Lithium batteries discharging

[redfazz1]

I have recently purchased a new to me 2022 Adria coral 670dl motor home , the current battery set up is 2x lithium batteries and a Victron dc to dc charger.
When I am driving the leisure batteries are loosing charge, I can monitor via a smart shunt and this is showing the batteries fluctuating between charging and discharging dramatically and usual I loose about 10% of charge every hour of driving, also is it normal for the dc 2 dc to be too hot to touch.

 

[Richard n Ann]

I have recently purchased a new to me 2022 Adria coral 670dl motor home , the current battery set up is 2x lithium batteries and a Victron dc to dc charger.
When I am driving the leisure batteries are loosing charge, I can monitor via a smart shunt and this is showing the batteries fluctuating between charging and discharging dramatically and usual I loose about 10% of charge every hour of driving, also is it normal for the dc 2 dc to be too hot to touch.

Sounds like the dc 2 dc charger keeps overheating and shutting down. Have you got a dc clamp meter?

 

[monzer]

Sounds like the B2B is not wired up correctly. Happened to mine. If I put on the cab fan heaters it would drain my leisure batteries. It's actually in getting sorted as we speak.

 

[AdrianChen]

If it is a Victron Orion TR 30 amp, then yes they do get hot if having to work hard, they are only around 80% efficient, and have no fan - they need to be in a well ventilated place, or have a fan. There method of staying cool(ish) is to derate the output. Mine used to go from 30amps to 20-24 if it had a lot to do. I could touch mine when it was hot, wouldn't be comfortable leaving my hand on it, and it was in free space in our large garage. This will give some idea . Having said all that, and accepting they are not particularly efficient, they do work acceptably when installed properly, albeit at around 23-4 not 30.

https://communityarchive.victronenergy.com/questions/46901/orion-dc-dc-overheating.html is a discussion where Victron's response was that they made changes to the early models to improve the situation, so worth checking the serial numbers/firmware just in case you have one of the early ones (unlikely though) - one responder quotes up to 75°C, but not sure how it was installed.

We had an absorption three way fridge, which at around 20amps when running doesn't leave much for the batteries.

The newer Orion XS is around 98%+ (IIRC) efficient, so doesn't get hot by comparison, and will reliably deliver it's rated performance.

Having said that my tr30 amp never worked in reverse, but the fridge was a continual load on a hot day, so if the Orion is switching on and off to protect itself then it may seem like it....

I would also want to check that any previous split charge type device had been removed when the Orion was installed.

 

[Pausim]

I have recently purchased a new to me 2022 Adria coral 670dl motor home , the current battery set up is 2x lithium batteries and a Victron dc to dc charger.
When I am driving the leisure batteries are loosing charge, I can monitor via a smart shunt and this is showing the batteries fluctuating between charging and discharging dramatically and usual I loose about 10% of charge every hour of driving, also is it normal for the dc 2 dc to be too hot to touch.

This can happen if there is a split charge relay and the DC2DC charger is wired directly to the leisure battery. The leisure battery can feed back to the engine battery through the redundant split charge relay and ends up powering the vehicle electrics. The relay has to be disabled if wired this way.

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[LithiumConvert]

There are quite a few negative comments about the Victron 30amp B2B on this forum.

I would replace it. (There are alternative makes - Schaudt & Sterling Power spring to mind)
My Schaudt 121545 works very well - as does the Sterling Power BB1230.

But you should also check for the presence of a split charge relay - and disable, if found)

If you decide to leave the existing B2B in place, then check it is set for lithium. It may have been installed before the batteries.

 

[Guigsy]

Although the rest of my kit is Team Blue, I installed a Votronic 30A B2B because of the Orion 30A inefficiency and thermal throttling issues.

 

[ChrisL]

There are quite a few negative comments about the Victron 30amp B2B on this forum

Just to be the odd one out, mine seems to work very well and whilst it can get a bit warm it's never got hot, I quite often see 28 amps out of it, but it is mounted in a space that has loads of ventilation and I haven't needed a fan for it. Another issue with them though is the start voltage setting, for some reason the default value seems to throttle the output, reducing this value to 13 volts or thereabouts will increase the output to nearer the rated value.