Check your charging circuit...

Canalsman

Canalsman

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I admit I haven't done this for a couple of years..

I have a Victron-based setup, mostly installed a few years back by @wildebus , and a few days ago I noticed that the Lithium battery wasn't charging fully. The SmartSolar controller was going into float mode early with the battery at only 85% charged according to its BMS.

What I observed was that there was more than a volt difference between the voltage reported by the SmartSolar and the SmartShunt. From this I deduced high resistance in the charging circuit. I checked the connections at the SmartSolar and then the two fused connections in the external locker adjacent to the battery.

Here I discovered a second problem. The 80 amp midi fuse for the B2B connection had failed, not through overload but rather a stress failure. This was evidenced by a split plastic housing that fell apart when removed. (See photo.)

David, @wildebus , advised that these fuses can get quite hot which might account for its failure.

So I ordered some replacement fuses from Amazon and in the meantime I cleaned all the connections in the locker - battery, SmartShunt and fuse holders. This alleviated the voltage difference observed earlier, in the main, but there had always been some variance.

Looking in the Victron Connect app I noticed something I'd not seen before. A signal strength gauge for the VE.Smart Network, this network connecting the SmartShunt and SmartSolar. This showed a very poor connection between the two with frequent dropouts.

Online research, AKA Google, revealed that this is a known issue (and apparently some poor circuit design by Victron). The remedy is to add a VE.Direct Bluetooth Smart Dongle to the SmartShunt, utilising its VE.Direct port, then disabling its onboard Bluetooth. With some careful positioning of the Dongle I was able to achieve a much stronger connection between the SmartSolar and the SmartShunt (via the Smart Dongle). (For me there was an additional problem, the Dongle didn't want to connect to the SmartSolar using the existing Smart Network. I created a new Smart Network on the SmartShunt and then added the SmartSolar to the new network.)

It's all working sweetly now following the installation of the replacement fuse. I changed the other fuse as a precaution given it was the same age as the one that failed.

So this proves that it is advisable to keep an eye on the various data provided by your charging system, and perhaps a routine cleaning of electrical connections in an external locker that is subject to cold and moisture is a good idea.

20240814_230055.jpg

(The Dongle cost £33 from Amazon.)
 
Fuses can be tricky.... The ANL/Mini-ANL are handy as you can visually check for a blown fuse, similar to the spade fuses, but they don't always like very high heat; the MEGA/Midi fuses don't seem to mind but covers are solid; and the strip fuses have no covers to get in the way and are the simplest, but can stretch and twist (affecting the rating) if insufficient care used when tightening down.
 
wildebus said:
Fuses can be tricky.... The ANL/Mini-ANL are handy as you can visually check for a blown fuse, similar to the spade fuses, but they don't always like very high heat; the MEGA/Midi fuses don't seem to mind but covers are solid; and the strip fuses have no covers to get in the way and are the simplest, but can stretch and twist (affecting the rating) if insufficient care used when tightening down.
Click to expand...

I'm finding it frustrating at the moment that you can't get certain size MEGA fuses and you can't get certain size ANL fuses. I was hoping to use the 6 way Victron fuse box (although for some reason one of the ports is not on the Busbar?) but due to the fact that I will need a mixture of fuse types it makes it more complex.
 
I think there's a general tendency to select fuses that are a lower value than necessary and this leads to overheating of the fuse. Ultimately a fuses job is to protect the cable in the event of a short circuit so often it's possible/advantageous to select a fuse of a larger value than you'd consider 'correct'. This is of particular importance with fuses in the charge circuits of lithium systems, because the voltage profile of lithium is very 'flat' it's important for the various chargers to know the EXACT voltage in the battery and cable and/or fuse resistance will ruin that.
So basic rules: keep cable runs between battery and chargers as short as possible, don't skimp on cable gauge and fuse rating especially with lithium.
 
Robmac said:
I'm finding it frustrating at the moment that you can't get certain size MEGA fuses and you can't get certain size ANL fuses. I was hoping to use the 6 way Victron fuse box (although for some reason one of the ports is not on the Busbar?) but due to the fact that I will need a mixture of fuse types it makes it more complex.
Click to expand...
Moving away from the original post, but a worthwhile discussion still .... There are quite a few multi-fuse boxes around. What are you connecting up that needs that?
The ones I have used myself are:
For multiple batteries and heavy/continuous loads, the Victron Lynx Distributor. 4 x Mega fuses, -ve Busbar and 1000A current capability - so big enough for anything you would ever do in a Motorhome.
A 4-way Midi fuse block with built in -ve busbar. Good for multiple chargers and connections and (IMO) better than using the Spade/ATO fuses when you are at the medium current ranges (30A -100A)
A 4-way Midi block with 1 x Mega Fuse. Nice combo and give more options but need an external -ve Busbar to go with it.
Multi-way (4 to 12) Spade blocks with/without -ve Busbar. Good for low-current (1A - 20A) 12V DC distribution.

You'll always end up with a mix of fuse types, but important point ... Midi and Mini-ANL are interchangeable... MEGA and ANL fuses are NOT.
 
wildebus said:
Moving away from the original post, but a worthwhile discussion still .... There are quite a few multi-fuse boxes around. What are you connecting up that needs that?
The ones I have used myself are:
For multiple batteries and heavy/continuous loads, the Victron Lynx Distributor. 4 x Mega fuses, -ve Busbar and 1000A current capability - so big enough for anything you would ever do in a Motorhome.
A 4-way Midi fuse block with built in -ve busbar. Good for multiple chargers and connections and (IMO) better than using the Spade/ATO fuses when you are at the medium current ranges (30A -100A)
A 4-way Midi block with 1 x Mega Fuse. Nice combo and give more options but need an external -ve Busbar to go with it.
Multi-way (4 to 12) Spade blocks with/without -ve Busbar. Good for low-current (1A - 20A) 12V DC distribution.

You'll always end up with a mix of fuse types, but important point ... Midi and Mini-ANL are interchangeable... MEGA and ANL fuses are NOT.
Click to expand...

I've got 2 x MPPT's, AC Charger, DC - DC, and cable to the Habitation fuse box of various Amperages up to 100A. I hadn't realised that Midi and ANL were interchangeable. So anyway, I've now been looking at this fuse box;

www.truckelectrics.com

MIDI Fuse Box / 7 Way

7 Way Fuse Box (7 x MIDI Fuses & 1 x MEGA Fuse) The MIDI fuse block box supports systems up to 32V DC and can hold up to seven MIDI fuses (30-100A) and one Mega fuse (40-200A). MIDI Fuse Box Specifications: Maximum Amperage: ANM Fuse Input: 40A-200A ANS Fuse Outputs: 30A-100A Maximum Voltage...
www.truckelectrics.com www.truckelectrics.com
 
Robmac said:
I've got 2 x MPPT's, AC Charger, DC - DC, and cable to the Habitation fuse box of various Amperages up to 100A. I hadn't realised that Midi and ANL were interchangeable. So anyway, I've now been looking at this fuse box;
Click to expand...
midi and MINI-ANL are. An ANL fuse is bigger and more akin to the MEGA fuse.

Robmac said:
www.truckelectrics.com

MIDI Fuse Box / 7 Way

7 Way Fuse Box (7 x MIDI Fuses & 1 x MEGA Fuse) The MIDI fuse block box supports systems up to 32V DC and can hold up to seven MIDI fuses (30-100A) and one Mega fuse (40-200A). MIDI Fuse Box Specifications: Maximum Amperage: ANM Fuse Input: 40A-200A ANS Fuse Outputs: 30A-100A Maximum Voltage...
www.truckelectrics.com www.truckelectrics.com
Click to expand...
That looks a nice fuse-block.
check out this link though .... https://www.wiredcampers.co.uk/coll...avy-duty-power-distribution-dc-7-way-fuse-box
same box at virtually same unit price but with fuses included and free shipping. Might get one to try out :)
 
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Robmac said:
I'm finding it frustrating at the moment that you can't get certain size MEGA fuses and you can't get certain size ANL fuses. I was hoping to use the 6 way Victron fuse box (although for some reason one of the ports is not on the Busbar?) but due to the fact that I will need a mixture of fuse types it makes it more complex.
Click to expand...
Just for you silver, and with led which lets you know when a fuse is out, this is what i have, very handy.
multi fuse box.png
 
Robmac said:
That's for blades though like my Habitation fuse box isn't it Trev?

For the Victron/Fogstar/Renogy setup I'm installing I need to be able to put in 16mm cables and ring terminals.
Click to expand...
yup, those blade fuseboxes are for low current circuits - cable size maxs out at 6mm2, fuse size *CAN* go up to 40A, but I'd never really go beyond 30A and even then for just limited use as the spade fuses and receptables tend to overheat at the higher currents with prolonged running.

16mm cable? depending on the cable run, you might want to go bigger than that? I go for 35mm2 cable for extended lengths on a 50A B2B for example. Inverters when supplied with cable invariably have too thin a cable and should be replaced.
 
wildebus said:
yup, those blade fuseboxes are for low current circuits - cable size maxs out at 6mm2, fuse size *CAN* go up to 40A, but I'd never really go beyond 30A and even then for just limited use as the spade fuses and receptables tend to overheat at the higher currents with prolonged running.

16mm cable? depending on the cable run, you might want to go bigger than that? I go for 35mm2 cable for extended lengths on a 50A B2B for example. Inverters when supplied with cable invariably have too thin a cable and should be replaced.
Click to expand...

Yes all short runs David. A couple of feet from the engine battery to the Fogstar and the shelf where the units are being mounted will be level with the top of the Fogstar and right next to it.

I'm doing away with the bulkhead where the old units are mounted, which is behind the drivers/passenger seats and having a shelf instead which will give me much more ventilation. I can also run the cables underneath the shelf which will look neater.
 
Would trips be any good, i have these each pos side of batery to batery cable links, from 20a to 100.
trip fuse.jpg
 
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