Advice needed about Correct Way to Jump Start and Charge Battery

longleydel · Post by **longleydel** » Tue Sep 14, 2021 11:32 am

Hi, I’m looking for advice about jump starting and charging a battery (in situ) and hope someone on the Forum had experience in the correct way of doing this. I own a 2005 E85 roadster.
When attempting to jump start, either by donor vehicle or using a battery jump start kit should you always do this via the relevant positive and negative posts in the engine bay?
Similarly, should you also connect a trickle charger in the same way i.e. to the terminals in the engine bay rather than directly to the battery in the boot? I didn’t want to remove or disconnect the battery.
I have searched on-line and looked at the owners’ manual which both indicate using the engine bay terminals (but, nothing about you must use these). While jump starting from the engine bay seems the most logical, would it be safe to connect a trickle charger direct to the battery in the boot without causing any damage to electrical components?

Derek

Dav the wheel nut · Post by **Dav the wheel nut** » Tue Sep 14, 2021 1:16 pm

Have a read of this thread
viewtopic.php?f=2&t=70451&hilit=Spike&start=45

longleydel · Post by **longleydel** » Tue Sep 14, 2021 7:43 pm

Hi Dav, thanks for your response and locating this very old series of postings. Really helpful. I did search the Forum before posting something, but must have missed these exchanges.

From what I have read it would appear sensible to jump start using the engine bay connections given the level of ampage that most of these emergency starters have. I have recently purchased a NOCO GB40 jump starter which has a 1000ah capacity to cope easily with the 3 litre engine. I have had to jump start my Z4 (using a donor vehicle) a few times now (via the engine bay connections). An autoelectrician recenlty checked all the electrics confirming everything was working as it should and recommended the GB40. The problem was not using the vehicle suffuiciently enough resulting in a drained battery (which is new).

I'm planning to get a NOCO trickle charger (2 amp or so, a slow charging rate) to keep the battery from draining too much. From what I have read the general concensus would suggest its fine to connect this direct to the battery in the boot. Its a smart charger and only charges when the battery needs it. These can be used with the battery still connected to the vehicle.

If anyone who reads this forsees any problem connecting a trickle charger direct to the battery, please let me know.

Thanks again.

Derek

buzyg · Post by **buzyg** » Tue Sep 14, 2021 9:47 pm

Jump start using the engine bay terminals. Mine was going flat in two or three days last summer. Jump started mine using the 1.6 zetec in my little Mazda2. It cost me two batteries, before I found what was killing them. It was the sensor on the fuel filler cap.

Zedebee · Post by **Zedebee** » Tue Sep 14, 2021 10:20 pm

I can recommend a CTEK. Mine has a split lead. One lead is permanently affixed to the battery terminals and the other is attached to the charger which I have mounted on the wall. When I park the car in the garage, I just plug the two leads together in the boot. Been doing this for a year now with no issues at all. Only thing I have to remember is to disconnect before I drive out of the garage again

Number5 · Post by **Number5** » Tue Sep 14, 2021 10:36 pm

When jump starting I’ve heard it’s good to allow the cables to be connected to both vehicles for a few minutes before attempting to start the dead car. This is to allow the battery to take on some charge before the demand of starting otherwise you’re more likely to cause more long term damage to the battery

longleydel · Post by **longleydel** » Wed Sep 15, 2021 9:04 am

Hi, many thanks for all your helpful comments/advice above. Really helpful. I'll also checkout the CTEK charger mentioned.

Thrustyjust · Post by **Thrustyjust** » Fri Sep 17, 2021 4:27 pm

Starting a battery and relying on the alternator to charge from flat is a sure way to damage the alternator. It is always best to recover the battery to a sensible level before attempting to start it. Number 5 gives a sensible approach of letting the good battery move power to the dead one before starting. On a trickle point of view. I have just fitted a Ctek and they do an adaptor to fit onto the power point , so thats what I do with mine. Works a treat.

longleydel · Post by **longleydel** » Sat Sep 18, 2021 10:30 am

Thanks Thrustyjust, that's helpful. Out of interset which CTEK model are you using? Any charger I buy needs a mains power cable of at least 6 feet as I need to locate the charger in the boot or engine bay and plug into an external weatherproof power socket (only the mains cable is exposed to the elements). CTEK don't seem to poublish main cable lengths, including on their website. Their online chat couldn't help either.

Interested to know a little more about the adaptor you mention.

Derek

Dav the wheel nut · Post by **Dav the wheel nut** » Sat Sep 18, 2021 11:51 am

Always used Ctec mxs 3.8 to charge my 3.0 e85 without any issues for either short or long term charging using connections under the bonnet as there is enough room to put the unit under the hood and close it feeding the cable out. The cable however is only 4 feet long.

longleydel · Post by **longleydel** » Sat Sep 18, 2021 2:05 pm

Thanks Dav, I was considering the CTEK 3.8, but unsure how long the mains power cable was - until now, thanks. Also own a 3.0 SE E85. 4 foot is too short for my needs so will probably buy a NOCO charger (one has at a least a 6 foot mains cable).

As a matter of interest, do you disconnect the battery whilst charging?

Derek

oldgitdave · Post by **oldgitdave** » Sat Sep 18, 2021 2:13 pm

longleydel wrote: ↑Sat Sep 18, 2021 2:05 pm Thanks Dav, I was considering the CTEK 3.8, but unsure how long the mains power cable was - until now, thanks. Also own a 3.0 SE E85. 4 foot is too short for my needs so will probably buy a NOCO charger (one has at a least a 6 foot mains cable).

As a matter of interest, do you disconnect the battery whilst charging?

Derek

I also use a CTek 3.8 over the winter period on mine. I bought an extension lead https://www.amazon.co.uk/CTEK-Connect-2 ... B00YBR8PFK & my unit is screwed to the wall near the power point.
The leads connect to the points under the bonnet which means I can close the bonnet, lock the car & put the cover on. No need to disconnect the battery at all. My car sits for 5 months or so on the CTek without issue.

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Dav the wheel nut · Post by **Dav the wheel nut** » Sat Sep 18, 2021 2:37 pm

longleydel wrote: ↑Sat Sep 18, 2021 2:05 pm As a matter of interest, do you disconnect the battery whilst charging?
Derek

As above, nope

longleydel · Post by **longleydel** » Sun Sep 19, 2021 9:04 am

Hi Dav, thanks for your message, a very clean engine bay. Oh I do wish I had a garage. Use a quality weatherproof car cover however. Maybe I can find a way to run a mains extension lead to the engine bay and rest the charger there. The CTEK ones appear designed for weather extremes so long as their dry.

Derek

enuff_zed · Post by **enuff_zed** » Sun Sep 19, 2021 9:14 am

longleydel wrote: ↑Sun Sep 19, 2021 9:04 am Hi Dav, thanks for your message, a very clean engine bay. Oh I do wish I had a garage. Use a quality weatherproof car cover however. Maybe I can find a way to run a mains extension lead to the engine bay and rest the charger there. The CTEK ones appear designed for weather extremes so long as their dry.

Derek

It's not too difficult to adapt a tupperware box to house the lead connections in to keep them weatherproof.

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