Some of these jump starters have a button that you press when the battery is completely flat and it can't recognise that a battery is connected.
Jump start power packs - any advice?
- Thread starter UFO
- Start date
Some of these jump starters have a button that you press when the battery is completely flat and it can't recognise that a battery is connected.
Hi. I am intrigued by the use of super capacitors to start a car. The link below shows a guy starting a 4 cycl petrol engine with 6 x "D" size supercaps in series, I think that its pretty impressive. From what I can gather the very low internal resistance of supercaps, allows the high current flow to the starter motor. Whereas lead acid batteries have higher internal resistance.
I have seen other articles where a smaller 12 battery is wired in parallel with the bank of supercaps to compensate for their discharge and to keep them topped up. I am surprised that portable battery starter manufacturers havent applied this technology to products.
I have seen other articles where a smaller 12 battery is wired in parallel with the bank of supercaps to compensate for their discharge and to keep them topped up. I am surprised that portable battery starter manufacturers havent applied this technology to products.
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Thanks for that. I have an SJS branded unit. Had to read the fine print to discover that it does in fact have such a button. The quick start guide doesn't mention it. The button itself is recessed, so just feeling for a protruding button doesn't help.
I must say it is a relief to discover said button - I had been thinking that the jumper pack was a bit of a white elephant, but I was able to use it to start a car with a totally dead battery this morning.
Well thats a good bit of kit. Being capacitor based, it can use some current from a "flat" battery to charge the caps, then being able to deliver the "concentrated" current in the half a second or so needed to run the starter motor. I'm still impressed that it works so easily.
In the U-tube link i posted above, the guy had removed the lead/acid battery from his car and replaced it with a bank of supercaps. So I can only assume that in normal driving, that providing the alternator could provide for all current demands made of it, it would be fine. The Achilles heal would be on the occasions when the total demand from the alternator was more than it's output and a lead/acid storage battery could make up the deficit.
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SJS are decent units... and the latest gen have decent clamps...
Something to look out for when shopping around for these... they can claim as many cca as they want but if the clamps aren't decent you simply won't get the contact to meet the spec...
So good clamps are really important...
I ve managed to start a 4.2 diesel with the sjs1200 and a Bentley with remote battery connectors...
Very underrated and carry some serious punch...
Also for those using these its really important to disconnect the pack from battery asap after car starts...
Cheers
Dino
Hi Whippet
Actually the car always runs on the alternator normally. The battery is only for starting and to provide lights if stopped on the road side. That is why modern cars have BIG alternators and sometimes pissy little batteries. Although that is changing with 'smart' ecu controlled charging and extra braking. The days of a 30A alternator went many years ago, a 70A is probably the smallest now and 110A on family cars. Bigger on others.
That u-tube setup would probably not comply with Australian ADRs on battery capacity for emergency lights. Even electric cars have to have the minimum specified from a seperate battery
Jaahn
I bought one of those small portable jump starters off eBay. Cost under $70 and works well. Is about 2-3 times the size of a mobile phone. If it lasts 5yrs or so, I’d be annoyed, but figure it’s been worth it.
I still prefer jumperleads that live in the car (I know they'll work if I need them). I find I'm usually the one that is asked when anyone needs a jump start..... Generally people look around for the shittiest/oldest car in the carpark .... and go ask that person if they have jumperleads (which invariably means they ask me if I'm there!). Everyone must figure the one with the oldest car will have tools onboard.
Hi Dino, May I ask why?
A number of reasons...
First... its a starting device... not charging.
Once the device has achieved its primary objective... it should be switched off and removed.
Remember, once the car is running and depending on alternator set up... there will be a charging voltage to the battery... ie. Lithium packs are designed to be charged via the charging port at specific rate... not by a cars alternator...
Second, on most cars the jump starter pack has to be placed somewhere where its secure as the car starts and possibly shakes while starting or running... leaving the starter in the engine bay longer than needs increases the chance of unit slipping and possibly hitting a cooling fan or clamps coming off and contacting sensitive electronics... just no need for the increased risk...
Car starts... remove unit. Done. Alternator will do the rest.
Cheers
Dino
While the potential to jump into the wrong place is certainly real, my SJS unit electronically disconnects the moment the engine starts, thus protecting itself from alternator current (& voltage).
This also means there is no danger of a short if the alligator clamps get shaken off the battery and contact something that they shouldn't.
This also means there is no danger of a short if the alligator clamps get shaken off the battery and contact something that they shouldn't.
With all advice, I hope UFO is able to make an informed choice. Craig let us know what you decided. Twoud be interesting to find out.
Ken
Ken
Yes... the reverse charging protection is there... but its a protection that imo shouldn't be relied on once the engine is running... even the instructions (and you ll find this is the case with most units on the market) state that unit should be disconnected IMMEDIATELY...
Cheers
Dino
Yeah well, it's a bit like trying to see my car's brake lights - I press the pedal, but just can't run fast enough to see if the brake lights are actually working.
Unless I have an assistant, then the jumper start pack will just have to wait while I get out of the driver's seat and walk around to the front of the car. I don't do IMMEDIATELY!!
Unless I have an assistant, then the jumper start pack will just have to wait while I get out of the driver's seat and walk around to the front of the car. I don't do IMMEDIATELY!!
yeahhh... but thats why I said ASAP... I think thats probably what they mean... I just dont think they want people having a cup of coffee after the car has started...
The reason I mention it is because I m aware of one instance where the porsche owner used the starter to start the car and then just left it running with the starter connected... the clamps overheated from initial cranking and the am not sure whether reverse charging protection failed or not... but yeahh... melted plastic around clamp and hugely overheated positive cable...
common sense... not always very common...
cheers
dino
there are some very special people out there... I had to chase up a replacement cable for a wall mounted trickle charger because the owner didnt disconnect as they drove out of their garage...at least he was honest... and surprisingly wasnt a porsche owner... we all stuff up sometimes...
But on a serious note... my biggest issue with the packs is that under the bonnet of some cars its a real struggle finding a spot where the pack can sit without sliding or falling down... and its not like cars have a special area to place the starter pack... I just think its best to err on caution and remove from under bonnet of running engine asap... this is probably why i m so biased towards units with strong clamps as often this is the only thing stopping them sliding away under cranking conditions... sjs clamps are top notch considering size...
cheers
dino
Well I had to use my old jumper leads this afternoon, Mrs Whippet was driving her elderly father to a medical appointment in his vehicle, Staccato clicking, engine wouldn't crank. Phone call, locate old jumper leads and drive down, get an adjacent park. So I had to locate the battery in my work car. Well I'm embarrassed to admit, but I have hardly opened the bonnet on the vehicle, and soon discovered there was no battery under the bonnet, but conveniently there are two points to connect jumper leads onto in the engine bay. I made these jumper leads many years ago when a diesel apprentice, like many others described above, larger cross section cable with decent clamps, adequate length, still worked fine. Brownie point credit.
its not a bad idea having the remote contact points... dont have to worry which way the car is facing... but i think you ll find the BMW will have its rather large battery in the boot...
Cheers
Dino