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Disconnect the battery to charge

13K views 34 replies 16 participants last post by  Tricolour 
#1 ·
Hi all,

I have one of those computerised battery chargers for the bike that has the harness that can be permanently attached to the battery and plug into the charger. Is there any harm not disconnecting the battery when charging? The charger is designed to cycle the battery and finish with a maintenance charge and is designed for small batteries?

My old beliefs were to disconnect batteries when charging, but this thing shouldn't kill the onboard computer? What do you think?

Charlie


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#2 · (Edited)
It absolutely does no harm to leave the battery connected to the bike while using a small float charger.

When the charger detects battery voltages lower than a set threshold, it turns itself on with an amperage that seldom exceeds more than about 1.5 amps. When the cut-off voltage point is reached, the charger turns itself off. At no time is the bike's ECU in any danger. The bike's alternator is capable of producing much more amperage than that little float charger.
 
#4 ·
I have the Optimate charger sold specifically by Triumph and supplied with the permanent connector. As triumph say nothing to the contrary I would assume its OK to use with the permanent connector. I have now used it on more than half a dozen bikes and cars without any problems.
 
#13 ·
Well as Einstein said "Science is not consensus"

There may well be opinions on this subject, but there's also the real truth and in this case it IS perfectly ok to connect a charger without disconnecting the battery.

NO battery charger can supply anything like as much current as can the alternator on the bike. The only possible issue is if the charger created a serious over voltage and any of the modern 'float' chargers, or battery 'tenders' are designed specifically to not do that sort of thing. I wouldn't recommend a big basic car type charger on a battery with very low charge, or some internal problem that might cause the voltage to get a bit high, but otherwise it won't be a problem. Particularly for the Optimates and CTEKs etc that are designed specifically to be used without having to disconnect the battery.
 
#9 ·
It's a Yuasa YTX12-BS Same battery fits the Air-Cooled twins. Shorai recommends LFX18A1-BS12 in that application. Saves 5.3 lbs but is only about 3 amp-hours reserve vs the 10 amp-hour stock battery.
 
#11 ·
My Bimota, Bonneville SE, Thruxon R, my previous Ducati 916's, MV F4 etc. all came with a factory/dealership fitted charging cable.
I have never disconnected a battery to use a charger and I occasionally run my bikes in the garage with the chargers attached and have never had an issue. The chargers have reverse polarity protection and over voltage protection.
Because of the small capacities of these bike batteries I have them on chargers when not in use.I use plug pack Projecta chargers, they charge at 0.9 Amp max and float/trickle at about 200mA.
 
#19 · (Edited)
I start and run my cars and bikes with the new technology chargers attached and have done for years.

They don't seem to care.......they know things......:wink2:

They come with fuse protection because they can be used as a 12 volt power supply.....

I run my accessories from this plug and my USB power adaptor.
 
#20 ·
Yes you can use them as a power supply, conversely I have a Hella Powerlet socket fitted and use that to plug my charger into.

I'm not saying that you can't run the engine with charger connected, just that I think its best not to. Anyway I stop here before the thread turns into another oil/tyre thread. :laugh2:
 
#21 ·
I have permanent battery "tender" leads on each of my 4 cycles. I do not disconnect the batteries while charging not because I'm worried one way or the other about that issue but because the batteries in my fleet have those silly free-floating nut plates inside the terminal. If I take out the terminal bolt, I have to hope that the nut plate doesn't move very much or I'll have to fish it back into place. Without the additional tender lead in place, that's not too hard to accomplish because the bolt can still make contact with the nut plate and thread its way in. HOWEVER if I add the thickness of the tender lead to the connector stack at the terminal, the bolt will NOT reach the nut plate and engage. (We're talking....oh...maybe .025" difference in the stack of terminal rings) In that case, bringing the nut plate into position so the bolt will engage it can be an extremely frustrating project. I spent nearly an hour trying to get the bolts and nut plates to meet each other on my Street Triple. That's why I won't disconnect it again just to charge the battery! If the battery guys would make those bolts .050" longer, life would be good.
 
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