Which Battery Tender to use on Z4M?

[pal]

I just got the Active Autowerke Simon Flashloader and looking through their instructions, it appears that the Z4M ECU take about 50 minutes to download the stock flash and hence they recommend using a battery charger to keep voltage above 12V.

I ran to Pep Boys and picked up a Battery Tender Plus 12V@1.25amps (see below link). Looking through the instructions, it says not to use it on a dry cell battery. Should I use this on our AGM battery or return it and mail order their GEL optimized tender?

Regular Tender
http://batterytender.com/products/au...-at-1-25a.html

GEL optimized Tender
http://batterytender.com/products/au...t-1-25a-1.html

Looking at the batterystuff.com link below, it appears that AGM is more like an in-between dry cell and regular lead-acid. I never thought picking up a charger would lead to so much confusion

http://www.batterystuff.com/kb/artic...el-vs-agm.html

AGM (absorbed glass mat) is a special design glass mat designed to wick the battery electrolyte between the battery plates. AGM batteries contain only enough liquid to keep the mat wet with the electrolyte and if the battery is broken no free liquid is available to leak out.

Gel Cell batteries contain a silica type gel that the battery electrolyte is suspended in, this thick paste like material allows electrons to flow between plates but will not leak from the battery if the case is broken.

More often than not AGM Batteries are mistakenly identified as Gel Cell Batteries. Both batteries have similar traits; such as being non spillable, deep cycle, may be mounted in any position, low self discharge, safe for use in limited ventilation areas, and may be transported via Air or Ground safely without special handling.

AGM Batteries outsell Gel Cell by at least a 100 to 1. AGM is preferred when a high burst of amps may be required. In most cases recharge can be accomplished by using a good quality standard battery charger or engine alternator. The life expectancy; measured as cycle life or years remains excellent in most AGM batteries if the batteries are not discharged more than 60% between recharge. There are some AGM batteries we sell that offer excellent 80%+ deep cycle abilities.

Gel Cell Batteries are typically a bit more costly and do not offer the same power capacity as do the same physical size AGM battery. The Gel Cell Battery excels in slow discharge rates and slightly higher ambient operating temperatures. One big issue with Gel Batteries that must be addressing is the GEL CHARGE PROFILE. Gel Cell Batteries must be recharged correctly or the battery will suffer premature failure. The battery charger being used to recharge the battery(s) must be designed or adjustable for Gel Cell Batteries. If you are using an alternator to recharge a true Gel Cell a special regulator must be installed.

Thanks.

[psygnosis]

I have a BMW one that just plugs into the cigarette lighter.

[pal]

Originally Posted by psygnosis

I have a BMW one that just plugs into the cigarette lighter.

Please can you look at the specs on that (amps etc) and post up if its not too much trouble? Thanks.

[Pheonix]

I have been using the Battery Tender Plus on my Mcoupe (and my Ducati) for years without issues.

[SD ///M4]

I bought a CTEK 3300 mostly for my wife's 2011 335is Coupe but I use it on my car as well, both in AGM mode. Full specs are here: http://smartercharger.com/products/b...multi-us-3300/

BTW, the E9x have horrible battery drain. Her car was 2 years old last Sunday and has just over 23,000 miles on it. The battery was replaced in late March when we took it in for the battery cable recall. It showed 28% capacity. She's been extremely busy at work and from January 3 to late March averaged only 20.1 miles/day, apparently not enough driving to keep the battery charged.

[pungo]

I have a BatteryMinder 122248. I've been able to keep a optima red top going for over 12 years with it. It's a Charger/Maintainer/Desulfator all in one. Works on lead/acid, gel and AGM. I use it on all my cars, including my lawn tractor. You can find it for around $100. Read up on charging at the site I linked.

[pal]

On searching the Battery Tender website, I found this gem that basically classifies standard and AGM into one category and GEL into another. So I went ahead and hooked it up to the car and ran Simon to download the stock software to send to AA.

During the download, the battery dropped from 12.2V to 11.85V but it appeared that the Battery Tender was able to keep it there for the duration of the download. I let it stay connected to the car post download for another hour until the battery was up to 12.4V.

since the technical staff at Deltran has developed charging software that works equally well for both STD & AGM batteries, the only choice to be made is between 2 models: either STD & AGM or GEL software

Pheonix- I am guessing you are using the same Battery Tender Plus that I am using (12V@1.25amps) and not the GEL one?

SD Z4MR/pungo - Both the options you guys presented look excellent. I will have to do some more research and pick up a more powerful one. BatteryStuff.com folks recommended the Power Tender 5amps unit saying that modern cars draw a lot of amps. Looks like the BatteryMinder and CTEK are both more powerful and I like the desulphation feature as well.

I am on the 6th year with my car and since I drive the car every 2-3 weeks in the winter, it seemed to be working for me. I don't want to push my luck much further and plan to get another OEM battery later this year. The reason for the need for a charger today was to start the process of flashing my car with AA software.

[kklin]

I've used the same Sears DieHard battery tender on my Z4 M Coupe, E36 M sedan, Honda Civic, Lexus RX Hybrid, and Mazda3 over the years. It's quite nicely designed so that the connector end is detachable. The connectors include one for a cigarette lighter (I use it on my Z4MC), alligator clips, and pigtails that you can attach to your battery posts. It was fairly inexpensive too - http://www.sears.com/diehard-battery...p-02871219000P

[chickdr]

I also have the CTEK 3300 and love it. very nice charger. It worked with both the OEM AGM battery and now with the LA battery I replaced it with.

[ZeD4Mr]

Originally Posted by pal

The reason for the need for a charger today was to start the process of flashing my car with AA software.

Off-topic - I just got mine back today with AA tune loaded. Haven't had a chance to drive it well. I'll start another thread on it. I can feel it right away in the 10 miles that I drove. I think you'll have some fun with it, too

[Pheonix]

To OP, you are correct. I am using the same you have on the first link. I wasnt aware there are special ones just for GEL batteries. I have been using it during winter storage (in CT) and now i even plug it in if the car isn't beeing driven for more than a few days.
IMHO, there is no need for fancy battery tenders; any decent brand should work perfectly ok.

[G80indy]

Originally Posted by ZeD4Mr

Off-topic - I just got mine back today with AA tune loaded. Haven't had a chance to drive it well. I'll start another thread on it. I can feel it right away in the 10 miles that I drove. I think you'll have some fun with it, too

a bit OT but, does AA post HP/TQ gains with typical dyno results? if so, will you please post in your other thread?

[SD ///M4]

Originally Posted by Pheonix

IMHO, there is no need for fancy battery tenders; any decent brand should work perfectly ok.

I did a lot of research before I decided on the CTEK. I read a lot of posts where people said that their Battery Tender died within the warranty period but that Battery Tender's customer service was so poor regarding warranty items including having to pay for return shipping that they just decided to go out and buy another non-BT charger.

Some chargers have more advanced features like a desulfation function and are able to revive a nearly-dead battery. The CTEK 7002 is another very popular charger that has this capability.

The CTEK chargers have a water and dust resistant design while the Battery Tenders are open. CTEK chargers also have some handy accessories including a protective rubber case to prevent scratching and pigtails with diagnostic LEDs that can be permanently installed.

However, if the sole purpose of buying one is to maintain a steady voltage while doing a flash, then I agree that a cheaper unit would probably do the job.

[pal]

Thanks SD Z4MR. I will have to look at the CTEK more closely. While I was able to complete flashing the car today with my BT unit, the voltage did drop to a low of 11.6 momentarily to worry me that the flash would fail, but voltage came back up to 11.8'ish and the flash continued and finished. The flash process appeared to continually run what I can only guess was the fuel pump (whirring sound from the fuel tank area on the passenger side) the entire time. So I want to get a more powerful "tender/charger" (maybe 8-10 amps) for flashing purposes but would want something smart enough to keep the battery charged on continual use.

330indy - I will update my other thread with more info Re: AA tune.

[JasonH]

CTeks are expensive and generally overkill. Your standard battery maintainer will work fine, whether it's a Schumacher, DieHard or Battery Tender. For flashing purposes, if you're concerned about voltage dropping below 12v, you really just need a cheap "charger", not a tender (or a tender/charger.) A properly working tender will never let the charge go above 12.4v or so, but a charger will pump it up to 14.4v or thereabouts pretty easily.

[XMetal]

OP...just FYI...the CTEK US7002 have a "supply" mode, which serves as a power supply unit that can run 12V equipment up to 7A. This sound exactly what you need.

However, my experience with the US7002 wasn't great. It didn't charge properly on my X5, where it would just continuously cycles through its 8 charging process instead of staying in the "charge/float" states. A search found that other people also experienced this. I did returned it and exchanged it for the US3300, which had been performing flawlessly in past 4 years, but it does takes about 8-12 hours to fully charge and maintain a mostly charged battery (battery voltage at or slightly above 12.0V to start).

[Nate4641]

Bringing back this thread,

can we use the cig lighter socket chargers on the Z4M? I thought I had read something awhile ago saying they weren't good for our cars. My car sits in my parents' garage for a long time as I'm overseas and I want to get something to leave on the car long term. The car gets driven a little bit maybe once a month at best just to get fluids warmed up, but the battery was dead when I went home earlier this month. The car also stays under a cover so something under the hood would be a little bit of an inconvenience.

[XMetal]

I've used the cig lighter socket to charge mine without issue.

[BAK613]

I went to the posted links.

Is a 1.25 amp tender adequate to maintain the battery?

I see cycle gear has a Duraboost 1000 on sale for $25.

Thanks
Bruce

[XMetal]

It will work, but just takes more time to charge/top up your battery. It takes 8hrs+ to get my battery to top up using my CTEK US3300, which is 3.3A if I leave the car sitting for about a week+ without driving.