Lithium upgrade EHU workaround

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tomosllyr

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I know there are plenty of threads on lithium LB upgrades but can't find the answer to my conundrum.

I have a converted camper that we use for 1 or 2 night weekends away, and the occasional 1 week long trip. We live off battery for the smaller trips and use EHU for the longer trips so we can use sockets and the microwave (I don't have an inverter).

I already have a Victron DC-DC charger with a lithium profile. I am booked in to have a solar panel fitted with a Victron MPPT. Once that was done I was hoping to fit a lithium battery (in fact I've already bought it).

But I've realised that my PowerPart PDU has a built in charger for when the EHU is connected which is not lithium compatible.

A conversion company I've spoken to has said that it doesn't matter that the EHU charger is incompatible as long as I use it infrequently and the battery has BMS (which it does).

Is this true?

If not, is there a straightforward way of updating my system so that the EHU can charge a lithium battery?

Or is there a way of turning off the EHU charger when connected to EHU in order to protect the battery and depend on the solar/dc-dc to keep the battery charged?
 
Do you know. Or can't you get the spec of the PowerPart PDU?

Or may be a fixed 13.8v output?.

Or possibly a multistage charger?

Lithium you need to stay under 14.6v.
 
I’m not familiar with your PDU (and don’t like all in one units) but have in the past modified a similar unit in my friend’s Motorhome.
What I did was open up his PDU, disconnect, remove and discard the internal power supply unit (PSU).
Then I rewired the MCB that originally provided power to the PSU to instead provide the 230Vac feed to an external Victron charger and then wired the new Victron’s charger output back into where the original PSU output connected. I ensured that the Victron charger didn’t supply more current than the original PSU due to not knowing the internals of the PDU (PCB track sizes etc) or the size of some of the external wiring (which was hidden and a complete rats nest anyway). However if you can connect the output of the new charger right back to the leisure battery then you can suitably fuse and size the wires and ignore the PDU; just utilising it’s MCB.
From the manual you linked to the 6A MCB is dedicated to feeding ac power to the internal power supply.
I expect there is also a dc fuse for the output of the power supply, but I couldn’t see that mentioned.
Wouldn’t be difficult for a competent person to update it for you.
 
@EAN path is what I'd advise for a regularly used camper. I'd just wire the output of the charger direct to the battery (suitably fused) rather than looping back onto the low voltage side of the PSU.

If it's infrequently used then as far as I can see the internal PSU is on the dedicated 6A breaker - just turn that off.

It means you will draw a little more from the new lithium battery on EHU, but the capacity of the lithium will help offset that. And it sounds like you mostly use EHU for 240v.

In the interim you could buy a Victron/CTEK/NoCo mid level maintenance charger with a lithium profile to top the battery up if you needed. It's a useful thing to have around anyway.

So for your use I'd just carry on converting things to lithium and turn the breaker off - maybe put some tape over it as a reminder not to flick it back on. If you find everything is fine off the battery job done, if you find you need a bit more on long trips buy a maintenance charger to top up the battery.
 
Generally around here the Victron ones are well recommended, but there are CTEK and NoCo options too and those are well regarded brands.

Be aware AFAIK CTEK don't have an option that can charge Normal Lead Acid/AGM/Lithium so if you want maximum flexibility to top up any battery rather than something dedicated then keep that in mind.

You don't mention what size battery but if it's purely for maintenance rather than rapid charging anything in the 7-15A region should be fine, and will be physically smaller and runs cooler.
 
Just something to charge my 100ah lithium when we are on hookup.

The battery does 2 nights running the fridge and lights, but any longer would require some extra juice.
 
As a suggestion then get the IP65 15A Victron - not a bad price and should give you a decent charge rate to top up without being a big lump.

www.12voltplanet.co.uk

Victron Energy Blue Smart IP65 Charger - 12V 15A (Bluetooth Built-In)

Victron Blue Smart IP65 12V 15A professional charger with built-in Bluetooth & 7-stage charging algorithm. Ideal for larger leisure batteries & boats.
www.12voltplanet.co.uk

I'd suggest getting the quick connect and having that fitted for ease of use

www.12voltplanet.co.uk

M6 Eyelet Connector With 30A Fuse For Victron Energy Blue Smart IP65 Charger

Accessory connector cable for Victron Blue Smart IP65 chargers featuring M6 eyelet battery connectors & in-line 30A fuse. Other accessories available.
www.12voltplanet.co.uk
 
So just wanted to provide an update in case anyone was looking at this in the future.

I've spoken to the guys at Roamer who are satisfied that their batteries are safe to use with non-lithium compatible chargers. They did say that ideally it shouldn't be done too often to protect the life of the battery, but were happy that my usage of EHU one or two trips a year is fine. So I've gone for one of their batteries.

For the PDU in particular, after a bit of a play with it I've realised that when charging on EHU it is fixed at 13.8v, which makes it fairly lithium friendly, but that also if you switch the 'Power Supply' breaker off then the only thing that switches off is the battery charging. Everything else including sockets remain functioning.

So my plan is to have this switched off and have a small plug-in lithium charger to hand. It is reassuring to know though that if I ever forget the lithium charger I can switch it back on to charge the battery periodically.
 
That's a fair plan. If the breaker is a regular MCB and you have the space a possible thought is to get one of the MCB Lock Out devices used during electrical work, that way you know it won't be knocked on accidentally but it's easy enough to pop off when needed.

Something like this, there are a few designs around and they're only about the cost of a pint.

 
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