I don't drive my FD much. In winter, not at all.

Over the past 3 years my batteries only last about a year. If I go a month without driving, the battery voltage gets low. I make sure to shut all of the doors and check that no lights are staying on. Sometimes it will weather a one month storage just fine, other times it's dead after the same period.

I'm currently using a Deka EXT30L. Before that I had two Braille B2131's. Those are both AGM type.

After recovering the Deka from under 8v more than once in 2013 it too needs replaced.

A couple of times I've checked the amp draw and got under 20mA. Over the course of a month that's only 14Ah, which is half of the battery capacity.

1) Is 20mA normal current drain for a fully "off" car?
2) Anyone have tips for troubleshooting this, if it turns out to be an intermittent drain issue?

David

 

they could both possibly just have a dead cell in them and that would cause them to drop in power and never really have an ongoing full charge. have you checked your alternator?

iv been using one of those green top interstate batteries, i take it out of my car every winter and charge it maybe twice for the 6 months my fd is in storage. have had it for nearly 3 years now without a problem.

 

You should look into a battery tender or disconnect the battery for long periods of non use. I killed a couple batteries too just letting them sit for long periods of time.

 

20mA is not bad, that's within the service manual specs for total current drain with the key in the off position. One more vote for a battery tender or trickle charger if the car sits for long.

 

Quit wasting money on batteries and get a Battery Tender for crying out loud. Was having similar issues 2 or 3 years ago. Battery Tender has totally taken care of the issue

 

Battery Tender cost 20.00 dollars. Well worth the money . Unless u like swapping battery's for no reason. If your car sits for more than a week go with a battery tender.

 

Batteries self discharge over time as well + the minor drain could be the reason.

I personally use a circuit breaker to disconnect the battery, since I rarely drive the car. 1-2 times a month.

Also that deka battery does have a low amp-hr rating compared to a normal sized battery.

 

Rlee429

Is that circuit breaker from a kit or something u through together.

 

I understand that the Deka / Braille is a smaller capacity. It's the largest one they make and it's signficantly bigger than a PC680, which is why I didn't think I was taking a big risk.

I guess what puzzles me is that I get such varying results. I've let it sit a month and checked voltage and it barely drops a fraction of a volt. But I've also come back a month after that and found it stone dead at 7v.

As far as bad cells go, 3 batteries in a row is horribly bad luck.

David

 

Do you have an aftermarket alarm on the car?

 

No aftermarket alarm.

The only electricals that aren't stock are a water temp gauge and a PFC. Hardly the stuff of battery drain.

 

Temperature could be a factor; I'm not knowledgeable enough to say this will affect the discharge rate, but they definitely don't like cold.

My memory is fuzzy on this, but I think a professor once claimed it's preferable not to let lead-acid batteries sit on conductive materials like metal... it would be better to have them mounted on something non-conductive like plastic if possible.

 

I just solved this issue for one of my customers about 3 months back.

FD came in, discharging the battery completely from full to 8V in the space of 24 hrs. Went right through the car and found a dark current draw of 0.9V constantly coming out even when in sleep mode (IE the ignition key illumination light goes off and car enters sleep mode)

Rewired the aftermarket alarm and reduced draw down a LOT. They had twisted wires together by hand and had masking-taped them together. Worst mess I've seen in any vehicle yet. Complete fire hazard.

(My stock auto car for comparison draws 25mA dark current which is within factory spec. I've never had a battery drain issue with my car.)

Anyways, after rewiring his alarm and reducing dark current draw, was still getting a dead battery within 24 hrs. So removed the battery and recharged it. Left it at full charge sitting in the garage. Came back to put it in his car the next day. It had gone dead flat 8V without even being connected to the car. Battery was defective. It was one of those "Fullriver" yellow top sealed batteries, only 6 months old. Took it back, replaced it, all good, no more mysterious drain.

So sometimes it is the battery :/

 

CTEK Battery Chargers - The World's Smarter Battery Charger

I love these chargers. It keeps my battery at peak condition. When I get in, it's ready to start!

I have the CTEK Multi US 7002. Owned it for about 4 years now.

 

Not certain how to test for it, but could the internal regulator on the alternator have gone bad and be overcharging/cooking the batteries?

 

Hi,

You need to be aware of the relationship between self discharge and the temperature the battery is stored at.

I deal with a few different types battery banks on a daily basis. 1 month if they are truly open circuit and disconnected is nothing to worry about. They certainly can go bad after a number of months, 3-6 depending on temperature. And when you try to recover them even with the most expensive battery recovery chargers they still bloat and expand most of the time.

I'm guessing you have a parasitic draw more than self discharge going on however.

 

This crossed my mind too; however, it's more likely it's undercharging the battery.

It would be helpful if the OP would check the charging voltage (after everything is warmed up) and post it up. Also note the ambient temp near the battery.

 

My car was doing something similar a couple of years ago...and it turned out that for some unknown reason the keyhole light in the driver's door was staying on. Never knew what caused it, nor why it suddenly 'fixed itself'.
Not sure if the keyhole light is even active with an aftermarket ECU though...

 

It'll be a bit before I get any diagnostics going. First I need to order a new battery. I have since finished moving (2013 has been a busy year) so the car is now parked where I can leave it on supply voltage with my Genius 7200 charger.

I have seen the voltage on the PFC when the car is running and although I don't remember the exact number it seemed normal for charging (normal being 13, 14 volts?).

David

 

I've always had to put a trickle charger on my fd in the winter. Don't need to on the fb though.
Something has to be draining besides the cold. But it's not killing my battery as long as I charge it in winter.

 

Cold is good, that slows down self discharge.