What is the consensus of kind of battery maintainer/charger for a 8d start battery.
Trik-L-Start and Amp-L-Start were THE solution...sadly both defunct and NLA. Victron makes a nice 18amp b2b charger that I've seen used as an alternative, but 5 times the price. Amazon.com: Victron Energy Orion-Tr Smart DC to DC Charger (Bluetooth) -... (https://www.amazon.com/Victron-Orion-TR-Isolated-Charger-Supply/dp/B0851TPKV7/ref=sr_1_6?crid=M0LDPPQONIVN&dib=eyJ2IjoiMSJ9.6BvpT6G0uCteYo2s2xcB_lNg_svmZHYcz7IpdMjFUsnhIsTcgTnjj6DhpHiurLAQkWPd8WEKFun0fGO98LmZWmWEtulzQlUxY4dIOxqi4wcQ30syZ2MoxIbJt58oFsnBWJBrir3sIrGJDgJd5reW0UZauSw_pCmrZ9wW2xeh_PPDVzNTzQC7oPu_bO29QgzjYDYcq5_9cILQbksUORqVXQAmmoH54_AR_NZeGtMKEIsqpbfTsCtLeYgE6BxsT7cGTBBLMGXLn-PTSUS3gcfU4ip9ARIx2DTuz_E4bd2fXZHmfkrgPUMC1cMEf-Qqb60VtFz5Rydx7ONR9GkDu_A5cegtDa7jabbvxwcpu4SDrIRZJcCQ4VXhgWHRSjlXGEOwpuJU5PLE0fTkuWfHzyhXAc1OoQM0y1vRtqo2s8Tq330jAPuJocIC0qYnCw5M4mu-.kETp0LDwEWcpAmDHeWHUeSLbLKKybl_0Ri7GUDzgUZw&dib_tag=se&keywords=battery+to+battery+charger&qid=1739409413&sprefix=battery+to+battery+charg%2Caps%2C214&sr=8-6)
My inverter/charger drops to 13.6 volt float the lithium's are fully charged. I then just close the boost switch and let the chassis batteries float with it. 13.6 excellent float voltage for AGM.
I use a Progressive Dynamics converter/charger on our house AGMs and using a coiled jumper, connect the two lighter plugs on the dash and HWH panel to also keep the three engine conventional 31 series charged. The voltage is the PD default rate of 13.2V. The AGMs were new in '08 and the 31s are bout 6 years old. Twin digital voltmeters on the dash are on 24/7 at home or dry camping. See my old posts for photos.
The converter/charger does a desulfation higher voltage 15 minute shot every 21 hours. I called the AGM mfg and they said it wall well within limits for the house batteries.
In my opinion, Progressive Dynamics products are give longer life and more stable voltage than WFCO products.
Pierce
I made my own using two 40 amp diodes but now I use a 500 amp blues sea latching remote latching relay.
Can I get reality check on what I am doing. I have a victron IP 22 for the 3 group 31 lead acid that I use to maintain them. I leave the 3 house 8D AGMs isolated. Is the B to B only important if you are doing a lot of boondocks? I don't see more than a week at a time in my future. Is the primary reason for a B to B so you can stay isolated and not have the alternator overloaded if for instance I failed to isolate the batteries when on the road. I purchased a Blue Seas latching combiner but have not installed it. I may not so I can keep it simple and idiot proof.
Am I doing it correctly or is there a downside I am missing?
The B to B is just for the protection of the alternator when you have lithium. Not needed for your AGM's
My coach uses a VSR - Voltage sensing relay to keep both battery banks charged.
Amazon.com: BEP 710-140A Digital Voltage Sensing Relay (DVSR) 12/24V :... (https://www.amazon.com/BEP-Digital-Voltage-Sensing-Relay/dp/B0108LNWT6/ref=sr_1_10?crid=39281W4LB38T2&dib=eyJ2IjoiMSJ9.nOJ4ZOrHvN07A7FbzA_Yw8q7gRYu0lMZIhfNyvpW29NWvGOrEChWGjeKXY9IuDLBcj_FhCsjVfX2MZDXcbfWfoKvNd9kTjtLURvEuYmJ_sY_5u439uMy1NI0RgWfNFgPNUxjs-s6r9vEEXKWZcR-2XZLHzSgrReVr3rsVgs7RMsjgkY1czZalgZLoJ4zde-maNp0BcJSokbEEY2ACTK8lTlH_pvYkI1oyZzNxg1hpvg.c9FfSd8Y7o5WMLVjTZoP4g82HJndxFPdYLbJgYn3Q9k&dib_tag=se&keywords=voltage+sensing+relay&qid=1739440295&sprefix=voltage+sen%2Caps%2C123&sr=8-10)
AGM may accept 15 volts, but 15 volts to a GEL battery could permanently damage it.
This battery is a flood cell. I was looking a 5 amp battery minder.
Any small smart charger will work fine. Amazon has them for about 50/60. You should target around 4-8 amps , like you stated . Imho
Or a 60 watt solar panel should put out about 4 amps. I use a 35 watt / 3 amp panel for my airplane.