Multi Meter reading for transformers
- Thread starter Furkin
- Start date
Sponsored Links
I would strongly advise against that with any form of lead acid battery, as you will soon damage it, nor would I suggest doing it with any form of battery. There seems to be a myth that fully discharging a battery helps eliminate the so-called 'memory' effect, but you should never fully discharge the battery by leaving it on load for long periods of time. It's not necessary with lead acid chemistry, and even with 1.2v NiMh/NiCd rechargeables, it's not recommended that you discharge below 1v/cell on a regular basis.
- Joined
- 27 Jan 2008
- Messages
- 23,691
- Reaction score
- 2,670
- Location
- Llanfair Caereinion, Nr Welshpool
- Country
A number of points.
1) What method of regulation is being used as with switch mode power supplies when the load is removed they often auto switch off so will give completely wrong readings with any meter unless under load.
2) Many cheap chargers use the fact that the peak voltage is above the RMS value to complete the charging cycle. So 11 when squared then times 2 then take root gives 15.55634919 so measuring 11v RMS will likely still charge a battery.
The lead acid battery comes in two major types the vehicle battery and the traction battery the latter in golfing trolleys to fork lift trucks and the ideal charging method is often considered for a 12 volt battery 14.8vdc until the charge rate drops to 10% of amp hour rating and then it drops to 13.2 volts this is normally considered as three stage charging.
1) Constant current
2) Constant high voltage (Bulk Charge)
3) Constant low voltage (Float Charge)
Better chargers may pulse charge and monitor the voltage between each pulse and may also have a equalising charge where every so many charges it slightly over charges.
Acid batteries are opposite to alkaline in the way you care for them. When working on alkaline you discharge the battery and with acid you charge them. Some alkaline batteries were thought to have a memory problem and some chargers do discharge first before charging however in discharged state crystal growth can can short the battery out so with Ni/Ca batteries you don't let them completely flatten although there is no need to recharge at regular intervals. The Ni/Iron wet battery you store in discharged state. But the Lead Acid must be stored in charged state and should be either kept on float charge or recharged at not more than once a month or the plates will sulphate. And the lead acid battery is not normally deep cycled unless of special design.
1) What method of regulation is being used as with switch mode power supplies when the load is removed they often auto switch off so will give completely wrong readings with any meter unless under load.
2) Many cheap chargers use the fact that the peak voltage is above the RMS value to complete the charging cycle. So 11 when squared then times 2 then take root gives 15.55634919 so measuring 11v RMS will likely still charge a battery.
The lead acid battery comes in two major types the vehicle battery and the traction battery the latter in golfing trolleys to fork lift trucks and the ideal charging method is often considered for a 12 volt battery 14.8vdc until the charge rate drops to 10% of amp hour rating and then it drops to 13.2 volts this is normally considered as three stage charging.
1) Constant current
2) Constant high voltage (Bulk Charge)
3) Constant low voltage (Float Charge)
Better chargers may pulse charge and monitor the voltage between each pulse and may also have a equalising charge where every so many charges it slightly over charges.
Acid batteries are opposite to alkaline in the way you care for them. When working on alkaline you discharge the battery and with acid you charge them. Some alkaline batteries were thought to have a memory problem and some chargers do discharge first before charging however in discharged state crystal growth can can short the battery out so with Ni/Ca batteries you don't let them completely flatten although there is no need to recharge at regular intervals. The Ni/Iron wet battery you store in discharged state. But the Lead Acid must be stored in charged state and should be either kept on float charge or recharged at not more than once a month or the plates will sulphate. And the lead acid battery is not normally deep cycled unless of special design.
- Joined
- 27 Jan 2008
- Messages
- 23,691
- Reaction score
- 2,670
- Location
- Llanfair Caereinion, Nr Welshpool
- Country
Sorry did not understand what the booster was! Then it twigged. The ones I have seen use a very basic way to charge and measuring at the coax plug likely only 11vdc with a normal meter. You need to measure voltage at the clips for battery and if voltage measured before you plug in is less than voltage after you plug in (Leave about 15 mins before second measurement) then it's charging.
You should put on charge at least once a month and if you have a meter then don't unplug until voltage is 13.2 or over. I will guess around 16 hours if not used but if used then it could take a week to charge.
It's a very small charger for a very big battery.
The voltage of 11vdc measured at coax plug is RMS but the charger has no regulation so unless the base voltage is kept low it could if left in 24/7 overcharge as peak voltage would be 15.5vdc.
RMS stands for Root Mean Squared and if you think of a right angle triangle with two equal sides then each of those equal sides is the RMS value and hypotenuse is the max value hence the words root and squared so with 230volt AC we have 325v peak value. Don't really need to know how and why but accept that measured 11v can charge to 15 volt.
You should put on charge at least once a month and if you have a meter then don't unplug until voltage is 13.2 or over. I will guess around 16 hours if not used but if used then it could take a week to charge.
It's a very small charger for a very big battery.
The voltage of 11vdc measured at coax plug is RMS but the charger has no regulation so unless the base voltage is kept low it could if left in 24/7 overcharge as peak voltage would be 15.5vdc.
RMS stands for Root Mean Squared and if you think of a right angle triangle with two equal sides then each of those equal sides is the RMS value and hypotenuse is the max value hence the words root and squared so with 230volt AC we have 325v peak value. Don't really need to know how and why but accept that measured 11v can charge to 15 volt.
Sponsored Links
FURTHER UPDATE:
Thanks so much to you all for the technical stuff on the subject. I've certainly learned a few things.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I put the battery on charge (my normal car battery charger) for 4/5 hours.
Whilst it's charging, the charger leads (when connected to the battery) read 12.6vdc. (for some reason I expected more !?)
The battery went up to 12.3v, when I disconnected the charger for the night.
Next morning the battery showed 11.96v, so I guess the either the battery is failing, or I didn't put enough into it yet.
At 12v, the LEDs on the 'booster' still only show Good [next to the highest one = Flat > poor > good > best]
I have the battery on charge again at the moment.
As someone said at the beginning, the cost of a half decent battery for these things is more than a booster costs. Having said that, this Blackspur thing wasn't as cheap as some,,,, & I got it as it has the inverter & compressor built in.
Fortunately, I've only needed to use it once for my own use, before I changed cars, & it's only very seldom used (when my son or a neighbour is in trouble). Up to last week, it's been reliable,,,, but probably bu@@ered by myself, by running it down once in a while - Lesson 1) that won't happen again.
Regulation: I have no idea, but as it's a Blackspur item, I rekkon it's the most basic thing there is.
I'll report back after a decent charge, to see if the battery is taking/holding a full charge.
thanks again
Thanks so much to you all for the technical stuff on the subject. I've certainly learned a few things.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I put the battery on charge (my normal car battery charger) for 4/5 hours.
Whilst it's charging, the charger leads (when connected to the battery) read 12.6vdc. (for some reason I expected more !?)
The battery went up to 12.3v, when I disconnected the charger for the night.
Next morning the battery showed 11.96v, so I guess the either the battery is failing, or I didn't put enough into it yet.
At 12v, the LEDs on the 'booster' still only show Good [next to the highest one = Flat > poor > good > best]
I have the battery on charge again at the moment.
As someone said at the beginning, the cost of a half decent battery for these things is more than a booster costs. Having said that, this Blackspur thing wasn't as cheap as some,,,, & I got it as it has the inverter & compressor built in.
Fortunately, I've only needed to use it once for my own use, before I changed cars, & it's only very seldom used (when my son or a neighbour is in trouble). Up to last week, it's been reliable,,,, but probably bu@@ered by myself, by running it down once in a while - Lesson 1) that won't happen again.
Regulation: I have no idea, but as it's a Blackspur item, I rekkon it's the most basic thing there is.
I'll report back after a decent charge, to see if the battery is taking/holding a full charge.
thanks again
If it is standard type of Lead Acid Battery, ( gell or liquid ) then the voltages being measured strongly indicate a dead cell.
You could check with the manufacturers in case the battery has some unusual chemistry that makes its normal off load voltage 12 volts and not the usual 13.4 nominal of lead acid batteries.
There were 10 cell NiFe (Nickel Iron) batteries that were nominal 12 volt in use ( 1.2 volt per cell ) and these are used in rough use applications as they are (were) much tougher for harsh conditions.
http://www.mpoweruk.com/nickel_iron.htm
Some cheap PSUs dont have any smoothing circuitry in them hence the output isn't a nice streight DC line, it has peaks going to the + voltage and troughs going all the way back down to 0v, 100 times per second.
If you tried measuring the voltage of the battery terminals when it is connected you will probably see a higher voltage.
If you tried measuring the voltage of the battery terminals when it is connected you will probably see a higher voltage.
- Joined
- 27 Jan 2008
- Messages
- 23,691
- Reaction score
- 2,670
- Location
- Llanfair Caereinion, Nr Welshpool
- Country
I will guess the battery has sulphated plates. Sometimes a long low charge will bring them back from dead. Assuming the original charger works then I expect it would need to be on charge for at least a week.
If it were mine I would first measure voltage. Second plug in original charger. Third leave for an hour. Four recheck voltage if it has gone up even by just 0.1 volts then I would leave on charge a week.
If the volts don't rise then I would use external charger set to lowest charge rate available according to charge rate I would leave for extended time.
At 17AH then if you can charge at 1A then I would leave on charge for 24 hours. If you can't turn charger down that low then monitor battery temperature and switch off if it gets hot.
P.S. Battery will cost around £40 link to data sheet max charge rate 5A at 25 deg C temp.
If it were mine I would first measure voltage. Second plug in original charger. Third leave for an hour. Four recheck voltage if it has gone up even by just 0.1 volts then I would leave on charge a week.
If the volts don't rise then I would use external charger set to lowest charge rate available according to charge rate I would leave for extended time.
At 17AH then if you can charge at 1A then I would leave on charge for 24 hours. If you can't turn charger down that low then monitor battery temperature and switch off if it gets hot.
P.S. Battery will cost around £40 link to data sheet max charge rate 5A at 25 deg C temp.
Thanks again folks,
I had it on my normal charger yesterday from about 12:00 noon till I went to bed at about 12:30 this a.m.
The charger started off at about .8 amp, and within minutes went down to .5 and settled there.
The batt measured 12.62 volts when I left it last night,,, and this morning shows 12.36v. - so it is losing charge just by standing in my kitchen.
The battery dosn't get hot - or even warm - when on charge. I kept feeling it when I started using the external batt charger as opposed to the charging system of the kit.
The original transformer - on the other hand - did (does) get quite warm/hot when charging normally. Would it be o.k to leave this charging for days on end ? (my original thoughts were that this was faulty - before taking the unit apart).
As the 3rd party charger is charging at .5a, will it be o.k to use this for a lengthy charge ?
If not, I'll put the unit back together & use the original t/former.
If I do have to get a battery, will I have to stick to 17Ah ? There are quite a few around at 18/20Ah etc.
cheers
I had it on my normal charger yesterday from about 12:00 noon till I went to bed at about 12:30 this a.m.
The charger started off at about .8 amp, and within minutes went down to .5 and settled there.
The batt measured 12.62 volts when I left it last night,,, and this morning shows 12.36v. - so it is losing charge just by standing in my kitchen.
The battery dosn't get hot - or even warm - when on charge. I kept feeling it when I started using the external batt charger as opposed to the charging system of the kit.
The original transformer - on the other hand - did (does) get quite warm/hot when charging normally. Would it be o.k to leave this charging for days on end ? (my original thoughts were that this was faulty - before taking the unit apart).
As the 3rd party charger is charging at .5a, will it be o.k to use this for a lengthy charge ?
If not, I'll put the unit back together & use the original t/former.
If I do have to get a battery, will I have to stick to 17Ah ? There are quite a few around at 18/20Ah etc.
cheers
- Joined
- 27 Jan 2008
- Messages
- 23,691
- Reaction score
- 2,670
- Location
- Llanfair Caereinion, Nr Welshpool
- Country
Looking at the voltages quoted in earlier posts seems it is charging. I would expect any battery to reduce voltage when left over night that is normal.
Good the idea is power from charger can be converted to two types of energy. "Chemical or Heat" while battery is cold it means it is charging all power is causing the chemical change as wanted. Once fully charged then it will heat up. Talking about heat of battery not charger.[/quote]
The original transformer - on the other hand - did (does) get quite warm/hot when charging normally. Would it be o.k to leave this charging for days on end ? (my original thoughts were that this was faulty - before taking the unit apart).
As the 3rd party charger is charging at .5a, will it be o.k to use this for a lengthy charge ?
If not, I'll put the unit back together & use the original t/former.
If I do have to get a battery, will I have to stick to 17Ah ? There are quite a few around at 18/20Ah etc.
cheers[/quote]
Either charge can be used but lets look at some figures. 0.5A with no loses will charge battery in 17 x 2 = 34 hours. There will be at least 20% loss so from flat you are looking at 48 hours to fully charge. And at 0.5A there will be very little heat same as 100W bulb if nothing goes into battery it would in the end dry out battery but it would take some time.
As to size only the physical size is really important 17AH to 20AH would make no difference really.
The 3rd party charger may over charge battery but as long as you check it every 6 hours or so to see if battery getting hot no real problem. I would say main problem is you expected a little charger to re-charge the battery far quicker than it was able and all it needed was an extended re-charge time.
As the battery starts to become charged the little charger will not get so hot so likely now some charge in in the battery you could just plug in the charger that came with it and leave for a week on charge.
Cheers Eric,
The battery is certainly climbing up now - 13.4v.
I think by tomorrow, I can put it back in the unit (& rebuild) and if necessary, return to the transformer to finish it off.
After going through this, & learning a bit about battery/charging, I must have thrown away some good, but mis-handled, car batteries in the past ! I just hope that this knowledge will help my Son if he gets similar problems with his car / battery in the future.
Will update tomorrow.
thanks again
The battery is certainly climbing up now - 13.4v.
I think by tomorrow, I can put it back in the unit (& rebuild) and if necessary, return to the transformer to finish it off.
After going through this, & learning a bit about battery/charging, I must have thrown away some good, but mis-handled, car batteries in the past ! I just hope that this knowledge will help my Son if he gets similar problems with his car / battery in the future.
Will update tomorrow.
thanks again
- Joined
- 27 Jan 2008
- Messages
- 23,691
- Reaction score
- 2,670
- Location
- Llanfair Caereinion, Nr Welshpool
- Country
Remember you need an equalising charge once a month.
It is called an equalising charge as a battery is made up of cells and over time some cells become over charged and some become under charged so slightly over charging brings all cells to same charge.
In old days of the dynamo the battery was being charged and discharged all the time and this was very important. However with Alternators once started the car battery now has very little work and so the need for equalising charge has mainly gone. Also with sealed batteries you can't top up after so could do more harm than good. However all batteries self discharge so when not in use either batteries are fully charged then emptied (Lead Acid) and dried and sealed this is refer to as dry charged and not done with anything but new batteries. Or it needs a refreshing charge once a month.
With Ni/Ca or Ni/Iron the rules are very different this is only for lead acid.
It is called an equalising charge as a battery is made up of cells and over time some cells become over charged and some become under charged so slightly over charging brings all cells to same charge.
In old days of the dynamo the battery was being charged and discharged all the time and this was very important. However with Alternators once started the car battery now has very little work and so the need for equalising charge has mainly gone. Also with sealed batteries you can't top up after so could do more harm than good. However all batteries self discharge so when not in use either batteries are fully charged then emptied (Lead Acid) and dried and sealed this is refer to as dry charged and not done with anything but new batteries. Or it needs a refreshing charge once a month.
With Ni/Ca or Ni/Iron the rules are very different this is only for lead acid.
Thanks Eric for updating me on that.
I was satisfied that the battery was taking & holding a charge when using the 3rd party charger, so yesterday I re built the Booster, & finished it off on the original transformer.
This morning it had held a good charge of 12.74v and the 'Good' (well charged) LED is now lit.
I'll be putting it back onto transformer again tomorrow, (as per a link on earlier reply) and, as you say, to equalise it.
I've already marked my calender to remind me to charge it - regularly.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I've certainly learned quite a bit from this thread - thanks to you all.
It just shows - You can teach an old dog new tricks.
many many thanks.
I was satisfied that the battery was taking & holding a charge when using the 3rd party charger, so yesterday I re built the Booster, & finished it off on the original transformer.
This morning it had held a good charge of 12.74v and the 'Good' (well charged) LED is now lit.
I'll be putting it back onto transformer again tomorrow, (as per a link on earlier reply) and, as you say, to equalise it.
I've already marked my calender to remind me to charge it - regularly.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I've certainly learned quite a bit from this thread - thanks to you all.
It just shows - You can teach an old dog new tricks.
many many thanks.
- Joined
- 27 Jan 2008
- Messages
- 23,691
- Reaction score
- 2,670
- Location
- Llanfair Caereinion, Nr Welshpool
- Country
Not after a Furkin though. 72 Pints is a little over my capacity.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
