If you are using a system such as the T-Max one or a National Luna or even a simple VSR such as the Durite one, they will isolate the second battery if the main voltage drops below 12.8V and will charge when it rises above 13.3V. Once they are installed, you don't need to worry about actively managing the second battery.1972 Range Rover Classic 2 door V8
2013 Land Rover Discovery 4 HSE - SCRAPPED
2016 Land Rover Discovery 4 Landmark
2022 Volvo XC40 T5 PHEV 282HP FWD 3 cylinder!
18th Aug 2017 8:04 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14111
thks guys answering my question ref the aux battery charging up
would i be right in saying that if u do the permanent live mod to the 12 volts ports that the aux battery takes over and prevents the crank battery from discharging
or are they used together then when the system detects the crank battery is getting down to a certain voltage will automatically disconnect it to prevent it from going flat and allow just the aux battery to be used
hope that makes sense
18th Aug 2017 8:07 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 73070
Problem with a VSR is the alternator on a D4 with a fully charged crank battery will often put out less than 12.8V, especially on a long haul. The reason not putting a VSR in the D4, just the old solenoid from the D3.
Last edited by DSL on 18th Aug 2017 8:08 pm. Edited 1 time in total
18th Aug 2017 8:08 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14111
TigerRecovery wrote:
If you are using a system such as the T-Max one or a National Luna or even a simple VSR such as the Durite one, they will isolate the second battery if the main voltage drops below 12.8V and will charge when it rises above 13.3V. Once they are installed, you don't need to worry about actively managing the second battery.
many thks
just saw ur post after i had posted mine
18th Aug 2017 8:08 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14111
DSL wrote:
Problem with that's is the alternator on a D4 with a fully charged crank battery will often put out less than 12.8V, especially on a long haul. The reason not putting a VSR in the D4, just the old solenoid from the D3.
been reading about that , with newer cars the alternator isn't supposed to put out the 14.5 volts like the older ones did
18th Aug 2017 8:09 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 73070
I've been watching the Vs via the ciggie readout which is very close to what the car sees and, if the battery is full, most of the time it's showing less than 13v, sometimes less than 12v. New(ish) Exide AGM battery.
If you think about it, the main battery will be going above 13.3V on charge just after you've been cranking to recharge the battery and you are only maintaining the charge on the second battery while driving.
If it turns out the second battery isn't charging enough, I'll look at something a bit more intelligent to charge the second battery.
I can't imagine for one minute that all the people running dual batteries with a VSR are seeing issues though.1972 Range Rover Classic 2 door V8
2013 Land Rover Discovery 4 HSE - SCRAPPED
2016 Land Rover Discovery 4 Landmark
2022 Volvo XC40 T5 PHEV 282HP FWD 3 cylinder!
18th Aug 2017 8:28 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14111
is it true plse that ur not suppose to allow the aux deep cycle AGM batteries to go flat , i.e. if u haven't got the engine running and using lights etc
if that's the scenario would the split charge system protect the aux in not allowing it to drop to an unacceptable voltage level to prevent damage or just the case of keeping an eye on the volts
thks guys
18th Aug 2017 8:53 pm
tayaste
Member Since: 15 May 2013
Location: Chester
Posts: 7633
When separated from the cranking battery, it's just you and the battery. If you run it till it's dead there's nothing to prevent you from seeping every last drop from it.
18th Aug 2017 8:58 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14111
thks buddy , aplogises for asking the daft questions
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