how long is that ground cable? can it be to the point that theres too much resistance?

 

I had this problem as well.. and it was probably wiring related (which is pretty shameful since I did automotive electronics for years) mostly because I used a jeg's or summit battery relocation kit that came with some crap 2AWG cable which I would never have used back in the car stereo days to install a second battery, etc.

I had scraped paint and grounded to the seat belt lower bolt under the bottom portion of the back seat.

I took the car out of daily driver service over the summer and put a mini battery kit back up front, cranks over like normal again.

 

still slow cranks after changing the grounding spot, it cranks better but not great, I switched to the rear strut bolt. Length of wire shouldn't be the issue since others have used this length and this gauge with no issues, so I bought two of these for soldering

http://www.2xpower.com/10-Battery-Te...lamp_p_32.html

I am going to up my ground with atleast 2 gauge, I am also going to solder the ring terminal that grounds the battery, this was the only "screw down" connection will be the circuit breaker. I will keep all posted with results.

 

I'm betting on the too much resistance too. You're losing too much voltage. Also don't know if you covered it yet but how old is the battery you put back there?

 

Holy crap, so much bad info here, and no time for me to properly address it. Anyway, for now-

1)The dude telling you that you NEED soldered terminals is wrong.

2)You NEED to run a ground cable from the battery DIRECTLY to the engine block.

 

I have to agree here. Soldering the connections alone might help some, but I don't believe it will eliminate this problem. I suffer from the same problem when i relocated my battery to the trunk, my solution: redo all grounding cables, up the gauge, and see what happens. This should be enough to keep me occupied for a little while.

 

Slower crank than with the oem battery in the oem location is common with relocated mini batteries. I had that same issue with my oddysey. I swapped it out and put that same mini battery, which tested good, in an oem location on a 1991 toyota mr2 turbo. Cranked slower than the oem battery, and cranked just like my car did. Makes sense when you consider the oddysey has a 220cca rating iirc. Well anyways alot less than an oem battery.


I dont believe that soldered connections are necessary, although I do like to solder any wiring or cable if I can help it. I DONT beleive you NEED to run your ground to the engine block. I look at the trunk mounted batteries Mercedes puts in their cars everyday at work and I see the ground cable going straight to the chassis with no issues, and these cars are REALLY finicky with resistance values in their wiring. I feel that so long as you have a good ground to the chassis, you should be fine. You can run ground cables all over your car if youd wish, end of the day, a good ground is a good ground.

Once you get your wiring all setup all you need to do is get acccess to a dmm and test your wiring for any voltage drops and you will know right away if you have a good ground or not, simple as that. .

Im not a big fan of the mini battery anymore and im willing to sacrifice some weight for the sake of getting good, clean voltage to my setup so thats why Im looking at putting a rather hefty 800AH EN battery in the back. Plus, I get them REALLY cheap and supply is plentiful if they ever go bad. my.02

 

well you can always pull out a dvom and really find the problem. run voltage drops across your connections and find your culprit

 

I run double(2) grounds to my battery (4gauge). Relocated to trunk.

 

Battery is new, there is alot of different opinions going on in here, kinda hard to figure out a direction to go......

 

How did this turn out?
What was your solution for fixing the problem?

Thanks

 

I'd be willing to bet his issue was that the engine was not grounded to the chassis properly. That's something that's commonly overlooked when doing a battery relocate and causes a lot of these issues. Curious to see what wound up fixing it also though

 

Issue is a coupe things:

Ground- go big or go home, I went from a 4 gauge to 2 gauge to 0 gauge, large grounds offer noticeably better cranking/current.

Wire length- the shorter the better, longer wire offers greater resistance regardless if you go with a thicker wire. I cut two feet out and it helped with cranking, I plan on rerouting and cutting another 4-5 feet out, I think this will help completely eliminate the problem.

I hope this helps anyone trying to relocate their battery and exp slow cranking. Feel free to message me if anyone has any questions.

 

Well more then likely its a bad connection, either where your old positive battery terminal is underhood. Or your negative cable underhood is not grounded well. On my setup, where the underhood negative battery cable is I grounded it with a bolt to the chassis on top or the trans mount área.....use that area and make sure to use a grinder to grind down the paint to ensure a good metal contact.....good luck should help unless batterys weak..