4agte battery problems

[mlewis]

Found my battery is turning over like its semi flat. even with the battery from my daily driver, and using a fully charged battery pack.

Any other ideas why it could be cranking like it has a semi flat battery even when it has a fully charged battery

[Dell'Orto]

Lack of earths on the motor/head/box

[mlewis]

does there have to be a certain amount of earths on each or doesn't it not matter as long as it equals a certain total?

[Bling]

Just needs to be enough to provide enough of an earth I guess. Not total as such, just enough to provide enough capacity. At least that's my non-sparky theory. Just add a few more rangi'd up ones to test if that's the problem. If it is, then make some proper ones.

Would be like welding and having the earth clamp only just touching, you'll not get much power to the tip to weld with.

[sergei]

Basically the "drain" (earth) should be equal (or more) to the "supply".
If not it will heat up the weakest link, and will use paths that not meant to (eg: it will try to go through random sensor earth and blow the ECU in worst case).

[AE82 FXGT]

Basically the "drain" (earth) should be equal (or more) to the "supply".
If not it will heat up the weakest link, and will use paths that not meant to (eg: it will try to go through random sensor earth and blow the ECU in worst case).

This, get some big meaty earth cables on you motor and chassis to the neg battery terminal.

[mlewis]

My battery is in the boot so was going to hook up some wires ranging from head, block, gearbox to different parts of the chassis? would that work or do they need to get to the negative terminal?

[Dell'Orto]

Nope, body is fine

[iOnic]

My battery is in the boot so was going to hook up some wires ranging from head, block, gearbox to different parts of the chassis? would that work or do they need to get to the negative terminal?

This is how SW20's do it since the battery is in the front and engine is in the back. Perfectly fine as long as your negative terminal has a good connection to the chassis.

[matt dunn]

bad starter motor??

[mlewis]

im hoping the starter motor isnt the problem but will find out once ive sorted the fuel leak and run some more earth wires

[evil_si]

Were did you earth the battery? In the boot? Did you make a good metal to metal contact?

If you suspect the engine to chassis are bad, chuck a jumper lead between the engine and chassis and test

Are the battery and starter terminals tight?

[mlewis]

battery and starter terminals are tight and the battery ground in the boot hasn't changed in the 3 years I've owned the car so no idea where its grounded to. will be running more earth cables in the next couple of days and if thats the problem will make them more permanent

[AE82 FXGT]

Make sure you get some good cable going from your battery neg to the chassis (sand away any paint under the contact area). Then in the engine bay make sure you get good cables from the chassis to motor.

[jacobrjett]

see what voltage you are getting with a multimeter?

that will at least narrow it down from bad ground

[mlewis]

car is fitted with a voltage gauge thats reading 12v ( or just under) with battery pack attached. was hoping to get day off tomorrow to sort it out but havnt been so lucky so wednesday it has to be. by then hopefully i can drop it off the jacks on a decent day and roll it outside

[gt4dude]

yes to lack of earth.

with battery to boot relocation you should also run a negative which grounds the boot, the engine bay and the original grounding location on the gearbox.

rubber or nolathane engine mounts aren't very conductive


the starter supply terminal is a perfect place to mount your main positive wire

[Mister]

Alot of people over complicating a simple problem on here...

1st Step) Check your battery for drains with a multimeter and the key off then charge your battery fully.

2nd Step) Do a battery load test, or get a workshop to do one for you and test the battery, even new battery's fail on a regular basis luckily warranty claims are easy due to being common.

3rd Step) Do a voltage drop test from the starter motor earth to the battery earth (If you don't know how to do this I can tell you, or google can, it is easy) this is the most reliable way to check you have a good earth before you go bolting up any heavy cables all over the show (Ugly stuff imo)

4th Step) Check the current draw from the starter motor with an oscilloscope or just strip the starter motor and check it for issues.

One of these steps should lead you in the right direction,
Churs brah,
Mister.

[gt4dude]

voltage will show 12/off 14/on everywhere, its the amount of current (amps) that the connections carry that is the issue, and the symptoms he describes is very typical with battery to boot relocations that just ground to the boot.

ive had 2 cars, that nomatter where i ground to in the boot, the starter doesnt get full juice... this includes cleaning bolts/holes with crc, sanding back paint, etc... no help, tried mounting to main rear seat bolt (m8? or m10), strut mount, new hole, etc...

and by the sounds of it, everyone else that has replied similarly, has found the same.

[allencr]

Lots of spot welds & different pieces of sheet metal between the engines ground strap and the battery's earth? Most likely are, and being old & flexy doesn't help, but the body is a perfectly suitable path in most cases..

Feel the cables, connectors/terminals after trying to start it. The warm one is where the resistance is.