Fogstar drift 105ah DC-DC charging issues

Stowaway

Stowaway

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I am hoping some kind sole could please point me in the right direction with my Fogstar drift charging issue. I have a 105ah Drift on my Chausson Flash 10 Transit. Charging through the CBE onboard system I get about 17amps as indicated on the Fogstar app, (not totally reliable I know). This charges the hab battery (but not on lithium spec I know). I wanted to boost this charge rate, so I have fitted a Renogy DC-DC dual input 50A (solar disconnected at moment).
Using 16mm wiring all seemed good except that when charging from both the CBE onboard system and the Renogy DC-DC, the 60A breaker from the DC-DC charger trips when the DC-DC output is set to 50A. Fogstar app indicated max charging reached is about 40A, then 'click', no more from DC-DC. I have changed breakers, replacing the 60A with a new one, and for a trial even tried replacing the 60A with an 80A in the DC-DC line. Both 60A and 80A continue to trip even though the Fogstar app still indicates 40A charge then 'click'. I have reduced output on the DC-DC charger to 30A and max charge indicated on the Fogstar battery app is about 35A but no breaker tripping. As the spec for the battery indicates 100A max charge, where am I going wrong? Any suggestions most welcome. Thanks.
G.
 
What kind of breaker are you using? My Renogy DC-DC came with a 60A fuse, but no circuit breaker.
 
Both 60a and 80a are the inline breaker type. I wanted to ability to disconnect various parts of my system, ie b2b from CBE input if required.
 
Stowaway said:
Both 60a and 80a are the inline breaker type. I wanted to ability to disconnect various parts of my system, ie b2b from CBE input if required.
Click to expand...
It would be useful to know the make and model as I believe some of these automatic breakers are notoriously inaccurate in their ratings, though from what I have read they mostly trigger at much higher than rated loads so don't give much protection from overloads to the wiring. You also need to ensure that any breakers used are specifically rated for DC rather than AC use. You should probably have suitably rated inline fuses as well in any case. I would trust a good quality fuse much more than a breaker.

If you don't have a fuse already, you could fit one, say 40A or 50A, and if that does not blow but the breaker operates then you will know the breaker is the problem. Instead of combining the function of fuse and switch in one device it might be better to use fuses for protection and a manually operated isolation switch for connecting stuff - like the following. I use one of these for isolating my solar panels.

 
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Unless you used a quality DC breaker (they cost about £60) they will be a waste of time, the cheap ones are totally unreliable.

Reguarding the CBE charger have you check if it has an automatic equalization phase because if it has it is not suitable for charging Lithium.

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Another thought on this. When you say you get 17A charging through the onboard CBE system, is that through a split relay connection directly from the starter battery/alternator when the engine is running? If so I don't see how you can be charging from both the CBE and the Renogy B2B unit. Surely it is one or the other?

As I understand it a B2B normally takes a starter battery connection as input and outputs a boosted version of this voltage to connect to a power distribution unit in place of the original direct battery connection. So, the output of the B2B should take the place of the direct battery connection into the CBE split charge relay. At least that's how it works with my system. You absolutely do not want the boosted voltage coming out of the DC-DC connecting to the same input as a direct connection from the battery.

The other thing you could try is sending the output from the B2B directly to the leisure battery rather than through the CBE. I this case you would need to disconnect the starter battery from the input which normally goes to the split charge relay in the CBE. I have done this with my system and it works fine. The starter battery connection to the split relay input on the Electroblock must be left unconnected in this configuration.
 
Last edited:
Have you disconnect
the split charge relay in the CBE distribution unit?

If you haven't it will short out the B2B, some units you can do it by snipping the zero ohm link R37 otherwise you may need to fit a bypass relay.
 
Thanks for the great suggestions. Based on the above, the split charger (CBE) and DC-DC are both connected to the hab +ve terminal. I understand that my CBE charger does not have a lithium profile, but I usually only charger it to about 90% so I figured this isn't too much of an issue, unless of course I am advised otherwise!! I have now observed that using split charger alone through CBE, I get as stated, about 17amps indicated charge on the Fogstar app. When I then engage the DC-DC, the Fogstar indicates that the charge current received goes to about 40amps, then, after a few seconds the breaker in the DC-DC +ve line trips, unless DC-DC charger output is set to max 30amps. Fogstar thens shows about 34amp combine charge received. The Renogy DC-DC is connected between the starter battery +ve terminal, then the DC-DC unit , then direct to hab battery +ve and common ground. I have now disabled the CBE split charger so that when the engine is running, no charge is going to the hab battery from the CBE system. With the split charger disconnected and only the Renogy DC-DC connected to the hab. battery, the same results occur, ie. 60A or 80A when positioned in the +ve line out from the DC-DC are tripped if I use an output from the Renogy higher than 30amp. I am now in process of making a 50A fuse to fit instead of the breakers as suggested and also making a relay connection to shut off the the d+ to the split charge CBE system when the engine is running. Strewth.
 
I will be interested to hear how that goes. I am still a bit unclear about what your existing system comprises and am not familiar with CBE stuff. However if what you have is similar to the CBE kit in the following link then it does state the following:

"It should be noted though this kit is designed for use with Lead acid Batteries and pre smart alternator charger systems. To use alongside a smart alternator (euro5 onwards) you will need to fit a separate battery to battery charger, following the CBE instructions to disable the split charge facility."

camperhappy.co.uk

CBE 180 KIT 12 Volt Campervan / Caravan Battery Charger & Power Distribution Kit - Camper Happy

The CBE PC180 is a LED is an all in 1 electrical kit for campervans & motorhomes It has everything you need all in the one unit to control and monitor your electrical systems. With the addition of level sender, it can even monitor water and waste levels. These kits are made in Italy and are...
camperhappy.co.uk camperhappy.co.uk
 
Thanks Fred_jb. Thats' pretty much what's fitted, albeit the Chausson slighty adapted version. When on hook up, the CB516 does what it is supposed to (non-lithium I know) and when engine running, I thought that the split charge went direct from the alternator to the hab battery via the distribution block DS300-TR. Vehicle is Euro 5 but non-smart alternator. Looks like the way forwards is to relay the d+ but that still doesn't answer why the trips are failing at 40A with only DC-DC connected.

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Stowaway said:
I have now disabled the CBE split charger so that when the engine is running, no charge is going to the hab battery from the CBE system.
Click to expand...
How did you disable the CBE split charger?
Stowaway said:
I am now in process of making a 50A fuse to fit instead of the breakers as suggested and also making a relay connection to shut off the the d+ to the split charge CBE system when the engine is running.
Click to expand...
I'm not very familiar with the CBE system, but often the D+ is used for several different things, apart from the split charge relay. If you cut off the D+ then often other functions stop working, like the fridge on 12V, step retraction etc. With CBE systems there is often a way of cutting off just the split charge relay. It involves snipping a link resistor on the circuit board, such as R37 or R28. It should be detailed in the manual.
 
Stowaway said:
I understand that my CBE charger does not have a lithium profile, but I usually only charger it to about 90% so I figured this isn't too much of an issue, unless of course I am advised otherwise!!
Click to expand...
Have you checked that is doesn't have the automatic equilisation phase, if it does I wouldn't use is with Lithium.
 
Stowaway said:
I thought that the split charge went direct from the alternator to the hab battery via the distribution block DS300-TR.
Click to expand...
Yes, but the output from the DC-DC also goes to the hab battery, and that is my concern. If you don't disable the split charge relay you potentially have the starter battery/alternator connected to the same place as the output from the DC-DC, namely to the +ve terminal on the hab battery. This effectively means that the input of the DC-DC (starter battery/alternator) is connected to its output. Who knows what the effect of that would be, but it might cause a surge which trips the breaker.

I know you have said this happens without the CBE connected, but are you sure there is not still a path via the split charge relay for the starter battery to be connected to the hab battery direct, rather than as it should be, only through the DC-DC? Disabling mains charging from the CBE will not stop DC charging via the split charge relay.
 
autorouter said:
How did you disable the CBE split charger?

I'm not very familiar with the CBE system, but often the D+ is used for several different things, apart from the split charge relay. If you cut off the D+ then often other functions stop working, like the fridge on 12V, step retraction etc. With CBE systems there is often a way of cutting off just the split charge relay. It involves snipping a link resistor on the circuit board, such as R37 or R28. It should be detailed in the manual.
Click to expand...
There is a 3amp fuse on the fuse box which cuts the d+. You are correct in that it also cuts the fridge power. Once I figure out why the breakers are tripping at about 40amp when only the DC-DC is connected, I think the system might be going for the 'snip'. I'm a little concerned over which relay it is as the Chausson and CBE manuals are as clear as mud.
I don't think the charger has an equalisation phase, so another nail in the coffin for a resistor !
 
Stowaway said:
Vehicle is Euro 5 but non-smart alternator.
Click to expand...
That means a DC-DC booster is not essential, but if you do choose to fit one you still have to follow the CBE instructions to disable the split charge relay as you would with a smart alternator installation.

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Something to consider would be using a clamp meter to measure the actual current passing through your cables. Then you'll know exactly what current is passing through your tripping breakers. I have one on order!
 
Can you post a picture with the breakers that trip please? Ideally the printed data on them clearly readable.
 
Raul said:
Can you post a picture with the breakers that trip please? Ideally the printed data on them clearly readable.
Click to expand...

20241029_195727.jpgScreenshot_20241028-195031_Amazon Shopping.jpg
 
Update to the above saga....I have replaced all fuses and switches to good quality kit as advised, yet the problem still persisted, ie, no more than 30A at the leisure battery with a reduced output setting on the DC-DC controller. I contacted Renogy who were excellent in their assistance. After following their guidance steps to measure voltages etc across the DC-DC controller, they confirmed that it was knackered and sent me a new one. Job done! Thanks for the guidance. G.
 

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