Guest neilseficab Posted May 30, 2016 Share Posted May 30, 2016 I have an issue with my battery draining after a few days or so. The battery is not that old really. When the car is running at idol it reads around 15.5 volts which increases slightly with higher revs.i dont ever remember any of my older cars ever having a charge voltage that high. I have now removed the battery and put it on charge. Once fully charged i'm going to monitor the rate at which the volts drop over hours/days etc just to see if its losing its charge too quickly. I suppose it could be rapidly losing voltage as soon as load is introduced but reading fine every other time. I'll get the basic checks done but before hand wanted to know if this charge rate maybe having an adverse effect on the battery. Any advice would be appreciated. Quote Link to comment Share on other sites More sharing options...
Guest username Posted May 30, 2016 Share Posted May 30, 2016 Charge voltage sounds a bit high TBH but could be down to a dead cell in the battery. First step is making sure the battery can hold its charge over a few days (12.7 or so is reasonable, dropping to much under 12.5 I'd consider nearly dead) and if possible perform a load/drop test to make sure it's pushing out the amps. If the battery is dead, obviously get a new fully charged one and fit that but monitor the charge rate straight away as overcharging would ruin the new battery over time too, through overheating and boiling off electrolyte/warping the plates. (usually accompanied by accelerated rust in the battery box through corrosive fumes, and possibly an eggy/sulphur whiff in the air) if you still have over 15v charging with a good battery it's time to look into repairing/replacing the alternator. Quote Link to comment Share on other sites More sharing options...
Himanshu Posted May 31, 2016 Share Posted May 31, 2016 That charge rate is too high. about 13.5v -14.5 v is acceptable. Quote Link to comment Share on other sites More sharing options...
gingergman Posted May 31, 2016 Share Posted May 31, 2016 Sounds like the regulator in the alternator is nackerd, allowing it to over charge, it will bugger your battery if you leave it like it too long too. Quote Link to comment Share on other sites More sharing options...
Guest nicholas huntley Posted June 2, 2016 Share Posted June 2, 2016 I think a max of 14.2 volts is OK. If you can locate a dead cell, I see on the internet, sometimes you can revive them by addition of one teaspoon of Epsom Salts. Give the battery a good shaking and recharge normally, say max 8 amps or so. Overnight may do the trick. 12 volt battery should hold above 12.6volts for a few days if healthy. I revived a few that can hold 12.7+ for over two weeks,(if not used, or course). You need to check charge rate from alternator though, too high will boil and potentially ruin any battery. Quote Link to comment Share on other sites More sharing options...
Guest nicholas huntley Posted June 2, 2016 Share Posted June 2, 2016 I think a max of 14.2 volts is OK. If you can locate a dead cell, I see on the internet, sometimes you can revive them by addition of one teaspoon of Epsom Salts. Give the battery a good shaking and recharge normally, say max 8 amps or so. Overnight may do the trick. 12 volt battery should hold above 12.6volts for a few days if healthy. I revived a few that can hold 12.7+ for over two weeks,(if not used, or course). You need to check charge rate from alternator though, too high will boil and potentially ruin any battery. Quote Link to comment Share on other sites More sharing options...
Guest neilseficab Posted June 4, 2016 Share Posted June 4, 2016 cheers guys. The battery has been checked every morning now off the car for 3 days and it reads 14.2 volts everytime. I've put a battery tester on it and it reads: GOOD - 100% life remaing with 360ah . According to the battery its any a 330 ah battery. I'm guessing its fooked. Quote Link to comment Share on other sites More sharing options...
Guest username Posted June 5, 2016 Share Posted June 5, 2016 14.2??? guessing that's a typo and the battery is at 12.4 off the car? If that's the case then first step would be a new battery, but as soon as it's charged (ideally leave a new battery on trickle overnight before using) and fitted don't drive the car but start the engine and check your charging voltage again. anything over 14.5 would be "iffy" IMO and near 15v I'd call excessive and could damage the battery if left that way. As mentioned further up, overcharging with a new battery would point to dodgy regulator pack (in the back of the alternator) so you could either replace that or, better still, fit a new/refurb alternator from a reputable source. Quote Link to comment Share on other sites More sharing options...
Guest nicholas huntley Posted June 8, 2016 Share Posted June 8, 2016 No thats not a typo! Any healthy battery can manage 14.2volts after a normal overnight charge, 4 to 8 amp charge for 12 hours. Let battery rest for a while, say 1 hour. Now check voltage. High but normal can be max 14.4 volts. Dud battery would be anything less than 12.2 volts. If battery is able to hold over 12.8 v for a week or more, (of not being used) I think its probably O.K. The higher the voltage held, the healthier the battery. If starting is sluggish, hard to get engine to turn over, although you may have 12.8 volts or more, you don't have the amperage/power or capability to store the power, in the battery. Thats when its probably shot, or should be! If you do have to buy a new battery, personally I always go for the bigest battery that will fit into the space, thats just me tho! But it does give you that bit extra if you encounter starting problems. Or if you have additional spot lamps etc. I think you first need to check alternator output and condition of regulator, if power output and/or voltage is too high you will ruin any new battery or the existing battery. So a new or recon alternator may be your first option, but get yours checked, any auto electrician should be able to check this for you. Good Luck! Quote Link to comment Share on other sites More sharing options...
Guest username Posted June 10, 2016 Share Posted June 10, 2016 New one on me that lol, but then so is a battery coming back to reasonably decent life after sitting, flat, outside for over 8yrs (see my other thread on that lol) +1 on fitting the biggest/most powerful battery that will physically go in the battery box though, always nice to have a bit of extra reserve for sitting down back lanes stargazing (brownie points with the missus haha) with the stereo on or going camping etc Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.