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Would it work / how sensible would it be, to make an optimate to Optimate lead as a jump lead?

Situation is 2 DCT bikes travelling together (so no option of push starts) (traveling so chargers not ideal) both bikes have female optimate pig tail leads, so how about a male to male lead in the event of a problem to use as a jump lead?

Thinking of https://www.that auction site.co.uk/itm/2x-Connector-Adapter-Plug-Socket-Male-Female-Optimate-Accumate-Battery-Charger/112411299284?epid=2100084807&hash=item1a2c3c4dd4:g:CH8AAOSwjqVZHXI~ plus some cable.

Edited by New

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Andy m

It'll work but the cable needs to be big enough. As a charger it uses single figure currents through double digit rated cable. Jump leads of your standard crocodile clip type will do hundreds of amps as with bad connections, damp etc. that's what they might see locally. 

 

If the plan is to connect the two batteries together, wait until the charge levels settle and then disconnect before starting it gets a whole lot safer. Fit a fuse that matches the cable and plug rating. 

 

Andy

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rogersavery

dont do this - there will be no resistance to the current flow and you will burn out the cables and possibly set fire to both bikes. You could add a fuse, but it will blow as soon as you connect the batteries.

 

you will need to put a current limiting device between the 2 batteries, something like this: https://www.that auction site.co.uk/p/Draper-12v-DC-Vehicle-to-Vehicle-Booster-C2cb-46544/1734008432?iid=292490131420

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SteveThackery
Posted (edited)
1 hour ago, rogersavery said:

dont do this - there will be no resistance to the current flow and you will burn out the cables and possibly set fire to both bikes. You could add a fuse, but it will blow as soon as you connect the batteries.

 

What?  Why on earth would that happen?  I do this frequently, and in fact I jump started a car just a couple of weeks ago like this.

I simply connect the good battery across the flat battery, then start.  A flat battery doesn't take much current at all to raise its terminal voltage to that of a good battery, so of course some current will flow as the flat battery begins to charge off the good one, but not very much.  Single figure amps, for sure.

 

You need to raise the terminal voltage much higher (14.4V typically) to push a lot of current (tens of amps) into a flat battery, and that's way above what a fully charged lead acid battery can deliver (I've got one in my garage - last topped up a couple of days ago; the terminal voltage is 12.76V).

 

Having said that, I don't know how much current that Optimate cable will handle, but it won't be much.  If you do try to use it as a jump lead, operate the starter for very short bursts so the cables don't get too hot.

Edited by SteveThackery

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embee
Posted (edited)

 

If this is for a specific case not a general thing, then as long as you understand what you are doing it could save the day. However, as said by others, a bike starter could take perhaps 100A as a surge current, probably more like 50A continuous (I'm guessing, but 1kW is a decent sized starter motor so a medium bike unit would probably be more like 600W as my guess). 

If you rated the wiring for 50A continuous, that'd be around 6mm^2, that's not ridiculous.

 

You would need the connectors to be able to cope with it, not sure what the Optimate ones would tolerate for short bursts, the modern genuine ones are reasonably good quality and robust but 50A would probably stress them quite a bit. The ones in the link would be of no use I'm afraid. As said, if it was for emergencies and you knew exactly what you were doing you could probably get away with it briefly. A way round it would be a bigger connector on each bike, and a smaller adapter lead to be able to plug in the Optimate. For example https://www.gsparkplug.com/durite-connector-2-pole-high-current-red-50-amp-bg1-0-432-05.html

To jump the 2 bikes take the adapter lead out and fit the link lead to the big connectors. You would have to make sure the leads could only possibly connect one way round, 2 batteries looped in series would make a good fireworks display.

 

This is getting quite close to just using jump leads.

 

If you need to jump one bike from another (I've been involved in several incidences of folk doing it), then always start the donor bike, connect the jump leads, positives first then connect the negatives together, and run the donor at a couple of thou revs for  a few minutes to get some charge into the receiver battery. STOP the donor engine then try to start the receiver. If you have the donor running when you start the receiver you risk putting the donor alternator and reg/rec under extreme current draw (a starter motor is a very low resistance, almost a short initially) and potentially irreversible damage could result. A flat battery will accept quite a bit of charge quite quickly, a few minutes will make all the difference.

 

 

Edited by embee
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Malcolm1975

On a side note I've just got my optimate is the general consensus to drill the battery cover in the storage area to fit the wiring to the battery 

 

It's a brand new bike and I don't want to cock it up 

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wendeg

I did not drill the cover. Put the connector behind it and just undo the two screws holding the cover when I wish to connect the Optimate... Undoing the screws takes only a few seconds and this is only done when the bike has been unused for more than, say, ten days. A healthy battery should keep its charge for at least that time.

 

Alternatively you can route the connector to the left or right hand side of the bike and cable tie it to the frame (near where the water pump is, for example) for easier access.

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elbee
2 hours ago, wendeg said:

I did not drill the cover.

 

Neither did I.

 

Originally I routed the short optimate lead from the battery straight down to the side of the bike but found it a bit of a faff fiddling around the top of the engine to connect to the optimate for charging. Plus the socket on the short lead might corrode.

 

Instead, I simply screwed the black battery cover back with the short optimate lead poking through the side. The end of the lead is held safe behind the tool kit when not in use. Frunk lid rests gently on the long optimate cable as it charges in the car port.
 

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Malcolm1975

Thank you

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trisaki
On 9/30/2018 at 14:39, New said:

Would it work / how sensible would it be, to make an optimate to Optimate lead as a jump lead?

Situation is 2 DCT bikes travelling together (so no option of push starts) (traveling so chargers not ideal) both bikes have female optimate pig tail leads, so how about a male to male lead in the event of a problem to use as a jump lead?

Thinking of https://www.that auction site.co.uk/itm/2x-Connector-Adapter-Plug-Socket-Male-Female-Optimate-Accumate-Battery-Charger/112411299284?epid=2100084807&hash=item1a2c3c4dd4:g:CH8AAOSwjqVZHXI~ plus some cable.

If you  have an optimate lead already  fitted , I think  optimate  do a solar panel  charger  , so if room to carry it take it with you  , think it has the same connection  , worth investigating 

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ste7ios

The output of that solar panel is 0.8A.It’s good to maintain the top charge of a battery but it will never charge an empty battery.

 

It will take more or less 13 hours to charge an 11 Ah lead acid battery supposing that you have a strong sun all that hours...

 

You need a normal panel (it’s bigger than the bike...) or more to have enough Wh...

 

Prevention is the best way to avoid jump staring. Keep the battery in good condition, know her status, replace it in time, and use relays when necessary to avoid parasitic drain.

 

A jump starter can be used in emergencies, it’s convenient,  but it’s not always a good idea under some circumstances (shorted cells, etc.).

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sad vampire

If I was considering a jump cable between two bikes, I'd use Anderson connectors & some pretty chunky cable, & this gets fairly bulky to carry around.

 

Alternative for me would be to carry 4 of my 15AH LiFePO4 cells, which linked together would provide a 13.2V 15AH battery, enough to act as a replacement to start & run a bike, although without some circuitry (balance charger) you'd not want to run it from that battery alone for any distance. This is where a small jump start pack can work of you have space for it, I believe you can get ones that will double as a power bank for USB devices.

 

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ste7ios
Posted (edited)

LiFePO4 is fully compatible with AGM charging systems. You don’t need any circuitry (BMS) to use them, It may be good to have one but not necessary.

 

Also the cells must be of the high discharge type. Not all cells are able to provide the necessary current to start an engine.

 

You’ve to check their specs and be sure that the links/bridges between them are proper for so much current...

 

You must know what you’re doing with batteries. They can be dangerous.

 

Jump starters contain LiCoO2 cells because of their bigger energy density.

Edited by ste7ios

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sad vampire

A charge only BMS, if properly constructed would get rid of any potential problem with the charging voltage, 3.65V per cell max, so 14.6V, would prefer around 14.2V for longevity.

Cell voltage is 3.3V, so 13.2V, much the same as an AGM & little in the way of Peukert effect so it will hold up near that voltage until near dead.

 

Yes, my LiFePO4 cells are only 10C, so 150A max discharge constant, so starting the bike on them alone would eventually degrade them. The solution is to fit 8 in total to give 300A. If just linked to the original battery in the bike then they are easily capable of providing enough current though.

 

Bridges are proper bus bars, no worries there. Cables are 6 AWG silicone stranded, so good enough for short distance, can bolt cells directly onto the battery leads anyway.

 

Batteries can indeed be dangerous, but I'm used to using LiFePO4 cells in power packs of far far greater capacities & my PL8 charger can keep an eye on the cells. My primary worry in a motorcycle is the stability of the voltage regulator.

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ste7ios

Yes the conditions are less than ideal with a motorcycle’s charging system and a full BMS can’t exist for that usage (they only balance the charging and protect from overdischaring) but they can perform flawlessly for many years (my 4Ah+ Ballistic without a BMS is almost 6 years old now and still cranks strongly.).

 

With that usage they give us less charge cycles than the expected theoretical number but it’s still enough...

 

The most important is to use quality cells (like A123 Systems) and a capacity big enough to accept the charge rate. Practically this is the size of the OEM AGM battery or near that size... This is difficult too because a LFP battery of that capacity is usually bigger than the available space...

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