[R2D2]

Originally Posted by GTO

Switch off the C7 for 5 minutes and restart it every morning? I can tell my staff to do this.

Simplest and a zero cost solution.

Any other trickle charging model? Please suggest.

CTEK MXS 5.0 EU Car Battery Charger for BMW, Audi, Mercedes, Lamborghini, Ferrari.

Expensive (ouch) but you won't go wrong with a CTEK. It is way more compact that the Bosch C7 and even the C3 and CTEK thoughtfully provide a soft pouch. You can just keep it in the car's boot. Or, if you're a nut case like me, in your laptop bag when travelling. To read more visit www.ctek.com. For lux and sports cars with sensitive electronics I'd recommend CTEK as one of the most highly recommended by lux car owners. You could check for feedback on BMW/M-B/Porsche fora overseas for the most up to date information. Do note, CTEKs are replaced not repaired. I guess warranty replacements will take time.

I dealt with Naredi the seller back in '17 for 3 chargers the MXS 5, 10 and 25, with 10 and 25 being provided with a temperature probe and temp. sensitive charging. The owner is a very pleasant gentleman. He was based in the UAE, at least back then. Their India business is based out of New Delhi. To visit their site - www dot naredi dot in. My collection of chargers has grown to ridiculous levels in the past 2 decades each one has their own quirks so one has to be prepared. Of course the wife hates 'em because my home looks more like a workshop

Can I change the behaviour of the Bosch C7 to bypass this?

Nopes, it's in the firmware on the ROM chip in the charger. The C7 is a pretty stable product while has a few "what-the-heck!" fits, its smaller stable mate the C3 is a bit of a whacko and rather unpredictable. I'd never leave the C3 connected for a long time. I rarely use my C3.

[androdev]

Originally Posted by GTO

- Switch off the C7 for 5 minutes and restart it every morning? I can tell my staff to do this.

This would be a good option. Staff can just turn off the mains for maybe 30 mins and turn it back on. No need to access the car or mess with the charger.

- Any other trickle charging model? Please suggest.

CTEK is what all OEMs use but it is either expensive or not available in India. Don't want to deal with 110v business if I get it from the US. I was checking this out until I found Bosch locally available.

- Can I change the behaviour of the Bosch C7 to bypass this?

I have no idea but I doubt it.

Could, but I want to keep it in "auto mode" as much as possible (without intervention required from me).

Yeah I am also disappointed that it can't stay on permanently. However I find this text in the manual:

Trickle charging: The charger can be left permanently connected to maintain the full battery charge. After charging, the charger switches automatically to the trickle charge mode.

This contradicts with the 41 hr limit mentioned in my previous post. Are they saying 41 hrs limit for "regular charging" (which means the battery it not reaching 100% even after 41 hrs of charging so it is cutting off) or just an overall limit for 41 hrs including trickle charging. Can you confirm it reaches trickle mode within few hours on your battery?

Given it is from BOSCH and having feature-to-feature parity with CTEK, I tend to believe this is state-of-the-art charger and should support permanent connection. One of these days I will keep my charger on for 3+ days and see what happens.

[R2D2]

Originally Posted by androdev

CTEK is what all OEMs use but it is either expensive or not available in India. Don't want to deal with 110v business if I get it from the US. I was checking this out until I found Bosch locally available.

Actually CTEKs are available here in India. Please see my reply to GTO.

This contradicts with the 41 hr limit mentioned in my previous post. Are they saying 41 hrs limit for "regular charging" (which means the battery it not reaching 100% even after 41 hrs of charging so it is cutting off) or just an overall limit for 41 hrs including trickle charging. Can you confirm it reaches trickle mode within few hours on your battery?

Actually that's what it means. Charging mode is different from trickle or float mode. I have kept my C7 on for 3 days without a break and it worked just fine.

PS - @GTO, before you pony up money for a new charger give the C7 another chance just to be sure it wasn't a power cut/surge/sag that cause it to shift to standby mode.

[Comrade]

Originally Posted by GTO

What is the solution?

- Switch off the C7 for 5 minutes and restart it every morning? I can tell my staff to do this.

You can buy something like below which will automatically switch on and switch off at specified times every day. I had previously used similar device in the US to switch on christmas lights at 7:00 PM and switch off at 1:00 AM, and they were also waterproof.

Programmable Electronic Timer

[androdev]

Originally Posted by R2D2

Actually that's what it means. Charging mode is different from trickle or float mode. I have kept my C7 on for 3 days without a break and it worked just fine.

Interesting and that's good to know. Like @Vid6639 said, maybe trickle charging is not resumed after a power outage? I know for sure that regular charging is resumed after power outage.

Originally Posted by Comrade

You can buy something like below which will automatically switch on and switch off at specified times every day. I had previously used similar device in the US to switch on christmas lights at 7:00 PM and switch off at 1:00 AM, and they were also waterproof.

Programmable Electronic Timer

Aquarium shops would know about this - they use this to control the lighting of the aquarium. However it looks like the charger can be used permanently - maybe an UPS/uninterrupted power is required?

[R2D2]

Originally Posted by androdev

Interesting and that's good to know. Like @Vid6639 said, maybe trickle charging is not resumed after a power outage? I know for sure that regular charging is resumed after power outage.

I am going to charge my batteries again in the coming days just to keep them in tip top shape. This time around I'll keep the C7 on float mode for >3 days and report back on my findings.

I would encourage GTO to try again as it may have been a one-off instance. I would also suggest connecting a 3 or 4 socket Belkin spike guard for better charger protection.

[GTO]

Thanks a ton, guys! So I observed things for a couple of days.

- The Jeep's charger (12V mode) goes on trickle indefinitely. I just checked and it's a week+ since it's doing its job and keeping the battery topped up in trickle mode.

- It is just the BMW where the C7 goes on standby mode. I attached it on Sunday, then checked on Monday and it was on proper trickle mode. But this morning, my staff reports that its again gone on standby with the blue light.

Is this an AGM setting thing? Why on earth is the BMW's charger going on trickle? And yes, I did swap the chargers to rule out a defective unit, but even after swapping, only the BMW's AGM charging is moving to standby mode.

It is highly unlikely that this is due to a power interruption or someone messing with the wire.

[androdev]

Just curious, which +/- connection points do you use in your BMW? Please share pics if possible.

[Vid6639]

Originally Posted by GTO

Is this an AGM setting thing? Why on earth is the BMW's charger going on trickle? And yes, I did swap the chargers to rule out a defective unit, but even after swapping, only the BMW's AGM charging is moving to standby mode.

It is highly unlikely that this is due to a power interruption or someone messing with the wire.

Ok this gives some clues and I have a hunch it is the BMW's DME/IBS system protecting itself. The DME is the Digital motor electronics and the IBS is Intelligent battery sensor.

Both of these work together to decide what is best for the car and battery. If battery drain is too high it will start disconnecting things inside the car like corona rings, seat electric adjust, mirrors folding etc.

I have a feeling the system is isolating the battery somehow when it reaches full charge and this means the Bosch trickle charger stops seeing a load and goes into standby to protect itself.

It could be that other chargers like C-TEK take this into account but the Bosch is not as smart as the BMW's DME and thinks there is no battery to charge.

I also found this highly technical document to read on BMW's IBS and DME which mentions that the DME will isolate the battery using it's own microprocessor logic.

[mygodbole]

I don't know if this off-topic since topic says Bosch battery charger, but I have been using Optimate chargers for over 10 years. Current avatar is Ampmatic 6, used it to keep my 75AH SUV battery in top shape in temperatures ranging from over 45C to 4C. Had to replace battery only once in that time after the car had an accident and the battery was cracked open.
Was suggested the Optimate by Triumph Motorcycles in 2009 after my bike battery started going flat after about a week of non-use. Changed two batteries in two months, complained to Triumph, got suggestion and the next seven years, the same battery served flawlessly.
So when I bought an SUV 2012, also purchased a higher version for the bigger battery. Still have that charger. Used to charge the battery overnight once every three months. Whenever I had to go on vacation, just unhooked it, brought it home, plugged in and left it on the balcony under a cover. Return, hook up and drive off. No mess, no fuss.
Also used it to re-charge flat and dead batteries of friends, though once it took almost three days to recharge a 120AH battery.
Looked up the price and Amazon India is asking for an insane price, cheaper to ship it in from Amazon US.

[akash.1318]

Originally Posted by GTO

- It is just the BMW where the C7 goes on standby mode. I attached it on Sunday, then checked on Monday and it was on proper trickle mode. But this morning, my staff reports that its again gone on standby with the blue light.

Is this an AGM setting thing? Why on earth is the BMW's charger going on trickle? And yes, I did swap the chargers to rule out a defective unit, but even after swapping, only the BMW's AGM charging is moving to standby mode.

I have left mine plugged for about 3 days at a stretch on my G20, has always stayed in trickle mode for me once it was full. You can try pairing it up with something like Smart Plug/Outlet and put it on a schedule.

Also,
I am trying to get a hold of the quick connector part that clips into the terminal on the car and the device's connectors so that it'll be easy to switch between cars. Anyone with any leads on this?

[GTO]

The Bosch C7 is such a boon!

I've had two test-drive cars in the recent past (drove them around Bombay), and an outstation trip for which I flew down to another city. As a result, I haven't started the 530d in 10 - 12 days.

No stress on the electronics though. My staff sent me a pic of the charger from this morning. Fully topped up:

[GTO]

An idea whose time has definitely come! A solar-powered battery maintainer - full details here. Any BHPian experiences with these?

Where my cars are parked, the sunlight isn't directly on them, so no use for me. But this will be excellent for those who park under the sun and don't have an electrical socket close by.

[Prowler]

Originally Posted by GTO

Where my cars are parked, the sunlight isn't directly on them, so no use for me. But this will be excellent for those who park under the sun and don't have an electrical socket close by.

Might be a good idea with a beefier Solar panel. With the current set up it can offer a maximum of 150 mA which is not enough to trickle charge a good sized battery. I will throw in some example here:
My Safari's battery is 85 AH and my home made trickle charger comes up with about 500-700 mA when the battery reaches 13 V. If it is less it goes all the way to 5 A.

I have left the charger hooked up for days with no adverse effect on the battery or the charger.

[aditya.bhardwaj]

Hi guys, just ordered the C7. Got it for 6k on amazon. Now I know that it will charge my punto's battery easily (using a 60ah) but will it be able to charge a Duke 390's battery which is 8ah. I understand C3 was specifically made for such uses but I bought the C7 as it will be future proof.

Can someone please clarify.

Thanks