Battery care on a short tripper?

[Quattro Pete]

The 530i in my sig is primarily short tripped these days, and parked outside. It uses a traditional (flooded, sealed) battery. Due to short tripping and low use/few miles, the battery is usually undercharged. What approach would you suggest to keep a battery in such vehicle in good shape?

1. Put it up on a charger every week or two?
2. Replace battery with AGM type battery?
3. Other suggestions?


(1) is sometimes hard to do due to subfreezing temps during winter. Having to remove the battery from the vehicle to charge it is too much PITA.

Regarding (2), is it even advisable to put an AGM battery in a car that didn't come with one from the factory? Without manual top off charge, it'll still be undercharged, but I've read somewhere that AGM handles being undercharged better than a lead-acid type battery that likes to always be fully charged. Not sure by how much this would increase battery life. I don't want to pay double for an AGM battery, but only maybe get 1 or 2 extra years of life, as compared to a traditional lead-acid battery.

In the past, I've gotten about 5 (maybe 6) years of battery life in this vehicle, but it was short tripped less and it was garaged then. Not horrible, but I'm just trying to learn if there are things I could do to make it last longer.

BTW, intentionally going on an extended drive just to let the alternator charge the battery is not an option. I won't go out of my way and waste time and fuel just to do this.

Thanks!

 

[eljefino]

Solar panel charger? Leave it on the back package shelf.

 

[Snagglefoot]

You can put the charger on it say once a month. An "intelligent" charger works best because it can optimize the charge rate and maximize the charge without damaging the battery. I do it with my low use backup car / winter beater 2000 Taurus. I don't disconnect the battery when I do this.

 

[RooflessVW]

I'm assuming it is not garaged?

I would install an AGM and a Battery Tender - with solar panel on the back deck. Or sunroof, if you're feeling froggy.

If it's garaged just wire a permanent lead somewhere accessible and plug it in from time to time.

 

[jeepman3071]

My friend has an e46 330i ZHP he now rarely drives except on nice days. He keeps a smart tender on it when he is not driving it and it has worked very well so far.

 

[Quattro Pete]

Down to what temp is it still OK to charge a lead acid battery? I've read somewhere -4F is the low limit.

 

[Quattro Pete]

Originally Posted by eljefino
Solar panel charger? Leave it on the back package shelf.
Interesting idea.

Where the car is parked, there is very little sunlight available. Maybe an hour or two in the morning, if that. Not sure if that would suffice. Also, the back window has heavy tint which probably makes it even worse. Routing the cable from rear shelf back to the battery would be a challenge.

Can these solar chargers be permanently hooked to the battery, or do they need to be disconnected before you drive the car?

 

[andyd]

Cheapest is probably the one from HF. $4.99 with coupon. I use them on the Rat and my mower. Not on constantly , just every so often. What is the 530i regulated to ? The 528e was set to 14.1 v though a 14.3 was used in later models. You hafta drive an E 28 quite a ways to float a dead battery.

 

[Quattro Pete]

Originally Posted by andyd
Cheapest is probably the one from HF. $4.99 with coupon.
Cheapest what? i already have a bunch of chargers/maintainers. That's not a problem.



Quote
What is the 530i regulated to ? The 528e was set to 14.1 v though a 14.3 was used in later models.
14.1V I think, but I'd have to check.

 

[eljefino]

Originally Posted by Quattro Pete
Down to what temp is it still OK to charge a lead acid battery? I've read somewhere -4F is the low limit.



You don't want to charge a frozen battery but they get frozen by being discharged! I know of no lower limit and a little current can only be good for it!

The solar panel chargers have diodes so they only do good. The rear tint's an issue but I guess you could use it on the windshield, then put it on the passenger floorboard when driving.

 

[nthach]

If that E39 can be coded to recognize an AGM and provide the proper charging for it, I don't see why not. And if not, an AGM, even a JCI one made in Spain or Germany will be much better than flooded - less acid vapor leaving the battery since they are valve-regulated.

If it were me, keep it on a Battery Tender or a Noco Genius on maintain.

 

[Onetor]

My local Walmart had a Platinum AGM battery with a 5 year warranty. Around $160. Not bad!

 

[Quattro Pete]

Originally Posted by Onetor
My local Walmart had a Platinum AGM battery with a 5 year warranty. Around $160. Not bad!
Thanks. It does appear that Walmart's AGM battery is not a whole lot more than a lead-acid one, although warranty is the same on both. And the specifications on that AGM one state:

Quote
Contained Battery Type: Lead Acid

What?

 

[Colt45ws]

I permanently installed a 5 amp battery tender under the hood and I plug it in each night with my block heater.

 

[Donald]

Do you have an outlet to plug in a charger? I am a fan of the Battery Minder brand. Not cheap ones like from HF. They have some that are temp compensated for high and low temps. You can attach a charger with the battery part connected all the time and a quick connect sticking out of the front grill and then just plug in the charger once every 2 weeks, Maybe once a week in the dead of winter. I have about 5 Battery Minders now for various batteries. All work fine. Some better than others. A battery in the basement does not need a temp compensated battery maintainer for example.

You could also get a tool to measure the charge of the battery. Maybe its getting fully charged even on short trips. With EFI and large alternators, there is not much juice taken to start the car and the alternator can put it back quickly.

Cars with points and carbs were a different story.

 

[Quattro Pete]

Originally Posted by Donald
Do you have an outlet to plug in a charger? I am a fan of the Battery Minder brand. Not cheap ones like from HF. They have some that are temp compensated for high and low temps. You can attach a charger with the battery part connected all the time and a quick connect sticking out of the front grill and then just plug in the charger once every 2 weeks, Maybe once a week in the dead of winter.

Since the car sits outside, I have to run an extension cord to connect up a charger. I don't envision doing it every night, but doing it every couple of weeks is no problem at all - that was option (1) in my original post. I was just asking if that was the correct option for me.

I have temp compensated smart chargers.

 

[Smokescreen]

Intelligent chargers are the way to go. CTEK or Noco Genius. These kind are what high end car owners (Porsche Mercedes all OEM supplies etc) use in the off season and for very good reason. They do more than just trickle charge like non-intelligent chargers. They can de-sulfate and some have functions to operate specifically in cold weather to keep a battery from freezing. They also perform other smart functions to keep the battery fit. It is worth the little extra money. I have used CTEK on my truck battery all winter for years. I have all the original factory batteries in all my cars, all work flawlessly in all temperatures, so I know my regiment of periodic battery tune ups work.

You can boil a battery dry even with 2A if left on continually with most non-intelligent chargers, even if it has a trickle charge function. I know because I have done it, even with Better Tender brand.

 

[Quattro Pete]

Guys please, I've got plenty of smart chargers. I am not asking about charger recommendations, other than maybe the solar charger which I hadn't considered before.

 

[Audios]

Id say the hassle of dragging a cord out easily beats out battery replacement and spending money. I charge my Ms about once a month, I leave the charger on the ground under the front of the car, and charge at the booster spots underhood, and then trickle it overnight. The hood can stay closed but not latched and no one will know its open at a glance.

 

[Donald]

So, determine if the battery is or is not getting fully charged with your driving habits. If not, use a smart charger every 2-3 weeks in warm weather and 1-2 weeks in winter.