Thread: Defender flattening battery when left sitting

Originally Posted by Blknight.aus

carefull....


the desulphation routine is, in a nutshell, a voltage spike. If you dont have filtered power supplies between the battery and some electronically technical items there is a risk that you might just let the smoke out of your electronics.

The kit ones from jaycar as well as some of their premade battery savers list a warning to this effect.

So, you would be suggesting I disconnect the battery from the vehicle before charging with the DTEK charger.....

Ok, I finally got a round to it.

I hooked my multi-meter up and checked the drain on the battery after another Fail To Proceed last weekend due to a flat battery.

Just a little background... if we drive the car and then leave it for 14-21 days (I know it's bad but it happens) then your chances of getting a start are minimal. At the 21 day end they are non-existant.

Anyway, I hooked it up and the drain was .08 of an amp. I started pulling fuses without seeing a change and got sick of it! I then dived under the bonnet and disconnected the electronic rust prevention system (it was under suspicion). The load dropped by .04 instantly. So, half the drain was the RPS and the other half is the normal car accessory load.

That's not all that much, but due to the design of the Traxide DBS the load comes from both batteries but it then isolates the main from the secondary, leaving the main to be drained until it can't start. (this is not in any way a criticism of the DBS). The car doesn't get driven all that much when it is driven so possibly the batteries aren't ever getting fully charged - this might be playing into the problem.

So, clearly I have four options here. These are arranged in order of likely-hood!

1. Buy a small backup charger and hook this into the car when it's not in use. This is the best option as it's not good for batteries being drained heavily.
2. Change the wiring so the ERPS draws from the auxillary battery. With the DBS this will stop the no-start problem, but I don't think it's good for the battery being flattened. It might get done, but probably in addition to 1.
3. Disconnect the ERPS entirely.
4. Drive more!

Interesting, as I had been having similar problems with my 110 county battery. Also with an ERPS fitted. Never had this happen until I fitted the ERPS. After checking around I found mine was drawing similar amps. At the moment I am getting over the problem by using the vehicle a bit more often but like you I am wanting to sort this out, so I think the best way around it is to wire the ERPS up to the aux battery so that it doesnt affect the start one. At least it wont affect the starting then and if your aux is a deep cycle then it wont harm it unduly by being drained. Good luck.!

Originally Posted by spudboy

So, you would be suggesting I disconnect the battery from the vehicle before charging with the DTEK charger.....

yes and no, that would be the absolute safest way.

I would just find the primary accessory feed, work out it maximum draw and then disconnect that feed, install a choke and then connect it all back up.

when you hook up the charger to the battery go straight to the battery and the choke protects everything sensitive.

Originally Posted by Blknight.aus

yes and no, that would be the absolute safest way.

I would just find the primary accessory feed, work out it maximum draw and then disconnect that feed, install a choke and then connect it all back up.

when you hook up the charger to the battery go straight to the battery and the choke protects everything sensitive.

Reading all that I think I might be better powering the ERPS off the aux battery and just try and drive the thing a bit more.

its not that hard....

in its simplest form a choke is just a few turns of wire around a magnet.

in reality if its not a td5 and you dont have a fancy alarm or any wierd power supplies that drive laptops or the like then you probabley dont need it.

Originally Posted by Blknight.aus

its not that hard....

in its simplest form a choke is just a few turns of wire around a magnet.

in reality if its not a td5 and you dont have a fancy alarm or any wierd power supplies that drive laptops or the like then you probabley dont need it.

It is a TD5!

I'll ask my automotive electrical engineer mate about this and see what he thinks.

Battery fighter make a small charger that just has a charge and float cycle. That may be adequate for the job and I can't see why it would cause any problems?