Battery Tenders and Gel Batteries

[ricky racer]

According to Battery Tenders website and their customer service people, it appears that your normal Battery Tender Plus should not or cannot be used on an Exide Gel battery. They say I will need a Battery Tender Plus Gel, Model # 021-0156. Ok I can accept that, but I don’t understand it. Why would you suppose the Gel batteries need a different charger? I have an e-mail into them now asking if the Model #021-0156 can be used on a lead-acid battery or if it is dedicated to just Gel batteries. I’ll let you know what I find out.

[RoLoo]

...I used, and still use a normal battery tender in combination with a gel battery...
...without any problems...

[sgoodwin]

Originally Posted by RoLoo

...I used, and still use a normal battery tender in combination with a gel battery...
...without any problems...

Ditto x2

[SergioK]

David Hough wrote up a very good comparison of several chargers including the BTplus in BMW ON several months ago. It wasn't ranked amongst the highest in terms of battery voltage. I think the gels need more voltage? He stated lots of info but just just can't remember now.

I recently came home and my less than 5 year old bt plus was done, as in aromatic 'well-done' wires burning up smell and all. I ordered an Optimate 4 to replace it.

[markjenn]

I've used both Optimates and BT Pluses for the Exide gel before without problems. (I much prefer the Optimates, but Roger and others here have an opposite opinion.)

Supposedly the reason you need these different chargers is because the smart chargers sense the response of the battery to rates of charging and infer when they're fully charged from this. The response curves for lead-acid, AGM are different. I didn't realize that gels are significantly different than AGM's though.

Just to be clear here, I think they're only talking about the true "gel" batteries made for BMW for some R-twins by Exide. Gels are not the same as AGM's although many use the terms interchangeably. Most non-wet batteries sold today are AGM's - BMW is kinda weird about spec'ing gels for some of the R-bikes. Speculation is that the gels have less voltage drawdown during cranking which reduces startup ABS faulting. I can somewhat confirm this as I was getting a lot of ABS faults with an AGM and switching to the BMW gel solved it. But this problem seens to vary a lot from bike to bike - many, perhaps most, run AGM's without an issue.

- Mark

[ricky racer]

Below is the response that I received from Deltran Corp. at batterytender.com:

Thank you for your email.
If you have an true gel cell, Exide branded battery in your BMW
motorcycle, you would not want to use our regular Battery Tender. We
manufacture a Battery Tender Plus, model 021-0156, that is specially
made to charge true gel cell batteries.

[EenyBear]

Recommend BT Plus - only because it's the one I bought after asking the same questions.
It has never failed me (or my battery).

Last weekend I reconnected with an old chum who had bought an R1150RS. Uh, we reconnected because I stopped to help a fellow rider stuck on the side of the road. Turned out to be him. Dead battery. Now, he too knows about a battery tender.

Cheers,
Ian

[tm1100s]

This whole battery charge/maintenance charge thing seems to be somewhat of a black art.

If you want to know more than you ever wanted about this, call Deltran (I did), or any one of the other charger or battery companies and their engineers will talk your ear off.

The engineers work in a different world. They work with the variables that we never see or at least wouldn't make any difference in real world use. Between the gel and regular batteries they might add .1 volt to the float or maintenance cycle for a couple minutes, or they may take it away. They use the numbers to theoretically extract the absolute maximum life expectancy from a battery in some concocted standard environment. But cook your battery out in Palm Springs in the summertime, or freeze it in winter storage in Chicago and all that goes out the window, I think.

They may tell you that you can't use a regular BT on a gel, but I'm not sure I'd ever know the difference. I've been using both types of chargers on all the batteries, all the batteries work fine, haven't had any batteries die in an unusually short time. If I get over two years from a batt, I'm almost happy. If I get 5 years, that's great. Somewhere in between is about right considering I don't spend a lot of time on batt maintenance. If I get stuck on the road with a dead battery (rare), it gets replaced and the charging system get checked. Not worth the uncertainty of a no-start.

[markjenn]

Originally Posted by tm1100s

They may tell you that you can't use a regular BT on a gel, but I'm not sure I'd ever know the difference.

I know the difference. I have one of the old BT non-plus models and if you hook it up to an half-charged AGM, it cycles off after a couple minutes without doing much charging.

- Mark

[tm1100s]

Sorry, my mistake. All my references are to BT-plus.

Of the three BT's I have, all of them are BT-plus. One is marked (by the factory) as 'Programmed for Gel batteries'.

Never had a regular BT, can't vouch for those.

[ricky racer]

Doing a little research on the Optimate 4. It looks like a more advanced unit than the BT Plus. The manufacturer says that it will charge Gel and lead-acid batteries and has several other features. I don't know if there is a manual setting for the gel batteries or if it senses it and adjusts automatically.

I e-mailed (twice) Battery Tender, asking them if the unit indicated for gel batteries could be used to charge lead-acid batteries too, or if it was dedicated to gel batteries only, but they have not bothered to get back to me. If it is dedicated to just the gel battery, and the Optimate 4 will do both, then it's a no-brainer, I'll go with the Optimate 4.

[roadrash666]

You can spend as much as you want on a charger, but a a standard b/t junior works just fine on a gel battery. Just my.02 and practical experience