Just had to jump start my pal's car again - I'm pretty sure he's got a parasitic drain problem but it's a big, fairly modern, luxury make and he doesn't want me "messing" with it. That's Ok by me - if I get something wrong it could end up with a very big bill! but he needs to see an auto electrician or competent dealer. So I was sitting on my garden bench this afternoon in the lovely warm sunshine, just like yesterday, which has been the first time it's been realistic this year without freezing, and I got to thinking that I've done a number of jump starts for family, friends and neighbours this winter - more than usual it seems to me? My perception is that modern cars with their EFB batteries seem to suffer more failures than the old cars with normal flooded batteries? Also, these EFB batteries seem to "fall off the cliff edge" to a far greater extent than the old type batteries?
So, having had that thought, I was then thinking "I'm finding it hard to lug my jump batteries around these days". As I've mentioned before, I have a medium sized battery out of my boy's Punto and a much bigger one taken from my SEAT Cordoba 1.9 diesel when I scrapped her. The Cordoba battery is a 77Ah jobbie and not something you can carry very far. On the other hand it packs quite a punch and has no problem cranking larger cars like my friend's. Trouble is he lives in the next street so I don't want to start my car just to run it for 5 minutes so I carry the battery round to his, but I'm pretty much done by the time I get there - he carried it back by the way. So I need a lighter solution and, ideally, something which can live in the car all the time. - It's not really a good idea to be carrying a large lead acid battery around in the boot all the time "just in case"!
So, I'm thinking again (I've mentioned these in the past) about a jump pack. What comes to mind at first is a battery based pack. These come in all sorts of sizes with traditional lead acid or Li Ion and other types of battery. They all have one particular problem, You've got to remember to keep them charged! There's also the problem that the batteries degrade with time and there are many reports of them becoming reduced in capacity and next to useless within around 3 to 4 years of purchase - I think the hybrid batteries last longer than the traditional lead acid type but they're all unusable if you don't keep them charged.
With all this in mind I've been looking at ultra (some call them "super") capacitor devices which are carried discharged and charged up over just a few minutes using what little charge is left in your vehicle battery (or the battery in another vehicle). These devices are a relatively new arrival on the motoring "scene" and I've been contacting manufacturers and retailers for information as well as scouring the internet more generally. These are pretty clever devices so here's what I understand about them so far. The pack itself contains no battery in the traditional sense (although there are hybrid devices which contain a small battery specifically to charge the capacitors. However they still have the problem that they require regular charging) So, the type which attracts me most contains a bank of five or six Ultra capacitors controlled by some smart electronics. They have two main leads with battery clamps - just like jump leads - which clamp to the car's battery (red to positive and black to negative). Next thing to understand is that most "flat batteries" are not in fact "flat" but just discharged to the point where they don't have enough oomph to turn the engine over - typically around 10 to 11 volts. So there's actually a lot of electricity still available in that battery, just not enough to crank the engine - starter motors need a lot of current. Now, from what I've understood so far, each capacitor is rated at 2.7 volts so, when first connected to the vehicle battery, the "clever" electronics connects the capacitors in parallel. Now with each capacitor rated at 2.7 volts they will very happily charge up fully under the influence of the voltage still available in the battery. Most seem to take about 5 minutes to fully charge but it varies. Then, when fully charged the electronics connect the capacitors in series so that's going to be 13.5 volts for the string of 5 capacitors and 16.2 for the units which use 6 caps. (in practice the six string devices are limited to 15 volts by the electronics) which gives plenty of current to turn the engine over for long enough for it to start - as long as there's not some other technical or mechanical reason why it's not starting in the first place. If the vehicle battery is under about 5 volts then you're stuffed because it can't charge the caps with this low a supply voltage. However most of the time it's going to work as battery voltage is not that low very often unless the vehicle has been left standing for a very long time - and maybe, in that case, a new battery is going to be the best option anyway as it's going to be needed due to the original battery being sulphated.
Here's an add for one of the more popular units available in the UK:
There are others if you look. Autowit is a popular one in the US which sometimes turns up over here too:
I thought I'd finish by saying, in my experience, as long as you are very careful about making your connections correctly ie, positive on jump pack/slave battery to positive on vehicle battery and neg to neg - I always connect the negative to chassis/engine block not directly to battery terminals as is now recommended by most manufacturers, then you're unlikely to have problems - but not guaranteed to be "safe" so you just need to be aware there's always a risk when jump staring of doing serious and expensive damage, especially if you're inexperienced - for instance connecting a well charged slave battery to a mostly discharged vehicle battery will likely produce a spark due to the difference in potential voltage between the two, so always make your final earth connection to the engine block or chassis earth well away from the battery. Most risky of all is to do it the "traditional way" by which I mean car to car using jump leads. Connecting the battery from one car to another in the "traditional" way is effectively connecting together the electronics in one vehicle to the other and they may not be compatible so is very risky. If you really have to do it then make sure the car's bodywork is not touching the other vehicle and DO NOT RUN BOTH CAR ENGINES AT THE SAME TIME. So, if you really must, with both engines off, connect the jump leads up pos on donor car to pos on flat battery then neg on donor to neg (chassis/engine casting) on flat car and try starting the flat car. On no account even turn the key in the donor vehicle and certainly don't run it's engine. With both batteries connected and both engines running the ecu's controlling the charging current in either/both vehicles can become "confused" and may spike the supply voltage thus ruining electronic control units - and that can be hideously expensive. I just don't do it. Either use a jump pack or, like I have been doing for years, use a slave battery. Even then you need to be very careful to make good and correct connections. Just remember batteries produce highly flamable hydrogen and oxygen gasses when working and they will produce it in quite large quantities when they've been working hard, as they will when trying to start an engine. So sparks from making connections are always unwelcome and you can make sparking worse by being "silly" when making connections. Jump packs are pretty good in this respect because they usually require you to press a button before heavy current can be passed. It's also worth mentioning that some vehicles, Honda was always a favourite, are very sensitive to messing about with their batteries and can lock you out of the ignition inhibitor if the key is left in the ignition when a battery is disconnected - and expensive dealer visit will be needed to recode the key. So, unless you need to run the vehicle engine I'd always keep any key well away from the donor car when trying to start the vehicle with the flat battery.
So, with all this in mind, I'll say again that I just don't do car to car jumping any more and I'd advise you not to either. Using a slave battery has many attractions because a slave will give you a good long, or multiple short, periods of cranking - but you need to be very careful connecting your cables because of the risk of sparks. All in all a jump pack is probably the safest and very convenient for keeping in the vehicle but, if battery powered needs to be charged from time to time. I've made up my mind I'm going to go with a capacitor type jump starter and I'm in the final stages of deciding which one to opt for. Should be able to confirm my choice this coming week.
I'll just finish by saying again that messing about attempting a jump start is not a very safe activity, especially for the inexperienced. The things I've talked about above have worked for me but may not for you so if you give it a go and it all goes pear shaped don't say I didn't warn you to leave well alone.
So, having had that thought, I was then thinking "I'm finding it hard to lug my jump batteries around these days". As I've mentioned before, I have a medium sized battery out of my boy's Punto and a much bigger one taken from my SEAT Cordoba 1.9 diesel when I scrapped her. The Cordoba battery is a 77Ah jobbie and not something you can carry very far. On the other hand it packs quite a punch and has no problem cranking larger cars like my friend's. Trouble is he lives in the next street so I don't want to start my car just to run it for 5 minutes so I carry the battery round to his, but I'm pretty much done by the time I get there - he carried it back by the way. So I need a lighter solution and, ideally, something which can live in the car all the time. - It's not really a good idea to be carrying a large lead acid battery around in the boot all the time "just in case"!
So, I'm thinking again (I've mentioned these in the past) about a jump pack. What comes to mind at first is a battery based pack. These come in all sorts of sizes with traditional lead acid or Li Ion and other types of battery. They all have one particular problem, You've got to remember to keep them charged! There's also the problem that the batteries degrade with time and there are many reports of them becoming reduced in capacity and next to useless within around 3 to 4 years of purchase - I think the hybrid batteries last longer than the traditional lead acid type but they're all unusable if you don't keep them charged.
With all this in mind I've been looking at ultra (some call them "super") capacitor devices which are carried discharged and charged up over just a few minutes using what little charge is left in your vehicle battery (or the battery in another vehicle). These devices are a relatively new arrival on the motoring "scene" and I've been contacting manufacturers and retailers for information as well as scouring the internet more generally. These are pretty clever devices so here's what I understand about them so far. The pack itself contains no battery in the traditional sense (although there are hybrid devices which contain a small battery specifically to charge the capacitors. However they still have the problem that they require regular charging) So, the type which attracts me most contains a bank of five or six Ultra capacitors controlled by some smart electronics. They have two main leads with battery clamps - just like jump leads - which clamp to the car's battery (red to positive and black to negative). Next thing to understand is that most "flat batteries" are not in fact "flat" but just discharged to the point where they don't have enough oomph to turn the engine over - typically around 10 to 11 volts. So there's actually a lot of electricity still available in that battery, just not enough to crank the engine - starter motors need a lot of current. Now, from what I've understood so far, each capacitor is rated at 2.7 volts so, when first connected to the vehicle battery, the "clever" electronics connects the capacitors in parallel. Now with each capacitor rated at 2.7 volts they will very happily charge up fully under the influence of the voltage still available in the battery. Most seem to take about 5 minutes to fully charge but it varies. Then, when fully charged the electronics connect the capacitors in series so that's going to be 13.5 volts for the string of 5 capacitors and 16.2 for the units which use 6 caps. (in practice the six string devices are limited to 15 volts by the electronics) which gives plenty of current to turn the engine over for long enough for it to start - as long as there's not some other technical or mechanical reason why it's not starting in the first place. If the vehicle battery is under about 5 volts then you're stuffed because it can't charge the caps with this low a supply voltage. However most of the time it's going to work as battery voltage is not that low very often unless the vehicle has been left standing for a very long time - and maybe, in that case, a new battery is going to be the best option anyway as it's going to be needed due to the original battery being sulphated.
Here's an add for one of the more popular units available in the UK:
There are others if you look. Autowit is a popular one in the US which sometimes turns up over here too:
I thought I'd finish by saying, in my experience, as long as you are very careful about making your connections correctly ie, positive on jump pack/slave battery to positive on vehicle battery and neg to neg - I always connect the negative to chassis/engine block not directly to battery terminals as is now recommended by most manufacturers, then you're unlikely to have problems - but not guaranteed to be "safe" so you just need to be aware there's always a risk when jump staring of doing serious and expensive damage, especially if you're inexperienced - for instance connecting a well charged slave battery to a mostly discharged vehicle battery will likely produce a spark due to the difference in potential voltage between the two, so always make your final earth connection to the engine block or chassis earth well away from the battery. Most risky of all is to do it the "traditional way" by which I mean car to car using jump leads. Connecting the battery from one car to another in the "traditional" way is effectively connecting together the electronics in one vehicle to the other and they may not be compatible so is very risky. If you really have to do it then make sure the car's bodywork is not touching the other vehicle and DO NOT RUN BOTH CAR ENGINES AT THE SAME TIME. So, if you really must, with both engines off, connect the jump leads up pos on donor car to pos on flat battery then neg on donor to neg (chassis/engine casting) on flat car and try starting the flat car. On no account even turn the key in the donor vehicle and certainly don't run it's engine. With both batteries connected and both engines running the ecu's controlling the charging current in either/both vehicles can become "confused" and may spike the supply voltage thus ruining electronic control units - and that can be hideously expensive. I just don't do it. Either use a jump pack or, like I have been doing for years, use a slave battery. Even then you need to be very careful to make good and correct connections. Just remember batteries produce highly flamable hydrogen and oxygen gasses when working and they will produce it in quite large quantities when they've been working hard, as they will when trying to start an engine. So sparks from making connections are always unwelcome and you can make sparking worse by being "silly" when making connections. Jump packs are pretty good in this respect because they usually require you to press a button before heavy current can be passed. It's also worth mentioning that some vehicles, Honda was always a favourite, are very sensitive to messing about with their batteries and can lock you out of the ignition inhibitor if the key is left in the ignition when a battery is disconnected - and expensive dealer visit will be needed to recode the key. So, unless you need to run the vehicle engine I'd always keep any key well away from the donor car when trying to start the vehicle with the flat battery.
So, with all this in mind, I'll say again that I just don't do car to car jumping any more and I'd advise you not to either. Using a slave battery has many attractions because a slave will give you a good long, or multiple short, periods of cranking - but you need to be very careful connecting your cables because of the risk of sparks. All in all a jump pack is probably the safest and very convenient for keeping in the vehicle but, if battery powered needs to be charged from time to time. I've made up my mind I'm going to go with a capacitor type jump starter and I'm in the final stages of deciding which one to opt for. Should be able to confirm my choice this coming week.
I'll just finish by saying again that messing about attempting a jump start is not a very safe activity, especially for the inexperienced. The things I've talked about above have worked for me but may not for you so if you give it a go and it all goes pear shaped don't say I didn't warn you to leave well alone.
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