Posting?

[Kitester]

I logged in, selected the correct forum and typed a post. When I submitted it said I had to login first and my carefully thought post disappeared....what’s up?

[martin300662]

Well this post worked just fine....

[GetawA-S]

You probably timed out. I do my particularly well thought out posts on a word processor and cut and paste. (There aren’t a lot of those.)

[bobmiller1]

Welcome to the forum wonders ! LOL Regards, Bob

[Kitester]

So I have a 1983 300. I am trying to up grade the system
To lithium. There is the old univolt and standard alternator charging system. How do I make them work together with dc to dc charger. I plan to ditch the univolt.

[martin300662]

Originally Posted by Kitester

So I have a 1983 300. I am trying to up grade the system

To lithium. There is the old univolt and standard alternator charging system. How do I make them work together with dc to dc charger. I plan to ditch the univolt.

The DC-DC charger replaces the alternator charging of the house battery. They are really simple, the coach battery connects to the charger, the house battery connects to the charger, the charger is connected to to the ignition and when the ignition is live, and if the coach battery has a high enough voltage, then the coach battery is used to charge the house battery using a multiphase charger profile depending on battery type. The univolt should be junked period and is not compatible with lithium.

[Kitester]

Thank you. The wire diagram in the instructions is simple and your explanation is easy. However, what happens to the original isolator? Do I just bypass or eliminate it and how is that done exactly. Also there is the matter of the separate solenoid. Do I pull power from it. The way the system is now the alternator powers the original isolator which then runs to the solenoid and the wire then ran to the starter (lead acid) and house ( AGM) batteries. These questions are not addressed in the instruction booklet and all the information I find on line is for trailers that don’t have isolators or starter solenoids in the first place. Thanks in advance.

[martin300662]

Originally Posted by Kitester

Thank you. The wire diagram in the instructions is simple and your explanation is easy. However, what happens to the original isolator? Do I just bypass or eliminate it and how is that done exactly. Also there is the matter of the separate solenoid. Do I pull power from it. The way the system is now the alternator powers the original isolator which then runs to the solenoid and the wire then ran to the starter (lead acid) and house ( AGM) batteries. These questions are not addressed in the instruction booklet and all the information I find on line is for trailers that don’t have isolators or starter solenoids in the first place. Thanks in advance.

Fundamentally the two approaches are very different. If running a DC-DC charger (I have the CTEK D250SE) then the alternator does not charge the house batteries, only the coach battery, so all the components associated with the alternator charging the house battery get removed (regular alternators are really not suitable for charging deep cycle batteries anyway, plus you do not want a float charge going to LiFePO4 constantly, they don't discharge 'spontaneously' like lead acid/AGM). So basically you set up for the alternator to continue to charge the coach (starter) battery and that's all.

[Kitester]

On the wire diagram for the dc to dc chargers I have seen like victron or renogy, the dc to dc charger charges the starter battery first then charges the lithium house batteries. They have bulk, absorption and float progression. When they reach a preset level they stop charging. The charger can be set to operate with a manual switch or through the ignition. True that regular alternators are not set up to charge lithium which is why the dc to dc charger regulates the amperage to prevent the alternator from burning up. Now understand that I am just saying what the literature and on line info says. That is not the problem. I need to know how to deal with original solenoid and isolator. The univolt is out and does not figure into he equation yet.

[Kitester]

Hi Martin
I looked up your charger. Looks like it does the same thing as the victron. Did you just ignore the original isolator or did you disconnect/ remove it? Or did you place your new one in line from the original isolator? And from your reply you said that the alternator only charges the starter battery. So how do you get charge to the house batteries? Is the dc to dc charger just attached to the alternator separately? The victron has an isolator in it already as I think yours does.

[Kvsterling]

The battery isolator works to keep the 2 battery banks separate until the engine is running. Then it supplies both battery banks with charge. If it looks original, I would replace it due to degrading components that seem to over draw the alternator or allow battery discharge.

This is separate from the univolt. The easiest solution…replace it with a converter/charger and back on the road. Progressive dynamics make a quality unit many of us have used.

The Victron multiplex is not the same. It has ability to do charger/converter as well as be an inverter to the entire coach (all 110v). It is very configurable, and what I used after a failed converter and separate inverter.

Doing inverter/charger is more complex and you are basically doing a complete re design of how your AC and DC systems run. One should be familiar with the systems in the RV and study wiring diagrams of others who have installed this. There are many of you google: victron multiplus wiring diagram.

[Mollysdad]

Originally Posted by Kitester

I logged in, selected the correct forum and typed a post. When I submitted it said I had to login first and my carefully thought post disappeared....what’s up?

Copy/Paste JIC.
Signing in probably changed pages and boom!

[martin300662]

Originally Posted by Kitester

Hi Martin
I looked up your charger. Looks like it does the same thing as the victron. Did you just ignore the original isolator or did you disconnect/ remove it? Or did you place your new one in line from the original isolator? And from your reply you said that the alternator only charges the starter battery. So how do you get charge to the house batteries? Is the dc to dc charger just attached to the alternator separately? The victron has an isolator in it already as I think yours does.

The DC-DC charger is a replacement for the isolator, the original isolator is removed and the only connection is via the charger. All house 12v systems runs from house batteries to keep things isolated. Alternator charges starter battery only, the house batteries are charged from the starter battery BUT using an appropriate (battery type specific) charge cycle. If you add a second charge source (charge, solar charge controller) they also route in via the DC-DC charger with appropriate 'add-ons'. Just remember this removes the option to use the house battery to charge the starter battery (or for emergency starting). It is a massively simpler system.