Lithium install b2b

[Dominic1961]

Hi all

I am about to install lifepo4 setup into my 2001 B694, the setup is EBL99, Victron mppt and 20 amp b2b Renogy. My question is how do i get these all to play with each other, can the B2B run through the EBL99 and if so how, at the moment the mppt is charging directly to the lead acid is that ok or is it better through the ebl if possible. Also what can be done to charge the starter battery and maintain it whilst parked up on solar now that all profiles will be set to Lifepo4, i am presuming the split relay will need to be disabled. Sorry that lot is a big ask.

 

[monzer]

Interesting question. I'm sure someone will be along shortly.

 

[Pausim]

If you feed the B2B through your EBL you will avoid the problem of creating a loop and back feeding the engine battery. 20A should be well within the capacity of the EBL. Remove the main engine battery connection from the EBL and use this as the power feed to the B2B input. Then connect the B2B output to the vacated connection on the EBL. This a a simplified summary of what I did with my EBL29 but the 99 is probably similar.

You might find it helpful to download the installation instructions for the Votronic VCC30 B2B which has a wiring diagram and instructions for connecting their B2B to an EBL. Obviously not the same as the Renogy but might help to explain the principles involved. https://www.12voltplanet.co.uk/user/downloads/Votronic-VCC-30A-DC-DC-charger-instructions.pdf

If you connect the B2B directly to the battery you will need to take steps to disable the original split charge arrangement which is much more complex. I can’t help with the mppt part of your question.

 

[Lenny HB]

As your van is more than a couple of years old do not connect via the EBL as the split charge relay contacts will have a build up of carbon on them reducing the charge rate.
You can just disconnect the starter battery input lead to the EBL and connect it to the B2B input then connect the b2B output direct to the battery. As the starter battery lead is disconnected from the EBL the split charge relay will be disabled.

For charging the starter battery I would fit an Ablemail Battery Maintainer, they are better suited when using Lithium.

A 20 amp B2B is a bit small for Lithium you will probably get a lower charge rate than the standard split charge relay, you need at least 30 amp preferably 45 amp. If going higher than 30 amps its best to replace the 50amp maxi blade fuse by the starter battery with either a Midi or Mega fuse.

 

[Pausim]

Do what Lenny HB says, it sounds better than my solution.

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[Dominic1961]

Thanks for the replies, very helpful. it seems lifepo4 isn't plug and play, i have resolved the mppt cold charging by buying a battery sense Bluetooth from Victron. On lithium mode it has low temp cut off. 45 euros a bargain, it talks to the mppt. now comes the brain picking bit. i have an idea and would like your opinions please. DC-DC charger has no cold protection cut of and since its switched on by D+ signal i am going to try and interrupt the signal with a temperature controller in the D+ wire. That way if its to cold and i start the engine the dc-dc wont see the signal and will stay of. here is the bit i needed opinions on, if i actually use the D+ wire to power it would that save on the parasitic draw, the unit has a memory status so on paper it should fire up with the settings it had before power down. what's your views on this.

 

[Hoovie]

Thanks for the replies, very helpful. it seems lifepo4 isn't plug and play, i have resolved the mppt cold charging by buying a battery sense Bluetooth from Victron. On lithium mode it has low temp cut off. 45 euros a bargain, it talks to the mppt. now comes the brain picking bit. i have an idea and would like your opinions please. DC-DC charger has no cold protection cut of and since its switched on by D+ signal i am going to try and interrupt the signal with a temperature controller in the D+ wire. That way if its to cold and i start the engine the dc-dc wont see the signal and will stay of. here is the bit i needed opinions on, if i actually use the D+ wire to power it would that save on the parasitic draw, the unit has a memory status so on paper it should fire up with the settings it had before power down. what's your views on this.

Are you trying to reduce the draw of the B2B in the circumstances where the Lithium is too cold to take a charge? I don't know how much power you will save off the total the Alternator is putting out? probably a miniscule amount.