Ignorance is bliss...

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08 Specialized Langster

The only time I see it maybe becoming a problem is if one of the batteries fails and the others masking the failure, making it overcharge the good ones because it can't balance the charge to the individual batteries it can only charge to what it sees as the full load on it.

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.

I leave the bikes on a dedicated Optimate for each and have for 10 years - so far I've had no problems Excellent bits of kit

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Better to Burn Out Than Fade Away

In the garage -

2001 X1
KTM390 Duke
Ducati 950 Monster +
CCM Spitfire Scrambler

Story of my life

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If your dreams don't scare you, they are not big enough.

I know what you're saying Kev, but my take on it was that it would be the same thing as a duff cell in a single battery - just a guess

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If your dreams don't scare you, they are not big enough.

I've used the Optimate to bring a battery back to life that the Battery Tender could not. Lasted another couple years. By only having one battery hooked up, it was able to constantly evaluate it and alter the charging program. Couldn't have happened with 2 batteries hooked up.

Also, the battery in my HD, Buell and dirt bike are different chemistries and need different charging programs. Hooking these up at the same time, I would most likely be damaging one or more of them. When I had the BMW, the CanBus was a whole 'nuther spanner in the system regarding charging programming.

Just buy a 2nd one ya cheap bastids.

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Bob Krzeszkiewicz
2012 XR1200X - 2011 Kawasaki Z1000SX - 1999 Buell X1

I've got 4 Optimates (but one is dedicated to my caving gear). My 1198 runs a Canbus system with a Lithium Shorai battery and that requires a dedicated charger.

However, with the lead/acids, the charger will monitor the individual cells - the more cells, the bigger the battery. Is the Optimate clever enough to determine that the cells are in a different battery case? In theory, I can't see how; in practise, I really have no idea

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If your dreams don't scare you, they are not big enough.

The only thing I can see is that just to round off the figures a standard 12v battery consists of 6 off 2volt cells in series to give the 12volt total , if you have an open circuit in one of the cells then that means you have no continuity through the battery. If you add a second battery you connect it in parallel to the first so the charger still sees a 12v battery connected but it has no idea that only one of them is good and the other is doing nothing. Also it will not know if they are different amp hour rated as it will just see the one load on the charger so in theory could be overcharging one of them
And what would the charger do if one battery was bad with only say 10volts and the other was good with 12 volts I see it being no problem as long as there is no problem

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.

I've never looked inside a battery, the only one I've seen in bits was on my old rs 100 Beemer (it exploded after I accidentally shorted it with a spanner - lesson learned )
I thought it was a load smaller 2v cells series connected to form a 12v cell and these were connected in parallel (more cells=more Amps), so the charger would 'see' 12V when individual cells reached that voltage, irrespective of which case they were in But, as before, I've no idea really what I'm on about
That said, I do have another knackered Optimate adapted for multicharging, that I remember getting much warmer than my other ones before it stopped working. The batteries it was trickle charging were fine though

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If your dreams don't scare you, they are not big enough.

Ironically, mine has just given up the ghost after 20 odd years. The wires are pretty rigid and knackered where they come out of the unit.
I've got to buy a new one now, so my youngest son can wrap it up and surprise me on Christmas Day.

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I started out with nothing and still got most of it left.

This thread has prompted me to read up a bit about split charging ..... a lot of articles suggest batteries should be of similar capacities and one tip if charging at over 10 amps is that the batteries be connected in parallel and the positive lead of the charger on the nearest battery and the negative on the furthest if that makes sense which balances the voltage drop across each battery and cable see figure 9 in this article

http://batterytender.com/resources/conn ... rgers.htm/

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.

A bit more reading about charging batteries

http://batterytender.com/resources/battery-basics.htm/

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.

And if you read the FAQ it says they should be the same type of battery

http://batterytender.com/resources/freq ... questions/

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.

Yep, a good read that Mind you, I did have to zip up my anorak first

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If your dreams don't scare you, they are not big enough.

Can you tell I'm home alone tonight

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.