Upgrade from Sargent EC155 Advice Request

[RikParr73]

Hi all

I've been running the Sargent EC155 for the last 5 years or so and it's done the job. I've just upgraded to a Lithium Fogstar battery from my lead acid LB and the Sargent now keeps alarming randomly for high voltage. I've not changed anything else and have read that the Sargent's don't like Lithium - so my first question would be is this correct? Secondly I am thinking of perhaps upgrading the Sargent for a better system (I have read that Sargent aren't the best, depending on who wrote what) so would welcome any suggestions/recommendations of a suitable upgrade. I just run the usual stuff, fridge, lights, and USB. I have a 120w fixed solar panel too that runs via Victron 100 MPPT. The Sargent is fitted on the panel of the T6 LWB behind the drivers seat area (Where the sliding would go if it had one on that side) with all the wiring going from there to under the passenger single seat. Could I potentially use the existing loom from the Sargent, anything else I should be aware of etc? Thanks in advance, Rik.

 

[roadtripper]

Have you connected your Fogstar directly in place you used to have an AGM battery?

If you don't have an existing DC-DC charger and haven't fitted one then you will be connecting your AGM van battery directly to your Lithium battery via the split charge relay in the Sargent - and that's a very risky thing to do given the very different voltage profiles. The PSU in the Sargent is also likely not charging the Lithium in a way that is good for it, if it's charging at all.

Likewise have you altered the charging profile in your solar charger?

 

[RikParr73]

Apologies, Yes I have the CTEK 250 DC-DC charger, prob should have mentioned that lol, sorry. With regards to changing the profile in the solar charger, I guess this is done in the victron app - i'll check that. Are the required profile settings obvious or is there a preferred setup I need to be aware of?

 

[roadtripper]

So how are the Sargent/Victron/CTEK/Battery connected?

Do you have diagrams or pictures?

Was the CTEK fitted as part of the change or part of the original install.

The problem is that fitting an EC155+CTEK is a way of supporting effective AGM charging on a smart alternator vehicle, but it doesn't support upgrading to Lithium as the CTEK can do that but the mains "charger" in the EC155 cannot.

 

[RikParr73]

 

[RikParr73]

So how are the Sargent/Victron/CTEK/Battery connected?

Do you have diagrams or pictures?

Was the CTEK fitted as part of the change or part of the original install.

The problem is that fitting an EC155+CTEK is a way of supporting effective AGM charging on a smart alternator vehicle, but it doesn't support upgrading to Lithium as the CTEK can do that but the mains "charger" in the EC155 cannot.

Had the CTEK in from original conversion. The lithium is being charged by the solar and the CTEK as I've ben away and used it. Albeit not much but the battery has done approx. 4 cycles in about 3 months if that helps?

 

[roadtripper]

On your diagram you do not have either the Fogstar you mention, nor the EC155?

 

[RikParr73]

On your diagram you do not have either the Fogstar you mention, nor the EC155?

The fogstar has replaced the battery in the diagram, just not updated the diagram. The sargent connects to the bus bar positive from memory.

 

[RikParr73]

On your diagram you do not have either the Fogstar you mention, nor the EC155?

Apologies for the diagram it was done for the benefit of building the auxiliary LB system :-(

 

[roadtripper]

Ok, then what you are doing is quite dangerous.

You've replaced an AGM profile battery with a Lithium profile battery but it's still being charged as an AGM by:

• Your CTEK
• Your Victron MPPT
• The basic PSU/Charger in the EC155

You can fix the first two via configuration, you can't fix the third as far as I know and damage is possible/probable if you continue.

Also if you plan to continue connecting the additional Lead Acid - don't.

The voltage profiles of AGM and Lithium are very different and both are capable of supplying and drawing considerable current - connecting two together is likely to damage something, and potentially cause enough heat for serious damage.

 

[RikParr73]

Ok, then what you are doing is quite dangerous.

You've replaced an AGM profile battery with a Lithium profile battery but it's still being charged as an AGM by:

• Your CTEK
• Your Victron MPPT
• The basic PSU/Charger in the EC155

You can fix the first two via configuration, you can't fix the third as far as I know and damage is possible/probable if you continue.

Also if you plan to continue connecting the additional Lead Acid - don't.

The voltage profiles of AGM and Lithium are very different and both are capable of supplying and drawing considerable current - connecting two together is likely to damage something, and potentially cause enough heat for serious damage.

Thanks. I wasn't going to connect the additional aux battery as it's lead acid, the diagram is out of date and merely for indicative purposes. I'm not sure how you 'configure' the CTEK though as there is no app for it? I will check the profile of the MPPT. As for the sargent, then I guess I need to replace it now that I am using Lithium? Thanks for your advice so far, appreciated.

 

[roadtripper]

Double checking the EC155 has a switch for the charger and a fuse, so you can disable this.

So for now your best bet is to change the CTEK and Victron to Lithium profile, leave the Sargent charger off and don't use the additional battery.

That will work fine so long as you can get enough charge into your Fogstar from solar and driving as you won't get any charge from EHU.

 

[roadtripper]

The CTEK is normally configured with a fly lead connected to ground or +12v - if it's old enough there is a risk it might not have a lithium profile - check in your manual?

 

[RikParr73]

The CTEK is normally configured with a fly lead connected to ground or +12v - if it's old enough there is a risk it might not have a lithium profile - check in your manual?

The manual is well gone, it's prob 5 years since it was installed - it's the CTEK 250SA (I think) and checking online it isn't compatible, so that needs to go too. So basically I need to replace the CTEK and Sargent - Any recommendations of suitable, future proof kit? Anyone want to buy a CTEK too? Lol!

 

[roadtripper]

Long term there are a few options.

You may find that you don't miss the EHU charging and are fine with leaving the EC155 in place to handle mains and 12v distribution. You always have the option of carrying a mains Lithium charger with you just in case on longer stays, you have an Anderson connector in place it looks like to make hook up easier.

You may want to update the DC-DC to get more charging off engine to replace the EHU.

You might also be able to find a way to hardwire an EHU charger in, this can be a bit more challenging as the EC155 is an all in one.

 

[RikParr73]

Long term there are a few options.

You may find that you don't miss the EHU charging and are fine with leaving the EC155 in place to handle mains and 12v distribution. You always have the option of carrying a mains Lithium charger with you just in case on longer stays, you have an Anderson connector in place it looks like to make hook up easier.

You may want to update the DC-DC to get more charging off engine to replace the EHU.

You might also be able to find a way to hardwire an EHU charger in, this can be a bit more challenging as the EC155 is an all in one.

Thanks, just dug out an old pic from some works I did and it is the CTEK250SA so I'll replace that. I'm yet to see how long I get out of the Fogstar as not been away as usual since installing it, but I need 3-5 days sometimes so would generally use EHU where available, but as you say, I could use the Anderson connectors to utilise a lithium charger to give the Fogstar a top up - thanks.

 

[roadtripper]

Bad news with the CTEK

You could replace it with the updated SE model, it only has 20A charging, but it would be very straightforward as it's physically the same shape.

You might want to consider a higher current DC-DC charger, but I would carefully check the size of wiring and fuses you have to ensure those would be suitable.

 

[RikParr73]

Bad news with the CTEK

You could replace it with the updated SE model, it only has 20A charging, but it would be very straightforward as it's physically the same shape.

You might want to consider a higher current DC-DC charger, but I would carefully check the size of wiring and fuses you have to ensure those would be suitable.

This is the current CTEK and cables, do you think they will be sufficient with a higher current DC-DC charger? Thanks again for your support.

 

[roadtripper]

Thanks, just dug out an old pic from some works I did and it is the CTEK250SA so I'll replace that. I'm yet to see how long I get out of the Fogstar as not been away as usual since installing it, but I need 3-5 days sometimes so would generally use EHU where available, but as you say, I could use the Anderson connectors to utilise a lithium charger to give the Fogstar a top up - thanks.

I think that's a good way forward, find that out before considering disruptive change.

I think also the voltage put out by the EC155 is low enough it actually wouldn't be enough to charge the Fogstar so in an emergency you could always turn that back on to support your 12v electrics if you had to. I'd just personally feel a bit uncomfortable having such a basic charger (it's not even that really just a power supply) in the mix all the time with a lithium battery.

My biggest concern was you had the Lithium directly connected to an AGM either via the split charge relay or the extra Anderson - but you're on top of that so it's now more about making the best use of the lithium.

 

[roadtripper]

This is the current CTEK and cables, do you think they will be sufficient with a higher current DC-DC charger? Thanks again for your support. View attachment 225737

That looks like you have the solar terminals connected as well?

As to the cabling the size should be on the sheath either as AWG or as mm2 - if you know that and the approximate length then you can compare that to the tables of wire size/length in the manuals of the chargers.