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-   -   Ownership Review: Bosch C7 Battery Charger (https://www.team-bhp.com/forum/technical-stuff/184814-ownership-review-bosch-c7-battery-charger-13.html)

You can say that again! I just bought my 3rd Bosch C7 charger, thanks to Androdev's thread (which has crossed 1.25 lakh views).

Now, on the Superb too:




You regularly use the 'quick connector' feature of this charger? I guess yours is an indoor garage, so you can leave the charger outside. Is the connector holding up well, even after regular use?

Asking the question again, Should the charging points be connected directly to the battery or to the jump start points? If not then the battery cover has to be removed every time we connect the cables.



Also should the Accessory battery used for start-stop be charged separately? Or would it charge along with the main one?

Jump start points should be good.

Which car you are referring to? Very rare for the cars to get two batteries, except EV's and earlier generations of Land-Cruisers :)

Quick connector made things very convenient for me. I use it regularly and exclusively for the S Class as it doesn't have much daily usage (I work from home). The connector is robust and should last long. I use it in the indoor garage, so I leave the charger next to the car. The connector pin is supposed to be weather proof to protect against rain and car-wash water but I am not too confident about this aspect and I am thinking of finding some jugaad cap for this connector pin for extra safety.

We are advised to use connection points away from "negative terminal" to prevent sparking and fire. For jump starting or charging the battery with alligator clamps, I try to use connection points away from the negative terminal such as jump start posts in Mercedes. In the case of quick connect, there is no question of sparking, etc. The quick connector is permanently connected to the battery terminals and the connection using the quick connector plug.

I don't have model specific information but in general each battery needs to be charged separately. The general advise is only to charge the battery that is responsible for starting the engine whose purpose is well understood and they handle voltage fluctuations better. Some auxiliary batteries, for instance, are responsible for providing a stable voltage to sensitive electronics and trying to charge those batteries might be harmful tp the electronics. Suggest to get a better understanding of model specific details before trying to charge batteries other than the one responsible for cranking the engine.

You can use vaseline periodically, the same way we do on the battery terminals.


I am not entirely sure about this; where are you getting this information from? Jumpstart points are different and away from the battery to facilitate easy connection more than anything else. Many EU cars have batteries in the trunk, which are not accessible. As long as you are not adding load or charge on a connected circuit, there are no risks of spark. So, in case of charging, it's recommended to keep the charger off until you have made the connections with the battery. Also, for negative, one can use any clean and strong point on the chassis.

Is testing the car battery after minimum 12 hours of non-usage to see if battery voltage is below 12.5 volts and trickle charging if it is below 12.5 volts a good way to determine WHEN trickle charging should be done?

I am looking at the c3 (again, doh!) and can it trickle charge if I leave it connected to my scooter for upto 3-4 weeks? C7 seems so over priced for such a simple task.

c3 is priced at 2799 with free shipping from boodmo. This is what I am eyeing. C7 is priced at 6242.

I own both C7(for Car battery) and C3(small Genset battery), and yes, both go into trickle-charge mode and can be kept charging for ever.

A quick difference guide between c3 vs c7 and then individual part numbers for the quick connectors and the clamps.

The use for the c7 as a power adapter mode gives a higher degree of versatility to the c7 that I had not considered before.

Hi guys, I have a MY2022 VW Polo 1.0 TSI with a 36ah 175A DIN / 300A EN Exide battery. My overall mileage in the past couple of months has been relatively low (one 10-15 km ride in a two weeks). The battery has died on me a couple of times. The surface charge after the drives would be around 12.6 volts but would drop to around 12.2V overnight. Upon cranking, the car usually starts with the voltage dipping to around 10V momentarily and then rises to 14.4V.

I recently got a C7 charger and was wondering if the Regeneration mode (Mode 4 16V) will be a good thing to try to repair if this is a case of sulfation? I know the battery is in warranty but the nearest ASC is 120 kms away and it isn’t possible for me to go there at the moment.

Somewhat off-topic but here are few notes:
VW tends to reject warranty claims if battery is not replaced by A.S.S. Stupid, but that's how VW works. As long as your car is under warranty, don't put a 3rd party battery in your car.

Any reconditioning type of exercise on the battery should be done after removing/disconnecting the battery from the car to avoid risk of damage to electronics of the car.

I have no interest in reconditioning a battery. I use normal charging mode of C7 regularly. If the battery is unable to start the car, etc. (which is yet to happen with my Mar-2017 battery), I will replace the battery immediately. Just for comparison, I replaced 3 batteries during 2012-2017 before buying C7.

Long story short, just use regular charging and if battery still gives you trouble, get it replaced.

Thanks for your reply. I would definitely love to get the battery replaced ASAP, but taking a day off from work is a bit challenging for me at the moment.

So if I were to recondition the battery, should I try Mode 4 or Mode 3? According to the manual, it is Mode 4, but I saw a few posts on multiple forums stating the use of Mode 3 for this purpose. I wasn稚 able to find a decent guide on this anywhere on the internet.

Stick to the user manual, have attached it here. Mode 3 is for providing backup power the car when battery is disconnected (to prevent settings from being erased). Mode 4 is for reconditioning.

Thanks @androdev

I will try reconditioning the battery and see if that helps with charge retention. I知 just a little worried about pushing 16V into a 12V battery. I値l do it in a well ventilated area just in case anything goes south :coldsweat

I値l keep this space updated.

Don't forget that the battery should be disconnected from the vehicle electrical system.