ok im no electronics expert the car is 4 liter Fairmontwith a computer /cpu unit . I am wondering if it is dangerous to the health of the computer to charge the battery WITHOUT disconecting it ( removeing positive terminal) just using a handyman type 3 amp charger overnight.
Logic would suggest just clip the charger on without removing the leads on battery , but the reason i ask is that chargers dont realy give a "clean" power supply (kind of a truncated sine wave rater than a flat clean DC.)
MY worry is that the "pulsing" of the charger could damage the CPU
any comments!.thanks
sgrants,
Sep 15, 4:54pm
It is advisable to disconnect the battery when charging!
ignoramus1,
Sep 15, 5:08pm
any particular reason why it is advisable! .
sgrants,
Sep 15, 5:31pm
spiking damage to electronics!
pup2,
Sep 15, 5:52pm
This is a good question. Would like to hear peoples opinion on this. We disconnect the battery when charging the battery in the car, but we also sell maintenance chargers that work at 1500mA and lower, with the sole purpose to maintain the battery when the vehicle doesn't get used very often. Customers fit these to their new cars (eg-ford boss), 4wd's etc. Battery is not disconnected when the charger is connected to the battery. Hasn't damaged any modules.
andrea_w,
Sep 15, 5:52pm
Also. remove the Negative terminal, not the Positive
crzyhrse,
Sep 15, 5:52pm
I've never bothered and never had any problem. I went through a spate of leaving the boot ajar and deep discharging the battery about 4 times in a couple of months and just charged it still connected. Same car too.
elect70,
Sep 15, 7:08pm
Hardly wise surely,srereo lose itsanti theft code, ECU , & other things with memories canlose itsrunning settings . . I leave my BMW on trickle charger permanantlyas its only a weekend warriorNever had problem . Even charged it on hi charge20 ampswhen it nearly went flatafter boot light switch stuck on.
ignoramus1,
Sep 15, 7:57pm
i would have thought surely that if the key was off teh computer would be protected whist charging!
pup2,
Sep 15, 7:59pm
computer has a full time power supply
bigfatmat1,
Sep 15, 10:01pm
waste of time I never disconnect batteries while charging them NEVER I say
phillip.weston,
Sep 15, 10:09pm
as above I've never disconnected the battery when charging them. The battery acts as a voltage stabiliser/buffer. I've even run the car electrics straight off a battery charger with no battery connected just fine.
richardmayes,
Sep 15, 10:25pm
Would a home trickle battery charger hit the electrical system of the car with (more power / as much power / less power) than the car's own alternator does during normal running!
ignoramus1,
Sep 16, 5:36pm
no it wouldnt .its only 3 amps .the point is that the cars power supply is fully regulated to give "pure dc" to the battery. Whith a charger it ISNT a "clean dc" power supply see original post .
I dont know the electrical terms but there is a difrence between what you get off a battery charger and cars supply.
OK now i have some unbiased opinions the reason I ask is becuase the car blew the computer THE DAY AFTER i fully charged the battery overnight.big coincidence or did the chargeing (without disconecting battery) stuff it.if its a coincidence its a big one!
sr2,
Sep 16, 11:28pm
Where on earth did that idea come from! I'd suggest you put a scope on an alternator and a battery charger, you might be suprised!
johnf_456,
Sep 16, 11:31pm
As someone in the trade I never disconnect batterys, for the sake of loosing stereo security codes and having to retune radios why bother.
dent,
Sep 16, 11:43pm
probably the main thing is not to disconnect the battery terminals but make sure when connecting and disconnecting the charge that its switched off. This will reduce the chances of spikes.
sr2,
Sep 16, 11:50pm
yes, good practice.
bigfatmat1,
Sep 17, 2:19am
Be a coincindence. Who diagnosed a blowen computer on the car and has this been fixed yet, or is this the assumed problem.
ignoramus1,
Sep 18, 4:13pm
Just going by what those who know more about it than me say. But I do know that running a 12volt horn off a battery charger and off a battery (motorbike horns) makes a huige diffrence to the sound (not just the volume)
ignoramus1,
Sep 18, 4:16pm
not assumed problem, comp was blown, diagnosed by auto electrician, its fixed , just trying to get to the bottom of likley casues of issue .looks like battery charger may have contributed if not caused.
bigfatmat1,
Sep 18, 9:35pm
It would be bad luck. power supplies in a ecu are diode protected and regulated for this reason Also about the ac ripple mentioned above this would be minimal .5v peak to peak and only on a crap charger roughly what you would see on a alt some chargers will rise to above 16v but a ecu can handle this voltage
loonee-dial-111,
Sep 20, 6:08am
Some fancy chargers put spikes on the battery to desulfate, I would read the manual on those before connecting. But in general if it's a cheap basic charger I wouldn't be concerned. I have charged many cars with the battery in place.
bae13,
Nov 12, 10:07am
this is true, i have seen latemodel bmws/vws overcharging at 22 volts and had no other issues. like has been said the output from an alternator is far from DC its a rectified ac output to replicate a dc but it still has peaks of ac in there. out of interest has the OP mentioned what vehicle it was! and by blowen ecu can you be more specific, like did the car have a miss, did it not start, has the repairer mentioned if it was missing spark, fuel etc
Since the public registrations are closed, you must have an invite from a current member to be able to register and post in this thread.
Have an account? Login here.