Trying to charge 12 v 5 ah battery using 12v 1.5 ah charger

[woodman-46]

Hi,
Although this isn't directly about electrics in the house I am hoping someone can help me.
My little boys radio control jeep runs off one of the smaller 12v batteries and we have two (new) that are each 5ah (pictured. ) I have bought a charger (made by Streetwize) that is for 12v batteries and charges at 1.5ah which I assumed would be ideal and take a few hours to complete charge.
The led on the charger is supposed to light red while charging and then another goes green when battery is charged and then stay on trickle with the green light going on and off while this trickle is in operation.
When I bought the batteries I tried them in the jeep but nothing worked and I so assumed they need charging because when our mower 12 v battery was connected the jeep powered up.
I have connected a battery to the charger but although the battery seemed to have no charge the green light lights up straight away and stays on . I have left it like this for a few hours but when connected to the jeep there is no power. This is the case with both batteries.
Sorry this is so long but does anyone have any idea why the batteries seem to need charging but the charger light goes straight to green when connected and from then don't charge even a few hours.

 

[endecotp]

If you don't have one, borrow a multimeter.

 

[stillp]

Have you a 12V test lamp? Easy enough to make one using a 12V bulb and a couple of lengths of flex. You need to connect a lamp across your battery, then connect the charger. What happens to the test lamp?
Does the charger behave as expected if you connect it to your mower battery?

 

[ericmark]

Take the 12 volt battery and pos to pos and neg to neg connect it to your car battery and leave for around 15 minutes to 1/2 hour. Then try to charge them with the new charger.

Most good chargers are designed not to work unless the battery volts are over a set limit. So it connected wrong way around no harm is done. However this will likely also stop them charging.

There are three basic ways to charge a battery.
1) Very slow and no control.
2) Stage charging this monitors the current and below a set limit it charges at one voltage and above that limit it charges at a lower voltage.
3) Pulse it charges then stops measures voltage and starts charging again. It is the measurement when not charging which is used to set the rate.

The stage charger has to be matched to battery so it will state some thing like 40 to 200 Ah or even 2 to 16 Ah as if the battery is too big then the current will not drop enough for it to go into final stage.

The valve regulated lead acid battery you have is easy damaged by over charging but no problem with under charging. The normal idea is 1/10th of amp hour rate. So a 5 Ah battery would normally be charged at 0.5 amp.

However the so called smart charger can charge them a lot faster as the battery gets near to 80% charged the charge rate is dropped. But to do that the battery must act as expected.

Lead acid batteries suffer from sulphation of the plates. The sulphur is soft when first made but with time is gets harder and harder as it gets hard so the battery will not charge. So a battery left discharged becomes useless.

However being used will often give them a new lease of life. So they may start to work again. The small VRLA do not have a very long life 2 to 4 years even when never allowed to go flat as the small amount of water gets past the valve with over charging.

That valve is a simple rubber cap, it will allow gas out but not back in. Some times you can remove the cover and rubber caps and put a couple of drops of distilled water in each cell and they will work again. However in theory they should be replaced.

In theroy 1.5A charger is too big for a 5Ah battery. But likely since it will not charge is will be regulated. A 13.2 volt power supply will charge any size of battery after a very long time. A 13.8 volt is some where in between it is the volts used for most car batteries. 14.4 volt is the start voltage to charge a VRLA battery, and 14.8 volt for an open cell lead acid battery where you can top up the cells. With stage chargers once 80% charged last bit will be at between 13.2 and 13.4 volts. If the charger stuck at 14.4 volt your battery would get hot and become useless, at 13.8 likely it would survive but with glass fibre VRLA really you don't want anything over 13.4 volt.

Hence why asked if you have a volt meter. But wired in parallel to the lawn mower battery and all put on charge together is the most likely way to get them to charge.

 

[winston1]

Those batteries are sold charged. If they were not they would be sulphated up and no good. Your charger also indicated they were charged.
So I can only assume you have made an error when connecting them to the jeep. Wrong way round perhaps. Poor connection perhaps.

 

[ban-all-sheds]

Most good chargers ...

Yes, but

 

[Mikefromlondon]

Your batteries must have been charged when they were sold as new, since discharged batteries would have sulphated if kept in discharged state for a prolonged period, so won't charge up again, or if they do they would not give you full capacity.

So as you have already been told to get hold of a 12v bulb, get one for the car headlight which draws around 50watts, take some wire and connect to bulb and place it across the battery terminals, if the battery is good and charged it should light up that bulb full bright. If bulb hardly lights up or extremely dim, your batteries are not charged, and you will then have to leave it on your charger that you bought for a prolonged period, like 24 hrs, or however long it takes for it to charge up,

usually lead acid batteries when they are not in a good state, like if they have partially sulphated, they will not absorb charge, so as soon as you connect your charger, as the charge is not being absorbed, the terminal voltage across your battery would jump straight to your charger's output voltage (usually 13.8V) and so the charger thinks the battery is fully charged so indicates as though your battery is fully charged, but it may be a badly sulfated battery , which is not drawing in any current.

But if you leave it overnight, it may slowly start recovering and as it does, it will start drawing more and more current and the terminal voltage will then start going down as it starts to draw more and more current, leave it connected and eventually its terminal voltage will start to creep up, until it gets fully charged to 13.8v and then the charging current will drop down to trickle and maintain it there.

 

[Jackrae]

If you bought those sla batteries as "used" then you've probably been sold dud ones. They may well show a voltage when providing little current but once you try and load them up their output collapses - as has been said, do the lamp test with at least a 12watt bulb (to draw 1 amp load).

 

[ericmark]

I see what BAS is saying but would have been better in plain English.

• Over-charging protection
• Short Circuit protection
• Overheating protection & Reverse Polarity Protection.
• LED power/charging indicators.

Nothing in that description says anything about control. It would seem it can give out the full 1.5A and although with a 15 Ah that's OK with a 5 Ah that's 3 times more than it should. It looked so like the Ctek charger which are expensive but good I thought it was the same. Lidi and Aldi have both done cheap versions to the Ctek which do have 7 stage control so sorry jumped to conclusion it was that type. But it seems it is cheap and likely to damage small batteries.

Both the gel and the glass fibre VRLA batteries need good quality chargers.

• 
  

 

[Mikefromlondon]

Thing about lead acid batteries is that they are heavy duty cycling batteries, they can tolerate high charging currents for short duration, though life may be reduced slightly, generally speaking they tolerate lot of abuse, a 1.5amp charging current is no sweat, since a good battery will absorb that charge rapidly and as the charge starts building up rapidly, the battery terminal voltage starts creeping up rapidly to about 12v, then creeps up slowly close to the charger potential (13.8v) the current drops down dramatically, almost to a few mili amps, (Last night i put a 20AH car boost starter and tyre pump) on charge across my 5amp bench power supply, I applied full 5 amps charging and within a few minutes the battery voltage crept up and started to draw less than 2 amps, and right now it has reached full charged potential of 13,8v and drawing just under 90mA.

Hence why lead acid batteries are used in cars where they suffer immense abuse, drain very high amps like 300-400amps in a few seconds and the have to absorb charge from car's alternator that is not regulated and is limited by the alternators current capacity often as much as 100AMPS Charging current! much more than its rated capacity of like 60Ah. many batteries can be charged at their rated capacity and evcen over, like Ni-Mh batteries but they must be closely monitored for over temeprature etc. won't go into it all the way, but sealed lead acids are fool proof batteries, they can take a lot of abuse.

 

[Jackrae]

Hence why lead acid batteries are used in cars where they suffer immense abuse, drain very high amps like 300-400amps in a few seconds and the have to absorb charge from car's alternator that is not regulated and is limited by the alternators current capacity often as much as 100AMPS Charging current! much more than its rated capacity of like 60Ah. many batteries can be charged at their rated capacity and evcen over, like Ni-Mh batteries but they must be closely monitored for over temeprature etc. won't go into it all the way, but sealed lead acids are fool proof batteries, they can take a lot of abuse.

Well there's a lot of useful misinformation

 

[Mikefromlondon]

Hence why lead acid batteries are used in cars where they suffer immense abuse, drain very high amps like 300-400amps in a few seconds and the have to absorb charge from car's alternator that is not regulated and is limited by the alternators current capacity often as much as 100AMPS Charging current! much more than its rated capacity of like 60Ah. many batteries can be charged at their rated capacity and evcen over, like Ni-Mh batteries but they must be closely monitored for over temeprature etc. won't go into it all the way, but sealed lead acids are fool proof batteries, they can take a lot of abuse.

Well there's a lot of useful misinformation

No it is not, and try not to be too smart and over the board, because I have been dealing with lead acid sealed or open vented batteries before you were probably born, and I deal with them bloody things on a daily bases, I make chargers so no need to get too smart.

You need to get grips with reality, how does a car alternator limit charging current? there isn't a limiter. An alternator belt may slip if it is loose, hence why some cars scream when you rev them, because the battery is sucking in 100s of amps.

 

[ericmark]

sealed lead acids are fool proof batteries, they can take a lot of abuse.

Sorry to say the fools are much cleverer now so batteries no longer fool proof. The open vented battery can take a lot of abuse, but the valve regulated glass fibre mat battery has very little H2SO4 in it and abuse will soon stop it working.

You need to get grips with reality, how does a car alternator limit charging current? there isn't a limiter. An alternator belt may slip if it is loose, hence why some cars scream when you rev them, because the battery is sucking in 100s of amps.

Vehicle alternators were always voltage regulated in the days of the old AC11 alternator but even the early ACR17 had the option to use heat sensors under the battery the orange lead. The CAV alternators did have current control the M1 and M2 terminals of the 440 regulator went across a resistor to measure current output. Times have moved on both original equipment and as an add on you can now convert alternators to stage charging and some also connect to the cars on board computer and try to only charge the battery when on over run. These have caused a complete re-think to split charging with caravans. Today the battery to battery inverter is being used more and more be it to charge a caravan battery or the bow thruster battery on narrow boats. It really is a whole new world from the days of the three brush dynamo.

In theroy a VRLA battery should last years when charged with a regulated battery charger but ask any alarm engineer or chair lift engineer how long their batteries last and lucky to do 4 years. There are exceptions my mothers mobility scooter is around 10 years old and still going fine. But her electric wheel chair only managed 3 years before a battery change and only used once a week in Asda.

It seems under 20 Ah the batteries are rather poor, they do not stand abuse well actually in some cases they work with abuse better than when cared for. Forget one for 6 months, then charge it, forget again for year and then charge it should be about the worse treatment they can get. However batteries treated that way for emergency radio equipment have lasted 20 years, but the battery looked after with a voltage regulated charger fail after 4 years. I will guess we use too high of a voltage 13.2 to 13.8 are all used for floating batteries and much depends on how often the battery is drained. On a stair lift used every day voltage set to 13.8 is great as it is recharging most of the time. But used once a week and the battery fails as it is being over charged.

I still think likely the battery here is so discharged that the charger has locked out on reverse connection protection.

But I have worked with batteries some 55 years from 2 volt gel cells to run radio valve heaters to those fitted in fork lifts, to those in glass jars. Also worked with many charging systems including 12 and 24 volt alternators for cranes, and the huge bus alternators designed to give out 60A on tick over. It has taught me to be wary, the more I learn the more I find there is to learn. I remember betting some one £5 that there were no 8 volt lead acid batteries in the stores. I lost my £5 they were designed it seems to improve car lights with 6 volt cars and included full instructions on how to alter the Delco regulator.

The French made single phase alternators and the warning lamp bulb never went fully out so had a thick coloured lens over it so you couldn't see the glow. Some only had two diodes and a fuse.

 

[Mikefromlondon]

Ericmark, my hat goes to you, if you have 55 yrs experience, then my absolute respect, my saying was for a basic average person, not a detailed chemistry of batteries, yes indeed one can continue to learn, my recent experience was I manufacture electronic equipment that uses Ni Cads as its simple charging was based on just one resistor and the batteries were as a back up in case of power failure, so did not need step charging, but it has now become difficult to get Ni cads for the same price and they are also being phased out, most batteries now are Ni-Mh, and I had no knowledge of how to charge them and when they are fully charged one needs sensitive measuring circuits to measure delta voltage, which can be just a few mili volts, and I read that Ni-mh batteries do not like overcharging unlike Ni cads, so it meant I had to modify my charging circuits, had to incorporate a cut off relay to prevent overdrain, set at 4 volts from 4 AA cells , and charge them at steady c/20 rate, the charging methods depends on individual applications, since these are not being used in power tools where fast charging is very important, and can also result in overcharging and heat build up, so with power tools you need a well designed intelligent charger that measures delta voltage, cuts down charging current and puts them on trickle charge. one has to meet new challenges on a daily bases.

One can never stop learning till dying day. thanks

 

[ericmark]

First came across the Delta V charger working on the building of Sizewell power station. We had PMR radios and these had two types of charger. The single battery charger had little switches in the base to detect battery size and that a battery was in the holder it then charged until the connection was broken and it latched until the switch was de-activated and re-activated. In the battery was a thermal switch. So it charged until the battery heated up then switched off.

The 6 modular charger however used the delta V the heart of the system is a very well controlled current and if the voltage dips it stops charging. This was with the old NiCad. The big problem with both is people would stick there radio in still switched on which would upset the system. Also it had the option to discharge the battery before is started the charge cycle. I would disconnect this feature on all but one bay as any power cut and it would discharge all batteries.

As the NiMh came out and the NiCad was banned except for medical and military the chargers became a problem. A standard AA cell can be anywhere between 600 mAh and 2800 mAh and the idea of charging in pairs has gone right out of the window. But basic is still there, energy supplied to a discharged battery is turned into chemical energy, and energy supplied to a charged battery is turned into heat. So constant current and a temperature sender still works well. I still place my finger on a battery to see if charged, cold leave it warm fully charged simple ways are still best.

Be it any type of rechargeable battery the real problem is where the battery is used at the same time as being charged. The solar panel chargers are very clever they measure the voltage dropping as the charge is switched off while still using the solar panel to charge a capacitor ready to be put into the battery if required. The device turns the solar panels DC to AC and transforms it to higher or lower voltage so as the day progresses the solar panels voltage is kept to the best point to extract maximum wattage. You look at the size and price of these devices and think how do they do it. Sterling who make boat systems have a very good site showing how the pulse charger works. It is really the only way to bulk charge a battery and use at the same time.

With the narrow boat with 3 x 160 Ah batteries we had a 35A stage charger and this would charge flat out until volts hit 14.8 it then started to measure current, when the current dropped to 3.5A it would drop the charge voltage to 13.4 volts and on shore power it would likely stay like that but should the battery drop to 11.5 volts the high rate of charge was re-started. The problem was at night with lights on the current would never drop to 3.5A so using the 3 KVA inverter with 6 kVA peak could drop the battery volts drawing 200A tends to do that, and the stage charger would re-start the sequence, which would continue to charge at 14.8 volts until we turned the lights off. Over charging the batteries.

Now that 3.5A is also dependent on battery size, the larger the battery the larger the losses so with say 500 Ah of battery it should have been set at more like 5A not 3.5A which is why stage chargers have a range of Ah they can work with. The pulse charger does not have this problem so the Ctek can be used from 2 Ah to 2000 Ah it does not matter, well maybe that's going too far but 1.2 Ah to 160 Ah it will do. 40 amp is about largest in range starting at 0.8A the 0.8 amp is claimed good for 1.2–32Ah however clearly at just 0.8A used as a caravan charger it would struggle to maintain the battery. And at 0.8A still costs £30. Both Lidi and Aldi both do chargers which do nearly the same but a lot cheaper I have the Lidi version which I use to charge the wheel chair battery. Again I here caravan users complain saying they are useless which is not surprising considering all the battery supplies the poor little thing must really be doing over time.

They cost around £14 much cheaper than the Ctek but can't pretend they are as good. But good enough for most people. www.lidl-service.com/static/2844174/52513_GB.pdf is the instructions.