batteries with a car battery charger
Never use a car battery charger without some form of regulator between it and the battery. They do tend to be a bit vicious for our size of battery. Lead acid types will require voltage limiting and probably current limiting, NiMH and NiCad both need current limiting and all need to have a careful eye kept on them. Commerical "proper" chargers should do this for you. Lithiums I wouldn't even think about using a home-made device.
hi there i have been charging my sealed lead acid batterys with a halfords car charger it has a A sealed battery mode on it, and its one of thoes smart charges that detect when the batterys are full then keep them topped up.Is this charger no use then . john
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Looking through some posts and seen that some members recharged batteries with a car battery charger
Never use a car battery charger without some form of regulator between it and the battery. They do tend to be a bit vicious for our size of battery. Lead acid types will require voltage limiting and probably current limiting, NiMH and NiCad both need current limiting and all need to have a careful eye kept on them. Commerical "proper" chargers should do this for you. Lithiums I wouldn't even think about using a home-made device.
hi there i have been charging my sealed lead acid batterys with a halfords car charger it has a A sealed battery mode on it, and its one of thoes smart charges that detect when the batterys are full then keep them topped up.Is this charger no use then . john
I must have the same type of charger ! as cos918
My car has a SLA yes it has a sealed battery which is a lead acid type (says so on the side) so do I need to get a special charger for this ? NO I think that from that we can understand that to charge a SLA you require a charger which is fitted with a control unit (thingy)
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I have one of these automatic Halfords chargers which I use for my full size boat battery. It has a "sealed" setting and a "bike" setting. The "sealed" setting is intended for sealed automotive batteries which may be of the gel type. The "Bike" setting is where smaller capacity batteries are being used which need a lower charge rate. However I think most bike batteries are around 20 amp hour capacity upwards which is way beyond most of the batteries we use in our boats.
In "Car" mode the charge rate is up to 7.5ah and in Bike mode 1.6ah. Although the charger may well turn off when the battery voltage reaches the fully charged level, even at the lower setting it could be charging at a much higher rate than the model boat battery is designed to accept which will damage the battery and could blow the seal. Maplins recommend that the max charge rate should be no more than 25% of the battery capacity which effectively means that your boat battery should be at least 12volt 7ah, preferably more. If your batteries are bigger than this and you are using "Bike" mode you should be OK. If your charger doesn't have a "Bike" mode then the charger will be pushing 7 amps or more through the battery which won't do it any good at all!
Unless your charger has a 6 volt setting you can only safely charge 12 volt batteries with it. There should be a plate somewhere on the charger, probably the back or the bottom, which describes the charging rates.
If your boat battery is below 7 amp hour or any 6 volt type then get a lower rated charger which is specifically designed for smaller gel cells - they aren't expensive.
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hi colin i took a photo of the plate on the charger. Please can you let me know if it is ok for 12v 12ah and 12v 7ah and 12v 3 ah . thanks john
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Hi John,
My plate reads differently but the charge rates seem to be the same. Therefore if you set the charger to "Sealed" and "Bike" then 12v 12ah will be OK; 12v 7ah is probably OK but maybe a bit marginal and 12v 3ah a definite No No! Get a charger from Modelpower, The Component Shop or somebody similar with a lower charging rate. It will only cost you around £6.
Colin
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thanks colin for that. O0 john
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As an empirical check, if your lead acid battery gets even more than slightly warm the charging rate is almost certainly too high!
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I have a good friend that works with gell cell batteries (works for a fire and burglar alarm company) his advice to me has always been charge at a low rate. He has even given me a secondhand charger out of an alarm system that is set at about 13.5volts and charges at HALF an amp per hour.
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I would agree with that Alan. if you are topping up a SLA gel cell then a low overnight charge is the best option.
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OK IL take your advice and save an old control panel next time we replace one at work. I keep the old battery's if there not totally dead. john
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A charger which charges at 1/2 amp is OK for a battery with a capacity of 5amp. O0 But not OK for a battery with a capacity of less than 5amp >>:-( The ideal charge rate for a sealed lead acid battery (Gel Cell) would be 10% of the batteries capacity IE: 5amp should be charged at 500ma, 7amp at 700ma and so on.
Try charging them any faster and you stand the chance of damaging the battery due to overheating >:( If you try charging them at a much lesser rate than 10% you won't damage the battery but it will take longer to charge and you will not create the correct chemical reaction within the battery to charge it efficiently.
Use a good quality charger ! :) your batteries will last longer and give you better service. Some of the cheaper chargers will not bring a battery up to spec after a deep discharge.
Regards Gary
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My GENUINE ex burglar alarm charger (mate fitter) has 2 outputs :- 24V 400ma and 12V 600ma fixed rates, but don't
forget, these rates are set cos the batteries are on CONSTANT trickle charge. I however would only charge at a lower
rate than using a 'Dump' charger on gell cells cos since these batteries are so much more powerfull than the old lantern
types, how low do you run them? and how fast do you REALLY need to charge them? ?
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i was always told never charge SLA at more than 600 milliamps.... i have seen the results of someone charging a 17ah 12volt gell cell with a car battery charger...... the top of the battery is seriously distorted and the gunk that oozed out is really not nice !!!
so be careful out there !
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hi
Didn't blow up the shed but gave the cells a good careful charge on the car battery charger.
Got brave and did get a bit of heat in the battery but after a few days sitting about it went down to 6volts and the other one to 10volts.
So I just bought 2 new ones. The 12v cost £14.99 and the 6v £13.99. saved a lot of hassle.
Last time I bought a battery it cost £20. so I saved in the long run. Will check these new batteries more often and keep them in the house in the winter.
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That time of the year again and I won't forget to charge mine this year. O0
I lost a good Gell Cell battery last year by putting it off to charge it. Never again,too dear to replace but I've notice that the prices of Gell Cells, SLAs have come down, but are they cheapos or second hand or from abroad.
Seaspray
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hey guys this is the charger i use for everything
(http://i136.photobucket.com/albums/q162/bigfordf550/hcap0100-1.jpg)
its a hobbico multicharger and they list gell cells but dont say what setting to charge at
Added - http://hobbico.com/chargers/hcap0100.html (http://hobbico.com/chargers/hcap0100.html)
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Some interesting methods for charging your batterys , Myself i have a 6-12v charger that kicks out 1200ma , a bit savage for single 6v 4ah batterys but good for 12v7ah ones .
I do have a large quantity of batterys in the shed ,mainly from wheelchairs/scooters and some from alarm systems , the batterys are normaly good and hold over 70% of their charge and have been replaced as an anual check .
My method of charging such a number of batterys and to keep them topped up is to make a set of leads up with spade connectors for the batterys and all linked together ,connected to the charger . This way if i connect 10 x 12 7ah batterys together to the charger then they all recieve 1200ma divided by 10 = 120ma , a trickle charge .
works for me .
daz
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I use the Mtronics model no.AD-1350800BS AC adaptor/ charger.
Its a dual one with setting are 7.5v and 13.5 for Gell cells. It is not a fast or a float charger.
It's current output is 800mA. Or you might consider a little lower overnight charge, if that is any help bigford
Seaspray
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seeing as i cant edit my post :-)) here is the front of my charger
what would be the right setting for 12 volt 7amp gel cell
(http://i136.photobucket.com/albums/q162/bigfordf550/tug079Small.jpg)
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I have always been told that Gell Cells should only be charged at half an amp an hour, this is because they are sealed and a high rate of charge may cause them to explode because the gases cannot escape. I have been told this by 2 Alarm engineers, and they worked for different companies and I believe didnot know each other.
Alan
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i only charge my gell cells at 500ma :-)) i have a 4 'robbe ' leader6 chargers that do the job O0 i get about 5years out of them before i get new one's
regards ray
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slightly changing from the original thread, I had my battery changed in my burglar alarm two weeks ago after a power cut in the local area. The burglar alarm failed. the chap came around and told me it was a kaput battery.
A new one cost me £20.00 and I asked if I could keep the old one.
I put it on the bench yesterday and charged it up( a 12v 2,4 amp/hr battery)
This morning I put a buhler 12volt motor onto it at 09.45.
It's now 20.05 and ( granted there is no load on the motor) the little motor is still going as strong as it was this morning without any thought of giving up.......
the moral is.next time you see your friendly burglar alarm fitter.ask him if he has any "kaput" batteries that he's throwing out...........mabe all they need is a good charge. :-))
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Any "sealed for life" battery has a pressure relief valve to prevent excess internal pressure. The trouble is, when the excess pressure is vented, some of the liquid from the inside is now outside, with no chance of putting it back. This can cause the remaining fluid to start bubbling faster, and if it gets to the point where the temperature rises above the flash point of hydrogen and oxygen, the rate of increase of pressure can overcome the ability of the valve to get rid.
Hence "sealed for life". Once its gone, its gone.
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seeing as i cant edit my post :-)) here is the front of my charger
what would be the right setting for 12 volt 7amp gel cell
Hi Bigford - I would use the 500ma setting - far right socket, switch fully down - initially. If your 7aH battery were fully flat in theory it would take 14 hours at that rate to fully charge. However, after 8-10 hours I would switch to a lower setting - say 100ma and leave it on that.
Barrie
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Once you are happy that the battry is charged. Leave it sit for an hour or two up coupled from the leads and do a voltage check. I think I would be happy with anything just above or near to the twelve 12volts.
Do what Barrie says then do the above you'll get the experience knowing what you charger does and its times for charging over a period of time.
Seaspray
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slightly changing from the original thread, I had my battery changed in my burglar alarm two weeks ago after a power cut in the local area. The burglar alarm failed. the chap came around and told me it was a kaput battery.
A new one cost me £20.00 and I asked if I could keep the old one.
I put it on the bench yesterday and charged it up( a 12v 2,4 amp/hr battery)
This morning I put a buhler 12volt motor onto it at 09.45.
It's now 20.05 and ( granted there is no load on the motor) the little motor is still going as strong as it was this morning without any thought of giving up.......
the moral is.next time you see your friendly burglar alarm fitter.ask him if he has any "kaput" batteries that he's throwing out...........mabe all they need is a good charge. :-))
thats how i get most of mine ,and if they are realy duff then use them as weights for gluing ,especially when i use gorilla grip glue , or ballast :-)) .
daz