Any battery trickle charger recommendations

shanra · April 22, 2020

Ctek MXS5.0 here also and always does the job!

Charlie Alder · April 22, 2020

Hello

This may be a silly question so I apologise become hand. I have a MY17 CT200H. The lable on the aux Battery says the max charge rate should not exceed 4.2amps. Does this mean the CTek MSX 5 would charge at too high a rate?

MLW · April 22, 2020

Is 4.2 amps with the Battery disconnected? How high can you charge connected and not fry the ECU and other electrics?

BoutTime · April 22, 2020

7 hours ago, Charlie Alder said:

Hello

This may be a silly question so I apologise become hand. I have a MY17 CT200H. The lable on the aux battery says the max charge rate should not exceed 4.2amps. Does this mean the CTek MSX 5 would charge at too high a rate?

I'm no expert but I wonder if that label is written with constant current 'dumb' chargers in mind. The Ctek is a smart charger and will charge at full current (5A) up to 80% full charge. It will then charge at a decreasing current to 100% full charge.

malcolmw · April 22, 2020

The maximum charge rate on AGM batteries is related to the recombination capability of the Battery before gassing occurs and consequent loss of electrolyte. This only occurs in overcharge when charged from "dumb" constant current chargers. The CTEK will be perfectly fine and will not damage the Battery.

I know this sounds a bit trite but I am an expert on this subject as our firm makes the Varley race car batteries.

www.dmstech.co.uk

SH20 · April 22, 2020

My Ctek MSX 5.0 has charged my ES300h a few times in the last few weeks and there have been no issues regarding auxiliary electrics while driving to the supermarket once a week. As BoutTime says Ctek chargers are smart and monitor what the battery's state is before deciding what it needs to do to get the Battery fully charged. The old type chargers could easily fry a Battery if just left on charge constantly whereas once a Ctek charged Battery has reached full charge the machine knows not to keep charging and lights up the green fully charged LED, number 7 on the display. Moreover Lexus UK customer relations replied to me when I asked about using smart chargers on Hybrids and they said it was ok to used trickle chargers while cars are spending more time sitting around and not being used so much. They even sent out an email to registered Lexus owners advising the method to make sure your car's electrics are ready to go by saying turn on the car with the green ready light lit and the hybrid Battery will top up your 12 volt Battery. The engine may fire up but this is ok and it will cut in and out while charging the 12 volt Battery. The only issue is the car needs to be in the ready mode for around 60 mins. I would rather use my Ctek just to save time and not have the engine cutting in and out.

SH20 · April 22, 2020

Hi Malcolm, may I ask if you can clarify what type of Battery do you think I have in my ES300h, (Separate Post) . I am not convinced that Lexus customer relations were right when they said my ES has a AGM (Absorbent Glass Matt) type Battery . All AGM Battery videos on YouTube talking about AGM batteries show them to be sealed for life with a no spill design, no top up plugs and the letters AGM clearly showing.

My Battery has top up caps for the 6 cells and I can see the top of the electrolyte when I look down into the cells. This would suggest my 12 volt Battery is a flooded lead acid Battery and also has no markings whatsoever indicating it's AGM. This is relevant for this thread as my Ctek charger has an AGM option that can be selected but I opt not to select when I charge my 12 volt Battery.

I'm not saying Lexus don't fit AGM batteries but I'm not convinced my car has one. So if you can top up a Battery is this because it must be a flooded lead acid type Battery?

Moreover, the Battery has one clear window top up plug currently showing blue when you look down it. Blue means Battery is OK. There is a little traffic light key on a sticker on the case and if the indicator cell turns clear the Battery requires topping up , if it turns red it needs charging so if you need to top it up how can this be an AGM Battery. I would have thought Lexus would clearly mark a Battery as AGM if one was fitted. Any thoughts?

Charlie Alder · April 22, 2020

Thank you all for your replies and the advice given. Much appreciated. Live long and prosper.

malcolmw · April 22, 2020

@SH20

AGM batteries by their very design operate sealed but have safety vents which open if severely overcharged. If you can open the vents on your Battery and see electrolyte, then your Battery is a flooded type. AGM batteries operate with a "starved" electrolyte which means that the limited amount of acid is absorbed in a fibreglass mat separator (AGM = absorbent glass mat). If operated at below gassing voltage, AGM batteries remain sealed and do not lose electrolyte.

Because of the limited electrolyte, AGM batteries are generally more resistant to sulphation if left partly charged and hence why they are commonly used in hybrids.

SH20 · April 22, 2020

Thanks Malcolm for the quick response and confirmation that my Battery appears to be a flooded lead acid Battery and that whilst commonly used in Hybrids Lexus may not always use them in every Hybrid.

ColinBarber · April 22, 2020

2 hours ago, SH20 said:

Thanks Malcolm for the quick response and confirmation that my battery appears to be a flooded lead acid battery and that whilst commonly used in Hybrids Lexus may not always use them in every Hybrid.

Steve, where is the Battery location? The Prius IV has a flooded Battery where previous gens have used AGM - but the location is in the engine bay rather than boot.

CVLex · April 22, 2020

Another vote here for the CTEK MXS 5.0....great bit of kit.

SH20 · April 23, 2020

Hi Colin, the ES300h Battery is in the boot on the right hand side under the dummy floor. Rather small compared to batteries in other cars I've owned. I guess if other ES owners confirm their Battery also has top up plugs rather than a sealed unit it would suggest the ES is better served by a conventional flooded lead acid Battery unless it's all about cost. Car manufacturers are well known for costing things down to the lowest possible price when dealing with thousands of individual parts that make up a car.

BoutTime · April 23, 2020

I would imagine the main criteria for Lexus when deciding on fitting an AGM Battery to a hybrid vehicle would be the likelyhood of Battery damage/spillage into cabin during a collision. Plus potential for gases entering the cabin. So a hatchback would be treated differently to a saloon I would imagine if the Battery is in the boot.

ColinBarber · April 23, 2020

2 hours ago, BoutTime said:

So a hatchback would be treated differently to a saloon I would imagine if the battery is in the boot.

yes, although the criteria should include whether the seats fold like with the IS300h or fixed like the ES. Gases from charging are covered as some flooded batteries have a central vent which can be plumbed outside, but gases from a damaged Battery from an accident could still come through the ski hatch if open.

On the Prius IV (2016 onwards) they have moved the Battery back to the engine bay, and flooded - plus made it a little larger compared to the previous generation.

bobjol · April 23, 2020

Hi guys,

Hope I'm not too late to contribute to this post. I've

had 2 flat batteries since just before Lockdown. Car only used a couple of times recently and high capacity Battery fitted less than a year ago.

Friend suggested that Battery drain may be due to Smart Key system, where car is constantly sending out signals to detect Smart Key. Car handbook says that

the Smart Key system should be disabled if vehicle not in use for long period. Unable to find the button to disable the Smart Key system. Can anyone suggest any remedies to this problem ?

ColinBarber · April 23, 2020

you will probably need to get your head in the footwell and look up - similar position to the tyre pressure reset switch on other Lexus vehicles which people struggle to find just by feeling about.

Malc · April 24, 2020

14 hours ago, bobjol said:

Smart Key system,

seems an amazingly " unsmart " system to me ..... oh for the joys of pre high-tec gizmos that bring woe to the beholder

Malc

ColinBarber · April 24, 2020

7 hours ago, Malc said:

seems an amazingly " unsmart " system to me ..... oh for the joys of pre high-tec gizmos that bring woe to the beholder

Malc

Newer system in current vehicles have an auto cutoff after 10 days of no activity. Not sure how much power it actually draws, not that much really I suspect.