Battery repeatedly going bad 2004 C70

dcaton · Post by **dcaton** » 29 Apr 2018, 16:48

I have a 2004 C70 that hasn't been used much in the past 2 years. Sometimes it will not even get started for a few weeks or occasionally a few months. Would that in and of itself cause a battery to go bad? I've replaced the battery four times in the past 2-3 years. I take it in to be tested, it tests bad, they give me a new one and in 6-9 months its bad again.

I just put a new battery in it a couple of months ago. Yesterday I went to start it up and it was dead. Probably hasn't been started in a month or two so I jumped it and let the car run for at least two hours. Turned it off and it started right back up. Today I go out to start it and it's won't start. Voltage was about 8 volts.

When the car is off, it draws between 0.020 - 0.022 amps, with occasional spikes to 0.035 amps. I've left the meter attached for over an hour with min-max memory enabled, and it never went outside that range. Doesn't seem excessive, so I don't think there's anything stuck on that's draining the battery when the car is off.

When running, voltage at the battery terminals ia about 13.1 volts and the battery was drawing about 5 amps. The car will run without the battery connected. Am I correct in assuming the alternator is ok? Any way I can test it without taking it out and having it tested at a parts store? The service light isn't on and the OBDC thing doesn't show any error codes.

I'm really at my wits end here trying to figure this out. I'm about ready to take the current battery in to have it tested. I can't believe that I've gotten four bad batteries in the past few years though. During one warranty exchange, the salesperson said that the Florida heat kills batteries and they rarely last their full warranty period. Any truth to this? I've lived down here for over 25 years and never had problems with batteries dying prematurely before. The last 3 or 4 batteries were Bosch. Current one is a Champion.

Post by **misha** » 29 Apr 2018, 17:14

Not starting a car for two weeks with a brand new battery will result in drain battery...and you are talking about months.
When you are not using the car for at least once a week,you must disconnect negative battery cable....or it will die prematurely.
Discharged battery MUST be recharged mostly 2 days after discharging or sulphatisation will kill the cells inside!
1ST rule for cars with ECU(s)....NEVER disconnect the battery while engine is running.You will fry all the electronics in the car!

Post by **oragex** » 29 Apr 2018, 17:58

dcaton wrote: ↑29 Apr 2018, 16:48I just put a new battery in it a couple of months ago. Yesterday I went to start it up and it was dead. Probably hasn't been started in a month or two so I jumped it and let the car run for at least two hours. Turned it off and it started right back up. Today I go out to start it and it's won't start. Voltage was about 8 volts.

It is not so easy to diagnose these things. I'll just throw my own experience with a parasitic drain issue. At 8 volts, the battery is basically empty. In fact, we consider a battery almost fully discharged from 12V and under. The charge should be at least above 12.4V. It means the battery is still somehow good for a while. Ideally it should read 12.7V.

It is true that hot climate doesn't help with batteries. It is also true that using the car only rarely doesn't help either if the car is used only for short drives now and then. But this doesn't mean the battery shouldn't last longer.

The first thing I would do is buy a car battery switch and disconnect the battery before parking the car for several days. This will at least preserve the battery if there is a small parasitic drain. Keep in mind these cars can be sensitive disconnecting and connecting back the battery, sometimes they can act.

To see if there is a parasitic drain, measure the voltage after parking the car then the next morning and notice the difference: more than 0.2V difference or so on a good battery may mean there is a parasitic drain somewhere. Now to measure the voltage correctly, open the hood and let the car shut off everything (on my 2003 S60 it takes about 10 minutes, there is a small relay buzz after 10 min when all computers go off - the interior lights will shut off well before this). Then wait another 10 minutes for the battery to stabilize and measure the voltage.

When you did you measure the 0.022 amps I believe the hood was open so the hood switch was not activated but also the whole alarm system was not activated. So there may still be something wrong with the items that were not active.

The way the battery wears is when it's charged while driving and discharged (ie parasitic drain) while parked. Batteries are not made to be cycled. Also, a faulty alternator will damage the battery.

As for the alternator voltage, normally it should show around 14.4V but the alternator will not put all this voltage out if the battery is already worn. The only way to measure properly the alternator is with a known good battery (preferably a new one), then it should show the 14.4V or so voltage.

Post by **wizechatmgr** » 29 Apr 2018, 18:07

Try checking voltage cell to cell in the battery at the plates - it could be a bad cell. I personally think that alternator is a bit low, I like seeing a minimum 13.5V, a dead cell could also cause this as the others will end up over-charged (if my logic holds true.) I love gel cell/AGM batteries - they seem to take the most abuse from me.

+1 on what misha said - they often are given to customers at less than 100% state of charge due to sitting in the store.

If you're going to be leaving the car for that long again, I would suggest hooking up a battery tender. This should avoid a flat battery in the future. I would get one that's about 1.5A (1500mA) so that it has more than enough capacity to maintain and could even potentially super slow charge the battery if needed (likely 3-4 days+ required)

Post by **FLXC90** » 01 May 2018, 01:37

+1 for wize, yes our climate drains batteries. Lack of maintenance finishes them prematurely. Your situation sounds like a good call for a tender.

dcaton · Post by **dcaton** » 05 May 2018, 13:33

Thanks to all that responded. wizechatmgr, how could I possibly check individual cells in a sealed battery??? In any case, I took the battery in to be tested and it was bad. I've got a new one and will leave the car running for a few hours to make sure it's fully charged, in case it doesn't have a full charge already. Then I'll see what happens overnight.

I understand that it's not the best thing for a battery to not to start a vehicle for a few weeks or more. However, when the C70 was my primary vehicle that I used every day, I had an Explorer that I only used to get stuff from Home Depot, etc.. It would sit for weeks or longer without ever being started, and it always started up just fine and I never had battery issues with it. I'm not sure what's different with the C70, but that's why I wasn't concerned about the battery.

I'll make sure I start the car every few days and will check voltages soon as I get a chance. If I was keeping the car maybe I'd get a tender (or just get into the habit of starting it every few days) but at this point I'm just getting it cleaned up and ready to put up for sale.

Post by **misha** » 05 May 2018, 14:26

Alternator is not capable to fully recharge the battery when engine is idling.
You must use battery charger for that.

Post by **wizechatmgr** » 05 May 2018, 15:12

dcaton wrote: ↑05 May 2018, 13:33 Thanks to all that responded. wizechatmgr, how could I possibly check individual cells in a sealed battery??? In any case, I took the battery in to be tested and it was bad. I've got a new one and will leave the car running for a few hours to make sure it's fully charged, in case it doesn't have a full charge already. Then I'll see what happens overnight.

Some of the sealed ones still have an access port on them. Many don't. Glad to hear they were able to confirm your battery is toast.