Battery question

[JamesL]

I just had to replace my battery (A000 982 3008 - £108 from a main dealer)

The car lives in a lock-up with no power away from my house. I have put a solar trickle charger on the roof to keep something in the battery.

This past weekend I went to start the car and got no crank - fuel pump  radio, lights etc but not enough oomph to drive the starter motor. I have a battery pack that gives an amp boost and used that to start the car (it's power went from 100 to 65% in the process). On Saturday I  put the battery on a charger and all seemed (from that) to be OK. I started the car (with the charger attached) went out for a drive but on stopping for fuel the car again would not start. Fortunately I had the battery pack and used that (power did not shift from 100%). I tried that again when I got home and the same thing happened - 3 hours driving and still not enough oomph to start the car, despite voltage being 13v+. Battery pack stepped in to add extra oomph.

It's the MB battery with an indicator telling me the acid levels are OK, but a sealed unit

I put a CTek conditioner on on Sunday and overnight and this time it confirmed that the battery was dead. Quick call at 8am and I already have fitted a replacement and disposed of the old one.

So the question is... am I better putting some juice in the battery from the solar trickle charger OR letting it run down with nothing doing (other than the immobiliser) and using the battery pack to start the car when needed? To be fair, lockdown has meant that the car has sat unsued for longer than normal.

I have a second lockup with power that I could use but it's got more damp in it than a swimming pool and I'd rather a flat battery than a damp/mouldy car

[lpeterssen]

Dear JamesL

If you can buy a quick battery disconnect terminal to eliminate any possible load from the car when sleeping in the garage. They have a green knob on the top that you turn clockwise to connect energy flow and counterclockwise to suspend.

You attach your actual battery cable terminal to the new terminal post, and the other side to your battery.  This is done on the NEGATIVE cable.

Ampper Top Post Battery Disconnect Switch, Battery Master Switch Isolator for Power Disconnect Cut Off https://www.amazon.com/dp/B07JYYXJH7/ref=cm_sw_r_cp_tai_yyMoFbV0EECX9

By this way there will be a much lower self discharge rate on the battery. Remember parasitic currents..... due to aged cable insulation.....

You can let your solar juice charger connected if you want with clamped terminals directly to battery. It will not hurt anything.

A battery let this way can easily withstand more than 60 days.

Your old battery probably died because was old and lack of use.

Of course always have with you that battery boost pack you mention.

And finally check your Voltage regulator and alternator, since 13V when working is toooo low. Battery voltage is 12.6V with car off.  Battery voltage with car running should be above 14V.   13V -12.6 = 0.4v which makes me think that the charging system is not ok.

Best regards
L.peterssen

Ps: yes the dry storage garage is better than the damp.

[Peter van Es]

To add to the info from L. Peterssen. The CTEK charger is intelligent. It monitors battery condition, prevents overcharging, reconditions the battery and will keep your battery good for long periods. I use one of these and it works very well, for over 8 years now on the same battery.

If your solar charger does not have the intelligence of the CTEK charger, you may be better off using the solar pack to power the CTEK to monitor the battery. If that is possible of course given that the CTEK wants 220-240V AC and you may have to use a converter.

Connecting a battery disconnect terminal is also useful in any case.

Peter

[wwheeler]

My understanding is that lead/acid batteries do not like to be run down, rather stay at a healthy charge. I think they produce sulphites when they discharge and that is bad for battery life. I am no expert but what I have read.

Using a smart battery charger is always a good idea. Batteries are expensive and using a high quality charger is well worth it. I never leave my battery charger attached for more than a few weeks at a time when the car is dormant. I have heard too many horror stores about accidental overcharging during storage. I got almost 10 years of life from my previous “white” Mercedes battery which is almost unheard of.

I wonder about the solar power - Does it supply enough power on a day to day basis for the charger to be effective? Not sure I trust those internal battery indicators.

[ejboyd5]

A strong second to the recommendation that you install a battery disconnect switch. On my '50s-''60s era M-Bs I've been getting 16-20 years of battery life without any charger usage. Be careful about switch selection as some of the green knob variety are cheaply made; I prefer Cole Hersee or Hella switches that are permanently mounted.

[mdsalemi]

I wonder about the solar power - Does it supply enough power on a day to day basis for the charger to be effective? Not sure I trust those internal battery indicators.

I had a deep cycle "car batter" powering my boat lift. Each lift action, taking a 3500# boat out of the water on a hoist/pulley cable system, took quite a bit of the battery charge. There was a solar powered trickle charger that kept the battery topped off. Even on a busy day you may only lift the boat 2-3x, and the battery could handle that. The trickle charger worked well; I want to assume that cranking an engine is equally as draining on a battery, but once that engine starts if your alternator is working, you are charging immediately. So, if you have a place where it's appropriate to use a solar charger, I'd prefer this to a "battery tender". When my car was stored, I never liked the concept of something plugged into a "mains outlet" when I was hundreds of miles away, for months at a time...

[wwheeler]

Agreed, not a good idea to leave a battery tender plugged in to household current while you are away for long periods. If you didn’t want to install a disconnect switch, couldn’t you just disconnect one of the battery cables? Which would be the best? I assume the positive?

[lpeterssen]

Agreed, not a good idea to leave a battery tender plugged in to household current while you are away for long periods. If you didn’t want to install a disconnect switch, couldn’t you just disconnect one of the battery cables? Which would be the best? I assume the positive?

Always should be disconnected the NEGATIVE

[mrfatboy]

I think the negative cable is the proper one to remove. Counter intuitive 🤣

[66andBlue]

Why the negative and not the positive, does it matter which one??
What is the scientific reason for this?

[mrfatboy]

Here is some reading.

https://electronics.stackexchange.com/questions/230609/why-to-disconnect-the-negative-ground-terminal-not-positive

[wwheeler]

That suggests that disconnecting the positive first is more dangerous because it can arc and find a ground (namely You) . I get that and agree. 

Which terminal do most disconnects attach to? Looks like from what I can find, most say negative. Some state issues with computer issues when disconnecting the positive first. We don't have that issue here but maybe the ground is the correct answer.

Just seems like to me with the positive cable still connected to the battery, all of the electrical components are aggressively looking to find a ground to complete the loop. I would think grounds are easy to find considering the car is siting on about the best one. 

[ejboyd5]

Most, if not all, race sanctioning organizations require that the battery disconnect switch severs the negative side.

[mdsalemi]

Agreed, not a good idea to leave a battery tender plugged in to household current while you are away for long periods. If you didn’t want to install a disconnect switch, couldn’t you just disconnect one of the battery cables? Which would be the best? I assume the positive?

when stored, I always disconnected the ground wire from the battery. Always.

[Benz Dr.]

I was told that your alternator runs all of your auxiliaries and only charges the battery for starting your engine. On a car with a generator, the generator keeps charging your battery and it's the battery that runs your auxiliaries.   

[mdsalemi]

I was told that your alternator runs all of your auxiliaries and only charges the battery for starting your engine. On a car with a generator, the generator keeps charging your battery and it's the battery that runs your auxiliaries.

Almost, but not quite. When the car is running down the road (as opposed to sitting at idle), the alternator runs all of your auxiliaries AND charges your battery. If you are at idle, the RPMs of the alternator from the belt might not be enough to do both; but when the car is running down the road, surely it does both.

And for the benefit of Alfred, asking for some science, here's one for you...  https://www.mi.mun.ca/users/cchaulk/eltk1100/ivse/ivse.htm

[66andBlue]

That suggests that disconnecting the positive first is more dangerous because it can arc and find a ground (namely You) . I get that and agree. 
Which terminal do most disconnects attach to? Looks like from what I can find, most say negative. ....

Hi Wallace,
my guess is that most disconnects are for the ground (-) cable because it is frequently a thinner cable and needs much less insulation than the positive one and is thus cheaper to make.
I am aware that repair manuals usually start a job description like this: "Removal: Disconnect the ground cable at the negative terminal of the battery" (see BBB Job No. 15-1).
With only a few diodes and sparsely a transistor in later models I believe it doesn't really matter which pole you disconnect.

But long time ago I got startled by a spark, jumped up and hit my head that required stitches, and since then I have always preferred to disconnect the positive cable. In all my three Pagodas I installed a kill switch, now I am much more relaxed knowing that I am not a potential Franklin rod. 

And for the benefit of Alfred, asking for some science, here's one for you...  https://www.mi.mun.ca/users/cchaulk/eltk1100/ivse/ivse.htm

Hmm 🤔, you call this science?
I remember when I was about 8 years old we had a teacher who explained to us why we could get a shock after rubbing a woolen sweater or how a lightning rod works. She drew similar sketches on the blackboard. Well, back then, all Elementary School teachers knew enough about electricity to explain this but they wouldn't have called it "Science".

[wayne R]

Thought i would give my opinion, as i have owned dozens of different model cars over the years,
and since about 1989,especially when i lived in USA, i have used mostly Interstate  batteries,
becausei i think they are still the best, one 1972 Porsche 911 i owned a interstate lasted me 11 years.
and that car was stored half  the the time,Another  a Etype Jaguar 1966,a interstate lasted 12 years.
this current Pagoda has a Interstate mega trone plus,just happened to come from CA with it, but many
other classics i purchased from  there, ive paid the owner to have new Interstate fitted there before shipping.
---Have a look at this---Go to google---And put in the words---
Optima  VS  Interstate--which one is better---
May interest you.

[66andBlue]

Hi Wayne,
the Optima battery was in my 1966 230SL that I sold some time ago. The other two batteries are AGM DieHard batteries that I bought at Sears, 6 and 2 years ago respectively.
As to your question, which one is better, Optima or Interstate, you may be surprised to learn that both brands are now owned by the same company, Clarios, so the opinion polls of  a few year ago may no longer be relevant.

The whole automotive car battery industry has undergone a major restructuring in the last two to three years. When Sears owned the DieHard brand they were made by Johnson Controls (and for a short time also by Exide). In 2019 Sears sold the brand name to Advance Auto Parts, an aftermarket retailer, and Johnson Controls sold the unit that made the batteries to Clarios. How many different brands this new outfit makes is difficult to figure out: https://www.clarios.com/products. That is not too surprising since its owner is Brookfield Business Partners L.P. which in turn is owned by an asset management company, Brookfield Asset Management (https://en.wikipedia.org/wiki/Brookfield_Asset_Management), and those are usually a bit more secretive. 
Although this news release is surprisingly upfront about how they plan to make money:
Clarios is a subsidiary of Brookfield Business Partners, a business services and industrials company focused on owning and operating high-quality businesses that benefit from barriers to entry and/or low production costs. {emphasis mine}.

[Cees Klumper]

In reading James' original post, unless I read it wrong, it occurs to me he may have a wiring issue, where one or more of the (main) connections is/are loose or corroded. The solar trickle charger should keep the battery topped off fine, in my own experience and his symptoms sound to me like they could indicate a wiring issue - either that, or an excessive parasitic drain. I'd check both those possibilities.

[JamesL]

Cees, the car has been started once since February. It has an immobiliser which will be small drain.

Is the solar charger (NOT a conditioner, simply putting volts into the battery when the sun comes out) better for this situation than leaving the battery to drain?

Obviously lockdown meant the period was extended, but the risk of a battery being "boiled" by a solar charger is better or worse than a modern battery left alone to drain (and thus losing efficiency on a recharge)?

Clearly a cut-off switch would help reduce the drain

[mdsalemi]

Cees, the car has been started once since February. It has an immobiliser which will be small drain.

Is the solar charger (NOT a conditioner, simply putting volts into the battery when the sun comes out) better for this situation than leaving the battery to drain?

Obviously lockdown meant the period was extended, but the risk of a battery being "boiled" by a solar charger is better or worse than a modern battery left alone to drain (and thus losing efficiency on a recharge)?

Clearly a cut-off switch would help reduce the drain

What are you trying to achieve? Ask yourself the question, answer it, and craft a solution that addresses that.

I typically stored my Pagoda for many years in an unheated garage in mid-Michigan where the inside temperature in the winter was just above freezing. The car sat from October through April. I always disconnected the ground. Without fail, every spring, the battery had enough power left in it to start the car up. However, I always did charge it anyway.. This was "dead storage" as they say, I was not using or accessing the car during these months. I probably had 15 winters of experience with this method. If you have a battery that's 50% through its lifespan, it may not survive such a cold winter, even disconnected.

If you are storing your car in a place where you can get some sun, a solar charger will help; they are low watts (7-15); low current (maybe 400 mA) and use very thin cables. The cables on my solar trickle charger were no thicker than standard headphone cables (in fact they used the standard 12V pin connectors found on headphones!) and much thinner than the cord on a lamp. Obviously no sun in a closed garage, so this would not work for me. Besides I got good like out of the batteries I chose, so I never felt the need to "tend" to the battery when the car was stored.

[Pawel66]

Just an example of a cut off switch, I think it just looks less plastic. Maybe worth looking for one.

[PeterW113]

James,

I also use a disconnect, mostly for safety and use a Ctek conditioner/charger to keep the battery in tip top condition, but I have mains power.

Elsewhere I use a Carcoon which needs power but the lockup has none so I use a 12v battery to power it which in turn is powered this type of thing:

https://www.optimate.co.uk/products/optimate-solar-80w.

I do not use this particular product but this serves to illustrate.

The key point is it has a regulator of sort to maintain the battery and not overcook it, a bit like a Ctek.

Worth considering if you haven’t and can be bought separately ?