Removing - charging battery on a modern vehicle

  spuds 08:59 04 Nov 2014

Apologies for addressing this question to a computer forum, but I know that there are some motor vehicle geeks out there, who might have the answer.

With the older vehicles, I fully understood the workings, especially on the electrics, nowadays with modern technology I am no longer sure. Even searching quickly on internet, there appears to be a variety of answers.

Question: Best way to check or recharge a vehicle battery. If i remove, then apparently a whole host of re-programming problems might occur. Charge in-situ, and the vehicles electrics might default to possible damage or problems.

What is the correct process. Here's a link that probably make the point I am raising click here

  spuds 10:45 04 Nov 2014

Anyone, with any ideas or advice!.

  onthelimit1 11:09 04 Nov 2014

A trickle charger will not do any damage. When I replace a battery now, I connect my 12v bike battery to the car electrics with jumper leads. That keeps the radio code etc energised while I change the main battery.

  spuds 11:09 04 Nov 2014

Jock1e - thanks for the input.

I was just curious about the latest procedures, and what others might have done. Looking on the internet, it would seem that there are a number of ideas, but its the correct ideas that will not cause problems or damage that seem to have concerns, depending on what you read.

  spuds 11:16 04 Nov 2014


I have an old heavy duty Crypton charger, and also one of those 'intelligent'chargers. Using the 'intelligent' charger on batteries, seems to work like it suggests. But would this 'intelligent' charger do something to the vehicle electrics, if the battery is left in-situ.

Possibly the answer to that, is to contact the charger manufacturer for further advice. Hope I still have the instruction book and manufacturer's contact details easily available.

  bumpkin 11:26 04 Nov 2014

This would be my suggestion as a precautionary method. Using another battery if available or another vehicle, use jump leads to maintain voltage to your vehicle then disconnect and charge your battery, re-connect it and then remove the jump leads.

  spuds 11:32 04 Nov 2014


Thought about doing that, but wondered if anyone else had used that method.

This query will go away over the next few days, because I have friends's in the motor trade, who I will call on. But in the meantime, I was wondering if anyone on this forum had the answer. Not just for me, but possibly other people as well, who might have thought about this possible situation.

  Batch 11:54 04 Nov 2014

Take a look at click here. Reiterates some of what has gone before.

I've also see small 12v battery units that plug in to the cigarette lighter socket that maintain enough current when the battery is disconnected. Nice idea, but I believe that on many cars that have so called 12v sockets (not allowed to call them cigarette lighters now?) the socket is not live unless the ignition is turned on (at least part way). Whereas old cigarette lighter sockets were probably live all the time.

  wee eddie 12:14 04 Nov 2014

Thinking about it: When the engine is running, the Alternator is constantly recharging the Battery.

So: a Trickle Charger, aren't they all, with the battery insitu would probably be the best way.

Incidentally: using Jump Leads does not appear to cause any damage, but I believe that no battery, for anything but a very short period of time, does.

  BT 12:52 04 Nov 2014

I've topped up my battery without removing it. Run an extension lead out and put the whole lot, charger and all, under the bonnet. I've also got one of those Engine Starter units, basically a battery in a box and you just clip the leads on, wait 5 mins and start the engine. Top it up indoors now and then to keep it charged. It does also come with a Cig Lighter lead but I've not tried that.

When I took it in for a Battery check, they started the engine and let it idle while they disconnected the battery to do the tests.

  spuds 16:37 04 Nov 2014

Some interesting comments in my absence, but going on the link that I provided, some similar comments were raised without a final conclusion.

Would it depend on the individual vehicle or manufacturer, or are the systems based on the very same idea, in which case, all vehicles would need the same precautions. It doesn't seem so, going on the comments from the link.

"I've topped up my battery without removing it. Run an extension lead out and put the whole lot, charger and all, under the bonnet"

That's how I have done it in the past, but would that do nowadays with later models.

The 'intelligent' charger I mentioned earlier, is suppose to sense a batteries condition, then charge from that finding, which may 'interfere' with the voltage the battery as, but thinking about it, might lead to a under voltage or over voltage at some stage. Again returning to the question of possibly an expensive damaged system.


Perhaps a word of warning. I had two of the type of starters you are talking about, both scrapped now, because I didn't maintain a regular test and charge in the units.

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