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Post by davrav on Apr 22, 2020 17:34:30 GMT
Thanks David. So presumably my Civic will have one of those ? As it seems above my CTec charger won’t work what do I need to charge the battery ? Which CTEK do you have Charlie?
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Post by charliefarlie on Apr 22, 2020 19:06:26 GMT
Thanks David. So presumably my Civic will have one of those ? As it seems above my CTec charger won’t work what do I need to charge the battery ? Which CTEK do you have Charlie? The one you kindly recommended David. I bought the best one they had at the time. Just over a year ago... It’s down in the garage locked up just now 👍👍
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Post by philip42h on Apr 22, 2020 19:46:25 GMT
So, I queried CTEK with regard to the CTEK MXS 5.0 and if it could automatically detect regular V AGM batteries and this is their reply: Dear Sir,
Thank you for your query.
No, charger does not choose for you, you still have to press the button and decide which program you want to use.
Recommendations regarding charging voltage vary a bit. There are many different battery manufacturers and battery models on the market. Please check with the battery manufacturer to get the correct information for your particular battery, as CTEK does not have the particular recommendations for each and every battery brand and model.
All EFB and most AGM- batteries are recommended to charge with normal 14.4V voltage. Some AGM- batteries can be charged with 14.7V for most effective charge.
If no information is possible to acquire, use normal charging option, 14.4V That setting will not harm any battery.
It suits very well most lead/acid batteries, including GEL, EFB, AGM, etc. It is better to charge with a bit too low voltage than too high.
Yours, sincerely,
CTEK SUPPORT TEAMThat seems consistent with what my charger's user manual says - the only stated difference between 'normal' and AGM charging is that normal charges at 14.5V and AGM charges at 14.8V. And yet this seems at odds with what the various web sites seem to be saying, namely that you must not use a regular charger with AGM batteries because the need to be charged slowly (that sounds like a lower voltage to me) and can be damaged by overcharging. It may be the case that the normal setting on a modern smart charger is perfectly safe to use on all batteries but unless and until I get to understand this a little better I'll just keep swapping modes as I move the charger between the cars.
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Post by philip42h on Apr 22, 2020 19:48:10 GMT
Which CTEK do you have Charlie? The one you kindly recommended David. I bought the best one they had at the time. Just over a year ago... It’s down in the garage locked up just now 👍👍 A modern / one year old CTEK will have a mode button and a setting for AGM batteries - if that is what your Honda has ...
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Post by davrav on Apr 22, 2020 20:18:55 GMT
Yup, as Philip says Charlie, if you have the MXS 5.0 it will have the mode button that will allow you to select 'AGM'.
As to what some websites are saying, I suspect that there is a lot of confusion and misinformation out there with regard to AGM batteries and their charging/maintenance requirements. Personally I trust what CTEK have told me. They make battery tenders that get badged for most top marques.
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Post by bigkev on Apr 22, 2020 22:12:42 GMT
The one you kindly recommended David. I bought the best one they had at the time. Just over a year ago... It’s down in the garage locked up just now 👍👍 A modern / one year old CTEK will have a mode button and a setting for AGM batteries - if that is what your Honda has ... Correctful in the extreme.......mine has exactly said facility. One cannot “recondition” an AGM battery the destructions assure me.
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Post by shcm on Apr 22, 2020 22:24:16 GMT
If you're going to charge a lead-acid "properly", it's basically done in 3 (sometimes 2) stages. 1. The first stage is constant current. The charger at this point is a constant current source. That means the voltage measured at the charger will not be held constant, but will rise as the battery charges. The current applied at this stage should really depend on the battery capacity (C). The charge current is usually a fraction of C. The AGM batteries, generally can't take as higher constant charge current as an equivalent wet lead acid. That will be what you refer to as a "slow charge". This is almost certainly the major difference between a charger for wet and for AGM. The AGM button probably limits the constant current charge to a lower value compared to the wet. The hybrid RAV has a AGM for the aux (not the traction) battery. The absolute max charging current is 5A for a approx 50AH battery (5/50 = 0.1C). Of course a charger can't really tell the capacity of a battery, unless you tell it, although maybe you can estimate it by watching the rate of change of terminal voltage, during the first bit of this constant current phase (I don't know, I've never done the comparison, but it seems not unreasonable). 2. Once the terminal voltage reaches a certain point, the charging switches to constant voltage (called topping charge). The charging current now begins to drop over time, until it reaches another fraction of C. 3. At this point the applied constant voltage is lowered slightly and this is now the float charge. The cell voltage (a 12V battery has 6 cells) can vary slightly with an AGM compared to wet battery. That may also be a slight difference with the charger. The cell voltage will also change slightly with temperature anyway. All the above assumes a healthy battery. Some of the above stages also have time limits applied, as a faulty battery may just suck current indefinitely, without the terminal voltage reaching the switch over to constant voltage charging. AGMs tend to have a shorter lifespan compared to wet lead acid. There's a lot of "pish" talked and it's obvious because you see "current" and "voltage" used in completely the wrong way and interchangeably, which shows people don't have a scooby. If you really want to know what's going on, put an ammeter in series with the charging lead and a voltmeter across the charger output. I've done that more than once.
You also have to remember each cell will not quite behave in exactly the same way. To be really anal about it, you'd want to charge each cell individually, but you can't because they are all in series & you don't have access to the "internal nodes". All a small compromise, so not worth getting worked up about.
The ctek information is dumbed down a bit, so as not to confuse I suspect.
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Post by Deleted on Apr 22, 2020 22:39:55 GMT
I recently bought one of these chargers.
Repco Battery Charger 9 Stage 6V/12V - 2.5 Amp - RBC25SS3 SKU: A1290054
5 Year Warranty 6V/12V - 2.5amp Weather Proof Multi Chemistry Charging Spark Protection
Auto Diagnostics De-Sulphation Reconditioning Set and Forget Charging
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Post by philip42h on Apr 23, 2020 9:37:33 GMT
If you're going to charge a lead-acid "properly", it's basically done in 3 (sometimes 2) stages. 1. The first stage is constant current. The charger at this point is a constant current source. That means the voltage measured at the charger will not be held constant, but will rise as the battery charges. The current applied at this stage should really depend on the battery capacity (C). The charge current is usually a fraction of C. The AGM batteries, generally can't take as higher constant charge current as an equivalent wet lead acid. That will be what you refer to as a "slow charge". This is almost certainly the major difference between a charger for wet and for AGM. The AGM button probably limits the constant current charge to a lower value compared to the wet. The hybrid RAV has a AGM for the aux (not the traction) battery. The absolute max charging current is 5A for a approx 50AH battery (5/50 = 0.1C). Of course a charger can't really tell the capacity of a battery, unless you tell it, although maybe you can estimate it by watching the rate of change of terminal voltage, during the first bit of this constant current phase (I don't know, I've never done the comparison, but it seems not unreasonable). 2. Once the terminal voltage reaches a certain point, the charging switches to constant voltage (called topping charge). The charging current now begins to drop over time, until it reaches another fraction of C. 3. At this point the applied constant voltage is lowered slightly and this is now the float charge. The cell voltage (a 12V battery has 6 cells) can vary slightly with an AGM compared to wet battery. That may also be a slight difference with the charger. The cell voltage will also change slightly with temperature anyway. All the above assumes a healthy battery. Some of the above stages also have time limits applied, as a faulty battery may just suck current indefinitely, without the terminal voltage reaching the switch over to constant voltage charging. AGMs tend to have a shorter lifespan compared to wet lead acid. There's a lot of "pish" talked and it's obvious because you see "current" and "voltage" used in completely the wrong way and interchangeably, which shows people don't have a scooby. If you really want to know what's going on, put an ammeter in series with the charging lead and a voltmeter across the charger output. I've done that more than once.
You also have to remember each cell will not quite behave in exactly the same way. To be really anal about it, you'd want to charge each cell individually, but you can't because they are all in series & you don't have access to the "internal nodes". All a small compromise, so not worth getting worked up about.
The ctek information is dumbed down a bit, so as not to confuse I suspect.
Thank you ... I think that I've followed that (I hesitate to say 'understood') - to check: - When the charger destructions say that it provides 14.5V / 10A for a 12V battery (and 14.8V / 10A for an AGM battery) they should all be considered as maximum values
- During what you describe as phase 1, the charger will deliver a lower than maximum voltage in order to provide a suitable charge current (appropriate to the battery type) raising that voltage as required to maintain the charge rate. (I suspect that this phase is indicated by one or two red flashing LEDS on the charger.)
- During phase 2 (constant voltage) it will use the stated voltage - 14.5V or 14.8V dependent upon battery type. (I suspect that this phase is indicated by a flashing amber LED on the charger.)
- And finally, I suspect that phase 3 (float charge) is indicated by a flashing / steady green LED ...
On the RAV, the battery started with 12.1V before I connected the charger and finished with 12.6V after I had disconnected the charger. Next time I'll have to measure the voltages as things proceed - well you just have to, don't you.And meanwhile I'll try to remember to switch modes between the two cars ...
Thanks again.
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Post by shcm on Apr 23, 2020 11:01:59 GMT
- When the charger destructions say that it provides 14.5V / 10A for a 12V battery (and 14.8V / 10A for an AGM battery) they should all be considered as maximum values
Yes. Typically for a wet lead acid: In constant current mode phase, depending on a little bit on actual battery, you'd be using a constant current of between 0.1C and 0.3C (AGMs look to be typically max 0.1C). Exceeding the max charge current is the damaging thing. Lower currents generally just mean longer to charge. In the topping "constant voltage" phase you'd be applying typically 2.3 or 2.4V per cell (2.4x6=14.4V). The low end (2.3V) is supposed to give a longer service life, but possibly sulphation. The top end - no sulphation but shorter life and potential gassing. There's also a temperature variation on these figures of about -3mV/C. During what you describe as phase 1, the charger will deliver a lower than maximum voltage in order to provide a suitable charge current (appropriate to the battery type) raising that voltage as required to maintain the charge rate. Yes. The charger will adjust the applied voltage (up to a limit) to supply a constant charge current into the battery. Current fixed, voltage varies. During phase 2 (constant voltage) it will use the stated voltage - 14.5V or 14.8V dependent upon battery type. Yes, you're now in constant voltage mode. The charger is now what most people would recognise as a power supply. (For some reason, I think some people struggle with the concept of constant current, but are OK with a constant voltage power supply). Voltage held constant and battery sinks what ever current it wants. It shouldn't be held at this voltage for more than a day or so. It's about 14.4V. Voltage fixed, current varies. And finally, I suspect that phase 3 (float charge) is indicated by a flashing / steady green LED The voltage is dropped to about 2.25Vish per cell (2.25*6=13.5V). In theory it can be left at this.
Leave the battery a couple of hours after removing the charger, before measuring the voltage.
The "repair" modes generally force a much larger currents into the battery in short (<1sec) pulses. In theory it can recover some batteries, without the danger of them over-heating. It all weird chemistry though.
AGMs have subtle variations on all the above figures, hence the slightly different charging requirements. The biggy problem will probably be if a AGM bat is being made to sink more than about 0.1C current.
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Post by bothwellbuyer on Apr 23, 2020 12:25:38 GMT
Read most of this string of posts.... then partook of a handful of diazepam (easier to buy on the street than paracetomol nowadays)
Think its a Ctek charger I have - used it for the 2 wheelchair batteries I have as I learnt if you let them go flat, they refuse to take a charge....and the power extension I have would only allow me 30m before the plug pulled out - but thats a back up if I've used my daily walk for something and need to go back out!! Never read anything about wheelchair lockdown lol
I've 2 big batteries in my green goddess, which incidentally has a stop start function....normally kicks in at roundabouts or junctions. Other than its sense of humour at causing traffic jams; I found the key a miraculous stop method....and of course it has a push button starter switch. Anyway: now the cover is off the GG its time to charge its batteries up again.
And I've never really looked at the Volvo XC90 battery...think its in the boot if I remember but having read all of this then I'll need to look. Thankfully I am getting a daily trip out as I collect dated food from supermarkets to give to charities supplying poor people, homeless and so on.
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Post by bigkev on Apr 23, 2020 18:08:27 GMT
Good on ya, Boffs min.
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Post by Hoovie on Apr 23, 2020 21:41:46 GMT
OK, since during lock-down our cars probably aren't going far enough to recharge the battery after starting the engine, I thought it might not be a bad idea to invest in a new-fangled smart battery charger and put both cars on charge once a week or so. With the RAV this is really straightforward ... connect up the charger, preferably the right way round, select 12V battery and an hour or so later I have a reassuring green light telling me that "bulk charge is complete; optimising battery for extended life" - it did start off showing less that 25% charge! So far so good ... The wife's V40 XC has a stop-start system. Being a Volvo it obviously has to have two batteries - a big one (the starter battery) that you can see and a not so big one (the support battery) hidden away low down underneath. And the support battery is, of course, an Absorbed Glass Mat (AGM) battery - and you can't / mustn't use a standard charger on an AGM battery. I knew none of this 24 hrs ago! Fortunately, the new-fangled smart battery charger I bought does have a selectable AGM battery mode. So, presumably, I can select that to charge-up the Volvo batteries ... ? I.e select AGM mode, connect across the starter (i.e. non-AGM battery) and charge away ... ? So that's my question / confusion really - what is it about AGM batteries that requires a special charging mode? My understanding, so far, is that they can't stand being charged too quickly ... So can I select AGM mode 'permanently' and use it for both the standard and AGM batteries - albeit that it might not charge a standard battery quite so quickly? Does anyone understand this stuff? ... Kev? This would be my take on this subject... A vehicle battery with stop/start should not actually be charged fully in the same way as a 'normal' car as the battery needs "room" to take any excess power from regenerative braking. To take account of this, the Alternator fitted to these type of vehicles are 'Smart' Alternators that take account of this requirement. I would think that for this reason you shouldn't keep a charger left on the car long term, just for maybe a couple of hours a week (base the length on any voltage drop). I wonder with the Volvo if it is the 'hidden' AGM Battery that takes this regenerative braking charge? I don't believe an AGM battery has an issue of being too quickly, as in quicker than a standard starter battery. It is actually the opposite - most wet cell starter batteries should not be charged quicker than 10% of their capacity (so if it is a 100Ah battery, don't charge with a current over 10A), but an AGM can be higher and quite often upto 25%. What most AGM batteries prefer is a charge voltage in Absorption mode (also called Constant Current mode) at around 14.4V, whereas a Wet Cell battery is a couple of 10ths of a volt lower. So if you are charging both types of battery, you should ideally change modes. Any decent modern charger can do different profiles for different batteries. If you are having to do both batteries together, I'd go for the lower voltage. Can you see the battery makes/codes and then get the data sheets to check what voltages they prefer?
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Post by Hoovie on Apr 23, 2020 21:52:58 GMT
So, I queried CTEK with regard to the CTEK MXS 5.0 and if it could automatically detect regular V AGM batteries and this is their reply: Dear Sir,
Thank you for your query.
No, charger does not choose for you, you still have to press the button and decide which program you want to use.
Recommendations regarding charging voltage vary a bit. There are many different battery manufacturers and battery models on the market. Please check with the battery manufacturer to get the correct information for your particular battery, as CTEK does not have the particular recommendations for each and every battery brand and model.
All EFB and most AGM- batteries are recommended to charge with normal 14.4V voltage. Some AGM- batteries can be charged with 14.7V for most effective charge.
If no information is possible to acquire, use normal charging option, 14.4V That setting will not harm any battery.
It suits very well most lead/acid batteries, including GEL, EFB, AGM, etc. It is better to charge with a bit too low voltage than too high.
Yours, sincerely,
CTEK SUPPORT TEAMThat seems consistent with what my charger's user manual says - the only stated difference between 'normal' and AGM charging is that normal charges at 14.5V and AGM charges at 14.8V. And yet this seems at odds with what the various web sites seem to be saying, namely that you must not use a regular charger with AGM batteries because the need to be charged slowly (that sounds like a lower voltage to me) and can be damaged by overcharging.It may be the case that the normal setting on a modern smart charger is perfectly safe to use on all batteries but unless and until I get to understand this a little better I'll just keep swapping modes as I move the charger between the cars. There is a LOT of misinformation about battery charging on quite a few websites. I suspect I know one of the sites you might have read a comment like that on. Also, to know the best voltage to charge at depends on the battery. the Spec sheets from the makers is the only way to be sure. Those voltages quoted by CTEK look too high to me (and significantly so! I would not charge an AGM battery at 14.8V for any length of time). CTEK might quote those values as they are a Swedish company (the cooler a battery is, the higher the charge voltage can be - typically 12mV/Cell per Deg C, so 14.8V would be fine in the wintertime (or a Swedish summer) but not summer) Also, the speed of charge is not really related to the voltage level, but the current. Finally, your idea of swapping modes between cars is the right thing to do. Keep doing that. A Smart Charger is not smart in that it can detect battery type and adapt, it is smart in the way it will change voltage and current rates as it reads the battery demand. A dumb charger will just have a set voltage output for example - either too low so never properly charges, or too high and cooks the battery when left on permanently (both are very common scenarios with caravans and motorhomes)
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Post by davrav on Apr 23, 2020 22:29:34 GMT
The CTEK MXS 5 compensates for ambient temp Hoovie👍 I guess it's one of the features that makes it 'smart'.
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