Charging a battery whilst still on the vehicle.

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Tim4x4

Tim4x4

Well-Known Member
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In the shed. Making engines for ME
Hi, I it Ok to charge a battery whilst the battery is still connected to the vehicle.
Defender TD5 110 CSW,
120A alternator
Odyssey 115Ah battery
10A battery charger.
The battery is new and currently not needing a charge but if it ever needs a charge I have a couple of Anderson plugs/sockets fitted directly to the battery via a 25A fuse (used for an air compressor). I was thinking of fitting a suitable socket on the charger and attaching via the Anderson plug if a charge was required.
 
Last edited:
The type of charger is the key IMHO - 10A constant at 15 V is unlikely to end well.

We run maintenance chargers on equipment with the batteries connected - they are "accumate pro's" and monitor the battery and give it what it needs for good battery health. (like evil bay item # 141442133211 ) - connected using a similar connector to the Anderson you mention.

Batteries last longer, and the equipment is always ready to go ...
 
discool said:
Not a problem with any 'regulated' charger, maintenance or other wise and both have been around for years.
Click to expand...
What is a regulated charger? The charger I have is a connect it and forget-it giving out a maximum of 10A three LED indicate red power on, amber battery charging and green battery is on float charge. No settings to adjust or Ammeter to indicate charger output the charger cost £94.00 so not cheap (but I did feel ripped off at the time).
 
There's quite a lot of bolleaux talked about how modern cars shouldn't be jump-started, but I won't go into that other than to say that you should read your manual, and if it says it's OK then follow its guidance on how to do it.

I mention that because when you do, you're connecting up to 100A and more than 12V more or less unregulated - and that does no harm to the car. It's the same as if you connected your 12V mobile 'phone charger directly across the battery (it'll work quite happily) - an electrical device will only take the Amps that it needs. Different story with Volts.

Where it isn't so good is that a modern regulated charger does clever things by playing with Volts to get your battery charging nicely, but then if you've let your battery get that flat you've already seriously shortened its life.
 
Ive always left batteries connected when charging using a smart charger or a run of the mill charger.
 
Tim4x4 said:
What is a regulated charger? The charger I have is a connect it and forget-it giving out a maximum of 10A three LED indicate red power on, amber battery charging and green battery is on float charge. No settings to adjust or Ammeter to indicate charger output the charger cost £94.00 so not cheap (but I did feel ripped off at the time).
Click to expand...

That it, what u have 10amps reducing down to a float charge, your battery must be very low (on the floor) if the charger thinks it needs a max charge of 10amps

I have an 8amp max charger (£55) and when the battery won't start my disco, which happens a few as it's a weekend use vehicle, my charger shows 8amp for around 10 minutes then drops slowly over a 3/4 hour period to 4amps and stays there, then after a overnight charge the amp meter is sitting on 2amps, never seen it lower, as now I can disconnect the charger.

My charger has a half power switch so I just set it to that for the overnight charge I don't need the full charge.
Then 8amp as 10amp charger is handy if for instance you found you had a flat battery and needed to go somewhere, even go and get a replacement battery, within an hour maybe two there will be sufficient in the battery to enable to start, with a lower amperage charger that could be twice as long.

My Ctec maintenance charger takes 24hours to fully charge a non starting battery.
 
I've charged cars / Landrovers / bikes / motorboats many times over the years never had a problem. I believe the advice not to do so is positively ancient, dating from the days of dynamos and unregulated poorly designed chargers. With modern chargers / batteries / car electronics it is impossible that a serviceable charger could cause a problem.
 
Thank you lads just checking nothing untoward would happen (a TD5 will do that on its own without my help).
I will connect an Anderson plug to the charger and if the battery needs a charge just connect it via the Anderson socket fitted to the vehicle.:)
 
Wifes just bought a new car well new to her and it appears if you charge the battery which is in the boot you have to charge it via the jump start pegs under the bonnet this is apparently because if you dont the alt keeps chucking in power thinking the battery is low and can cook it and also works the other way if car shut down and was happy with battery and you replace the battery the car wont know whats going on and wont charge it fully, it may think its charged if fully but its hasnt, Im sure theres more to it than that but this is the way tech is going.
Apparently the D4 is the same depending if you have a std or AGM battery fitted you have to tell the car whats what so it doesnt cook the AGM version which takes less volts to keep it tip top.
 
lynall said:
Wifes just bought a new car well new to her and it appears if you charge the battery which is in the boot you have to charge it via the jump start pegs under the bonnet this is apparently because if you dont the alt keeps chucking in power thinking the battery is low and can cook it and also works the other way if car shut down and was happy with battery and you replace the battery the car wont know whats going on and wont charge it fully, it may think its charged if fully but its hasnt, Im sure theres more to it than that but this is the way tech is going.
Apparently the D4 is the same depending if you have a std or AGM battery fitted you have to tell the car whats what so it doesnt cook the AGM version which takes less volts to keep it tip top.
Click to expand...

How ridiculous - what's next, asking for permission to drive the damn thing !??!?!??!:D
 
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