jump start from is300h

lex3 · August 4, 2020

My wife's Renault Clio has a dead Battery and won't start. Should I connect jump leads to the 12v Battery in my boot and attempt to start the car from my Battery?

Ianj

royoftherovers · August 4, 2020

5 minutes ago, lex3 said:

My wife's Renault Clio has a dead battery and won't start. Should I connect jump leads to the 12v battery in my boot and attempt to start the car from my battery?

Ianj

Any advice in your Handbook Ian as some people here will say NO and at least one other will tell you YES ?

I would tell you NO.

Herbie · August 4, 2020

NO, NO and thrice NO!

The reason for this is that a conventional car uses the Battery to crank the engine and will draw 300A or more to do this. Once the engine is running then the alternator takes over the role of supplying all the car's electrical needs, so a car with a flat Battery will draw on the donor car's alternator, not it's Battery.

Hybrids don't have starter motors or alternators and take much, much less current to get our cars started, in fact less than 20A.

Our equivalent of an alternator is the DC/DC converter and because it doesn't need to spin a conventional starter motor it was never designed to supply the amount of current that an alternator does. If you tried to pull, say, 300A from it, hopefully some current-limiting circuitry will prevent it but if not, there's likely to be a huge bang, lots of smoke and a badly-dented wallet.

It may - and I do stress may - be ok to jump start your wife's car from your hybrid if you do not have your car in READY mode, or even switched on at all.

However, in your shoes, I would just take your Battery out, carry it over to your wife's car and then stick jump leads on it there, so no risks are taken at all.

lex3 · August 4, 2020

Thank you both, I was a bit dubious about jumpstarting from my precious IS300h but needed a word from the experts - thanks!
I like the idea of removing my Battery and connecting leads to my wife's. I'm guessing that will not harm my Battery?
You've both helped my decision, thanks again!

Ianj

Herbie · August 4, 2020

2 minutes ago, lex3 said:

I like the idea of removing my battery and connecting leads to my wife's. I'm guessing that will not harm my battery?

Not in the short term, no. But do remember that the 12V batteries in hybrids are only small and don't have much capacity, so don't leave it for an hour in a bid to sort of 'charge up' your wife's Battery or your's may well end up flat too. Just connect it and get the Clio fired up as soon as you can and everything will be fine.

5 minutes ago, lex3 said:

You've both helped my decision, thanks again!

You're very welcome Ian. There tends to be some helpful characters in here so never be frightened of asking for help and advice :thumbsup:

200h · August 4, 2020

i have a spare car Battery in the garage and if i ever need it i know its ready to be used

i bought it back in 2016 when my Battery went flat on my IS due to my car not being used for 3 weeks

in winter its nice to have a get out of jail card to play if needed

Hadrian · August 6, 2020

On 8/4/2020 at 9:02 PM, 200h said:

i have a spare car battery in the garage and if i ever need it i know its ready to be used

i bought it back in 2016 when my battery went flat on my IS due to my car not being used for 3 weeks

in winter its nice to have a get out of jail card to play if needed

I do something similar. I keep a couple of retired batteries topped up for emergencies.

Herbie · August 6, 2020

Rather than having a spare full-size old Battery in the garage, which would be no good if your Battery went flat while you were away from home somewhere, I carry a jump start battery pack similar to this one in the glovebox.

They're brilliant little things, worth their weight in gold just for peace of mind alone, they work fantastically well and they're so convenient to have handy if/when you or someone else needs a jump start - highly recommended.

PCM · August 7, 2020

9 hours ago, Herbie said:

Rather than having a spare full-size old battery in the garage, which would be no good if your battery went flat while you were away from home somewhere, I carry a jump start battery pack similar to this one in the glovebox.

They're brilliant little things, worth their weight in gold just for peace of mind alone, they work fantastically well and they're so convenient to have handy if/when you or someone else needs a jump start - highly recommended.

+1

And they DO work.

Used one on my wife's 3.5L Lexus...

royoftherovers · August 7, 2020

9 hours ago, Herbie said:

Rather than having a spare full-size old battery in the garage, which would be no good if your battery went flat while you were away from home somewhere, I carry a jump start battery pack similar to this one in the glovebox.

They're brilliant little things, worth their weight in gold just for peace of mind alone, they work fantastically well and they're so convenient to have handy if/when you or someone else needs a jump start - highly recommended.

And following many of Herbie`s numerous "sales pitches£, I have now bought one too !

https://www.amazon.co.uk/gp/product/B083NVVXV2/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

matt8 · August 7, 2020

12 hours ago, Herbie said:

Rather than having a spare full-size old battery in the garage, which would be no good if your battery went flat while you were away from home somewhere, I carry a jump start battery pack similar to this one in the glovebox.

They're brilliant little things, worth their weight in gold just for peace of mind alone, they work fantastically well and they're so convenient to have handy if/when you or someone else needs a jump start - highly recommended.

I'm sure they work well when they do.

But a Battery left in the glove compartment unused will be dead when you really need it the most.

I looked into these battery-less starters but they aren't suitable for hybrids (as the hybrid doesn't crank):

https://www.manomano.co.uk/p/sealey-e-start800-electrostart-batteryless-power-start-800a-12v-3098531

I want a solution but am not yet convinced the ones you mention Herbie will be useful when I need it the most.

My approach thus far has been to trickle charge the Battery if I haven't driven it for a while.

royoftherovers · August 7, 2020

Oh ye of little faith Matt !

matt8 · August 7, 2020

14 minutes ago, royoftherovers said:

Oh ye of little faith Matt !

Understandably though?

We're trying to solve a problem (the flaw of batteries discharging) with you guessed it... Batteries!

I worry about lithium ion batteries being left in the extreme heat and extreme cold of a car. I can't think that they'll retain their charge very long, neither will their lifespan be significant with the extreme temperatures and constant heating and cooling (or constant cold in the winter).

I'll keep trickle charging for now I think. But always open to new ideas and better ways!

Barry14UK · August 7, 2020

Surely the proof of the pudding is in the eating when it comes to using these jump start devices on our hybrid cars. Theoretically they should should work and only need charging very occasionally. It would be helpful therefore, if a few members could confirm they have actually used them successfully and without damage to their cars. I believe one person has done so but we have learnt that one person 'got away' with using his 12v Battery to start another car whilst still on his car which is not recommended. So I would be more happy to know that the start device had been used more than once.

royoftherovers · August 7, 2020

4 minutes ago, Barry14UK said:

Surely the proof of the pudding is in the eating when it comes to using these jump start devices on our hybrid cars. Theoretically they should should work and only need charging very occasionally. It would be helpful therefore, if a few members could confirm they have actually used them successfully and without damage to their cars. I believe one person has done so but we have learnt that one person 'got away' with using his 12v battery to start another car whilst still on his car which is not recommended. So I would be more happy to know that the start device had been used more than once.

Surely Barry, it is the contents of the Handbook (if any) rather than the anecdotal experience of a small number of drivers who have not had any problems, which should carry the day That is, until such times as the Handbook is changed on the basis of empirical evidence ?

royoftherovers · August 7, 2020

1 hour ago, matt8 said:

Understandably though?

We're trying to solve a problem (the flaw of batteries discharging) with you guessed it... Batteries!

I worry about lithium ion batteries being left in the extreme heat and extreme cold of a car. I can't think that they'll retain their charge very long, neither will their lifespan be significant with the extreme temperatures and constant heating and cooling (or constant cold in the winter).

I'll keep trickle charging for now I think. But always open to new ideas and better ways!

I see that a wise man who can be open to new ideas based upon empirical evidence lurks within you Matt !

Take care.

Herbie · August 7, 2020

2 hours ago, matt8 said:

I'm sure they work well when they do.

But a battery left in the glove compartment unused will be dead when you really need it the most.

I looked into these battery-less starters but they aren't suitable for hybrids (as the hybrid doesn't crank):

https://www.manomano.co.uk/p/sealey-e-start800-electrostart-batteryless-power-start-800a-12v-3098531

"Batteryless" can only mean one thing - it uses capacitors instead. But the capacitors have to be charged from something and they won't hold charge as long as a proper Battery does anyway.

As such, I can only imagine that they are a complete waste of (a lot of) money and although they are indeed suitable for hybrids (why would you think they aren't?), I wouldn't waste money on one.

The Battery packs that I and many others use are just that, batteries, and as such yes, they do need to be kept topped-up but they do hold their charge very well. The last time I charged mine was six months ago and I've just been prompted by this very topic to go and look, and it still has somewhere between 75 and 50% charge left, with three lights out of four still lit up.

This is still good enough to start two or perhaps even three or four conventional cars, assuming that they fire first time and nothing else is wrong except a flat Battery. If there's another problem and it requires more cranking then obviously that will affect things.

I would imagine that when talking about starting hybrids, that same 75 to 50% charge level will start a dozen or more cars.

As I've said many times, a conventional starter motor will draw more than 300A to crank a conventional engine, but to get my RX450h into READY mode (the equivalent) it takes less than 20A. And even that is only inrush current for a fraction of a second which almost immediately starts to fall, so it will take very, very little from a jump start Battery pack.

Another thing I've often said is that hybrids take so little current to get the systems up, they could be 'started' with a pack of 8 AA batteries - the discharge curves indicate that they could supply around 28A for up to one minute.

Herbie · August 7, 2020

1 hour ago, Barry14UK said:

It would be helpful therefore, if a few members could confirm they have actually used them successfully and without damage to their cars.

I've never had to use it on a hybrid yet but I can say that I've used it to start three different conventional cars and my little unit worked flawlessly, so I have utmost confidence that it'll do the same for me if I ever need to use it.

matt8 · August 7, 2020

34 minutes ago, Herbie said:

"Batteryless" can only mean one thing - it uses capacitors instead. But the capacitors have to be charged from something and they won't hold charge as long as a proper battery does anyway.

As such, I can only imagine that they are a complete waste of (a lot of) money and although they are indeed suitable for hybrids (why would you think they aren't?), I wouldn't waste money on one.

The battery packs that I and many others use are just that, batteries, and as such yes, they do need to be kept topped-up but they do hold their charge very well. The last time I charged mine was six months ago and I've just been prompted by this very topic to go and look, and it still has somewhere between 75 and 50% charge left, with three lights out of four still lit up.

This is still good enough to start two or perhaps even three or four conventional cars, assuming that they fire first time and nothing else is wrong except a flat battery. If there's another problem and it requires more cranking then obviously that will affect things.

I would imagine that when talking about starting hybrids, that same 75 to 50% charge level will start a dozen or more cars.

As I've said many times, a conventional starter motor will draw more than 300A to crank a conventional engine, but to get my RX450h into READY mode (the equivalent) it takes less than 20A. And even that is only inrush current for a fraction of a second which almost immediately starts to fall, so it will take very, very little from a jump start battery pack.

Another thing I've often said is that hybrids take so little current to get the systems up, they could be 'started' with a pack of 8 AA batteries - the discharge curves indicate that they could supply around 28A for up to one minute.

Indeed they use capacitors. From my understanding, you connect the pack to the Battery and it draws power slowly into the capacitors (a couple of minutes), ready to unleash it when you begin to start (crank) the car. Although the energy is available in the Battery, it cannot deliver it in a sufficiently short space of time to crank the starter motor. The capacitor stores it and delivers it in a way the depleted Battery cannot.

They do not work in hybrids because the engine is not cranked in order to start. It draws the power in the same way the capacitors would attached to battery-less jump pack. Therefore, it makes no difference filling up the capacitors.

Someone else may explain this more elegantly than me, but I'd choose a capacitor jump start pack over a Battery one. Of course a capacitor one would be useless if the Battery was truly flat, but that is unlikely in a conventional car.

Herbie · August 7, 2020

4 minutes ago, matt8 said:

Indeed they use capacitors. From my understanding, you connect the pack to the battery and it draws power slowly into the capacitors (a couple of minutes), ready to unleash it when you begin to start (crank) the car. Although the energy is available in the battery, it cannot deliver it in a sufficiently short space of time to crank the starter motor. The capacitor stores it and delivers it in a way the depleted battery cannot.

They do not work in hybrids because the engine is not cranked in order to start. It draws the power in the same way the capacitors would attached to battery-less jump pack. Therefore, it makes no difference filling up the capacitors.

Someone else may explain this more elegantly than me, but I'd choose a capacitor jump start pack over a battery one. Of course a capacitor one would be useless if the battery was truly flat, but that is unlikely in a conventional car.

Aha, now I understand how it works.

Yes, I agree that initially it seems better than a Battery pack but in reality it's probably only a 'one-shot' idea.

A Battery pack will allow multiple crank attempts at, say, about 4 seconds per crank, so plenty of time to pressurise fuel lines etc. The capacitors in that other unit are only acting as a short-term storage of electricity and they may discharge quicker than four seconds. I wonder if there's also a limit to the amount of times current could be shunted from Battery to capacitors and back again with a failing Battery, thereby limiting the time per crank and/or crank attempts?

I'll stick with my Battery pack :thumbsup:

Thackeray · August 7, 2020

4 hours ago, matt8 said:

I'm sure they work well when they do.

But a battery left in the glove compartment unused will be dead when you really need it the most.

A couple of years ago I bought a DBPower DJS40, It was £20 when I bought it but I have the impression that these devices have rocketed in price since a side-effect of coronavirus lockdown has been hundreds of flat car batteries. Herbie says he bought one that was more powerful than he needed so that he could help other people in cars with big engines - I'm afraid I didn't even think of this and bought the cheapest!

It has spent the last two winters in the glove box of the car. After the first winter I checked the charge and it was still on 100%. I plugged it in to charge for a bit anyway and left it for the next winter. In the second spring it was still on 100%.

I don't know anything about Battery technology but I'm not sure there's any reason to assume that a Battery is going to run down, depending on its chemistry, just because it's not being used. I had a pocket calculator which had been bought in 1976. Come 2016, wouldn't you know it, the Battery ran out. I decided not to complain as 40 years on one Battery didn't seem too bad.

As for whether the device works when you need it, my car has never failed to start, so like all those annoying reviewers on amazon all I can say about whether it works or not is "Sorry I haven't tried it."

However, during lockdown reading my tablet in the garden it occurred to me I could use the charger to keep the tablet charged up to save going inside. It supplies 2.1A at 5V on its USB output. So that was fine and charged up my tablet. To start a car it supplies 300 A at 12V and has a capacity of 8Ah - that compares with the actual car Battery of 45Ah but a fraction of the size.

Here's a demo of this model being used to start a three litre car.