Truma Solar Dual Battery Charger SDC 10/20

Grammarian47 replied on 23/04/2020 21:49

Grammarian47

Posted on 23/04/2020 21:49

I bought a new Motorhome (Autoquest 175) last year (breaking my heart to see it sat unused on the drive).
It has a 100w roof mounted solar panel with a Truma controller.
It enables me to set the type of battery and the percentage charge that goes to the battery if more than one battery fitted. (I only have one battery, (liquid), so it automatically sends all the solar charge to that).I understand the first 2 settings and have set them for the battery type ie liquid, and charge allocation. The 3rd setting allows me to set a PWM charging frequency (whatever that means) of 25Hz (preset), 50Hz or 100Hz. How do I find out which of these PWM settings to use as the handbook is not helpful on this? Any advice you can offer will be very much appreciated.

14 replies

DavidKlyne replied on 20/01/2021 14:31

Moderator

DavidKlyne

Motorhomer

Posted on 20/01/2021 09:39 by cyberyacht

I had a dual solar controller on previous MH. I found the 90/10 ratio worked perfectly satisfactorily. The current MH has a Batterymaster which cuts in, I think, if the voltage differential is 1v. It's OK but doesn't keep the cab battery at 100% all the time like the previous arrangement.

Posted on 20/01/2021 14:31

I have had the device fitted on both motorhomes and it has proved very reliable in the last 7/8 years. It obviously works whilst on EHU which I have the van connected to for at least part of the day, everyday. On my vehicle the cab battery is not charged directly from the EHU. With a solar panel, if that is all that is being relied on to keep the charge topped up, especially in weather where there is not much charge I imagine that it might struggle. The acid test is whether the engine starts when you want it to, so far so good!!!

David

PhilnShaz replied on 30/01/2021 11:04

Member

PhilnShaz

Posted on 19/01/2021 20:02 by DavidKlyne

Sounds a bit like my Bailey motorhome. Same controller but only connected to the leisure battery! The way I got round it was to have a Battery Master fitted which basically pushes any excess charge in the leisure battery to the cab battery. You can do what you are suggesting but the usual split is 90/10 leisure/cab and some have found the 10% not enough to keep the cab battery fully charged. Obviously you could change the ratio but the more you do that the less charge is going into the leisure battery which might no be the best idea?

David

Posted on 30/01/2021 11:04

Personally I don't understand why so many people want to charge their leisure battery more than the vehicle battery as the vehicle battery usually powers things like alarms and security devices as well as backing up the radio memory, whilst the leisure battery is usually turned OFF during storage, so I have my solar charger set at 90% vehicle and 10% leisure. Unfortunately I have not been able to go to the M/H since this lockdown to check how it is doing.