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Charging 12v hybrid battery with Ctek charger


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With the cars not being used (5th week now) I need to charge the batteries up. It's the Lexus CT200h I'm most concerned about.

I've got a Ctek MXS 5.0 charger, which charges at 5amps, the Lexus manual says to charge it at 4.2amps or under.  The wording in the manual says this is to prevent the battery from exploding! I've never bothered checking the specs for the Accord and MX5 as the cars aren't worth much and they don't have sensitive electrics. Both of those charge ok on and off the car with no issues, I've also used the recond mode with no issues. The CT200h battery is also an AGM one.

The Ctek comes with a comfort lead which can be connected to the battery directly and the connector left out for easy connection. The battery is in the boot under the trim on the CT200h. However, the Lexus manual also says when charging in the car to disconnect the negative cable first. That defeats the point of using the comfort lead though. There are jump terminals under the bonnet too for convenience. 

I'm sure this is just overthinking things and it would be fine but if I charge the battery in the car with or without the comfort lead and leaving the negative cable attached, are there any real dangers? Is the 5amp charger likely to damage the battery or cause it to explode? I wouldn't use recond mode with it connected to the car though as it pumps more voltage in to the battery.

Anyone here use this or other chargers with hybrid cars?

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20 minutes ago, Rich said:

With the cars not being used (5th week now) I need to charge the batteries up. It's the Lexus CT200h I'm most concerned about.

I've got a Ctek MXS 5.0 charger, which charges at 5amps, the Lexus manual says to charge it at 4.2amps or under.  The wording in the manual says this is to prevent the battery from exploding! I've never bothered checking the specs for the Accord and MX5 as the cars aren't worth much and they don't have sensitive electrics. Both of those charge ok on and off the car with no issues, I've also used the recond mode with no issues. The CT200h battery is also an AGM one.

The Ctek comes with a comfort lead which can be connected to the battery directly and the connector left out for easy connection. The battery is in the boot under the trim on the CT200h. However, the Lexus manual also says when charging in the car to disconnect the negative cable first. That defeats the point of using the comfort lead though. There are jump terminals under the bonnet too for convenience. 

I'm sure this is just overthinking things and it would be fine but if I charge the battery in the car with or without the comfort lead and leaving the negative cable attached, are there any real dangers? Is the 5amp charger likely to damage the battery or cause it to explode? I wouldn't use recond mode with it connected to the car though as it pumps more voltage in to the battery.

Anyone here use this or other chargers with hybrid cars?

When I bought my first Prius I used it little at times and soon ran into trouble with the 12v battery running down when the car was unused for an extended period.

There were warnings in the handbook about limiting the current used in charging the battery, so I sought advice from the Toyota dealer where I bought the car and was advised to get a tecMate Optimate 4 charger.

The connections were exactly as you described and I left the comfort lead exposed in the boot so I could make an easy connection when the car was in the garage. The Optimate 4 is a sophisticated, microprocessor controlled, charger but the most significant thing about it is that its maximum charging rate is only 0.8 Amps.

I used it successfully with both standard and plug-in Prius but I've never had need to use it on the Mitsubishi PHEV.

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If the manufacturer specifically says it, then I'd err on the side of caution.

It will take longer but can you leave on it's small battery 0.8A charge? It will get there, just take 5 times longer so you may have to restart a couple of times. The lower any charging current the better it is for any battery so not so bad in the long run.

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I've got a Toyota C-HR hybrid and a CTEK charger, I just use it when I need to. Connect to battery and leave it and check that has moved on from charge to care before I disconnect. Not read about an amps restriction, but not looked for one.

Just checked the website and it says 3.8amps max. Lucky ?

https://www.amazon.co.uk/dp/B00YBR8PFK/ref=pe_3187911_185740111_TE_item

 

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A 12v battery is just that, whether it's for stop/start or not. There are different types like wet and AGM/GEL. All the 12v battery does in the Lexus is run the alarm, keyless entry and start the computer so it's in a ready state. The engine is actually started using the traction battery.

It looks like that Optimate charges at a maximum of 1 amp, maybe they increased newer models. It's making me wonder why Ctek made a 5 amp one (and you can get higher) if there's a higher risk of damaging the battery. I doubt it charges at a constant 5 amps but the manual isn't very clear.

Yes I can use the bike mode on the MXS 5.0 and it'll charge at 0.8 amps. I'm not sure whether to use AGM mode too, it charges at an extra 0.3v on that setting. It's an AGM battery but I'm not sure what that offers over using just normal car mode.

The problem I've got is the car's parked on the driveway and I have no outside plug so would need to run it from a window. It would more than likely take over a day to charge at 0.8 amps and I don't want to leave a window or the car open. I think I might have to remove the battery and charge it indoors the first time to see how long it takes. Then maybe just hook it up every fortnight to maintain it if I start it early enough in the morning.

I was thinking earlier, I've used the 5 amp setting and recond mode on the MX5 battery and that's a GEL one as it's in the boot. The Ctek manual says to use recond mode for wet and Ca batteries (although it allows you to set it for AGM on the charger!). Hopefully I haven't damaged it doing that.

There must be thousands of people who just connect any old charger to the batteries. I wonder what affect they have on them.

Can anyone recommend a decent fairly priced battery tester, only that just had indicator lights to say if it's ok or not?

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Yes it would be difficult if the charge has become quite low. When I had my Bluebird (blast from the past) I had terrible troubles with batteries on it. I got a reel on mains cable and extended the croc connectors on the end. Had it running under my back gate and under through the engine so I could close the bonnet.  

I would imagine it would be ok at 5A as you would expect the charger to drop at around 80% of the charge to a lower current. GEL batteries are more sensitive to charging currents though so there is the possibility the manufacturer isn't just being over-cautious.  In saying that, it's only 0.8A of a difference and you would expect the tolerance margin to be larger than that.

I'm 50/50 on whether you should give it a go or not. I bet loads of people have lobbed on those crappy large 8A chargers Halfords used to sell.

For testing, do you still have your multimeter? Put on 20V setting and read the voltage. Should be about 12.4-12.6V. (If it's less than 11v, charge it) Turn the car on but don't crank it. See what the voltage drop is. Switch off, leave for 1 minute and do the same.  If it's more than 2v drop it needs a charge and may not be in best condition.

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On 23/04/2020 at 20:56, Rich said:

A 12v battery is just that, whether it's for stop/start or not. There are different types like wet and AGM/GEL. All the 12v battery does in the Lexus is run the alarm, keyless entry and start the computer so it's in a ready state. The engine is actually started using the traction battery.

It looks like that Optimate charges at a maximum of 1 amp, maybe they increased newer models. It's making me wonder why Ctek made a 5 amp one (and you can get higher) if there's a higher risk of damaging the battery. I doubt it charges at a constant 5 amps but the manual isn't very clear.

Yes I can use the bike mode on the MXS 5.0 and it'll charge at 0.8 amps. I'm not sure whether to use AGM mode too, it charges at an extra 0.3v on that setting. It's an AGM battery but I'm not sure what that offers over using just normal car mode.

The problem I've got is the car's parked on the driveway and I have no outside plug so would need to run it from a window. It would more than likely take over a day to charge at 0.8 amps and I don't want to leave a window or the car open. I think I might have to remove the battery and charge it indoors the first time to see how long it takes. Then maybe just hook it up every fortnight to maintain it if I start it early enough in the morning.

I was thinking earlier, I've used the 5 amp setting and recond mode on the MX5 battery and that's a GEL one as it's in the boot. The Ctek manual says to use recond mode for wet and Ca batteries (although it allows you to set it for AGM on the charger!). Hopefully I haven't damaged it doing that.

There must be thousands of people who just connect any old charger to the batteries. I wonder what affect they have on them.

Can anyone recommend a decent fairly priced battery tester, only that just had indicator lights to say if it's ok or not?

I've got one of those little hand held electronic testers that calculates the cca/ capacity/ internal resistance etc as well as charge and state of charge. I find it useful.

BA101. A link to amazon for reference:

https://www.amazon.co.uk/dp/B071NS74YK/ref=cm_sw_r_wa_apa_i_pQSOEb1YB9GKR

I can imagine lexus put that statement in the manual (at the time of manufacturer pre CTek world maybe) to stop people directly connecting older type of chargers that could potentially fry the electronics in the car. 

The CTEK charger is designed for such situations and I would personally use the "comfort" charger cable if it was easy to connect and charge.

If you're cautious why not just disconnect the negative battery lead as per the manual and try the ctek charger on the battery as a first charge, as it would adopt the charging strategy based on its algorithm? This is what I would do, not an advise not from me. 

Mind you, even disconnecting the negative lead would cause a risk of losing parameters in the ecu/ radio settings etc.

Good luck, prevention is cheaper than a failed battery, and I can imagine that once we are allowed to get back in the cars the AA/ RAC will be used a lit and there will be a battery and brake pad shortage from all the seized brakes.

Talking of which, I'll remind myself to take my own car around the block....!!

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So I've been doing some research and have found something interesting. The Lexus CT200h is exactly the same as the Prius, it's the same engine and drivetrain just with a different body. They also use the same battery which is a 45Ah one. I downloaded the manual for the Prius and that says to recharge the battery under 5A, yet Lexus says 4.2A!

I started looking at other hybrids across the range and the RX400h which also has a 45Ah battery says to charge under 5A. The Yaris Hybrid has a smaller 35Ah battery and Toyota says to charge at 3.2A or under. I'm noticing a pattern that they suggest charging 0.3A under the rating of the battery. Does this sound feasible and their recommendations are based on just the battery rather than the system as a whole.

As Nick says the Ctek is an intelligent charger and should be able to adapt. Battery chargers are nothing like they used to be.

I had a look at the MX5 manual, the car is 21 years old. The battery in that is a 35Ah and they recommend to charge at 3-4A for a trickle charge and 20A for a fast one. It also says to remove the battery and place in a tray half filled with water to keep it cool! First I've heard of that. The Accord uses a 4.7Ah battery so is closer to the 5A rating of the charger. 

So based on what I've read about the Prius (and other Lexus owners have used this charger at 5A) I'm going to disconnect the negative and charge it on 5A. Apparently it's only the radio that will lose any settings.

On 23/04/2020 at 21:46, Geoffers said:

Yes it would be difficult if the charge has become quite low. When I had my Bluebird (blast from the past) I had terrible troubles with batteries on it. I got a reel on mains cable and extended the croc connectors on the end. Had it running under my back gate and under through the engine so I could close the bonnet.  

I would imagine it would be ok at 5A as you would expect the charger to drop at around 80% of the charge to a lower current. GEL batteries are more sensitive to charging currents though so there is the possibility the manufacturer isn't just being over-cautious.  In saying that, it's only 0.8A of a difference and you would expect the tolerance margin to be larger than that.

I'm 50/50 on whether you should give it a go or not. I bet loads of people have lobbed on those crappy large 8A chargers Halfords used to sell.

For testing, do you still have your multimeter? Put on 20V setting and read the voltage. Should be about 12.4-12.6V. (If it's less than 11v, charge it) Turn the car on but don't crank it. See what the voltage drop is. Switch off, leave for 1 minute and do the same.  If it's more than 2v drop it needs a charge and may not be in best condition.

That sounds like a faff! If the Lexus was parked in front of the gate I could run the cable without it being seen as the boot will have to be left ajar or even tied shut.

I've got an old Challenge charger I don't use any more as it started making a humming noise! That is 8A fast charge and 3A slow. I used to charge all my batteries at 8A but always off the car. I didn't give the ratings a second thought then.

I've got my multimeter but I'd prefer something like Nick has suggested so will look out for something similar. I hate electrics at the best of times so just hooking something up that gives me a yes or no answer would be better :)

On 26/04/2020 at 15:36, SMARTLY said:

So I decided to fit the comfort lead this morning to make connection just a bit easier. Anybody know what the extra connections / bits are on the terminals apart from the posts?

No idea. Does it say in the manual? Where did you connect the comfort lead, to the bolts on the main clamps?

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Just do it. If it goes bang you'll know for future ref. :lol:

I'm sure it will be fine, I'm just reluctant to say on a public forum as the manufacturers have specifically said not to. (depending which manufacturer it really is). 

Put it this way - I would.

 

the-simpsons-s21e20-622134.jpg

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No idea. Does it say in the manual? Where did you connect the comfort lead, to the bolts on the main clamps?

Dunno, haven't looked at the manual. yes, I connected the comfort lead the the main clamps that tighten it round the posts.

Just looked online at manual it says to charge at 5 amps or less, picture of the battery is a sketch so of no use to anybody :( I'll take a pic.

 

Should have siad main manual is 712 pages and the satnav / media is 268 pages :(

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Yep I'll be giving it a try, I'm sure it'll be fine :)

I've just looked at the BMW manual and there is no mention of what type of charger to use or what amp it should be charged at. It does say to purchase their own charger though so I looked online and it's a rebranded Ctek with an extra £20 slapped on! :lol: The manual does say to charge using the terminals under the bonnet, there is a cap covering the positive one and a special nut on the body for the negative. No mention of disconnecting the negative first. Funny how each manufacturer has a different way of doing things.

48 minutes ago, SMARTLY said:

Dunno, haven't looked at the manual. yes, I connected the comfort lead the the main clamps that tighten it round the posts.

Just looked online at manual it says to charge at 5 amps or less, picture of the battery is a sketch so of no use to anybody :( I'll take a pic.

 

Should have siad main manual is 712 pages and the satnav / media is 268 pages :(

I looked at these too. The CHR uses a 52Ah battery, so that backs up my theory they recommend charging under each rating, I assume to preserve the life of the battery.

Yeah the manuals are long!! 

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I forgot to put this link on that I found on the Lexus site last week. They recommend running the car for 60 minutes a week to keep the batteries charged. Surely that is just a massive waste of fuel?

I also thought this didn't work on non hybrids as you need to load the alternator to charge it. I can see how it works on a hybrid with there being no alternator or starter motor. The engine charges the hybrid battery which in turn keeps the 12v battery charged.

https://blog.lexus.co.uk/lexus-hybrid-parked/

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A Ctek or a tecmate should be ok Adam but they're not cheap. Cheaper ones seem to charge at a higher amperage.

Well it seems I should've started the car like Lexus suggested or charged the battery much sooner - it's dead! Can't even start accessory mode and my jump pack did nothing.

I had to fold the rear seats and climb in to the boot to open it. Connected the comfort lead and it was on charge for 8 hours. It didn't get pass stage 2 on the Ctek, then the red error light appeared.

I've brought the battery indoors, cleaned the terminals and it's on the charger again but as it's the original so 9 years old it's done well.

The label on the battery also says to charge at 4.2a and no longer than 10 hours. Looking on the website it recommends to charge it at no more than 3a. The Prius uses the same battery but it's Toyota branded rather than Yuasa and that manual says under 5a. No wonder people get confused!

Lexus is the cheapest place for a new battery at £125 but they're all currently closed! There are some sellers on eBay and other online battery places but they cost more. It doesn't urgently need replacing but I'd like a new one asap. What a PITA.

20200505_174520_copy_1612x907.thumb.jpg.68f3bb21536be9760c8cc216249b2ab1.jpg

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Screenshot_20200505-181958_eBay.thumb.jpg.2ac101ee4c33bd16ef86d0f7f968c7d3.jpg

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The battery was on the charger for around 5 hours after bringing it indoors and reached stage 3. The charger was getting very warm though and I didn't fancy leaving it overnight so turned it off.

I took it outside and connected it the next day, it reached stage 4 within a couple of hours and 7 by 5 hours. The charger remained only slightly warm the whole time.

It's been sitting in the hallway waiting to go back on the car but I've been checking the voltage. It was on 12.9v after coming off the charger, which is expected but then dropped to 12.6v. But it's been dropping since and is now on 12.55v. Obviously batteries naturally discharge but I'm not sure if it should be doing it that quickly?

I've found a replacement of I need it but they're not delivering yet so unless I want to pay £50 more on eBay I'll have to wait.

https://www.lexuspartsdirect.co.uk/parts/lexus-ct/lexus-ct-2010-onwards/lexus-ct-engine-service-kits/lexus-ct-phase-1-12v-starter-battery/#

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Is that the right one Rich as it says 112 volts ? Does the Lexus not use the hybrid battery to start the car like my Toyota ? My 12v just turns the ignition on etc.

 

Ah ok - just realised it says phase 1 then a space the 12v :) 

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Yeah they should've used a one, I thought that at first!

Yes the hybrid battery starts the engine, the 12v just the electrics. So they don't need to be that powerful. Mind you the battery feels heavier than the ones in the Accord and MX5!

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We had loads of issues with our Prius battery , one failed under warranty and the other after about 3.5 years , I used a cteck to charge it without issue. Personally I'd fit a Varta from Tayna as my experience of Yuasa batteries has always been poor 

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