Regulating the output of a 'garage' battery charger

[stuhaynes]

Again this is not primarily for me, but it does concern me if there is a way to achieve it without a Phd.
I won't mention 'my mate' but this problem is affecting the operation of his Eber heater. So, here we go...

'Garage' battery chargers are not intelligent, I knew that! BUT, I've got one and 'my mates' got one too. I check my voltages half a dozen times a day. He doesn't understand this. HE has a D4 Eber that conks out, I think because of either too high, or too low voltage.

Is it possible to restrict the output of one of these garage chargers to 14.4 volts in his case, and 28.8 in my case? Some kind of simple regulator that will switch in and out and prevent overcharging. In my case, the charger provides 30 volts when the charger is on a high rate charge, in his case I don't know. What I do know is that his Eber was checked by the agent ( and filters changed ) only 2 weeks ago. I should also mention that his fuel is cleaner than a vicars toothbrush and he is connected to 3 x 110AH batteries in parallel. For myself, I just want optimum performance from my leaisure bank without having to spend £500 or more (which I can't afford) on a sterling system.

So, is it possible to rig up something that will regulate the voltage from 12 and 24 volt 'garage' type battery chargers. There is a virtual pint available for anyone that can help. Cheers! in anticipation....

 

[pvb]

The D4 has an upper voltage limit of 16.0v and I can't imagine his charger is exceeding this, otherwise he'd have had problems with his batteries (and possibly with other electronic equipment). He needs to put a simple voltmeter on the battery terminals whilst the charger's on, and see what it's actually delivering. If it's too high, it would probably be easier just to buy a better charger.

 

[lw395]

Probably the most cost effective way would be to throw it away and buy a regulated power supply?
If you want to be able to charge at high current it's not trivial to add a series regulator, but for trickle/float charging you can use something like an LM317. The trouble is, the voltage drop from the regulator may significantly reduce the output.

The other method is to use a shunt regulator, which simply dumps current into a load to drag the voltage down. This may need to dissipated the full power of the charger, so heat is an issue. I think these are sold for some solar panel applications?
In their simplest form they are just a big Zener diode, which is how the voltage was controlled on Triumph motorbikes in the 60's.

Their is also the issue that many battery chargers are deliberately designed to give a 'rough' output, it is said to help with reducing sulphation, so if you clip off all the noisy bits, the charging current may be reduced a lot.

 

[lw395]

The D4 has an upper voltage limit of 16.0v and I can't imagine his charger is exceeding this, otherwise he'd have had problems with his batteries (and possibly with other electronic equipment). He needs to put a simple voltmeter on the battery terminals whilst the charger's on, and see what it's actually delivering. If it's too high, it would probably be easier just to buy a better charger.

It's possible the DC level is less than 16V but the Ebersplutter is seeing a higher peak voltage.
If you look with a an oscilloscope or measure the 'AC' component with a multimeter it may enlighten.

 

[Plevier]

Their is also the issue that many battery chargers are deliberately designed to give a 'rough' output, it is said to help with reducing sulphation, so if you clip off all the noisy bits, the charging current may be reduced a lot.

Battery manufacturers - including the major one I worked for - generally specify the maximum permissible ripple voltage from continuous float chargers because it promotes grid corrosion and shortens the life. The same probably applies to desulphator gadgets. However if you have a battery that you operate under a poor regime that promoters sulphation, then it may be the lesser of two evils.

A lot of "garage" battery chargers have neither smoothing nor regulation, are not designed for continuous use and are bad for the battery in the long term. As others have said, no there is no simple way of adding regulation or a limit to a decent size existing charger. Before switched mode chargers came into general use, regulated chargers for e.g. telecoms work were big and expensive.

 

[rogerthebodger]

Any one considered using a solar panel regulator between the battery and an unregulated mains battery charger.

I got a similar device some years ago (before solar was available) from my local battery charger supplier.

You may need to fit a fat capacitor across the input to the solar regulator to reduce the electrical noise.

 

[stuhaynes]

It's possible the DC level is less than 16V but the Ebersplutter is seeing a higher peak voltage.
If you look with a an oscilloscope or measure the 'AC' component with a multimeter it may enlighten.

My mates idea is simply to connect a charger and everything will work. The Eber doesn't like it and packs up after 20 or 30 minutes. He's out of the country at present and it's cold here. I went round to his boat, and without turning his charger on, starter the Eber. 1/2 hour later went round and turned his charger (on low) on. I cranked the output of the Eber to No. 4. It's now 1 3/4 hours since I started and the Eber (gimme a second) is still running. It does suggest that:-

A. The Eber shop was right when they said they'd run the unit for 5 hours without a problem and..
B. It seems to be a voltage range problem where the fault is.

What do you think? Do you believe that he MUST get a smart charger? That realistically he cannot easily 'cap' the output of his existing charger.

 

[lw395]

I would echo Rogershaw's comment, shunt regulators are a bit fraught, particularly if they are going to be unattended long term.
How much power do you actually need from this charger?
If it is only to 'float' a battery that is initially charged, and make up for occassional light loads, then a device like an 'optimate' sold for motorbikes etc to prevent self discharge and cope with the background drain of alarms etc might be ideal.
If you use a lot of current for any reason, then bring in the big charger for a few hours.
Personally I have an adjustable power supply set to 13.8V keeping several batteries healthy in my garage.
edit:
Having looked, I see that optimates are 50 quid now, possibly best to look at a smart charger.

 

[halcyon]

Before switched mode chargers came into general use, regulated chargers for e.g. telecoms work were big and expensive.

Excuse me, we were making regulated chargers 28 years ago, majority still running, that gave a smooth fixed float charge, and they were competitive to other marine chargers. They were some regulated chargers around back then that were very simple but had a dirty output wave form. When switch mode came in there was more trouble with hi voltage spikes blowing bulbs, and effecting nav equipment, so not all rosey.

Yes you could fit a regulator that is simple, but still not cheap.

Are you running the heater full time ? if not run the charger when the heater is off.

Brian

 

[Plevier]

Excuse me, we were making regulated chargers 28 years ago, majority still running, that gave a smooth fixed float charge, and they were competitive to other marine chargers. They were some regulated chargers around back then that were very simple but had a dirty output wave form. When switch mode came in there was more trouble with hi voltage spikes blowing bulbs, and effecting nav equipment, so not all rosey.


Brian

I didn't mean to suggest switched mode is automatically super there are certainly cr*p ones! Wouldn't you agree however that it's the technology that has made regulated automatic multi stage chargers economic?
How were you regulating yours, what sort of current ranges did you cover?

 

[halcyon]

I didn't mean to suggest switched mode is automatically super there are certainly cr*p ones! Wouldn't you agree however that it's the technology that has made regulated automatic multi stage chargers economic?
How were you regulating yours, what sort of current ranges did you cover?

Actually no, the switched mode requires more complex electronics than we used, the difference mainly in the cost and weight of the transformer. In the early days of switched mode the main advantage was a wide input voltage operating range, that suited the low mains voltage on pontoons that was common then.

We used phase angle firing of thyristors in the rectifier bridge, later we changed to Schottky diodes and MOSFETs, which improved the efficiency, and the need for a fan. The units operated a 4 stage charge, power supply mode, monitored for loads ( deep freezer / fridge ) when in shut down maintenance mode, charged engine and bow batteries on a different charge cycle independent to service bank. We did up to 40 / 50 amp 12 volt, the 24 volt units operated on a split bank system that charged each half ( 12 volt bank ) independently. Gave up when people were keener to buy a re-badged switched mode charger from China for peanuts.

Brian

 

[EuanMcKenzie]

A thought but how much does it draw?

Some of the lower output intelligent chargers are sub£100 now. Could he segregate one battery as the chosen load battery for keeping the Eber running and turn the others off. I've got one of these and it will cope with two house batteries. You can also set it up to directly feed the system with a constant voltage

http://www.amazon.co.uk/CTEK-CTE-M1...D6JO/ref=sr_1_1?ie=UTF8&qid=1358623655&sr=8-1

There is a Motor Range one rated at 3-4 amps for circa £50 as well. A lot less hassle than buying bits and making something. I'm thinking you could have two battery chargers wired in parallel and decide which to use depending on what you are trying to achieve. A lot less than £500. Maybe not where you want to go but maybe food for thought.

 

[stuhaynes]

This looks as if it may be a solution! Is it?

A thought but how much does it draw?

Some of the lower output intelligent chargers are sub£100 now. Could he segregate one battery as the chosen load battery for keeping the Eber running and turn the others off. I've got one of these and it will cope with two house batteries. You can also set it up to directly feed the system with a constant voltage

http://www.amazon.co.uk/CTEK-CTE-M1...D6JO/ref=sr_1_1?ie=UTF8&qid=1358623655&sr=8-1

There is a Motor Range one rated at 3-4 amps for circa £50 as well. A lot less hassle than buying bits and making something. I'm thinking you could have two battery chargers wired in parallel and decide which to use depending on what you are trying to achieve. A lot less than £500. Maybe not where you want to go but maybe food for thought.

Mate bought his Eber, and a new 110AH to run it. Ran into problems of low voltage/ high voltage in a very short time and for him at least it's been a pain. Currently he has hooked the new battery to his leisure bank and so now has x3 110AH batteries. As I said before he's away but I've been round to his boat and with a bit of judicious use of charger on/off managed to keep it heating for just over 2 hours, then it packed up. I have no reliable way of measuring the voltage.

Do you reckon that the charger on Amazon would be capable of sustaining correct battery voltage during the day (while he's at work) and providing enough current to keep battery voltage within correct parameters while running the Eber overnight. It would be a bit of a Godsend if it were true. Thoughts??

 

[David2452]

A decent charger will be giving out under 15v so I question if it is the charger that is the issue, even "spikes" would need to be in exess of 16v and equally importantly for 20 seconds or so to cause an over voltage shut down, assuming the heater is all OK. Did the service centre ramp the power supply up to 15.8v and down to 11.8v for 10 munutes each during the test, did they give a proper report on the test readings, it's no use just hooking up to a bed and leaving it running for five hours without trying to duplicate the fault, the whole idea of a bench test in my view is to try and make it not work by running it just inside min & max tolerance for a period not just seeing it's Ok in ideal conditions.

 

[halcyon]

Do you reckon that the charger on Amazon would be capable of sustaining correct battery voltage during the day (while he's at work) and providing enough current to keep battery voltage within correct parameters while running the Eber overnight. It would be a bit of a Godsend if it were true. Thoughts??

You need a voltmeter to check voltage, turn off charger, let the batteries stand after charge for a few hours check voltage, check the voltage of the batteries when you switch heating on, and how fast the voltage falls. If it falls fast, the batteries are not holding charge, and you may be producing spikes thus your heater problem.

What time scale are you running the heating for ?

Can you charge the battery between Eber running cycles, turn off when Eber running ?.

Are batteries okay ?

What size charger are using ? a small one will normally not give a high voltage with Eber running, so again it's a voltmeter job.

You need to find the reason that the Eber fails, if voltage related, is it a battery problem.

Had a cheap Lidl 3 / 5 amp charger to play with, you get what you pay for, little charge and a lot of noise, that bad you cannot run it and a radio.

Brian

 

[Plevier]

Actually no, the switched mode requires more complex electronics than we used, the difference mainly in the cost and weight of the transformer. In the early days of switched mode the main advantage was a wide input voltage operating range, that suited the low mains voltage on pontoons that was common then.

We used phase angle firing of thyristors in the rectifier bridge, later we changed to Schottky diodes and MOSFETs, which improved the efficiency, and the need for a fan. The units operated a 4 stage charge, power supply mode, monitored for loads ( deep freezer / fridge ) when in shut down maintenance mode, charged engine and bow batteries on a different charge cycle independent to service bank. We did up to 40 / 50 amp 12 volt, the 24 volt units operated on a split bank system that charged each half ( 12 volt bank ) independently. Gave up when people were keener to buy a re-badged switched mode charger from China for peanuts.

Brian

Re yr 2nd para, isn't thyristor/MOSFET output rather noisy and difficult to smooth and filter at part load? (My contact with such chargers was in relation to telephone standby systems, maybe it's a particular problem there because of hum and noise.)

 

[VicS]

Do you reckon that the charger on Amazon would be capable of sustaining correct battery voltage during the day (while he's at work) and providing enough current to keep battery voltage within correct parameters while running the Eber overnight. It would be a bit of a Godsend if it were true. Thoughts??

It has a maximum output of 7 amps . It will be fine for re charging batteries up to around 100Ah in a reasonable length of time. It'll charge larger Ok but it will take longer.
CTek suggest it is suitable for batteries up to 225Ah.
It is also suitable to use as a power supply. Not all automatic chargers are. One which is not may not be suitable.
However a large enough battery should keep the Eber going on its own all night and a suitably rated charger will recharge it during the day.

See the full range of CTek chargers on their website and choose the most suitable. http://www.ctekchargers.co.uk/

CTek is a brand against which to judge other compact chargers.

 

[William_H]

Cheap battery chargers (garage type?) can be useful for getting full charge into a battery. The peaks of voltage come at each 50 hertz peak (either once or twice per cycle). When connected to a battery for charging the peak voltage will result in a peak of current so reducing the peak voltage somewhat.
i think OP should make sure that the battery charger connects to the battery terminals. Any connection into the system that might be "closer" to the eber take off than the battery would mean any volt drop in the wiring could present more voltage spike than necessary to the eber. No wiring shared by eber and charger.
It does seem like the OP has confirmed it is battery charging that has caused eber to drop out. Just remember that with no regulation a cheap charger will continue to charge with only a small reduction in current when battery is full.
A series voltage regulator like a LM 350 might give 3 amps but as said the voltage from the transformer may not be enough to cope with the inherent voltage drop in the regulator.
A simple option might be to fit a series silicon diode to the eber supply. This will reduce voltage by .7 volt which may be enough to keep eber happy. It should be easy to find a cheap diode rated at more than eber max drain.
Other crazy ideas might include a comparator to sense voltage at the eber. If voltage is too high switch in with a relay a series diode or several diodes to reduce voltage or a small value resistor in series.
Often these battery chargers have a switch to select a lower voltage tap on the transformer. Perhaps a comparator to a relay to select low charge when battery voltage rises.
It may be practical to open up the transformer and make a new lower voltage tap. I have done this successfully but then I am a crazy tinkerer.
A comparator is an op amp LM741 or similar with a zener stabilised voltage on one input and a sample of the tested voltage on the other input. When one exceeds the other you get the op amp turning of or on. This can feed a transistor to a relay and can be essence of a simple Voltage sensing Relay In the case of OP this relay could be used to reduce charger or eber voltage a little when voltage is too high.
good luck olewill (beware is rambling again).

 

[Beyondhelp]

What is the output current of the suspected battery charger in question? It would have to be fairly beefy to get 3x110ah batteries to the point the EBER shut down.

TBH a bit of a pointless thread unless an attempt at voltage measurement is made.

Need more information or everything else is purely speculation!

 

[Jegs]

Actually no, the switched mode requires more complex electronics than we used, the difference mainly in the cost and weight of the transformer. In the early days of switched mode the main advantage was a wide input voltage operating range, that suited the low mains voltage on pontoons that was common then.

We used phase angle firing of thyristors in the rectifier bridge, later we changed to Schottky diodes and MOSFETs, which improved the efficiency, and the need for a fan. The units operated a 4 stage charge, power supply mode, monitored for loads ( deep freezer / fridge ) when in shut down maintenance mode, charged engine and bow batteries on a different charge cycle independent to service bank. We did up to 40 / 50 amp 12 volt, the 24 volt units operated on a split bank system that charged each half ( 12 volt bank ) independently. Gave up when people were keener to buy a re-badged switched mode charger from China for peanuts.

Brian

Spot of thread drift, but did you consider switch mode isolating transformers which might be smaller & lighter than standard types?

John G