Second battery for winter use

[steve_bow]

After advice please, I have read the 120 threads on batteries and did not get the answer I was looking for.

 

Is there any harm in hooking up a second battery to help prevent the normal one discharging. Thinking about put a very large one used in Large car/truck, put in parallel with Caterham one and then recharge that every 2-3 weeks.

 

This is all down to NO power in the garage. The Solar option does not look good as we have less than 12hrs bright sun over winter.

 

Steve

[Nick Chan]

Steve,

 

If you were going to that effort, would it not be as easy to remove the Banner battery from the car and just have it in the house on a conditioner. It only take a couple of minutes to remove and refix it when needed.

 

 

HTH

 

Nick

 

Now the Orange HPC - A 2.0 VX - 😬

[Bricol]

OR if you already have the big battery, simply use jump leads from it if required . . .

 

Bri

[Peter Carmichael]

It isn't a brilliant idea to do this. Lead acids have some very strange characteristics which make this less of an issue than it might otherwise be, but if the cells in the two batteries are in different charge states/electrolyte concentrations etc, then the resting voltages of the two batteries will be different and a current will flow to counteract this.

 

Because of the lead-acid battery properties, the current flow will act to equalise the voltage imbalance and the cell inequality may well end up equalised... or it may not. This is akin to constant voltage charging for the weaker battery and constant voltage drain from the stronger battery. Twin batteries typically need twin isolation.

 

The best defence against a flat battery in winter is to disconnect the negative terminal (safer than the positive). If the battery is healthy and well-charged, then it will stay healthy and well-charged.

[Shaun_E]

SVC and others do a Battery Pillar Master switch which looks easy to fit and saves you having to undo the battery lead each time. From the picture it looks like the wrong type for the terminals on a Banner but I'm sure you could find something similar that would fit. The expensive option is to fit a proper battery cut-off switch but that is typically wired with the ECU and/or immobiliser still connected so won't really solve your problem.

 

Yellow SL #32

 

Edited by - Shaun_E on 15 Dec 2005 11:27:01

[tiddy1]

I ran a twin battery system most of last winter, worked well and had none of the problems peter described. second battery was in the boot, if you are worried you can fit on of the systems commonly used in caravans etc which switches the charging between batteries

 

Simon

[julians]

I have the same issue (Garage is .5 mile from the house with no power etc), I just disconnect the earth lead from the battery. Battery has stayed fully charged for a couple of month now.

 

I do however use one of the sealed batteries (odyssee type) which I remember hearing hold their charge better than a traditional lead acid battery.

[Peter Carmichael]

Hey, I just write the theory down. Like I said, lead acids have characteristics that make this sort of thing sort of viable... but if you are attempting to mask a fundamental problem with the battery expect trouble.

 

I disagree that there is a need to wire a bypass from the master switch to power the ECU and immobiliser. There is little or no harm in disconnecting all circuits from the battery on a typical K-series installation (the installation I know most about). You might have to resync the keyfob but that's about it.

[Myles]

Indeed.

 

The standard immobiliser 'remembers' whatever state it was in when the power was lost.

 

If it was armed, it will wake up armed next spring.

 

If it wasn't armed, it will wake up ready for your neighbourhood thief to drive away.

 

The MEMS 'quickly' relearns what little it forgot about your engine.

 

Project Scope-Creep is live...

 

Alcester Racing 7's Equipe - 🙆🏻™

 

Alcester-Racing-Sevens.com

---

[Shaun_E]

I agree that there is no need to keep the ECU and immobiliser connected. However, the Caterham Battery Master Switch kit and instructions include wiring for the ECU and immobiliser to bypass the switch - that would be a typical installation, especially if done by Caterham. If you wire it yourself or ask for it to be done without the bypass then your problem is solved (and you get a handy kill switch should you go sprinting or racing 😬).

 

Yellow SL #32

[Tom_C]

So does a Caterham-wired K series cut-off switch knock out all the electrics or not then? I've just bought an 05 academy car, and was hoping to use the master swich to look after the battery.

 

Tom.

 

[Shaun_E]

Tom - you'd need to check it to be sure, but the standard Caterham wiring would leave the ECU and (Ithink) the immobiliser still powered.

I have to say I'm becoming less sure about this so perhaps I just imagined it all!

 

Yellow SL #32

[Tom_C]

Would it function correctly as a kill switch if the ECU remains powered?

 

Might be time for some experimentation. I use a similar switch on my narrowboat to preserve batteries (not much differnce in speed, but you can't bump start a boat....) so I was hoping it would work

 

Tom.