Battery Charging

[scm2004red]

May be a daft question, but for various reasons my MR2 has to undergo a period of enforced idleness, and I have noticed a steady low parasitic drain over time which runs the battery down (a new one) up to a couple of volts over 2 or 3 weeks. On my older cars this isn't a problem, I just disconnect the battery when in storage and put it on a maintenance charge. As the older cars don't have any electronics or stored memory in anything the only thing that stops is the clock!

However I am not sure if it is wise to leave the MR2 battery disconnected, or whether it is wise to connect a maintenance charger to the battery whilst still connected. I really don't want to find I am blowing something expensive or losing some stored functions, or setting off alarms.

Opinion would be welcome (and yes I am aware it's better for any car to use it, but this is unavoidable!)

[Joesson]

@scm2004red
My 2 has been in my possession since June 2011 and has been used 6 summer months on 6 winter months off since then.
At first I disconnected the battery and kept it on charge or did so 2 weeks on 2 weeks of for the 6 months. More recently I have left it on for months at a time with the battery connected.
With the battery connected the clock keeps time otherwise it needs resetting. Similarly with the ECU / EMS the Brains of the system. Resetting this means simply driving the car for a while so not a real problem either way.
This all depends on the charger you use, mine has a trickle charge function and is a Lidl special.
My understanding is that it is not good for a battery to be discharged and so I don't let that happen.
The battery the car came with was the second since 2002.That was replaced in my ownership and  I have had the "current" Yuasa for 4 / 5 years.

[scm2004red]

Thanks, my main concern is whether I could safely leave it with the battery disconnected. I probably exaggerated the anticipated drain, having just checked the battery after a couple of weeks standing, it has dropped from about 12.65v to 12.30v, but clearly over time it is a problem.

I too use a couple of the Lidl chargers, good value I think, but there appears to be some confusion as to whether they can be connected to the battery whilst it is still connected to the car, not something I would normally do.

[SV-3]

Trickle Charger - Connect to Battery on the car and forget. (Have a look at Harrysgarage on Youtube - all his cars are on trickle chargers).

Full Charging - Remove Battery from the car and charge.

[Joesson]

As I write the charger is connected to the battery and the battery is connected to the car.

I have just found the link below that agrees with my actions,  but in doing so also looked at the RAC advice which is to disconnect the battery and wear safety glasses and gloves when connecting the charger.

https://www.batteryfocus.com/charging-a-car-battery-while-still-connected/

[scm2004red]

Interesting stuff, thanks all, can go ahead with peace of mind.

[onion86]

I've had one of these (now on 2nd after an 'incident' with the 1st one on the manifold when I forgot it was attached earlier this year) for a few years. Worked perfectly https://www.amazon.co.uk/gp/product/B0012U5BO2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
The new one actually has a 'battery full' light, where the old one (in the pics on Amazon) didn't.

[luggsonofmyll]

With reference to Joesson I was advised by a (Volkswagen) Master Tech for the winter six months that the car is off the road, take the battery off the car, as it may freeze in extreme weather and stick it under the stairs or wherever. Then charge to full every two months. I have been doing this for the 7 years I've had my Roadster and no problems whatsoever with the same Yuasa battery.

[moca2cv]

I've just reconnected my car after parking it up when the fuel crisis hit. Was fine I wouldn't fret too much, better than goosing the battery.