trying to make a 12-14v trickle charger to 12 v tender

[ratguzzi]

Ok, I travel for work. So yes, sometimes I ride and sometime I "gag" haul a bike in my work van. But depending on the trip, my Li Ion battery goes flat. I can do a 12v to 115 inverter to 12vdc trickle but seems a waste of step up and step down transformers. Soooooooooooooooooo at Harbor Freight today they have a cheapie trickle charger which has a plug that is a mini transformer from 115V to 12-15 v. I bet I cut those leads and put a 12v plug on it, it will tend my b attery while it's in my work van. Actually directly hooked to my van's power with a rectifier to prevent backflow during cranking should do it as well.
Thoughts?
JB

[Kentktk]

You are smarter than me, I don`t know.

[tris]

Am I missing something?

IF you battery keeps going flat, wouldn't that indicate a need for a new battery rather than a trickle charger??

[redrider]

Am I missing something?

IF you battery keeps going flat, wouldn't that indicate a need for a new battery rather than a trickle charger??

What brand battery? I have a Shorai Li-Fe that lives in whatever ambient temps are, low 30'sF overnight now, for several days and never fails to crank and start. I tried a Ballistic-junk, junk, junk. Oh, did I mention the Ballistic was junk? Even with the dedicated charger, it was junk. And that was the second one after the first went boobs up. (warranty replacement) Lithium Iron seems to be better than Lithium Ion Phosphate. My 2c

[chuck peterson]

how bout a solar trickle charger mounted on the van somewhere?

[bmc5733946]

If you have an accesory outlet in the van that is only on with the key use that. Many late model vehicles have accessory outlets that are able to have their output modified to "key on" or "key off" in either case they are probably "off"  in cranking mode. Check the owners manual for possibilities.

Brian

[charlie b]

Do not use a tender for the Li-Ion battery unless you have one made for Li-Ion batteries.  If overcharged it will burn up.  Many Lithium batteries do not like to be left at 100% charge for long periods.  A good mfg will have a circuit inside the battery to protect it, some do not.

Best would be to make sure it is charged, then use a disconnect.

Having said all that, if you know the specifics of the battery, and can make a tender that has a definite voltage output that is below the full charge level of the Li battery, then it will work OK.

[EldoMike]

I use one of these...

http://products.batterytender.com/Motorcycle/Battery-Tender-Lithium-Junior.html

[lti_57]

if you have a 12v source back there just but one of these, no reason to reinvent the wheel
http://www.harborfreight.com/80-watt-continuous-200-watt-peak-slim-power-inverter-66944.html

and what ever charger  you decide on.    done

[Old Jock]

If any battery is going flat then its either down to a duff battery or a parasitic drain

However some things are different with Li batteries to normal acid types

As Charlie stated Li batteries do not like being stored with a full charge for long periods. Ideally if storing the capacity is brought down to 60-80%, that's not proportional to Voltage that's charge capacity, you'd need to contact your supplier to determine what voltage range equated to that charge (charge to voltage is non-linear)

Li do not like being left badly discharged either, let voltage drop to under 9V and it may well be toast

They should be balance charged occasionally, to ensure all the in series cell packs are are the same voltage

They should not be charged with any charger that uses a de-sulpahte function as part of its charging cycle

Li actually loose less charge than normal lead acid if left to sit with no parasitic drain, of course if there is parasitic drain then they run down just as fast if not faster as the Ah equivalent is not the true capacity of the battery, the actual Ah is usually less. They are quoted that way to compare with a lead acid but their characteristics are different

I think it would be easier just to either disconnect the Li battery if there is drain or fit some sort of isolater to allow you to do that job easily if its hard to get to the battery leads (As Charlie has already said too)

If I'm reading the original post you are wanting to charge (or trickle) a 12V battery with another 12V battery, such items do exist. I'm a bit confused though is the mini plug simply a transformer type of step down so the input 12-15 you refer to AC? It sounds that way if you need a rectifier.........i f it was DC then just a diode rather than a diode bridge (rectifier) would surely do the job to allow current flow in a single direction

One more thing that springs to mind is if the charger is isolated via your diode or rectifier, will the charger shutdown? Otherwise you may end up with a worse drain by having your Li battery power the lights and circuits of the battery charger. I wouldn't imagine the drain would be much but I have no specifics on the battery capacity or what the charger would use if the Li back fed the charger

Sorry if you had thought/knew all this already

John

[Kiwi_Roy]

Ok, you have this lithium battery in your bike connected to a crude constant Voltage charging system.
The guzzi regulator hits it with pulses of current 40 Amps or more thousands of times a second and the battery is ok with that.

So why do you have to pussy foot around and treat it with kid gloves?

Put a diode from a switched circuit in Van's system to charge the bike, if you find it's getting overcharged hang a lamp in series
Lamps are like magic resistors they pull a certain amount of current then they heat up cutting the current back.

You shouldn't get hung up on what might happen if the battery is subjected to an unregulated trickle charger which could peak out at 18 or more Volts
The charger in this case is the 14 odd Volts the van system runs at, it cannot go any higher than the van battery in fact if a diode is used to prevent backflow
the highest Voltage the bike will see is 0.6 Volts less than the Van, since the van is only running part of the day the battery is only on part of the day as well.

It's sort of like a motor home with a chassis battery and a house battery

[charlie b]

It really isn't how much current for most of these batteries, it is the peak voltage that the charger imposes on the battery.

Some of the lithium batteries have some very good circuitry to limit the incoming voltage and current.  Some do not.  Some circuits will not protect against a 'trickle' charger that might be a bit too high in voltage, some do.  So, it really is dependent on the battery mfg and what they recommend.

Why would I 'pussy foot' around a lithium?  Because when they fail it is pretty spectacular  ;)

[DonTom]

Ok, I travel for work. So yes, sometimes I ride and sometime I "gag" haul a bike in my work van. But depending on the trip, my Li Ion battery goes flat. I can do a 12v to 115 inverter to 12vdc trickle but seems a waste of step up and step down transformers. Soooooooooooooooooo at Harbor Freight today they have a cheapie trickle charger which has a plug that is a mini transformer from 115V to 12-15 v. I bet I cut those leads and put a 12v plug on it, it will tend my b attery while it's in my work van. Actually directly hooked to my van's power with a rectifier to prevent backflow during cranking should do it as well.
Thoughts?
JB

Have you thought about a solar charger? Even next  to a window it should work well enough to keep a cycle battery well charged.

-Don-

[redrider]

It seems every Fall/Winter we have a battery/charging system thread. I found this:

http://www.autoshop101.com/asetest/asetest5.html

V x A = W

[Wayne Orwig]

Charge it however you want.
Blast it with power.


This is what might happen, but that is OK because I heard it on the internet.
Just don't park it near anything flammable.

[Kiwi_Roy]

Who was suggesting blasting it with power?

Sure you can step it up to 115 with an inverter and back down with a tender.
The van supply is nice and stable, it will never drop below 12 or go over 15 so all you need is a means of limiting the current to the bike, if the wires aren't enough add a simple resistor.
How can you overcharge it, not unless you overcharge the van battery also

Another approach would be to say "I don't need it to fully charge, just to 50% or so", easily accomplished by adding one or two diodes in series.

If LiIon batteries are so temperamental toss it out and put a decent Gel battery in there, the same technology as the van battery, then it could be just plugged in and fend for itself.

[ratguzzi]

Thanks for all the help. Yeah, many good pieces of advice. Most likely the power outlet is dead during cranking and I googled battery isolators and tons of stuff under $30. Now my 110v tender uses a 110v down to 14v then the "smart" box so if I cut off the transformer and use an isolator then the smart box, it should be safe and trickle as I want.
Not sure what is draining, it was perfectly fine with the acid battery but the bike sat a couple years so I swapped it for a new Shoei LiIon. My heated hand grips go through the hot for the front brake actuated brake light so can't leak when the ignition is off. My jacket liner control is "live" from the battery but with nothing plugged in , it really shouldn't drain.
Solar panel would be cool because I don't need to run the van and it would charge when parked but it's a commercial van with no rear windows.
Thanks for all the ideas!
JB

[Sack]

Being into RC aircraft I use Li-Po batteries all the time. As mentioned, for max battery life a Li-Po does not like sitting at full charge for too long. Full charge is universally accepted to be 4.2V/cell. Likewise, stored at too low a voltage can result in the cells not wanting to take a charge when needed, that's down ~3V/cell or maybe a tad lower. Storage charge for long term storage is ~3.80V/cell. At that storage voltage the battery pack has the best chance for a long life. That means a full battery reads about 12.6V, at low voltage 9V and storage for a Li-Po is 11.4. A Li-Po at storage voltage should have no trouble turning over the engine, which when running will charge the cells back up. Li-Po's pack a huge wallop!
Some batteries are Li-Fe and tend to be more robust than Li-Po batteries in that they can take a bit more abuse before harm comes to them.
My point being, unless your battery is being pulled down by some unknown load it has a very low discharge by itself. If there isn't a load present (test with VOM) then I can't imagine a healthy Li-Po discharging enough to not start an engine unless it's on its way out.
If there's no load present when bike is off and you know the battery only discharges so far when not ridden then I wouldn't sweat it. There are DC to DC power supplies/chargers that are inexpensive and are referred to as Buck Converters. They usually are constant voltage devices, current dependent on load, whereas dedicated Lithium chargers usually are constant current. I happen to use my Buck Converter as a charger at times and it would be easy to connect a lighter socket plug to its inputs, and whatever output connectors you desire.
Here's an example: https://www.amazon.com/DROK-Regulator-Converters-Step-down-Voltmeter/dp/B00WEBJRE8/ref=sr_1_13?ie=UTF8&qid=1479771607&sr=8-13&keywords=buck+converter

Good luck!

[Kiwi_Roy]

Now my 110v tender uses a 110v down to 14v then the "smart" box so if I cut off the transformer and use an isolator then the smart box, it should be safe and trickle as I want.

Not sure what is draining, it was perfectly fine with the acid battery but the bike sat a couple years so I swapped it for a new Shoei LiIon. My heated hand grips go through the hot for the front brake actuated brake light so can't leak when the ignition is off. My jacket liner control is "live" from the battery but with nothing plugged in , it really shouldn't drain.
 

Before you cut it up just confirm with your meter it is really 14 and not something higher.
To find the parasitic drain current
Connect a small 12 Volt LED in series with the battery, turn on a load to make sure lt's operating.
Then if it lights with nothing turned on thats indicating the drain current (>1 mA), then its just a matter of isolating one thing at a time.
You may have wondered why I didn't suggest measuring the drain with a multimeter, these are often misleading because the mA range fuse is blown so they naturally read zero.

[Howard R]

snippety
 My jacket liner control is "live" from the battery but with nothing plugged in , it really shouldn't drain.
snip snip snip

This might just be your culprit.  A lot of solid state controllers have a continuous draw for what is sometimes called "houskeeping" power even with no load connected to them.  It keeps the electronics alive, so it can watch for the appearance of a load, or even look for a signal from a "power" switch, sort of like  a computer or TV that draws a few mA from the wall power even when the device is nominally "off" so, for example, a TV can detect the "power on" command from a remote control.  Doesn't take much to do that, but could still deplete a battery over days or weeks.  This only applies if your controller is permanently mounted on the bike, if the bike just has a plug directly to the battery and you only plug in the contoller/jacket when in use then disregard what I just said.

Also, Sack mentioned buck controllers.  One thing to be aware of if you go this route is that a lot of power controllers require a few volts of "headroom" so that the output cannot be too close to the input.  The example he linked looks like it takes 36 VDC input but can only provide a maximum of 32 VDC out, so that's 4 volts of headroom.  VERY important if you want to run it straight from your van's DC power, so check the spec sheet of anything you consider, maybe post it up here so we can advise if you are unsure before you buy.  You might want to look for something described as "buck/boost" because that can have a wider range of output voltages, including higher than the input voltage.  (That's the "boost" part.)

If it was me (and maybe Kiwi Roy ) I would just make a simple plug to the van power with a series diode to isolate the bike, and make sure you don't exceed the rated resting voltage on the bike battery.  If you find the bike's voltage too high, just add another diode (or two) in series, remember you get about 0.6 volts drop from each diode. 

Howard

[Howard R]

After some further thought (and a nudge from Wayne, thanks for the PM) this is going to be a bit more complicated than I might have indicated.  To be safe, you are probably going to need some kind of controller to make sure you get the battery voltage right, and to prevent damage to either/both vehicles and/or wiring. 

Consider this scenario: you hook the bike up to the van, with the bike battery at "low-to-no" charge.  Van's system then tries to go full tilt boogie, possibly popping any series diode present, maybe even letting the smoke out of a too-small gauge wire, and most likely taking out the fuse on the van outlet.  None of which would be much fun.  If you decide to go this route, at least start with something like a turn signal (incandescent) bulb wired in series, to limit the current to a couple of amps, as Roy suggested.

Then there is the possibility of overcooking the bike battery.  That is somewhat less likely, as the battery seems to work well with the bike's charging system which should be pretty close to what you would get from the van's system.

Back to your original question, if this is what you saw at HF:
http://www.harborfreight.com/automatic-battery-float-charger-42292.html
for <$10 it looks like it might be worth a try.  Also, according to the spec sheet, it won't start charging if the bike battery is < 12 VDC so you'll have to start with a full charge on the bike and just use this thing (as designed) as a float charger.  I'm willing to bet that the "wall wart" plug/transformer is internally limited, but if it does burn up the (tiny) wires after you cut the transformer off and plug it into the van, you haven't lost a large investment.  The transformer output is almost certainly AC, so the intermediate box will already have the diode/rectifier inside so you likely won't even need to do anything except cut off the transformer and hook up the wires.  The spec sheet says it only draws 14 watts out of the wall, so the max output of the charger can't be more than an amp or so.  It also says the maximum voltage is 13.2 VDC so it probably won't cook the battery, and if it does that gives you the chance to get a better battery, anyway .  A word of caution, the lithium battery industry does have some interesting terminology in their warning propaganda.  I once read a battery spec sheet with a description of "venting, with flame" as a lawyer-inspired warning that these things can do a passable impersonation of a pipe bomb if they get angry enough.

I still recommend you start by looking for parasitic drain as has been suggested earlier, that might solve the problem with no further intervention required.  Finally, I just noticed that you said you hooked your heated grips to the DC side of the brake light switch.  The brake light is a very low duty application and knowing Guzzi's electrical proclivities they might well have used a severely undersized wire to feed the switch, thinking "Itsa no use much, should last for a while" so it might serve you well to check the size of the bike's original feed wire to where you made the connection for the heated grips to make sure you don't get into an overload situation.

Good luck!

Howard

ETA I just took a closer look at the product picture, if you zoom in on the wall wart it says its output is 15 VDC and 1/2 an amp.  This thing really is a very low current maintenance charger.

[n3303j]

I don't think you'll find transformers in any of this modern stuff. Probably find a switching power supply for changing AC to DC or visa versa at most any input/output voltage ratio you want. Solid state stuff is marvellous.

Go with a recommended charger for the battery you have and a quality inverter. Batteries are expensive.

Teslas have sat in Long Term parking at airports and self discharged to the point where their batteries were forever ruined. 

[ratguzzi]

The draining was caused by leaving the key in the ignition. I always leave my keys in the ignition on all my bikes. I unplugged the trickle charger and two days later the battery was dead. Start the trickle and the battery comes back quick. Let it charge, unplug it AND remove the key from the ignition and 5 days later, the battery is still fully charged.
JB