Again, old pic - the solar has been disconnected - pic was just for cable size thanks.
Upgrade from Sargent EC155 Advice Request
- Thread starter RikParr73
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- sargent ec155
What size Fogstar did you get BTW?
Right now I'd hold off for the replacement model - it's smaller and much more efficient so runs cooler but it will cost a bit more - but it's not a bad choice if you have good ventilation around it.
The other popular choice is the Renogy DCC50S which you can downrate to 30A in the app, will give you the same charge rate but cooler running.
The important thing is the capacity of your cables and fuses. Did you find size ratings in the cables?
Right now I'd hold off for the replacement model - it's smaller and much more efficient so runs cooler but it will cost a bit more - but it's not a bad choice if you have good ventilation around it.
The other popular choice is the Renogy DCC50S which you can downrate to 30A in the app, will give you the same charge rate but cooler running.
The important thing is the capacity of your cables and fuses. Did you find size ratings in the cables?
Hi, thanks, I literally just picked up on the Renogy from another post
I bought this Fogstar
RE the cables -I believe it is 8AWG, not 100% sure without taking seat out though, but happy to upgrade the cables if needed.
Also just to check but you have an existing cable to your CTEK that is an ignition on signal (so the DC-DC only runs with the engine) ?
I'm not sure, I think so but it was installed by the conversion company 5 years ago. Anyway I can check?
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Looking at the Fogstar website they are surprisingly relaxed about split charge relays, basically giving the same negatives as for any leisure battery system connected in this way.
I have a Sargent and noticed one of these batteries for sale in the forum so checked it out, with my dc-dc charger, solar MPPT I think the only issue left is the EHU charger in the Sargent and there are several threads on here about disabling or making a lithium charger work through the Sargent control panel. As it’s so neat, I’m tempted to keep it and find a work around to this issue (although not quite yet as AFAIK my AGM battery is still good)
Interested to hear how you get this fully functioning.
So for that capacity you don't really want to charge over 30A anyway.
For an easy life you could just swap the CTEK for the new one, they're physically the same so will take minutes. A 20A charge rate will recharge an 80% depleted battery in about 4 hours.
The Victron/Renogy will take more cable work but will charge at 30A so the same charge will take about 2 hours 40
I wouldn't advise a higher rate on the Renogy as it's over Fogstar advised charge rate, but in an emergency it could be increased a bit.
If you are under seat install you'll have around 3.0 - 3.5m cable run. 8 AWG is recommended by Renogy for both 30A and 50A at 3m.
For an easy life you could just swap the CTEK for the new one, they're physically the same so will take minutes. A 20A charge rate will recharge an 80% depleted battery in about 4 hours.
The Victron/Renogy will take more cable work but will charge at 30A so the same charge will take about 2 hours 40
I wouldn't advise a higher rate on the Renogy as it's over Fogstar advised charge rate, but in an emergency it could be increased a bit.
If you are under seat install you'll have around 3.0 - 3.5m cable run. 8 AWG is recommended by Renogy for both 30A and 50A at 3m.
On the advertising they are, when I asked them directly, not so much:
Lithium LifePo4 12v Batteries - Time For An Upgrade?
Just to follow up I did get a reply from Fogstar about the odd direct from alternator charge recommendation. Apparently this is only for traditional non-smart alternators
Thanks, cables look fine. OK, so just install the CTEK250SE seems the most logical thing to do here then right?
It's the most straightforward as you can just drop it in and reuse the existing cabling and mounting, just make sure you connect the battery select wire for lithium profile.
One thing to be aware of with the CTEK on lithium profile is that they choose to maximise lithium battery lifetime so don't have a float stage, so your battery may not stay fully charged and instead drop back a bit and then the charger kick in again.
One thing to be aware of with the CTEK on lithium profile is that they choose to maximise lithium battery lifetime so don't have a float stage, so your battery may not stay fully charged and instead drop back a bit and then the charger kick in again.
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I now understand, and yes the ignition is wired in sorry.
Thanks, just to confirm, I'll just run this battery select cable shown below to the neg bus bar or to the van chassis common - or either, or does it have to go direct to the Fogstar?
If you connect it to negative you'll set AGM profile - which is what you have now - you want to connect it to +12v to select Lithium profile
Hi all - update from Sargent and Fogstar below. I guess my only real option now is to find a replacement charging solution and leave the Sargent in place to run the 12v systems? Any advice welcomed please - thanks.
 | Dave (Fogstar Ltd) 2 Feb 2024, 08:41 GMT Hi Rik, Unfortunately, it looks as though this may not work, as the specs on the charger show a 13.8v charging current. We generally recommend 14.4v for bulk charging, and 13.8v for the float. This Sargent unit may work for topping up the batteries on a float charge, but I'm not sure that it will provide enough voltage to give a Drift battery a full charge. Kind regards, Dave |
Have you changed the CTEK to a lithium capable one?
One option is to just do that and see if that's enough to support your needs.
If you get enough from the DC-DC charger you can just leave the Sargent charger off (pull it's fuse)
If you find that you spend a few days on EHU and don't do enough driving for the DC-DC to keep reasonable levels of charge in the Fogstar then you can try leaving the Sargent charger on. Fogstar seem to be happy with that as float charge and it will provide something like 8amps to support your loads (so you won't take that out of the battery) - potentially that's actually a very gentle profile for a lithium battery.
If none of those work for your use then consider an external mains EHU charger like a Victron - but you may find it's not needed.
One option is to just do that and see if that's enough to support your needs.
If you get enough from the DC-DC charger you can just leave the Sargent charger off (pull it's fuse)
If you find that you spend a few days on EHU and don't do enough driving for the DC-DC to keep reasonable levels of charge in the Fogstar then you can try leaving the Sargent charger on. Fogstar seem to be happy with that as float charge and it will provide something like 8amps to support your loads (so you won't take that out of the battery) - potentially that's actually a very gentle profile for a lithium battery.
If none of those work for your use then consider an external mains EHU charger like a Victron - but you may find it's not needed.
Well more specifically they said it wasn't enough to bulk charge - it was fine for floating (in fact personal opinion here a lot of lithium chargers float too high for good cell lifetime)
Unless you are going to be drawing serious charge out of the battery while on EHU but not driving regularly I'm not sure a seperate EHU bulk charger is needed.
Unless you are going to be drawing serious charge out of the battery while on EHU but not driving regularly I'm not sure a seperate EHU bulk charger is needed.
Thanks all... before considering the charging element 'Dave' from Fogstar has thrown a further spanner in the works as per below...i'm confused even more so now......
 | Dave (Fogstar Ltd) 2 Feb 2024, 12:55 GMT Hi Rik, The 250SA looks like it will be fine, as it has a setting to charge at 14.4v. Unfortunately we can't reliably recommend DC to DC chargers as this is not something we stock I'm afraid. kind regards, Dave |
Not really a spanner, just not willing to make a recommendation (and therefore take responsibility) for something they don't sell?
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