Should I Not Use Maintenance-free Batteries?

[Adam Gravois]

I've got the familiar problem of battery--only six months old!--going dead after a few days of inactivity.

Googling the site's wonderful archives (and reading my Haynes), I see there are a bunch of things I need to examine (belts, drains, etc) but I'm really curious about this link someone pointed to, which claims BMWs should not use modern maintenance-free batteries since they need close to 15 volts to charge fully and BMW charging systems put out 13.8-14.5. He claims older lead-acids don't need as much voltage to charge. Has anybody else had this experience? My shop said they'd never heard of such a thing.

[Pete K]

I have a maintenance free battery in the 520i (because it's in the spare wheel well) and I've been using that for 2 years with no problems. I know I'm only getting 14 volts because my mechanic fixed some loose wiring I'd done and it came up from 12 to 14. I only drive it 8 times a year and it starts fine, even with the extra long cabling.

Cheers

[T.Hanson]

Interstate MT 47, $60. Available locally, they're heavy.

You can Google search here for as many more opinions as you wish. As the duty cheap grouch, the MT 47 fits perfectly, has a solid four year guarantee ( I tested it once after a year to get a free one ) and three have hung in there all the way with no problems. One was on five when I thanked it.

It does have strips, caps to check, replace water. I use tap, figuring it's good enough for me, what's lead know from tasty. If I'm distilled, imported Bavarian wrong, I'd think iffy trying for six on a four year at twenty below zero.

They do like clean connections, grounds, the big braided negative terminal strap. And they like cycling, charging, discharging being used. If you pull it for storage check it about once a month.

Check the fender box too. Acid and the white fluffy Chia Pet stuff can make it crunchy in thirty years.

[Adam Gravois]

Thanks, T., your retrogrouch stylings made me smile. "What's lead know from tasty?" indeed.

Yeah, I have clearly have electrical work to do in any case, and I'll ride this battery I already bought until O'Reilly stops refilling it... I was primarily wondering if this is a 'known issue' or a 'YMMV' issue. Seems like something as scienticious and mathemagical as batteries and electricity should have clear, hard solutions but there's a lot of mystery involved, apparently...

[Lenny D.]

There are clear, hard solutions. Electrons must flow, and they will. The tricky part is finding where they are not SUPPOSED to flow, but flow they will. Introduce a larger pipe for the flow and they will indeed flow, sometimes causing a fire....but I digress.

I looked for the MT-47 this past summer, and found it locally, but nobody stocked it except for Interstate themselves. No deal on any fronts - the quote on that battery was over 80 bucks. So I return to my usual of getting the highest amperage battery from the Mart that will fit (there's only one). Been doing that for years and have had better success with longevity than I did when I was forced into buying an Interstate battery many years ago at over a hunnert bucks. No thanks, it didn't last three years.

Just my story, YMMV.

[garyinwestoz]

I had a Delco sealed battery for about 8 years on my 320. 800maH start up power. cost me about $150 AU in 1995. I stopped driving it full time when I got my 77 528i - about 2003

I retired it about 2005 - too rusty & corroded head- still had the Delco.