Charging cab battery..

[pepe63xnotuse]

Good morning all..

I have had a lengthy rummage through some of the previous posts on this topic but many of the battery related threads seem to get very "involved", very quickly, so I thought I'd ask again, in the hope of getting "simpler", possibly even just yay-or-nay type advice..?

 

I've very recently bought a Toyota Granvia pop roof campervan (Wellhouse Leisure conversion) and as expected (by me anyway) the "cab" battery does not receive charge when it's hooked up (m'meter shows that they do both charge when engine running).

 

Whilst this is by no means the end of the world, as the batteries sit next to each other under the bonnet, it would be nice if there was a simple low tech get-around, that could be wired/installed there? (as oppsssed to stripping apart the van interior inorder to feed wires through!).

 

The "habitation" battery will probably will get very little use anyway, just a couple of led lights used sparingly? (and we wouldn't use the onboard water pump), so I was wondering if the batteries could just be wired in parallel? (this is how my other toyota van came as standard but that did not have a habitation conversion/split charger tagged into things!? and it would've had a factory fitted alternator up to the job from the off).

 

I haven't yet delved into what charger the Granvia already has, nor how it has been wired, nor the size of the wires used, the age of batteries etc etc etc..

Any thoughts?

 

(I can already hear shouts of "..fit a solar panel mate.." :-D and that might be what we eventually do further down the line?

shouts of "..leave well alone.." are just as valid! (lol) )

[arthur49]

Try a Van Bitz Battery Master. From your description should be dead easy to install if batteries are close - only 3 wires to connect, no fuses needed. Simple ...

 

https://www.vanbitz.com/the-van-bitz-battery-master/

[pepe63xnotuse]

Thanks for that Arthur'..

That was what the type of "gadget" that I was considering..

(..but in the past, I thought such gizmos had got a bit of a "bad press" from some of the forum battery-scientists? :-D )

 

But it sounds good enough for what I need - a simple- fit'n'forget solution. :-D

 

Thanks again.

[arthur49]

I forgot. I've never tried it but there is an even cheaper solution devised by Clive Mott, a bridging fuse

 

http://www.motts.org/BRIDGING%20FUSE.htm

[pepe63xnotuse]

Yes, I do recall that bridging fuse idea from some years back..but as the van will be used most days, the fit and forget Battery Master type of thing is probably the way I'll go..

(being my "daily driver", a lot of it's normal "day to day" use will just be 5-10 mile hops, so it will probably be taking more out of the battery than the runs are putting back in!).

But before I start bolting on "fixes", I think I'll just get my pet-mechanic to give the vehicle battery a proper test, to see what state it's actually in first..

 

[Mickt]

I,very had a battery mate for years and it seems t do the job ok.Simple to wire up.

[mikefitz]

There are a number of approaches that you could consider. Assuming lead acid batteries for the starter and leisure batteries, consider:

 

a) a battery maintainer, the CBE CSB2 and the similar Votronic battery master are the lowest cost and will provide a maintaining charge of a few amps.

 

Disadvantage is that it will not be able to fully charge the starter, only make up for self discharge and low currents taken by the van circuits. Should the starter battery become discharged it will pull down the leisure battery also, you may end up with two flat batteries.

 

https://www.southdownsmotorcaravans.com/205025-cbe-battery-power-distribution-unit-csb2.html

 

https://www.roadpro.co.uk/product/02e02-battery-maintainers/votronic-battery-master-c8451/C8451

 

b) a bidirectional split charge or battery combiner relay, the Victron Cyrix is ideal. This will combine the batteries, (connect in parallel), when either the engine battery or leisure battery is under charge and charge both batteries. The batteries are isolated from each other when no charging is active. This gives the advantage of full charge to both batteries and no danger of both failing. As an option, with suitable wiring and an additional control switch, the Cyrix can use the leisure battery as 'jump start' power in an emergency

 

https://www.12voltplanet.co.uk/victron-cyrix-ct-voltage-sensitive-relay-battery-combiner-1224v-120a.html

 

Mike

[spirou]

Victron cyrix ct. Or, if one of the batteries is gel/agm/efb or anything else with a resting voltage above 12.8V, the cyrix li-ct model.

https://www.victronenergy.com/battery-isolators-and-combiners/cyrix-battery-combiners

[pepe63xnotuse]

Mornin'...

Thank you all for the further advice..

 

Does that Victron Cyrix CT require inline fuses or is fusing "inbuilt" as with the Battery Master?

One of the reasons I ask, is looking at some videos of the B' Master online, I'm not entirely sure if the wires will be long enough to neatly route them as I'd like? ( I can't find their length mentioned?), so if I'm going be needing to extend them, I may as well just be using something that doesn't come "pre-wired"?

 

Being realistic either of them will probabaly do what I want/"need" though.. :-D

[Derek Uzzell]

There are Cyrix installation instructions on the Victron Energy links provided in the last two postings and those instructions include wiring diagrams (example here)

 

https://www.12voltplanet.co.uk/user/downloads/Manual-Cyrix-ct-120-EN-NL-FR-ES.pdf

 

The Votronic StandbyCharger is probably as simple as any to fit (details on this advert and image attached below)

 

https://www.12voltplanet.co.uk/votronic-12v-standby-charger-trickle-charger.html

 

and ought to be adequate for what you want. (You could fit a fuse in each of the two connecting cables, though the instructions do not mention this.)

 

[pepe63xnotuse]

Good morning all, and thank you all for your input

 

Been away for a few days(not in van) and on arriving home found a Cyrix-ct waiting for me in the porch.

 

So I'm looking to start gathering together the various bits'n'pieces required to fit the thing (when I actually get some time).

I would just like to pick peoples' brains still further as to their recommendations(cable size, fuse holder type/fuse size etc)

 

The only reference I have found to an actual cable "dimension" is of "10mm2" and that is in a "kit" (but that kit does not even include fuse holders, so I'm not sure how correct that cable size is?).

https://www.ebay.co.uk/itm/282178038097?hash=item41b31f2951:g:cV8AAOSwA3NZewh5

 

To those in the know, does that cable size sound okay? (the longest run would only be 24"-30" max)

 

Also fuse type/size- (forgetting the "start assist" feature for now) The fact sheet diagram only shows one fuse and that is to the "Domestic" battery.I was intending to put one in both battery positive lines. Do I need to?

I am pressuming that I should be using the "mountable" midi/strip type of fuse holders? but what fuse rating? (I suppose that would depend on what cable size has been "recommended"?)

 

Our "cab" battery is 95amp, whereas the added-on "leisure" battery sat next to it is a tiddler, 65amp (but other that a few led lights it will have nothing "to do")

 

Any assistance would be greatly appreciated. :-D

[Derek Uzzell]

The installation instructions on the Votrinic StandbyCharger link I provided above say

 

Connection:

- The device is simply connected to the Plus (+) battery terminals of the Board and vehicle Start battery.

- The connecting cables should have a cross-section of 1.5 mm 2 to 2.5 mm 2 and be protected against overload by short cIrcuit (cable firing), Fuse 10A.

- The negative (-) battery terminals of the batteries must be connected to each other, i.e. "vehicle mass / ground".

- The StandBy charger is ready for operation.

 

As the 'trickle charge' to the starter-battery will be 3A maximum, the cable dimensions would not need to be huge.

[pepe63xnotuse]

Hi Derek and thank you for your reply.

Are those sorts of figures still applicable to the Cyrix-ct though?

 

The spec sheet for that mentions figures like- "Continuous current- 120amp" and "Cranking rating- 180amp"

 

Until looking a bit more into it this morning, I had(wrongly?) assumed that I'd just be wiring it in with, as you say 2.5mm type cable/fittings etc (along the scale of the Vanbitz Battery Master cables I've seen in online installation videos )but looking now (eg 10mm2 in that kit), it seems I may need to be going "heavier"..?

 

:-S

[Derek Uzzell]

I'm sure mikefitz and/or spirou can advise on that device if that's what you want to use.

[pepe63xnotuse]

Yes, I'll wait a while to see if either of them pick this up.. but if they don't I may be cheeky and send them a PM pester..

I have contacted the vendor, and they pointed be to a cable sizing website..

https://www.solar-wind.co.uk/info/dc-cable-wire-sizing-tool-low-voltage-drop-calculator

 

But I'm not sure what "amps" figure I need to be entering into the above form...?

Should it be the amps that the alternator can produce or the 13amp that the hook-up will put in?

(The Cyrix-ct sheet states "120 amp continuous current" ..but it can't be that figure surely?. if I enter 120amp into that form, it comes back as me requiring a cable 25mm(not 2.5mm- twenty five)sq!?! (lol)

(it would've been easier if I'd have just opted for the pre-wired Vanbitz battery master and just extended those! it would've been on and forgotten about by now).

[Brian Kirby]

In the meantime, I think the 25mm cable size would only be required if intending to use the emergency starting feature of the Cyrix relay, as the current draw on the battery for cranking the engine when starting is extremely high. If you eliminate that function, then the lighter gauge cables should be fine, and should be fused as close to the batteries as possible. Then, were you to forget and try to use the emergency start function, the only consequence would be blown fuses. In the absence of those fuses you'd definitely burn out the connecting cables, and possibly start a fire into the bargain! Remember, the fuse is there to protect the wiring from overload.

 

If contemplating using the emergency start function you'd need to use pukka starter cable between both batteries and the starter motor, or an intermediate connection point ( the Cyrix?). I think you'd also probably have to replace that hab battery with one of higher capacity (ideally equal to that of the existing starter battery), and make sure it was also a dual purpose starter/habitation battery - as I imagine a 65Ah habitation battery would not take kindly to being asked to deliver the cranking load from the starter motor. You'll need also to check whether that might exceed the charging capability of both the alternator or your on-board charger.

[spirou]

There was a cyrix in our previous van wired with 4mm2 cable (I think, might be 6, it's fuzzy memory). It worked but wasn't enough as the voltage drop was quite noticeable. Also, front to back of van distance didn't help.

 

Basically go as big as you can. 10 or 16mm2 would be my choice, 25 could be hard to pull through any significant distance and tight spaces. Also becomes increasingly hard to find crimping tools for thick wires.

 

In any case, with 60&90Ah batteries you're sizing wires for about 30A max in practice. Neither will accept much more than that.

[pepe63xnotuse]

I did (cheekily) make a couple more enquiries with other sellers of the Cyrix-ct unit..and they (rightly or wrongly) came back with talk of 70-100amp fuses, 16mm(min!) battery cable, HD midi fuses etc etc..

Although a "do-able" task, it is clear that I had underestimated the "scale" of the components necessary to install the thing (it's only a 2" cube!) and that it was all probably "overkill" for what I needed (wanted) it to do?

(as already mentioned,installation wise, I was envisaging something along the scale of the vanbitz unit :-S )

 

So, I decided to just return the item this afternoon, and I'll just look to get a simpler, unit that is easier to install (along the lines of the Vanbitz or Votronic units mentioned up thread)..

 

Thanks all for the input. :-D

(sorry spirou, i crossed your post! :$ )