lithium dual battery ideas
Maca - a few questions for you to make sure you are getting the most out of your current setup (which should also help if you add a lithium battery to give you more storage capacity - keep an eye on what Tombie is up to in the “What happened to your D3/D4” thread as he just replaced two auxiliary batteries with a single ITECH120X lithium battery).
How is your solar panel charge controller connected to your batteries and have your checked it is all working correctly?
In the graphs you posted the only time I see your solar panel charging was when you isolated the auxiliary battery.
A faulty solar controller, or a failed diode on the solar panel could also cause problems and be draining the battery.
And is your dash-cam left permanently on? You mentioned the dash-cam draws 0.4A.
If the dash-cam is alway left on, then between the normal parasitic drain, the USI-160 (if not isolated), and the dash-cam you could be draining close to 0.8A - which over 24hrs is around 19Ah being consumed.
For comparison - this is the typical drain on my cranking battery overnight (D3 not D4) and daily recharge via 80W of solar panels that I see. I fully isolate the USI-160 when the engine is not running, which disconnects the auxiliary battery.
https://uploads.tapatalk-cdn.com/202...05b9ab770e.jpg
Not shown, but the auxiliary battery drops about 0.05v per week when isolated (with nothing connected to it other than the BM2 monitor).
lithium dual battery ideas
The next step I would be taking is to start disconnecting anything that has been added and revert back to the original set up - i.e. cranking battery only with nothing else added.
So no solar, no dash-cam left on, no Aux battery, and no USI-160 (disconnect the earth cable to power it down fully).
Then you will be able to confirm the alternator and cranking battery is all behaving as expected (watch for at least 3-4 days). At the same time see how the auxiliary battery holds voltage with no load on it over the same period.
Only then start adding extra’s one by one and monitor again for a few days each time you add one extra item back.
Personally - I think between the normal parasitic drain, the USI-160, and dash-cam you are already using up a large portion of your AUX battery storage capacity so everything needs to be in a good health just to handle this base load. And the 100W solar should be more than enough to cater for all of this.
Yes a lithium battery will give you more useable storage capacity, but I would want to confirm you don’t have another problem first (or at least better understand what true load you need to cater for).
By the way - I am also in Melbourne and my 80W solar set up performs perfectly fine over winter but where I park it gets full sun during the day. I probably only see 1 or 2 days a month it won’t recharge the battery fully.
lithium dual battery ideas
And wouldn’t be the first time the HVT-70D has needed to be replaced whilst still under warranty.
Would be good to do a test on it to see how much capacity it has lost.
lithium dual battery ideas
Tombie - what made you go with the ITECH120X?
I’ve read mixed reviews on the iTech products and their warranty policy where they reserve the right to deny any claim if they determine the battery was at end of life (even within the warranty period).