DC to DC charger over-charging?

[Jimm]

Hi, I'd be grateful for some advice/reassurance please!
I have a T6 with Euro 6 engine. Renogy DCC30S 30A DC-DC charger, connected to Xtreme AGM 110AH leisure battery - all connected, fused etc as per manufacturers requirements, no solar currently installed. Equipment and installation about 10months old.
I am finding recently that when then engine is running, the leisure battery is being charged at 15V, despite the fact that the charger is set to the factory 'AGM' setting, which has max boost voltage of 14.6V. It's also charging at 9 amps after an hour driving (and a couple of hours driving the day before).
I know the Euro 6 alternator/regen system means that its perfectly normal for the start battery to see 15V+, but my understanding was that the DC-DC was supposed to take this and deliver a more consistent charging pattern.
Should I be concerned about this?

Screenshots of the Renogy app attached for info.

(I have contacted Renogy - awaiting comment from them but would appreciate feedback from real-world users on here!)

Thanks,

Jim

 

[Mike23864]

I’m sure the resident expert @Dellmassive will be along shortly to advise.

 

[Sim60]

Hi, I'd be grateful for some advice/reassurance please!
I have a T6 with Euro 6 engine. Renogy DCC30S 30A DC-DC charger, connected to Xtreme AGM 110AH leisure battery - all connected, fused etc as per manufacturers requirements, no solar currently installed. Equipment and installation about 10months old.
I am finding recently that when then engine is running, the leisure battery is being charged at 15V, despite the fact that the charger is set to the factory 'AGM' setting, which has max boost voltage of 14.6V. It's also charging at 9 amps after an hour driving (and a couple of hours driving the day before).
I know the Euro 6 alternator/regen system means that its perfectly normal for the start battery to see 15V+, but my understanding was that the DC-DC was supposed to take this and deliver a more consistent charging pattern.
Should I be concerned about this?

Screenshots of the Renogy app attached for info.

(I have contacted Renogy - awaiting comment from them but would appreciate feedback from real-world users on here!)

Thanks,

Jim
View attachment 187330View attachment 187331View attachment 187332

14.6V is usually at nominal temperature (25C ?). This is raised as the battery temperature lowers. I havn't looked at the Renogy manual , but Dc-Dc usually spec a temperature compensation coefficient which shows how much the charging voltage is raised as the temp lowers. Does the Renogy allow you to spec the capacity or is it working it out for itself?


Simon

 

[t0mb0]

My votronic is 14.7v nominal but after temperature compensation, that can get up to 15v so yours is consistent with that. Mine does have a dedicated temperature probe taped onto the battery though - does your renogy have similar?

 

[Jimm]

My votronic is 14.7v nominal but after temperature compensation, that can get up to 15v so yours is consistent with that. Mine does have a dedicated temperature probe taped onto the battery though - does your renogy have similar?

Thanks T0mb0, Sim60,
Yes I have a temperature probe installed against the battery. The Renogy unit monitors (and displays) battery temperature and also the temperature of the charger itself, with cut-offs set for over-temp. I can't find anywhere that allows me to adjust temperature compensation but it is true that I have been testing it recently on cold mornings/evenings, which coincides with this apparent increase in charging voltage. Thats reassuring to hear that this voltage is consistent with your Votronic. I will dig a little deeper to see if I can find anything on this compensation.

Thanks - really useful feedback on here as always.

Jim

 

[Jimm]

Ok checked again and now I know the correct terminology, the info was there. If my numbers are correct, this all makes sense.....
Renogy Temperature compensation coefficient is -3mV/°C/2V (x6 cells = -0.018V/°C).
Nominal charge voltage at 25°C is 14.6V.
Temperature during test was 4°C.
4°C-25°C = -21°C x -0.018V/°C = 0.36V.
0.36V + 14.6V = 14.96V (so 15V).

This also looks to tie up with my battery's preferred temperature coefficient on the spec sheet.

Thanks All.

 

[Dellmassive]

looks like your all good from the reply's above,

might be worth adding some pics of the install and battery for reference.

 

[Jimm]

 

[Jimm]

looks like your all good from the reply's above,

might be worth adding some pics of the install and battery for reference.

See below pics from when I was part-way through installing.

 

[Dellmassive]

nice install, you should add you van to this thread :

Seat Base Electric + EHU + Solar Install + Charger + DC-DC -- How We Done it --

Seat Base Electric + EHU + Solar Install + Charger + DC-DC -- How We Done it -- id like to build a thread showing what's possible as regards to seat base builds. lets post a collection of our electrical installs, be it in the seat base or rear conversion. just EHU or SCR/VSR, charger, DC-DC...

www.t6forum.com

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