a 12V cunundrum for for you car/ mc guys

[ned]

Storage area has no power so a battery tender is not an option. I have a recently ridden Kawasaki with a charged battery parked next to a dead battery HD. Had the battery tender extension cord- sae plug each end just like the battery tender hook up on each battery....why not run that between the two bikes? The down battery will draw from the up battery- yes? Maybe I fat fingered the plug when connecting because I blew the 7.5 amp fuse on the battery tender from battery harness. But does it sound like it could work when I replace the fuse? nothing active in the circuit- just a 6 foot cable bike to bike plugged in where I would normally plug the battery tender lead if I had power.
I eventually got HD running with kick start but that gets harder each year.

 

[JFB]

Storage area has no power. . ,.
charged battery parked next to a dead battery.
battery tender extension cord- hook up on each battery....
why not run that between the two bikes?
The down battery will draw from the up battery- yes?
I blew the 7.5 amp fuse on the battery tender from battery harness.
just a 6 foot cable bike to bike plugged in where I would normally plug the battery tender lead if I had power..

So you are in effect using the battery tender harness as "Jumper Cables"

the battery tender can detect and adjust its current when connected to dead battery to limit less than 7 amps of the fuse's rating

a charged battery has no such circuit and will supply a LOT of current to the dead battery and thus the reason the 7 amp fuse popped.

 

[SAJohn]

Ned , I do not completely understand your post but it sounds like you tried a jump start with wires and a fuse that cannot handle the current flow.

I have to keep three trickle chargers going for my various vehicles. I use outdoor rated extension cords to reach the various locations with weather protection at all plug connection points.

John

 

[ned]

Sorry, I was afraid I explained that poorly. just a cable- you can buy an extension from the battery tender to reach further- battery tender itself is not involved. I did not attempt to start the bike when the cable was linking the two batteries--I just thought the charge would flow from up battery to down battery..
thanks for the help and ideas guys, I can't get power to the storage area and am hoping a fully charged battery could slowly bring the other one up.

 

[coach]

Nothing will kill a battery faster than leaving it discharged, other than letting it go dry. At least a monthly charge if the battery just sits. I agree with SAJohn that you essentially tried to jump charge the dead battery with wire & fuse that couldn't handle it. That's why jumper cables are so heavy. Any length extension cord can handle the power requirements of a battery maintainer. Or pul the battery and charge it elsewhere.

 

[JFB]

they make battery to battery "chargers" where you could use the running bike to charge the dead battery.
just looking at a simple V=IR balance, the worse case of between the two batterys, just a 2 ohm resister would limit the inrush current under 7 amps (to keep from melting the harness wires)

google hit for this item
https://www.vat19.com/item/easy-quick-jumper-jump-start-cables

 

[Pat-inCO]

I can't get power to the storage area and am hoping a fully charged
battery could slowly bring the other one up.

It could, if you had a current limiter in the line. Just a direct connection
between the two batteries will produce a current surge that is limited only
by the charged battery.

Phrased another way,
you will end up with two equally discharged batteries,
as long as they do not blow up.

Best bet, based on your description, is to pull both batteries and put them
in a garage that has access to 110V so you can run two battery minders.
BE SURE you do . . not . . try to do that inside. The reason? The gas
that is created by charging the batteries has to go somewhere, and inside
is a very poor place to vent them. A garage is not sealed up any where
near as tight as a house.

 

[ned]

Thanks JFB- I will look for that- I now know the dead battery tried to pull more than 7 amps from the charged battery--glad there was a fuse in the circuit. on 18 awg wire I might have had a very hot wire

 

[ned]

thank you too, Pat in CO--although I think you are up near Phoenix now...pull the battery, put on tender in well ventilated garage---new plan if I don't soon get the V=IR balance device JFB mentioned.

 

[certified angus]

could you use a solar powered Battery Tender? You would probably need one for each bike.

https://www.amazon.com/Battery-Tender-021-1163-Maintainer-Controller/dp/B004Q83TGO/ref=sr_1_fkmrnull_1_sspa?keywords=battery+tender+5+watt+solar&qid=1555203854&s=gateway&sr=8-1-fkmrnull-spons&psc=1

attach these to the batteries and then just plug and unplug as needed.

https://www.amazon.com/Battery-Tender-081-0069-6-Terminal-Disconnect/dp/B000NCOKZQ/ref=pd_bxgy_263_2/163-0150378-4115565?_encoding=UTF8&pd_rd_i=B000NCOKZQ&pd_rd_r=6096864d-5e51-11e9-aa61-a910d2132542&pd_rd_w=4REEt&pd_rd_wg=2KOhR&pf_rd_p=a2006322-0bc0-4db9-a08e-d168c18ce6f0&pf_rd_r=QRDN0WSFSJ37Q0JPH6DK&psc=1&refRID=QRDN0WSFSJ37Q0JPH6DK

you may need to get the extension cables also, in order to reach from the solar panel to the bikes.

Or maybe better yet, get one of these, remove the batteries during winter storage, and charge them at home.

https://www.amazon.com/Battery-Tender-022-0165-DL-WH-12-Volt-Management/dp/B000NCOKV0/ref=sr_1_3?crid=31FQM902MVMCX&keywords=battery+tender+2+bank&qid=1555204584&s=automotive&sprefix=battery+tender+2+%2Cautomotive%2C559&sr=1-3

 

[JFB]

. . . if I don't soon get the V=IR balance device JFB mentioned.

A basic electrical principle of the relationship between Voltage, Resistance and current (i).

with a battery in the running bike at ~13 Volts and the dead battery worse case 0 Volts, the voltage driving the current in the wire would be 13 -0 =13. the copper wire's resistance is very low so the inrush current of i = V/R would be 13/0.1 and thus a LOT of current

adding a resistor would limit the inrushing current. for example a 2 ohm would be 13/2 = 6.5 amps
as the dead battery builds up voltage, say to 11 volts, then the voltage accross the jumper wire would be 13 - 11 = 2 volts and the charging current will get less and less as the battery charges up

would I intentionally do this NO. Next difficulty would be finding a resistor right size.

I would think that "easy charge" would be much better as it would have more circutery

doing this with a battery not being charged could give you two half dead batteries

 

[ned]

what a resource this forum is--thank you. Ohm's law tells me I should ride more and keep the darn thing charged- I realize the folly of my previous plan. Great stuff.

 

[stubbfarmer]

If you plug the wires hooked to the batteries for a tender together aren't you hooking + to - unless you change the wires on one battery?

 

[coach]

I forgot about using small solar panels. I used to use one on a sailboat battery to keep it topped off. It worked well.

 

[Pat-inCO]

I forgot about using small solar panels.

Good point!

I looked and Amazon has them from about $20 on up.
My SIL uses one like them to charge the battery on his gate closer.
It is used daily, which implies to me that it would handle all you need.

 

[Captain America]

No disrespect but wouldn't it be easier to remove the battery after storing the bike so you could put it on a tender at a location with electricity? Battery removal on most HD models is a simple process.

 

[ned]

yep, and I know just the wrench to use- the one with the arc weld spot from when I hit the frame with it last time I replaced the battery. I got reminded of Ohm's law on this thread and added a corollary…...just ride the darn thing more...

 

[coach]

Always remove the ground cable first.

 

[protoolman]

As far as jump starting it when it's dead, why not but one of the smallest of the WalMart battery jump start units? They are pretty cheap and would seem to work. Also I have a set of jumper cables in a smaller guage with small clamps just made for motorcycles I bought somewhere. I've yet to use them but have always wondered if it was safe to use them to jump from a big battery on someone's car to my motorcycle? Anyone know?

 

[ned]

yep, I looked at one of those small jump start units while buying replacement fuses after my ill fated experiment....for now- ride more, and sell it when I can't kick start it any more. I have a set of those MC jumper cables--never used them either and did not have them with me yesterday--they will never wear out that way. I bet there is some art in going from a big car battery to a small mc battery- glad you asked- bet someone on the forum knows