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Discussion Starter · #1 ·
Two linked questions really.

I have just bought a lead-acid (liquid) battery for an old Honda I have. Old-style battery, filled with acid, but the shop told me not to use a car-charger as this could knacker the battery. Of course, they had an Optimate charger that they could sell me!

I've used my 12V car charger on old bike batteries before and did not seem to have any problems. The one I've got gives a maximum charge of about 5Amps but it usually settles down to 1-2Amps and I leave overnight.

Do you need an Optimate-type charger for old type batteries?

Second question is, why do they say not to use a car charger with the newer gel-filled batteries? I understand that this is the type in the FJR but I've never let it go flat. I always try to get out on runs in the winter to keep it charged up. I would not want it hooked up to the charger all the time with an Optimate anyhow.

I can see the point in using an Optimate to keep trickle-charged (if you want to) when the bike is laid up. What about if all you want to do is be able to do a 'proper' charge every now and then? Wouldn't just a normal 12V charger do the job?

Any advice here would be appreciated. Don't want to blow up the batteries but equally don't want to shell out on a charger that basically does the same job as the one I've already got.
 

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I have a car charger which I use to top up the battery on my 1976 GT750. Never had any issues with it.

Alan
 

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A car-type charger is fine for the lead acid type of battery - as long as you remember to disconnect it after a few hours.

The issue (I suspect) is that a car battery is big and bulky and will bubble away to itself for a long time if overcharged. By comparison a motorbike sized battery will overheat and boil dry if left connected as it can't dissipate the heat.

With regard to the FJR's sealed gel type, I've used an Optimate through long periods of the winter without a problem.
 

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Loads of us use Optimates or "battery tenders" Cliff.

The thing is, it keeps the battery very happy over the winter months, trickle charging when it needs it, switching "off" when it doesn't.

I have three bikes in the garage, all on Optimates when they are not in use, even for just a few days, summer or winter. My FJR battery is over 4 years old now, however, I'm sure I'll need a new one next spring to be on the safe side.

There has been loads of discussion on the old site regarding tenders - have a read some time.
 

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Discussion Starter · #6 ·
Thanks guys.

Sounds like my original guess was about right.

The normal battery charger will do for lead with liquid acid (as it is on my old Honda).But better to go with a more 'intelligent' Optimate-type charger for modern gel batteries.

Advice is appreciated.
 

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I stuffed the battery in my FJR using a car charger.
Recommend you do not use one on that type of battery.
 
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