How do I re-charge THIS battery... - Page 2 - PeachParts Mercedes-Benz Forum

MercFan · #16 11-25-2009, 10:48 AM

Quote:

Originally Posted by jkubica

Interstate is also good... the little paper round code stickers that they date batteries with - the first letter is the month and the number is the last didgit of the year.
Joseph

Getting a new one would be the last resort, but in preparation: where could I most likely find Interstate (AutoZone, Napa, Advanced Auto Parts)?

Regarding the sticker... no, I did not know that coding technique - I'll need to check the battery cover again.

Codifex Maximus · #17 11-25-2009, 11:30 AM

A battery hydrometer, then, measures the level of charge on a cell.
Measure the value on each cell and record in your notebook.
If the cells readings are way off, it might be easier just to get a new battery.
If they are spot on or real close, the battery will probably take a charge.
You can also buy a container of battery acid and equalize the cells specific gravity if you feel experimental - after all, if you've got a hydrometer, you have the tools.
All cells should be topped off to puckering with distilled water when you're done. Any addition of water will alter SG.
A trickle charge will deep-charge the battery and is the best kind of charge. Also, deep charges don't tend to shorten battery life.

MercFan · #18 11-25-2009, 01:33 PM

Quote:

Originally Posted by Codifex Maximus

A battery hydrometer, then, measures the level of charge on a cell. Measure the value on each cell and record in your notebook. ...If they are spot on or real close, the battery will probably take a charge.

Some questions regarding taking measurements (Need to purchase the hydrometer later today):
1) Do I then take out some liquid out of each cell to measure SG of each cell in the hydrometer, or do I just dip it in each cell?

2) Am I looking for any specific value with each measurement, or just simply making sure they are about even across all cells and adjusting the low readings by adding battery acid and topping off with distilled water?

thx

patbob · #19 11-25-2009, 02:12 PM

As the jumper cables warmed, their resistance went up, which is probably why the engine only turned over a few times then stopped. There's usually a very thick coating of insulation on cheap jumper cable wires, I presume to make the user think they are getting their money's worth. If they felt warm through all that insulation, the wire inside was probably quite hot and well into a higher resistance zone.

FYI even "sealed" car batteries are vented, else they'd explode. I've seen one case where they just recessed ordinary cell caps and put a sticker over them to hide it.

MercFan · #20 11-25-2009, 02:33 PM

Quote:

Originally Posted by patbob

FYI even "sealed" car batteries are vented, else they'd explode. I've seen one case where they just recessed ordinary cell caps and put a sticker over them to hide it.

I see - I'm just not used to seeing them, but that makes sense - if I thought about it it's basic chemistry and physics...

Yak · #21 11-25-2009, 07:38 PM

When jumping, connecting the cables to both sets of terminals causes some of the power to go into the dead battery. Connecting the negative cable from the good battery to the chassis ground on the bad car is supposed to divert the full current to the starter. That's why they recommend that procedure.

I'm not really sure what connecting a set of cables to an empty set of terminals would do - if that's really what you were doing.

MercFan · #22 11-25-2009, 07:55 PM

Quote:

Originally Posted by Yak

I'm not really sure what connecting a set of cables to an empty set of terminals would do - if that's really what you were doing.

I tried it both ways with identical results: first, I hooked jumper cables positive to positive terminal on the dead battery and negative to the chassis - where the neg. battery terminal connects to the body. Turned the starter - went 1.5 revolutions and stopped.

Then upon removing the battery I hooked it up directly to the open terminals on the battery-less car. Same results - not enough power to crank it.

Was thinking about and realized two things: 1) The car was pretty cold since it's been sitting in a cold for several days and 2) I have not yet changed the oil on it since I just purchased it and I think the PO was using /50 weight diesel oil (for whatever reason), so it's pretty thick....

Today while recharging the battery I've also hooked up the block heater for several hours. It's toasty warm now - just checked it.

Should be reinstalling the hopefully fresh battery now and giving it another try in about an hour - so keep your wrenches crossed for me... hehe

MercFan · #23 11-25-2009, 11:53 PM

I reinstalled the fully charged battery into the car tonight - it recharged fully with no trouble in about 24 hrs. I topped off each of the 6 chambers with distilled water. Placed the battery in the freshly finished battery tray... said a little prayer, then glowed and cranked.... it started in less then one revolution - yippie yahoo yeah!!!

Checking the voltage on the battery - it looks like it was holding steady at 12.96V with the car off and about 13.3-13.6V with the car idling... The Voltmeter was jumping around a lot, so I'm going to check the voltage regulater on the back of the alternator - see how those brushes look. But I think we're done here.

Thanks all for seeing me through this. Now on to other challenges...

JHZR2 · #24 11-26-2009, 02:47 AM

12.96 is indicative of a "surface charge", which is not a true voltage. Full-charge OCV is roughly 12.65-12.72V.

Nothing wrong with getting a reading of 12.96V, just mentioning that long-term after a tiny load, or just sitting, don't be suprised if you see more in the range that I mention - which is true "full charge".

13.3-13.6 is what I was getting at the readout from my cigarette-lighter voltmeter. Seems a bit low for my liking, but it is consistent with my car, so I think you're OK. I would prefer a regulator that provides ~14-14.2V when cold (the regulator will decrease voltage with temperature amongst other things). Keep in mind that lead acid batteries start to gas around 2.37V/cell, or 14.22V/battery. Some chemistries are doped to modify that slightly.

Glad to hear it worked out.

bustedbenz · #25 11-26-2009, 02:52 AM

The connect-and-start method works on smaller gas engines, but last time I jumped my diesel (from a smaller charging system) I found precisely what I expected -- that there wasn't enough current capacity from the Jeep through the cables to the Benz to crank it immediately. The trick is to sit there running the charging vehicle, connected with jumper cables terminal to terminal on the dead battery, for fifteen or twenty minutes, sometimes with slightly elevated RPM.

After you do that, you've essentially used the jumping vehicle as a "battery charger" for twenty minutes. Then, the dead Benz battery should have enough current to help the support vehicle pick up the rest of the slack and spin the thing over just enough to start it, if you're lucky. That's how I did it last time I drained mine, which was a 25 degree day last winter. Jumped it from a 600 or 700 CCA Jeep system by letting it charge fifteen minutes before attempting the start (after demonstrating that it wouldn't work instantly).

Food for thought. Probably old knowledge to most. Just because it doesn't crank immediately when you connect the cables doesn't mean you can't charge the dead system with the running good system for a little while and then try again.

soothappens · #26 11-26-2009, 03:49 AM

Quote:

Originally Posted by patbob

As the jumper cables warmed, their resistance went up, which is probably why the engine only turned over a few times then stopped. There's usually a very thick coating of insulation on cheap jumper cable wires, I presume to make the user think they are getting their money's worth. If they felt warm through all that insulation, the wire inside was probably quite hot and well into a higher resistance zone.

FYI even "sealed" car batteries are vented, else they'd explode. I've seen one case where they just recessed ordinary cell caps and put a sticker over them to hide it.

X2 Jumper cables for these and other diesels need to be made from some good welding cable I use 2/0 and attach it to heavy clamps . walmarts might work on a gasser but wont cut it on these. heres a good link for some cables BMW Battery Cable for Battery relocation