Kevin.Hutch
2011 Mercedes 313 906
Re: Kisae DMT1250 - my experience w/ a solar/alternator DC/DC charger & OEM AUX batte
1. The Aux battery output via the factory relay is conservatively specified as max 40 amp.
This is due to a combination of the 90 amp relay capacity, the cable voltage drop and the alternator surplus capacity.
2. We know from several installations that the alternator has spare capacity that may be available and we know from others that the 90 amp relay fails presumably when overload causes excessive sparking.
3. We know from the Mercedes specs that the standard cable from the start battery to the relay and hence to the standard AUX battery is 35 sqmm or approx 2 AWG.
If any of these issues are varied then a new design is necessary particularly to address the increase of lithium charge current. The DC-DC converter is probably the best way to address the current limit and the new design current needs to include that of the standard AGM Aux battery but how can it charge both AGM and Lithium.
If the standard AUX battery is to continue to be used, you would have to consider the DC-DC converter be fed from the AGM house battery and if controlled by the ignition switch what purpose will the standard AUX battery then serve.
Do not get all the issues mixed up;How would that not somehow affect the AGM factory aux battery and it's charging parameters having lithiums running thru it also being charged ??
Thats why I planned on using the Sterling set for lithium on a seperate circuit as a charger.... the house bank is not connected nor supplying any power to the aux system.. trying to find a way to charge lithiums but have the factory cut off relay and aux battery...
Or am I not even in the ballpark ?!?!
1. The Aux battery output via the factory relay is conservatively specified as max 40 amp.
This is due to a combination of the 90 amp relay capacity, the cable voltage drop and the alternator surplus capacity.
2. We know from several installations that the alternator has spare capacity that may be available and we know from others that the 90 amp relay fails presumably when overload causes excessive sparking.
3. We know from the Mercedes specs that the standard cable from the start battery to the relay and hence to the standard AUX battery is 35 sqmm or approx 2 AWG.
If any of these issues are varied then a new design is necessary particularly to address the increase of lithium charge current. The DC-DC converter is probably the best way to address the current limit and the new design current needs to include that of the standard AGM Aux battery but how can it charge both AGM and Lithium.
If the standard AUX battery is to continue to be used, you would have to consider the DC-DC converter be fed from the AGM house battery and if controlled by the ignition switch what purpose will the standard AUX battery then serve.