Zumo 590 & 595 Battery life & charge problems

[bar2]

Incredible, nasty Garmin! I just complained to Garmin that my second battery was already dead after one year and then searched for this topic. I tried the bending trick, lets see if it works.
THANKS!

[bar2]

I Think it worked! Last ride ended with full battery.
And Garmin is sending me a new battery for free

[Zumad]

My Zumo 595 displays a screen with 'Garmin' and also a battery icon with a flashing question mark over the battery icon. It won't get past this screen no matter what I press. I've searched the manuals & forums to see if there is an explanation of what this means but can't seem to find it.

I'm assuming it's something to do with the battery and the Zumo doesn't like it.
So far, I've tried a replacement (proper Garmin) battery and the original battery (again), powering up with USB lead, powered car mount, leaving on charge overnight on powered mount, the well documented 'connector pin' mod, and cursing. None of which have got the unit to get past the battery/question mark screen. It won't even work in a powered mount with the battery removed !

I did think there was a small glimmer of hope yesterday when I allowed one of the batteries to drain completely. When this (flat) battery was reinserted and I popped it into a powered mount, the unit booted up normally and the familiar satnav functions all worked ok. I went into the 'hidden' diagnostics screen & this showed the battery charge current was looking good (260ma charge to start with, falling to about 170ma after about an hour, with the temperature between 27-30C). So I allowed it to carry on charging a few more hours; on checking a while later, it had gone back to the now familiar battery icon + flashing ? screen.

I think my next step will be to try yet another replacement battery. But before I do this, can anyone offer any advice.....
- Has anyone found any info on what the battery + flashing ? screen really means?
- The proper garmin batteries are pretty expensive.... has anyone found the best place to buy these from? (I'm in UK)
- Has anyone any info on what the 4 wires are ? (I'll probably strip one of the old batteries down.... my guess is +/- and the yellow/green are to a battery temperature sensor
- Has anyone had any experience of 'repairing' a battery pack with a new 3.7v cell?
- the Zumo doesn't like running with the back cover off.... I assume there's a sensor the unit reads... is this the small magnet at the corner of the back cover & has anyone bypassed this ? (this would simply be to allow me access to the 4 wires to see what was going on with a test meter)

I'm reluctant to just write off the Zumo as junk yet, as it was pretty expensive and I do like it. I've had several other Garmins in the past (Streetpilot III, Zumo 550, GPSMAP62, Etrex etc.) and have found them good. The Zumo 595 however seems to be plagued with battery problems & I do hope to be able to resolve these........

[jfheath]

The magnet probably activates a reed switch under the cover. Any small magnet will do the same. I have just checked this out. Battery cover removed, index finger holding a small magnet in place. 590 is working fine. IT shuts down when the battery is removed, and reboots when it is replaced.

Its worth investigating the 'fixes' for the Zumo battery. One simple one is here.
https://www.totally4bikers.com/blog/bik ... w-minutes/

Another one that I have tried with some success is to remove each pin in turn and spread the blade to make better contact. It is fiddly work requiring a steady hand and a magnifying glass. Take a photo of how the leads fit in, or do just one contact at a time.

This method is documented by a fellow St1300 owner at this site.
https://www.st-owners.com/forums/thread ... ix.170214/

Just search for Zumo 590 battery fix - you'll get plenty of videos / images to show what can be done.

After a few years of faithful service, the white connector came detached from the circuit board. The pins were left upright on the board and I worked out which was the best way to splay them ever so slightly to make better contact. (You have to be extremely careful. The contacts are probably not wires but hollow tubes, and tubes tend not to bend very much before the buckle and break).
I glued the white bit back into place and now have a piece of card over the two joined halves of the connector so that there is a little more pressure applied by the battery cover. The aim was to stop the connector vibrating.

I bought a new battery - it made absolutely no difference. But it does run find if plugged into the charger or into the cradle, and it will last maybe 15 minutes before it loses power and shuts down.

Holding down the battery icon for 10 seconds shows the battery diagnostic page - which isn't much good if you cannot see the screen !

[Zumad]

I'd tried the battery connector fix previously and it didn't help on this occasion.
I stripped the Zumo down to check on the battery connector on the circuit board & all looked ok.
I ended up stripping one of my old Garmin batteries down to see why they are so expensive (note: please don't do this, LiPo batteries can be pretty dangerous). Under the Garmin skin, it was a Sanyo battery, with a small circuit board attached (a charge management unit). quite unremarkable really.... similar to many other LiPo battery units. It is 3.7v 1800mAh.
I checked with my local electronics stockist. They are selling similar 1800 units for £12.30 (inc VAT) but unfortunately with a 3 wire interface rather than the Zumo's 4 wire. The only conclusion I can draw is that Garmin are ripping us off with the Zumo batteries.

This got me thinking.... if the Zumo is clipped in to a powered mount, why can't it run without a functional battery?
If the battery failed when I was on a bike tour, the satnav would become useless. I may end up just chucking the Zumo into the corner of my garage and get something I can rely on! Had a look in my local Halfords and they were selling some EU map (car) sat navs for less than £90 - about double the price of a Garmin battery!

[jfheath]

The ultimate battery life fix. Which turned out to be maybe not such a good idea. See my comment next but one.

Discovered out of necessity. Last year, the bottom half of the white connector detached from the board. Before I got round to fixing it, I discovered that I got a better connection without it in place, if I placed a piece of card on the top of the battery half of the connector so that the battery cover stopped it from moving.

Today I went a step further. I broke off all 5 of the upright connectors jutting out from the circuit board. One of them by accident, which prompted the other four to be broken off deliberately.

Separation of the two halves, and lifting out the circuit board, I soldered red, green, blue, black wires (7 strand x 0.2mm) to the appropriate stub. (Ground down my copper tip to a point, and applied solder to the contact, and to the wire before soldering wire to the contact.) Snipped off the 4 battery leads close to the connector (one at a time). Laid a loop of 4 wires down the battery and up the other side and twisted the matching coloured ends together - one at a time, soldered and heat shrunk.

Back togther, the first test is brilliant. Battery showed full charge immediately and lasted on full brightness, not allowed to turn off for about 20 minutes before it gave a message that it was shutting down to protect from heat. It wasn't hot, so I powered it up again. This was at 4:30 pm. I've had it on and off all evening at 80% brightness and allowed it to shit down after 5 mins. Trying to get it to go flat. I kept using it to keep it alive, but there were times when it will have gone to sleep. IT wasn't until 11:30 that it eventually died. The first couple of hours it was on mostly all of the time and had just got down to show the battery at half power. After that, hit and miss whether it was on or not. But I would estimate easily 3 hours of use - probably nearer four.

That is a slight change to the 5-10 minutes that I would get before it announced that the battery was flat - which it has done since new.

I'll charge it up fully tommorrow when I can observe it.

If anyone wants more detail of the very fine soldering, please ask.

[bar2]

Impressive

[jfheath]

Impressive

Hmm. Not so impressive as it turns out.

I did wonder about doing this - but I now have a small problem. I don't think it was there before, but it might have been.

Now when USB cable is connected to a charging socket, after about half an hour it switches off and says it is closing down to prevent overheating.

When I hold down the battery icon for 10 seconds to get the diagnostic page, for the battery I get NTC fault. NTC seems to be a thermistor which alters the resistance according to the temperature. If I put the Full Tests on (on the battery diagnostic page), it sometimes mention DPPM reg. DPPM is the circuitry which governs the amount of charge going to the battery while allowing the device to continue working while charging (apparently).

I'm wondering - because I was forced to to connect the multiway connector while the battery was connected (normally this would be imposssible) - it seem distictly possible that I have damaged something - but there was no other way but to risk it.

Everything else seems to work and I don't know if it behaves like this on the bike. Its OK without being charged - but now getting it charged seems to be a problem. Someone said that they took a battery apart and discovered a chip was part of it. I was wondering if this may be the DPPM unit, which may mean that a new battery would solve my problem.

But it was a dead unit when the pin broke. Now it isn't dead and I can use it in hand for testing etc. It remains to be seen whether or not it will charge or run on the bike.

Update:

I've left my previous comments but put them in a quote box as things have moved on a bit.

A closer look at the circuit board where the 5 connector pins had been in place revealed that however they were connected - the contact had corroded. White oxide powder needed quite a bit of scraping off before I could get to shiny metal. Goodness knows what I managed to solder to, but one of the joins was not conducting.

It then turned out that under the copper strip of the circuit board were mounted small - no, extremely tiny - electronic devices. and by the time that I had finished scraping, one of them had no copper contact. I couldn't get it hot enough to accept any solder as it was securely fixed and surrounded by the circuit board. I tested the electronic devices, and they appeared to be Diodes - which I could replace with normal electronic components. But what sort of diodes ? Two were allowing current to flow to Earth, but not the other way. One was restricting the direction of flow to and from the +ve lead from the battery. I decided that these must be a different sort of diode, otherwsie, how would the battery get charged. So I looked up Zener diodes - which I believe will allow reverse flow if the voltage is over a certain limit.

At this point I lose a number of things:
Knowledge about how to work out what the threshold voltage may be;
Skill in performing the necessary fine wire connections;
The ability to get out of my head the fact that if I get this wrong I could short circuit the battery, which will then burst into flames;
Enthusiasm.

So the 590/5 has been laid to rest. It is fastened up again to keep the screws together and the screen firmly in place. One day I might find one with a broken screen that is looking for the bits that I have. Or not.

Annoying thing is that it was working OK on the bike and when plugged into the charger. But I suspect those corroded pins wouldn't have lasted much longer. I may contact Garmin to find out how much for a new board or whether it can be 'reconditioned'.

[Zumad]

Hopefully I've managed to attach a photo here of my disassembled 595 battery:

WIN_20221206_20_51_02_Pro.jpg (386.64 KiB) Viewed 7165 times

There is a CMU (Charge Management Unit) underneath all that wrapping.

[bar2]

U guys r very technical